WorldWideScience

Sample records for hydrodynamic model atmospheres

  1. Exobase properties of hydrodynamic and kinetic models of thermal escape from planetary atmospheres and notion of slow hydrodynamic escape

    Science.gov (United States)

    Volkov, Alexey N.

    2017-12-01

    Exobase parameters obtained based on one-dimensional spherically symmetric hydrodynamic Parker's and kinetic models of thermal escape are studied parametrically for monatomic and diatomic gases. For source parameters, when Parker's and kinetic models predict similar escape rates and atmospheric structures well below the exobase, the exobase parameters obtained based on the both models are different. Parker's model systematically underestimates the exobase distance and overestimates the exobase Jeans parameter. The assumption that the escape rate is equal to the Jeans escape rate at the exobase is not satisfied in both kinetic and hydrodynamic simulations. The ratio of the escape rate to the Jeans rate at the exobase predicted by the hydrodynamics model can be either a few times higher or orders of magnitude smaller than unity. The kinetic model predicts systematic enhancement of the escape rate compared to the Jeans rate at the exobase. This enhancement can be attributed to the bulk velocity only if the exobase Jeans parameter is smaller than 5. This is the domain of slow hydrodynamic escape. At larger exobase Jeans parameters, the enhancement of the escape rate is attributed to non-equilibrium distribution of molecular velocities. In the kinetic solutions obtained for the Maxwell gas, the escape rate is about 2-2.5 of the Jeans rate when the ratio of the mean free path of gas molecules to the atmospheric scale height is ˜0.2. This finding can be used to set up boundary conditions in the hydrodynamic model in order to bring it into agreement with the kinetic model.

  2. PROBING NEAR-SURFACE ATMOSPHERIC TURBULENCE WITH LIDAR MEASUREMENTS AND HIGH-RESOLUTION HYDRODYNAMIC MODELS

    Energy Technology Data Exchange (ETDEWEB)

    J. KAO; D. COOPER; ET AL

    2000-11-01

    As lidar technology is able to provide fast data collection at a resolution of meters in an atmospheric volume, it is imperative to promote a modeling counterpart of the lidar capability. This paper describes an integrated capability based on data from a scanning water vapor lidar and a high-resolution hydrodynamic model (HIGRAD) equipped with a visualization routine (VIEWER) that simulates the lidar scanning. The purpose is to better understand the spatial and temporal representativeness of the lidar measurements and, in turn, to extend their utility in studying turbulence fields in the atmospheric boundary layer. Raman lidar water vapor data collected over the Pacific warm pool and the simulations with the HIGRAD code are used for identifying the underlying physics and potential aliasing effects of spatially resolved lidar measurements. This capability also helps improve the trade-off between spatial-temporal resolution and coverage of the lidar measurements.

  3. Hydrodynamics of oceans and atmospheres

    CERN Document Server

    Eckart, Carl

    1960-01-01

    Hydrodynamics of Oceans and Atmospheres is a systematic account of the hydrodynamics of oceans and atmospheres. Topics covered range from the thermodynamic functions of an ideal gas and the thermodynamic coefficients for water to steady motions, the isothermal atmosphere, the thermocline, and the thermosphere. Perturbation equations, field equations, residual equations, and a general theory of rays are also presented. This book is comprised of 17 chapters and begins with an introduction to the basic equations and their solutions, with the aim of illustrating the laws of dynamics. The nonlinear

  4. Oxygen spectral line synthesis: 3D non-LTE with CO5BOLD hydrodynamical model atmospheres.

    Science.gov (United States)

    Prakapavičius, D.; Steffen, M.; Kučinskas, A.; Ludwig, H.-G.; Freytag, B.; Caffau, E.; Cayrel, R.

    In this work we present first results of our current project aimed at combining the 3D hydrodynamical stellar atmosphere approach with non-LTE (NLTE) spectral line synthesis for a number of key chemical species. We carried out a full 3D-NLTE spectrum synthesis of the oxygen IR 777 nm triplet, using a modified and improved version of our NLTE3D package to calculate departure coefficients for the atomic levels of oxygen in a CO5BOLD 3D hydrodynamical solar model atmosphere. Spectral line synthesis was subsequently performed with the Linfor3D code. In agreement with previous studies, we find that the lines of the oxygen triplet produce deeper cores under NLTE conditions, due to the diminished line source function in the line forming region. This means that the solar oxygen IR 777 nm lines should be stronger in NLTE, leading to negative 3D NLTE-LTE abundance corrections. Qualitatively this result would support previous claims for a relatively low solar oxygen abundance. Finally, we outline several further steps that need to be taken in order to improve the physical realism and numerical accuracy of our current 3D-NLTE calculations.

  5. Global 3D radiation-hydrodynamics models of AGB stars. Effects of convection and radial pulsations on atmospheric structures

    Science.gov (United States)

    Freytag, B.; Liljegren, S.; Höfner, S.

    2017-04-01

    Context. Observations of asymptotic giant branch (AGB) stars with increasing spatial resolution reveal new layers of complexity of atmospheric processes on a variety of scales. Aims: To analyze the physical mechanisms that cause asymmetries and surface structures in observed images, we use detailed 3D dynamical simulations of AGB stars; these simulations self-consistently describe convection and pulsations. Methods: We used the CO5BOLD radiation-hydrodynamics code to produce an exploratory grid of global "star-in-a-box" models of the outer convective envelope and the inner atmosphere of AGB stars to study convection, pulsations, and shock waves and their dependence on stellar and numerical parameters. Results: The model dynamics are governed by the interaction of long-lasting giant convection cells, short-lived surface granules, and strong, radial, fundamental-mode pulsations. Radial pulsations and shorter wavelength, traveling, acoustic waves induce shocks on various scales in the atmosphere. Convection, waves, and shocks all contribute to the dynamical pressure and, thus, to an increase of the stellar radius and to a levitation of material into layers where dust can form. Consequently, the resulting relation of pulsation period and stellar radius is shifted toward larger radii compared to that of non-linear 1D models. The dependence of pulsation period on luminosity agrees well with observed relations. The interaction of the pulsation mode with the non-stationary convective flow causes occasional amplitude changes and phase shifts. The regularity of the pulsations decreases with decreasing gravity as the relative size of convection cells increases. The model stars do not have a well-defined surface. Instead, the light is emitted from a very extended inhomogeneous atmosphere with a complex dynamic pattern of high-contrast features. Conclusions: Our models self-consistently describe convection, convectively generated acoustic noise, fundamental-mode radial

  6. Three-dimensional hydrodynamical CO5BOLD model atmospheres of red giant stars. VI. First chromosphere model of a late-type giant

    Science.gov (United States)

    Wedemeyer, Sven; Kučinskas, Arūnas; Klevas, Jonas; Ludwig, Hans-Günter

    2017-10-01

    Aims: Although observational data unequivocally point to the presence of chromospheres in red giant stars, no attempts have been made so far to model them using 3D hydrodynamical model atmospheres. We therefore compute an exploratory 3D hydrodynamical model atmosphere for a cool red giant in order to study the dynamical and thermodynamic properties of its chromosphere, as well as the influence of the chromosphere on its observable properties. Methods: Three-dimensional radiation hydrodynamics simulations are carried out with the CO5BOLD model atmosphere code for a star with the atmospheric parameters (Teff ≈ 4010 K, log g = 1.5, [ M / H ] = 0.0), which are similar to those of the K-type giant star Aldebaran (α Tau). The computational domain extends from the upper convection zone into the chromosphere (7.4 ≥ log τRoss ≥ - 12.8) and covers several granules in each horizontal direction. Using this model atmosphere, we compute the emergent continuum intensity maps at different wavelengths, spectral line profiles of Ca II K, the Ca II infrared triplet line at 854.2 nm, and Hα, as well as the spectral energy distribution (SED) of the emergent radiative flux. Results: The initial model quickly develops a dynamical chromosphere that is characterised by propagating and interacting shock waves. The peak temperatures in the chromospheric shock fronts reach values of up to 5000 K, although the shock fronts remain quite narrow. Similar to the Sun, the gas temperature distribution in the upper layers of red giant stars is composed of a cool component due to adiabatic cooling in the expanding post-shock regions and a hot component due to shock waves. For this red giant model, the hot component is a rather flat high-temperature tail, which nevertheless affects the resulting average temperatures significantly. Conclusions: The simulations show that the atmospheres of red giant stars are dynamic and intermittent. Consequently, many observable properties cannot be reproduced

  7. Superluminous Supernovae hydrodynamic models

    Science.gov (United States)

    Orellana, M.

    2017-07-01

    We use our radiation hydrodynamic code in order to simulate magnetar powered Superluminous Supernovae (SLSNe). It is assumed that a central rapidly rotating magnetar deposits all its rotational energy into the ejecta where is added to the usual power. The magnetar luminosity and spin-down timescale are adopted as the free parameters of the model. For the case of ASASSN-15lh, which has been claimed as the most luminous supernova ever discovered, we have found physically plausible magnetar parameters can reproduce the overall shape of the bolometric light curve (LC) provided the progenitor mass is ≍ 8M⊙. The ejecta dynamics of this event shows signs of the magnetar energy input which deviates the expansion from the usually assumed homologous behaviour. Our numerical experiments lead us to conclude that the hydrodynamical modeling is necessary in order to derive the properties of powerful magnetars driving SLSNe.

  8. Spatial heterogeneity in geothermally-influenced lakes derived from atmospherically corrected Landsat thermal imagery and three-dimensional hydrodynamic modelling

    DEFF Research Database (Denmark)

    Allan, Mathew G; Hamilton, David P.; Trolle, Dennis

    2016-01-01

    Atmospheric correction of Landsat 7 thermal data was carried out for the purpose of retrieval of lake skin water temperature in Rotorua lakes, and Lake Taupo, North Island, New Zealand. The effect of the atmosphere was modelled using four sources of atmospheric profile data as input to the MODera...

  9. Nanosecond surface dielectric barrier discharge in atmospheric pressure air: I. measurements and 2D modeling of morphology, propagation and hydrodynamic perturbations

    Science.gov (United States)

    Zhu, Yifei; Shcherbanev, Sergey; Baron, Brian; Starikovskaia, Svetlana

    2017-12-01

    A parallel 2D code for modeling nanosecond surface dielectric barrier discharge (nSDBD), combining a discharge description, detailed kinetics and hydrodynamics, is developed and validated. A series of experiments and numerical modeling for a single pulse nSDBD in atmospheric pressure air at a voltage amplitude of 24 kV have been performed. The measured and calculated velocity of the discharge front, electrical current, 2D map of N2 ({{{C}}}3{{{\\Pi }}}u)\\to {{{N}}}2({{{B}}}3{{{\\Pi }}}g) emission and hydrodynamic perturbations caused by the discharge on the time scale 0.2{--}5 μs are compared. The data are presented and analyzed for the negative and positive polarity of the streamers. A set of parametric calculations with different dielectric permittivities and different dielectric thicknesses is presented.

  10. Lotic Water Hydrodynamic Model

    Energy Technology Data Exchange (ETDEWEB)

    Judi, David Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tasseff, Byron Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-01-23

    Water-related natural disasters, for example, floods and droughts, are among the most frequent and costly natural hazards, both socially and economically. Many of these floods are a result of excess rainfall collecting in streams and rivers, and subsequently overtopping banks and flowing overland into urban environments. Floods can cause physical damage to critical infrastructure and present health risks through the spread of waterborne diseases. Los Alamos National Laboratory (LANL) has developed Lotic, a state-of-the-art surface water hydrodynamic model, to simulate propagation of flood waves originating from a variety of events. Lotic is a two-dimensional (2D) flood model that has been used primarily for simulations in which overland water flows are characterized by movement in two dimensions, such as flood waves expected from rainfall-runoff events, storm surge, and tsunamis. In 2013, LANL developers enhanced Lotic through several development efforts. These developments included enhancements to the 2D simulation engine, including numerical formulation, computational efficiency developments, and visualization. Stakeholders can use simulation results to estimate infrastructure damage and cascading consequences within other sets of infrastructure, as well as to inform the development of flood mitigation strategies.

  11. CALIBRATED HYDRODYNAMIC MODEL

    Directory of Open Access Journals (Sweden)

    Sezar Gülbaz

    2015-01-01

    Full Text Available The land development and increase in urbanization in a watershed affect water quantityand water quality. On one hand, urbanization provokes the adjustment of geomorphicstructure of the streams, ultimately raises peak flow rate which causes flood; on theother hand, it diminishes water quality which results in an increase in Total SuspendedSolid (TSS. Consequently, sediment accumulation in downstream of urban areas isobserved which is not preferred for longer life of dams. In order to overcome thesediment accumulation problem in dams, the amount of TSS in streams and inwatersheds should be taken under control. Low Impact Development (LID is a BestManagement Practice (BMP which may be used for this purpose. It is a land planningand engineering design method which is applied in managing storm water runoff inorder to reduce flooding as well as simultaneously improve water quality. LID includestechniques to predict suspended solid loads in surface runoff generated over imperviousurban surfaces. In this study, the impact of LID-BMPs on surface runoff and TSS isinvestigated by employing a calibrated hydrodynamic model for Sazlidere Watershedwhich is located in Istanbul, Turkey. For this purpose, a calibrated hydrodynamicmodel was developed by using Environmental Protection Agency Storm WaterManagement Model (EPA SWMM. For model calibration and validation, we set up arain gauge and a flow meter into the field and obtain rainfall and flow rate data. Andthen, we select several LID types such as retention basins, vegetative swales andpermeable pavement and we obtain their influence on peak flow rate and pollutantbuildup and washoff for TSS. Consequently, we observe the possible effects ofLID on surface runoff and TSS in Sazlidere Watershed.

  12. Quantifying Atmospheric Mass Loss using Novel Hydrodynamic Simulations

    Science.gov (United States)

    Rubanenko, Lior; Steinberg, Elad; Schlichting, Hilke; Paige, David A.

    2017-10-01

    After their formation, planets may accrete or lose atmospheric mass following impacts by planetesimals. Quantifying the relation between the impactor energy and the mass it erodes from a planet's atmosphere is crucial to our understanding of the final stages in planetary formation. Particulatly, it could help explain the significant differences between the atmospheres of the three larger terrestrial planets in the solar system.Here we adopt a new hydrodynamic model called RICH, originally developed to solve problems in astrophysics. RICH's implementation include a Voroni tessellation and a moving (semi-Lagrangian) mesh, which allows high resolution, efficient modeling of shockwave propagation in thin atmospheres. Using this model we evaluate the role of smaller planetesimals in eroding Earth's atmosphere compared to larger, Mars-size objects. Additionally, we verify the results obtained by a past 1D analytic model which showed the current differences in Earth's and Venus's atmospheres can potentially be explained by small differences in their initial atmospheric mass and impact history.

  13. A vegetation-focused soil-plant-atmospheric continuum model to study hydrodynamic soil-plant water relations

    Science.gov (United States)

    Deng, Zijuan; Guan, Huade; Hutson, John; Forster, Michael A.; Wang, Yunquan; Simmons, Craig T.

    2017-06-01

    A novel simple soil-plant-atmospheric continuum model that emphasizes the vegetation's role in controlling water transfer (v-SPAC) has been developed in this study. The v-SPAC model aims to incorporate both plant and soil hydrological measurements into plant water transfer modeling. The model is different from previous SPAC models in which v-SPAC uses (1) a dynamic plant resistance system in the form of a vulnerability curve that can be easily obtained from sap flow and stem xylem water potential time series and (2) a plant capacitance parameter to buffer the effects of transpiration on root water uptake. The unique representation of root resistance and capacitance allows the model to embrace SPAC hydraulic pathway from bulk soil, to soil-root interface, to root xylem, and finally to stem xylem where the xylem water potential is measured. The v-SPAC model was tested on a native tree species in Australia, Eucalyptus crenulata saplings, with controlled drought treatment. To further validate the robustness of the v-SPAC model, it was compared against a soil-focused SPAC model, LEACHM. The v-SPAC model simulation results closely matched the observed sap flow and stem water potential time series, as well as the soil moisture variation of the experiment. The v-SPAC model was found to be more accurate in predicting measured data than the LEACHM model, underscoring the importance of incorporating root resistance into SPAC models and the benefit of integrating plant measurements to constrain SPAC modeling.

  14. Hydrodynamic model in isospin channels

    Energy Technology Data Exchange (ETDEWEB)

    Lipparini, E.; Stringari, S.

    1987-08-31

    The Steinwedel-Jensen hydrodynamic model is generalized to study isovector collective modes excited in charge-exchange reactions. Results are given for the energy splittings between the different isospin components of the giant dipole and monopole resonances recently observed in (p,n) and (..pi../sup +- /,..pi../sup 0/) reactions. The quenching of the ..delta..T/sub z/ = +1 excitation strength in Nnot =Z nuclei with respect to the N = Z case is also discussed.

  15. Hydrodynamic Modeling and Its Application in AUC.

    Science.gov (United States)

    Rocco, Mattia; Byron, Olwyn

    2015-01-01

    The hydrodynamic parameters measured in an AUC experiment, s(20,w) and D(t)(20,w)(0), can be used to gain information on the solution structure of (bio)macromolecules and their assemblies. This entails comparing the measured parameters with those that can be computed from usually "dry" structures by "hydrodynamic modeling." In this chapter, we will first briefly put hydrodynamic modeling in perspective and present the basic physics behind it as implemented in the most commonly used methods. The important "hydration" issue is also touched upon, and the distinction between rigid bodies versus those for which flexibility must be considered in the modeling process is then made. The available hydrodynamic modeling/computation programs, HYDROPRO, BEST, SoMo, AtoB, and Zeno, the latter four all implemented within the US-SOMO suite, are described and their performance evaluated. Finally, some literature examples are presented to illustrate the potential applications of hydrodynamics in the expanding field of multiresolution modeling. © 2015 Elsevier Inc. All rights reserved.

  16. Magneto-hydrodynamical model for plasma

    Science.gov (United States)

    Liu, Ruikuan; Yang, Jiayan

    2017-10-01

    Based on the Newton's second law and the Maxwell equations for the electromagnetic field, we establish a new 3-D incompressible magneto-hydrodynamics model for the motion of plasma under the standard Coulomb gauge. By using the Galerkin method, we prove the existence of a global weak solution for this new 3-D model.

  17. On a model in radiation hydrodynamics

    OpenAIRE

    Ducomet, Bernard; Feireisl, Eduard; Nečasová, Šárka

    2011-01-01

    We consider a simplified model arising in radiation hydrodynamics based on the Navier–Stokes–Fourier system describing the macroscopic fluid motion, and a transport equation modeling the propagation of radiative intensity. We establish global-in-time existence for the associated initial–boundary value problem in the framework of weak solutions.

  18. Modeling multiphase flow using fluctuating hydrodynamics.

    Science.gov (United States)

    Chaudhri, Anuj; Bell, John B; Garcia, Alejandro L; Donev, Aleksandar

    2014-09-01

    Fluctuating hydrodynamics provides a model for fluids at mesoscopic scales where thermal fluctuations can have a significant impact on the behavior of the system. Here we investigate a model for fluctuating hydrodynamics of a single-component, multiphase flow in the neighborhood of the critical point. The system is modeled using a compressible flow formulation with a van der Waals equation of state, incorporating a Korteweg stress term to treat interfacial tension. We present a numerical algorithm for modeling this system based on an extension of algorithms developed for fluctuating hydrodynamics for ideal fluids. The scheme is validated by comparison of measured structure factors and capillary wave spectra with equilibrium theory. We also present several nonequilibrium examples to illustrate the capability of the algorithm to model multiphase fluid phenomena in a neighborhood of the critical point. These examples include a study of the impact of fluctuations on the spinodal decomposition following a rapid quench, as well as the piston effect in a cavity with supercooled walls. The conclusion in both cases is that thermal fluctuations affect the size and growth of the domains in off-critical quenches.

  19. An analytical model of flagellate hydrodynamics

    DEFF Research Database (Denmark)

    Dölger, Julia; Bohr, Tomas; Andersen, Anders Peter

    2017-01-01

    Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical......–right symmetric flagellar arrangements we determine the swimming velocity, and we show that transversal forces due to the periodic movements of the flagella can promote swimming. For a model flagellate with both a longitudinal and a transversal flagellum we determine radius and pitch of the helical swimming...

  20. A Hydro-Dynamical Model for Gravity

    Directory of Open Access Journals (Sweden)

    Corneliu BERBENTE

    2016-03-01

    Full Text Available hydro-dynamical model for gravity by using an analogy with the attraction of spherical sources in incompressible fluids is proposed. Information regarding a photon-like particle called graviton is taken using an author’s previous paper [6]. The substance and radiation interaction due to emission of gravitons takes place via an energy field made of the emitted gravitons and filling the entire universe. The energy distribution is considered uniform at the universe scale. A consequence of the proposed model is the increasing of the universal “constant” of gravity, as a function of the age of universe.

  1. Atmospheric Athena: 3D Atmospheric escape model with ionizing radiative transfer

    Science.gov (United States)

    Tripathi, Anjali; Krumholz, Mark R.

    2017-03-01

    Atmospheric Athena simulates hydrodynamic escape from close-in giant planets in 3D. It uses the Athena hydrodynamics code (ascl:1010.014) with a new ionizing radiative transfer implementation to self-consistently model photoionization driven winds from the planet. The code is fully compatible with static mesh refinement and MPI parallelization and can handle arbitrary planet potentials and stellar initial conditions.

  2. Hydrodynamic models for slurry bubble column reactors

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D. [IIT Center, Chicago, IL (United States)

    1995-12-31

    The objective of this investigation is to convert a {open_quotes}learning gas-solid-liquid{close_quotes} fluidization model into a predictive design model. This model is capable of predicting local gas, liquid and solids hold-ups and the basic flow regimes: the uniform bubbling, the industrially practical churn-turbulent (bubble coalescence) and the slugging regimes. Current reactor models incorrectly assume that the gas and the particle hold-ups (volume fractions) are uniform in the reactor. They must be given in terms of empirical correlations determined under conditions that radically differ from reactor operation. In the proposed hydrodynamic approach these hold-ups are computed from separate phase momentum balances. Furthermore, the kinetic theory approach computes the high slurry viscosities from collisions of the catalyst particles. Thus particle rheology is not an input into the model.

  3. Evaluation of parameters in hydrodynamic model

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Tae-Hoon [Hanyang University, Seoul (Korea); Lee, Jong-Wook [Korea Institute of Construction Technology, Koyang (Korea); Jegal, Sun-Dong [Kumho Engineering Company, Anyang (Korea)

    2000-02-29

    Generally speaking, a hydrodynamic model needs a friction coefficient (Manning coefficient or Chezy coefficient) and eddy viscosity. For numerical solution the coefficients are usually determined by recursive calculations. The eddy viscosity in numerical model plays physical diffusion in flow and also acts as numerical viscosity. Hence its value has influence on the stability of numerical solution and for these reasons a consistent evaluation procedure is needed. By using records of stage and discharge in the downstream reach of the Han river, 1-D models (HEC-2 and NETWORK) and 2-D model (SMS), estimated values of Manning coefficient and an empirical equation for eddy viscosity are presented. The computed results are verified through the recorded flow elevation data. (author). 26 refs., 7 tabs., 14 figs.

  4. Theoretical UV absorption spectra of hydrodynamically escaping O{sub 2}/CO{sub 2}-rich exoplanetary atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Gronoff, G.; Mertens, C. J.; Norman, R. B. [NASA LaRC, Hampton, VA (United States); Maggiolo, R. [BIRA-IASB, Avenue Circulaire 3, 1180 Brussels (Belgium); Wedlund, C. Simon [Aalto University School of Electrical Engineering Department of Radio Science and Engineering, P.O. Box 13000, FI-00076 Aalto (Finland); Bell, J. [National Institute of Aerospace, Hampton, VA (United States); Bernard, D. [IPAG, Grenoble (France); Parkinson, C. J. [University of Michigan, MI (United States); Vidal-Madjar, A., E-mail: Guillaume.P.Gronoff@nasa.gov [Observatoire de Paris, Paris (France)

    2014-06-20

    Characterizing Earth- and Venus-like exoplanets' atmospheres to determine if they are habitable and how they are evolving (e.g., equilibrium or strong erosion) is a challenge. For that endeavor, a key element is the retrieval of the exospheric temperature, which is a marker of some of the processes occurring in the lower layers and controls a large part of the atmospheric escape. We describe a method to determine the exospheric temperature of an O{sub 2}- and/or CO{sub 2}-rich transiting exoplanet, and we simulate the respective spectra of such a planet in hydrostatic equilibrium and hydrodynamic escape. The observation of hydrodynamically escaping atmospheres in young planets may help constrain and improve our understanding of the evolution of the solar system's terrestrial planets' atmospheres. We use the dependency of the absorption spectra of the O{sub 2} and CO{sub 2} molecules on the temperature to estimate the temperature independently of the total absorption of the planet. Combining two observables (two parts of the UV spectra that have a different temperature dependency) with the model, we are able to determine the thermospheric density profile and temperature. If the slope of the density profile is inconsistent with the temperature, then we infer the hydrodynamic escape. We address the question of the possible biases in the application of the method to future observations, and we show that the flare activity should be cautiously monitored to avoid large biases.

  5. RECENT ADVANCES IN MACROMOLECULAR HYDRODYNAMIC MODELING

    Science.gov (United States)

    Aragon, Sergio R.

    2010-01-01

    The modern implementation of the boundary element method (S.R. Aragon, J. Comput. Chem. 25(2004)1191–12055) has ushered unprecedented accuracy and precision for the solution of the Stokes equations of hydrodynamics with stick boundary conditions. This article begins by reviewing computations with the program BEST of smooth surface objects such as ellipsoids, the dumbbell, and cylinders that demonstrate that the numerical solution of the integral equation formulation of hydrodynamics yields very high precision and accuracy. When BEST is used for macromolecular computations, the limiting factor becomes the definition of the molecular hydrodynamic surface and the implied effective solvation of the molecular surface. Studies on 49 different proteins, ranging in molecular weight from 9 to over 400 kDa, have shown that a model using a 1.1 A thick hydration layer describes all protein transport properties very well for the overwhelming majority of them. In addition, this data implies that the crystal structure is an excellent representation of the average solution structure for most of them. In order to investigate the origin of a handful of significant discrepancies in some multimeric proteins (over −20% observed in the intrinsic viscosity), the technique of Molecular Dynamics simulation (MD) has been incorporated into the research program. A preliminary study of dimeric α-chymotrypsin using approximate implicit water MD is presented. In addition I describe the successful validation of modern protein force fields, ff03 and ff99SB, for the accurate computation of solution structure in explicit water simulation by comparison of trajectory ensemble average computed transport properties with experimental measurements. This work includes small proteins such as lysozyme, ribonuclease and ubiquitin using trajectories around 10 ns duration. We have also studied a 150 kDa flexible monoclonal IgG antibody, trastuzumab, with multiple independent trajectories encompassing over

  6. A hydrodynamic model for cooperating solidary countries

    Science.gov (United States)

    De Luca, Roberto; Di Mauro, Marco; Falzarano, Angelo; Naddeo, Adele

    2017-07-01

    The goal of international trade theories is to explain the exchange of goods and services between different countries, aiming to benefit from it. Albeit the idea is very simple and known since ancient history, smart policy and business strategies need to be implemented by each subject, resulting in a complex as well as not obvious interplay. In order to understand such a complexity, different theories have been developed since the sixteenth century and today new ideas still continue to enter the game. Among them, the so called classical theories are country-based and range from Absolute and Comparative Advantage theories by A. Smith and D. Ricardo to Factor Proportions theory by E. Heckscher and B. Ohlin. In this work we build a simple hydrodynamic model, able to reproduce the main conclusions of Comparative Advantage theory in its simplest setup, i.e. a two-country world with country A and country B exchanging two goods within a genuine exchange-based economy and a trade flow ruled only by market forces. The model is further generalized by introducing money in order to discuss its role in shaping trade patterns. Advantages and drawbacks of the model are also discussed together with perspectives for its improvement.

  7. Progress and Challenges in Coupled Hydrodynamic-Ecological Estuarine Modeling

    Science.gov (United States)

    Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational po...

  8. Hydrodynamic and optical measurements in the atmosphere boundary layer

    Science.gov (United States)

    2007-01-01

    The Volpe National Transportation Systems Center (Volpe) supports the NASA Wake Vortex program in data collection, analysis and modeling of the airplane work vortex data to improve operations at a number of airports that experience capacity constrain...

  9. Atmospheric Transport Modeling Resources

    Energy Technology Data Exchange (ETDEWEB)

    Mazzola, Carl A. [Stone and Webster Engineering Corporation, Aiken, SC (United States); Addis, Robert P. [Westinghouse Savannah River Company, Aiken, SC (United States)

    1995-03-01

    The purpose of this publication is to provide DOE and other federal agency emergency managers with an in-depth compilation and description of atmospheric dispersion models available to DOE and other Federal sites.

  10. Hydrodynamic and Salinity Intrusion Model in Selangor River Estuary

    Science.gov (United States)

    Haron, N. F.; Tahir, W.

    2016-07-01

    A multi-dimensional hydrodynamic and transport model has been used to develop the hydrodynamic and salinity intrusion model for Selangor River Estuary. Delft3D-FLOW was applied to the study area using a curvilinear, boundary fitted grid. External boundary forces included ocean water level, salinity, and stream flow. The hydrodynamic and salinity transport used for the simulation was calibrated and confirmed using data on November 2005 and from May to June 2014. A 13-day period for November 2005 data and a 6-day period of May to June 2014 data were chosen as the calibration and confirmation period because of the availability of data from the field-monitoring program conducted. From the calibration results, it shows that the model was well suited to predict the hydrodynamic and salinity intrusion characteristics of the study area.

  11. UASB reactor hydrodynamics: residence time distribution and proposed modelling tools.

    Science.gov (United States)

    López, I; Borzacconi, L

    2010-05-01

    The hydrodynamic behaviour of UASB (Up Flow Anaerobic Sludge Blanket) reactors based on residence time distribution curves allows the implementation of global models, including the kinetic aspects of biological reactions. The most relevant hydrodynamic models proposed in the literature are discussed and compared with the extended tanks in series (ETIS) model. Although derived from the tanks in series model, the ETIS model's parameter is not an integer. The ETIS model can be easily solved in the Laplace domain and applied to a two-stage anaerobic digestion linear model. Experimental data from a 250 m3 UASB reactor treating malting wastewater are used to calibrate and validate the proposed model.

  12. Concurrent multiscale modelling of atomistic and hydrodynamic processes in liquids

    Science.gov (United States)

    Markesteijn, Anton; Karabasov, Sergey; Scukins, Arturs; Nerukh, Dmitry; Glotov, Vyacheslav; Goloviznin, Vasily

    2014-01-01

    Fluctuations of liquids at the scales where the hydrodynamic and atomistic descriptions overlap are considered. The importance of these fluctuations for atomistic motions is discussed and examples of their accurate modelling with a multi-space–time-scale fluctuating hydrodynamics scheme are provided. To resolve microscopic details of liquid systems, including biomolecular solutions, together with macroscopic fluctuations in space–time, a novel hybrid atomistic–fluctuating hydrodynamics approach is introduced. For a smooth transition between the atomistic and continuum representations, an analogy with two-phase hydrodynamics is used that leads to a strict preservation of macroscopic mass and momentum conservation laws. Examples of numerical implementation of the new hybrid approach for the multiscale simulation of liquid argon in equilibrium conditions are provided. PMID:24982246

  13. Modeling Spitsbergen fjords by hydrodynamic MIKE engine.

    Science.gov (United States)

    Kosecki, Szymon; Przyborska, Anna; Jakacki, Jaromir

    2013-04-01

    Two Svalbard's fjords - Hornsund (on the western side of the most southern part of Spitsbergen island) and Kongsfjorden (also on the western side of Spitsbergen island, but in the northern part) are quite different - the first one is "cold" and second one is "warm". It is obvious that both of them are under influence of West Spitsbergen Current (WSC), which curry out warm Atlantic water and cold East Spitsbergen Current detaches Hornsund. But there is also freshwater stored in Spitsbergen glaciers that have strong influence on local hydrology and physical fjord conditions. Both, local and shelf conditions have impact on state of the fjord and there is no answer which one is the most important in each fjord. Modeling could help to solve this problem - MIKE 3D model has been implemented for both fjords. Mesh-grid of the each fjord has been extended for covering shelf area. External forces like tides, velocities at the boundary and atmospheric forces together with sources of cold and dens fresh water in the fjords will give reliable representation of physical conditions in Hornsund and Kongsfjorden. Calculations of balances between cold fresh water and warm and salt will provide additional information that could help to answer the main question of the GAME (Growing of the Arctic Marine Ecosystem) project - what is the reaction of physically controlled Arctic marine ecosystem to temperature rise.

  14. Hydrodynamic modelling of tidal inlets in Hue, Vietnam

    NARCIS (Netherlands)

    Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.

    2003-01-01

    Application of an one-dimensional numerical model for hydrodynamic simulation of a complex lagooninlet system in Vietnam is presented. Model results help to get a better understanding on the behaviour of the system. Based on the numerical model results and analytic solutions, stability of tidal

  15. Automatization of hydrodynamic modelling in a Floreon+ system

    Science.gov (United States)

    Ronovsky, Ales; Kuchar, Stepan; Podhoranyi, Michal; Vojtek, David

    2017-07-01

    The paper describes fully automatized hydrodynamic modelling as a part of the Floreon+ system. The main purpose of hydrodynamic modelling in the disaster management is to provide an accurate overview of the hydrological situation in a given river catchment. Automatization of the process as a web service could provide us with immediate data based on extreme weather conditions, such as heavy rainfall, without the intervention of an expert. Such a service can be used by non scientific users such as fire-fighter operators or representatives of a military service organizing evacuation during floods or river dam breaks. The paper describes the whole process beginning with a definition of a schematization necessary for hydrodynamic model, gathering of necessary data and its processing for a simulation, the model itself and post processing of a result and visualization on a web service. The process is demonstrated on a real data collected during floods in our Moravian-Silesian region in 2010.

  16. Modeling of nanoscale liquid mixture transport by density functional hydrodynamics.

    Science.gov (United States)

    Dinariev, Oleg Yu; Evseev, Nikolay V

    2017-06-01

    Modeling of multiphase compositional hydrodynamics at nanoscale is performed by means of density functional hydrodynamics (DFH). DFH is the method based on density functional theory and continuum mechanics. This method has been developed by the authors over 20 years and used for modeling in various multiphase hydrodynamic applications. In this paper, DFH was further extended to encompass phenomena inherent in liquids at nanoscale. The new DFH extension is based on the introduction of external potentials for chemical components. These potentials are localized in the vicinity of solid surfaces and take account of the van der Waals forces. A set of numerical examples, including disjoining pressure, film precursors, anomalous rheology, liquid in contact with heterogeneous surface, capillary condensation, and forward and reverse osmosis, is presented to demonstrate modeling capabilities.

  17. Advancement of Global-scale River Hydrodynamics Modelling and Its Potential Applications to Earth System Models

    Science.gov (United States)

    Yamazaki, D.

    2015-12-01

    Global river routine models have been developed for representing freshwater discharge from land to ocean in Earth System Models. At the beginning, global river models had simulated river discharge along a prescribed river network map by using a linear-reservoir assumption. Recently, in parallel with advancement of remote sensing and computational powers, many advanced global river models have started to represent floodplain inundation assuming sub-grid floodplain topography. Some of them further pursue physically-appropriate representation of river and floodplain dynamics, and succeeded to utilize "hydrodynamic flow equations" to realistically simulate channel/floodplain and upstream/downstream interactions. State-of-the-art global river hydrodynamic models can well reproduce flood stage (e.g. inundated areas and water levels) in addition to river discharge. Flood stage simulation by global river models can be potentially coupled with land surface processes in Earth System Models. For example, evaporation from inundated water area is not negligible for land-atmosphere interactions in arid areas (such as the Niger River). Surface water level and ground water level are correlated each other in flat topography, and this interaction could dominate wetting and drying of many small lakes in flatland and could also affect biogeochemical processes in these lakes. These land/surface water interactions had not been implemented in Earth System Models but they have potential impact on the global climate and carbon cycle. In the AGU presentation, recent advancements of global river hydrodynamic modelling, including super-high resolution river topography datasets, will be introduces. The potential applications of river and surface water modules within Earth System Models will be also discussed.

  18. Hydrodynamic modelling for relativistic heavy-ion collisions at RHIC ...

    Indian Academy of Sciences (India)

    Nz. 1. Introduction. The quark gluon plasma (QGP) is formed in high-energy heavy-ion collisions at Relativis- .... To obtain final hadrons, pure hydrodynamic simulations assume free hadron resonances directly emitted ... models is realized by a Monte-Carlo event generator, which transforms the hydrody- namic output into ...

  19. Modelling of hydrodynamic circulation in Benoa Bay, Bali

    DEFF Research Database (Denmark)

    Ningsih, Nining Sari; Muchamad, Al Azhar

    2013-01-01

    A simulation of water level, velocity, salinity, and temperature in the Bay of Benoa has been carried out using a three-dimensional hydrodynamic Estuarine and Coastal Ocean Model incorporating a main characteristic of southward transport of the Indonesian throughflow at the offshore area of the bay...

  20. Physical hydrodynamic propulsion model study on creeping viscous ...

    Indian Academy of Sciences (India)

    Physical hydrodynamic propulsion model study on creeping viscous flow through a ciliated porous tube ... Dates. Manuscript received: 7 February 2016; Manuscript revised: 20 July 2016; Accepted: 5 October 2016; Early published: Unedited version published online: Final version published online: 16 February 2017 ...

  1. Smoothed particle hydrodynamics modelling of fluids and solids

    Directory of Open Access Journals (Sweden)

    Lobovský L.

    2007-11-01

    Full Text Available The study is concerned about the application of the smoothed particle hydrodynamics (SPH method within the computational fluid dynamics and elastodynamics. A brief description of the SPH model for an incompressible fluid and for an elastic solid is presented. The implemented model of incompressible fluid is tested for internal flows as well as for flows involving a free surface of the fluid. The implemented elastic solid model is examined during the simulation of the mechanical response of rubber rings.

  2. Simulation and visualization of coupled hydrodynamical, chemical and biological models

    Directory of Open Access Journals (Sweden)

    Dag Slagstad

    1997-04-01

    Full Text Available This paper briefly describes the principles of hydrodynamical and ecological modelling of marine systems and how model results are presented by use of MATLAB. Two application examples are shown. One refers to modelling and simulation of the carbon vertical transport in the Greenland Sea and the other is a study on the effect of wind pattern for the invasion success of zooplankton from the Norwegian Sea into the North Sea by use of particle tracking.

  3. Statistical-mechanical approach to study the hydrodynamic stability of the stably stratified atmospheric boundary layer

    Science.gov (United States)

    Nevo, G.; Vercauteren, N.; Kaiser, A.; Dubrulle, B.; Faranda, D.

    2017-08-01

    We study the hydrodynamic equilibrium properties of the stably stratified atmospheric boundary layer from measurements obtained in the Snow-Horizontal Array Turbulence Study campaign at the Plaine Morte Glacier in the Swiss Alps. Our approach is based on a combination of dynamical systems techniques and statistical analysis. The main idea is to measure the deviations from the behavior expected by a turbulent observable when it is close to a transition between different metastable states. We first assess the performance of our method on the Lorenz attractor, then on a turbulent flow. The results show that the method recognizes subtle differences among different stable boundary layer turbulence regimes and may be used to help characterize their transitions.

  4. Modeling of the upwelling hydrodynamics in the Aegean Sea

    Directory of Open Access Journals (Sweden)

    Y.G. SAVVIDIS

    2004-06-01

    Full Text Available The special features of the hydrodynamic circulation in the Aegean Sea referring to the development of regional upwelling coastal zones are studied by means of a mathematical model. The modeling effort is focused on the tracing of coastal areas, where upwelling events are frequently observed during the summer meteorological conditions. These areas are characterized by the enrichment of surface waters with nutrients and, consequently, increased fish production. The phenomenon is studied by the use of a two-layer mathematical model comprising the surface heated zone and the rest of the water column. The numerical solution of the model is based on the finite differences method. The wind shear applied over the stratified basin, with predefined density stratification and initial water-layers thickness, and the gravity and Coriolis forces taken into account, constitute the basic external factors for the generation of the hydrodynamic circulation in the area of the Aegean Sea. The calibration and the validation of the model are performed by the comparison of the model output to the data and observations reported in valid scientific sources. The aim of the paper is to demonstrate the significant contribution of numerical models to the better understanding of the hydrodynamics governing the Aegean water circulation as well as the tracing of upwelling zones.

  5. The potential of 3D radiation-hydrodynamics models for white dwarf asteroseismology

    Directory of Open Access Journals (Sweden)

    Tremblay P.-E.

    2013-03-01

    Full Text Available White dwarfs with hydrogen-rich atmospheres (DA are the most abundant of all degenerate objects. In recent years work has been dedicated to increase the accuracy of their model atmospheres. Most notably, convective motions are now treated with 3D radiation-hydrodynamics instead of the standard mixing-length theory. We present and describe selected 3D model atmospheres close and within the instability strip of the pulsating ZZ Ceti white dwarfs. Our 3D simulations depend only weakly on numerical parameters and compared to 1D models, they provide more realistic determinations of the depth of the convective zone. The 3D structures can then be adopted as input for asteroseismology.

  6. Hydrodynamic modeling of semi-planing hulls with air cavities

    Directory of Open Access Journals (Sweden)

    Konstantin I. Matveev

    2015-05-01

    Full Text Available High-speed heavy loaded monohull ships can benefit from application of drag-reducing air cavities under stepped hull bottoms. The subject of this paper is the steady hydrodynamic modeling of semi-planing air-cavity hulls. The current method is based on a linearized potential-flow theory for surface flows. The mathematical model description and parametric calculation results for a selected configuration with pressurized and open air cavities are presented.

  7. On nano-scale hydrodynamic lubrication models

    Science.gov (United States)

    Buscaglia, Gustavo; Ciuperca, Ionel S.; Jai, Mohammed

    2005-06-01

    Current magnetic head sliders and other micromechanisms involve gas lubrication flows with gap thicknesses in the nanometer range and stepped shapes fabricated by lithographic methods. In mechanical simulations, rarefaction effects are accounted for by models that propose Poiseuille flow factors which exhibit singularities as the pressure tends to zero or +∞. In this Note we show that these models are indeed mathematically well-posed, even in the case of discontinuous gap thickness functions. Our results cover popular models that were not previously analyzed in the literature, such as the Fukui-Kaneko model and the second-order model, among others. To cite this article: G. Buscaglia et al., C. R. Mecanique 333 (2005).

  8. Data Assimilation in Hydrodynamic Models of Continental Shelf Seas

    DEFF Research Database (Denmark)

    Sørensen, Jacob Viborg Tornfeldt

    2004-01-01

    of a stochastic state propagation step using a numerical hydrodynamic model and an update step based on a best linear unbiased estimator when new measurements are available. The main challenge is to construct a stochastic model of the high dimensional ocean state that provides su cient skill for a proper update....... Assimilation of sea surface temperature and parameter estimation in hydrodynamic models are also considered. The main focus has been on the development of robust and efficient techniques applicable in real operational settings. The applied assimilation techniques all use a Kalman filter approach. They consist...... and forecast skill in the Inner Danish Waters. The framework for combining data assimilation and off-line error correction techniques is discussed and presented. Early results show a potential for such an approach, but a more elaborate investigation is needed to further develop the idea. Finally, work has been...

  9. Hydrodynamic and kinetic modelling of complex radio-frequency plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Goedheer, W J; Venema, J [FOM Institute for Plasma Physics ' Rijnhuizen' , Association EURATOM-FOM, Trilateral Euregio Cluster, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Land, V, E-mail: W.J.Goedheer@rijnhuizen.n [Center for Astrophysics, Space Physics and Engineering Research, Baylor University, Waco, TX 76798 (United States)

    2009-10-07

    In this paper hydrodynamic and kinetic approaches to model low-pressure capacitively coupled complex radio-frequency discharges are discussed and applied to discharges under micro-gravity. Complex plasmas contain dust grains with a large negative charge and are characterized by a strong coupling between the properties of the plasma and those of the dust grains. After a discussion of the physics and methods involved, examples are presented from modelling of experiments under micro-gravity in the PKE-Nefedov reactor on board the International Space Station. These discharges are simulated with a 2D cylindrically symmetric hydrodynamic model. Kinetic effects are studied with a 1D particle-in-cell plus Monte Carlo model in which capture and scattering by dust grains is included. Since experiments are often performed at low pressures, the electron energy distribution function is no longer determined by the local plasma properties. This has consequences for the charging of the dust. Results of simulations with this model are compared with the hydrodynamic results. In addition, we address the behaviour of the dust charge in decaying plasmas.

  10. Modeling the hydrodynamics of Phloem sieve plates

    DEFF Research Database (Denmark)

    Jensen, Kaare Hartvig; Mullendore, Daniel Leroy; Holbrook, Noel Michele

    2012-01-01

    understood. We propose a theoretical model for quantifying the effect of sieve plates on the phloem in the plant, thus unifying and improving previous work in the field. Numerical simulations of the flow in real and idealized phloem channels verify our model, and anatomical data from 19 plant species...... are investigated. We find that the sieve plate resistance is correlated to the cell lumen resistance, and that the sieve plate and the lumen contribute almost equally to the total hydraulic resistance of the phloem translocation pathway....

  11. Hydrodynamic characterization of Corpus Christi Bay through modeling and observation.

    Science.gov (United States)

    Islam, Mohammad S; Bonner, James S; Edge, Billy L; Page, Cheryl A

    2014-11-01

    Christi Bay is a relatively flat, shallow, wind-driven system with an average depth of 3-4 m and a mean tidal range of 0.3 m. It is completely mixed most of the time, and as a result, depth-averaged models have, historically, been applied for hydrodynamic characterization supporting regulatory decisions on Texas coastal management. The bay is highly stratified during transitory periods of the summer with low wind conditions. This has important implications on sediment transport, nutrient cycling, and water quality-related issues, including hypoxia which is a key water quality concern for the bay. Detailed hydrodynamic characterization of the bay during the summer months included analysis of simulation results of 2-D hydrodynamic model and high-frequency (HF) in situ observations. The HF radar system resolved surface currents, whereas an acoustic Doppler current profiler (ADCP) measured current at different depths of the water column. The developed model successfully captured water surface elevation variation at the mouth of the bay (i.e., onshore boundary of the Gulf of Mexico) and at times within the bay. However, large discrepancies exist between model-computed depth-averaged water currents and observed surface currents. These discrepancies suggested the presence of a vertical gradient in the current structure which was further substantiated by the observed bi-directional current movement within the water column. In addition, observed vertical density gradients proved that the water column was stratified. Under this condition, the bottom layer became hypoxic due to inadequate mixing with the aerated surface water. Understanding the disparities between observations and model predictions provides critical insights about hydrodynamics and physical processes controlling water quality.

  12. Numerical modeling of hydrodynamic in southwestern Johor, Malaysia

    Science.gov (United States)

    Jusoh, Wan Hasliza Wan; Tangang, Fredolin; Juneng, Liew; Hamid, Mohd. Radzi Abdul

    2014-09-01

    Tanjung Piai located at the southwest of Johor, Malaysia faces severe erosion since a few decades ago. Considering the condition in this particular area, understanding of its hydrodynamic behaviour should be clearly explained. Thus, a numerical modelling has been applied in this study in order to investigate the hydrodynamic of current flow along the study area. Hydrodynamic study was carried out by applying a numerical modelling of MIKE 21 software based on flexible mesh grids. The model generally described the current flow pattern in the study area corresponding to the several flows from surrounding water regime which are Malacca Strait, Singapore Strait and Java Sea. The interaction of various water flows in the area of Tanjung Piai which is located in the middle part of the meeting of the currents to have a very complicated hydrodynamic conditions. The study area generally experienced two tidal phase in a day as the water flows is greatly influenced by the adjacent water flow from Malacca and Singapore Straits. During first tidal cycle, the most dominant flow is influenced by a single water flow which is Malacca Strait for both ebbing and flooding event. The current velocity was generally higher during this first tidal phase particularly at the tips of Tanjung Piai where severe erosion is spotted. However, the second tidal phase gives different stress to the study area as the flow is relatively dominated by both Malacca and Singapore Straits. During this phase, the meeting of current from both straits can be discovered near to the Tanjung Piai as this occurrence makes relatively slower current velocity around the study area. Basically, the numerical modelling result in this study can be considered as basic information in describing the condition of study area as it would be very useful for extensive study especially the study of sediment transport and morphological processes in the coastal area.

  13. Assessing satellite sea surface salinity from ocean color radiometric measurements for coastal hydrodynamic model data assimilation

    Science.gov (United States)

    Vogel, Ronald L.; Brown, Christopher W.

    2016-07-01

    Improving forecasts of salinity from coastal hydrodynamic models would further our predictive capacity of physical, chemical, and biological processes in the coastal ocean. However, salinity is difficult to estimate in coastal and estuarine waters at the temporal and spatial resolution required. Retrieving sea surface salinity (SSS) using satellite ocean color radiometry may provide estimates with reasonable accuracy and resolution for coastal waters that could be assimilated into hydrodynamic models to improve SSS forecasts. We evaluated the applicability of satellite SSS retrievals from two algorithms for potential assimilation into National Oceanic and Atmospheric Administration's Chesapeake Bay Operational Forecast System (CBOFS) hydrodynamic model. Of the two satellite algorithms, a generalized additive model (GAM) outperformed that of an artificial neural network (ANN), with mean bias and root-mean-square error (RMSE) of 1.27 and 3.71 for the GAM and 3.44 and 5.01 for the ANN. However, the RMSE for the SSS predicted by CBOFS (2.47) was lower than that of both satellite algorithms. Given the better precision of the CBOFS model, assimilation of satellite ocean color SSS retrievals will not improve CBOFS forecasts of SSS in Chesapeake Bay. The bias in the GAM SSS retrievals suggests that adding a variable related to precipitation may improve its performance.

  14. Hydrodynamic Modeling on Suciu River (Maramures County

    Directory of Open Access Journals (Sweden)

    Năsui Daniel

    2016-06-01

    Full Text Available The GIS database containing the topographic and land use information was made in 2012, followed by field measurements surveys in 2013 and 2014. A number of 11 cross-sections were topographically apprised in the valley along the 11 km river reach. The geometric data requirements for the modeling software were prepared in ESRI’s ArcGIS™ 9.2 software using the HEC-GeoRAS extension. The steady flow data was edited in the HEC-RAS one-dimensional flow modeling software. Four scenarios were used for the river discharge, from normal to overflow. The results come in different forms, from tabular output, to stage hydrograph, to velocity distribution or 3D diagrams, all of which give a clear vision on the overflow high risk areas. The results were exported back to the GIS extension for additional spatial operations. Flow velocity maps were generated for each discharge scenario. Although the scenarios included very high discharge values, the flood impact on people assets is minimal. The reasons for this are the high slope of the riverbed and the proper placement in the floodplain, due mainly to the flood management works that took place after the 1970 flood.

  15. Hydrodynamics of Explosion Experiments and Models

    CERN Document Server

    Kedrinskii, Valery K

    2005-01-01

    Hydronamics of Explosion presents the research results for the problems of underwater explosions and contains a detailed analysis of the structure and the parameters of the wave fields generated by explosions of cord and spiral charges, a description of the formation mechanisms for a wide range of cumulative flows at underwater explosions near the free surface, and the relevant mathematical models. Shock-wave transformation in bubbly liquids, shock-wave amplification due to collision and focusing, and the formation of bubble detonation waves in reactive bubbly liquids are studied in detail. Particular emphasis is placed on the investigation of wave processes in cavitating liquids, which incorporates the concepts of the strength of real liquids containing natural microinhomogeneities, the relaxation of tensile stress, and the cavitation fracture of a liquid as the inversion of its two-phase state under impulsive (explosive) loading. The problems are classed among essentially nonlinear processes that occur unde...

  16. Differential invariants in nonclassical models of hydrodynamics

    Science.gov (United States)

    Bublik, Vasily V.

    2017-10-01

    In this paper, differential invariants are used to construct solutions for equations of the dynamics of a viscous heat-conducting gas and the dynamics of a viscous incompressible fluid modified by nanopowder inoculators. To describe the dynamics of a viscous heat-conducting gas, we use the complete system of Navier—Stokes equations with allowance for heat fluxes. Mathematical description of the dynamics of liquid metals under high-energy external influences (laser radiation or plasma flow) includes, in addition to the Navier—Stokes system of an incompressible viscous fluid, also heat fluxes and processes of nonequilibrium crystallization of a deformable fluid. Differentially invariant solutions are a generalization of partially invariant solutions, and their active study for various models of continuous medium mechanics is just beginning. Differentially invariant solutions can also be considered as solutions with differential constraints; therefore, when developing them, the approaches and methods developed by the science schools of academicians N. N. Yanenko and A. F. Sidorov will be actively used. In the construction of partially invariant and differentially invariant solutions, there are overdetermined systems of differential equations that require a compatibility analysis. The algorithms for reducing such systems to involution in a finite number of steps are described by Cartan, Finikov, Kuranishi, and other authors. However, the difficultly foreseeable volume of intermediate calculations complicates their practical application. Therefore, the methods of computer algebra are actively used here, which largely helps in solving this difficult problem. It is proposed to use the constructed exact solutions as tests for formulas, algorithms and their software implementations when developing and creating numerical methods and computational program complexes. This combination of effective numerical methods, capable of solving a wide class of problems, with

  17. CHF Enhancement by Surface Patterning based on Hydrodynamic Instability Model

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Han; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    If the power density of a device exceeds the CHF point, bubbles and vapor films will be covered on the whole heater surface. Because vapor films have much lower heat transfer capabilities compared to the liquid layer, the temperature of the heater surface will increase rapidly, and the device could be damaged due to the heater burnout. Therefore, the prediction and the enhancement of the CHF are essential to maximizing the efficient heat removal region. Numerous studies have been conducted to describe the CHF phenomenon, such as hydrodynamic instability theory, macrolayer dryout theory, hot/dry spot theory, and bubble interaction theory. The hydrodynamic instability model, proposed by Zuber, is the predominant CHF model that Helmholtz instability attributed to the CHF. Zuber assumed that the Rayleigh-Taylor (RT) instability wavelength is related to the Helmholtz wavelength. Lienhard and Dhir proposed a CHF model that Helmholtz instability wavelength is equal to the most dangerous RT wavelength. In addition, they showed the heater size effect using various heater surfaces. Lu et al. proposed a modified hydrodynamic theory that the Helmholtz instability was assumed to be the heater size and the area of the vapor column was used as a fitting factor. The modified hydrodynamic theories were based on the change of Helmholtz wavelength related to the RT instability wavelength. In the present study, the change of the RT instability wavelength, based on the heater surface modification, was conducted to show the CHF enhancement based on the heater surface patterning in a plate pool boiling. Sapphire glass was used as a base heater substrate, and the Pt film was used as a heating source. The patterning surface was based on the change of RT instability wavelength. In the present work the study of the CHF was conducted using bare Pt and patterned heating surfaces.

  18. Hydrodynamic behavior of tumor cells in a confined model microvessel

    Science.gov (United States)

    Khan, Zeina S.; Vanapalli, Siva A.

    2012-02-01

    An important step in cancer metastasis is the hydrodynamic transport of circulating tumor cells (CTCs) through microvasculature. In vivo imaging studies in mice models show episodes of confined motion and trapping of tumor cells at microvessel bifurcations, suggesting that hydrodynamic phenomena are important processes regulating CTC dissemination. Our goal is to use microfluidics to understand the interplay between tumor cell rheology, confinement and fluid forces that may help to identify physical factors determining CTC transport. We use leukemia cells as model CTCs and mimic the in vivo setting by investigating their motion in a confined microchannel with an integrated microfluidic manometer to measure time variations in the excess pressure drop during cell motion. Using image analysis, variations in excess pressure drop, cell shape and cell velocity are simultaneously quantified. We find that the throughput of the technique is high enough ( 100 cells/min) to assess tumor cell heterogeneity. Therefore, in addition to measuring the hydrodynamic response of tumor cells in confined channels, our results indicate that the microfluidic manometer device could be used for rapid mechanical phenotyping of tumor cells.

  19. Hydrodynamic model of temperature change in open ionic channels.

    Science.gov (United States)

    Chen, D P; Eisenberg, R S; Jerome, J W; Shu, C W

    1995-12-01

    Most theories of open ionic channels ignore heat generated by current flow, but that heat is known to be significant when analogous currents flow in semiconductors, so a generalization of the Poisson-Nernst-Planck theory of channels, called the hydrodynamic model, is needed. The hydrodynamic theory is a combination of the Poisson and Euler field equations of electrostatics and fluid dynamics, conservation laws that describe diffusive and convective flow of mass, heat, and charge (i.e., current), and their coupling. That is to say, it is a kinetic theory of solute and solvent flow, allowing heat and current flow as well, taking into account density changes, temperature changes, and electrical potential gradients. We integrate the equations with an essentially nonoscillatory shock-capturing numerical scheme previously shown to be stable and accurate. Our calculations show that 1) a significant amount of electrical energy is exchanged with the permeating ions; 2) the local temperature of the ions rises some tens of degrees, and this temperature rise significantly alters for ionic flux in a channel 25 A long, such as gramicidin-A; and 3) a critical parameter, called the saturation velocity, determines whether ionic motion is overdamped (Poisson-Nernst-Planck theory), is an intermediate regime (called the adiabatic approximation in semiconductor theory), or is altogether unrestricted (requiring the full hydrodynamic model). It seems that significant temperature changes are likely to accompany current flow in the open ionic channel.

  20. Modeling of dynamically loaded hydrodynamic bearings at low Sommerfeld numbers

    DEFF Research Database (Denmark)

    Thomsen, Kim

    by environment and other wind turbine components. In this work a numerical multiphysics bearing model is developed in order to allow for accurate performance prediction of hydrodynamic bearings subjected to the challenging conditions that exist in modern wind turbines. This requires the coupling of several...... performance and related phenomena: • a new wear model is proposed which can, with only moderate efforts, be implemented into existing EHD models. • it is discovered that radial tilting pad bearings can exhibit discontinuity effects when subjected high dynamic loads. • the influence of compliant liners...

  1. Development of a Hydrodynamic Model of Puget Sound and Northwest Straits

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Khangaonkar, Tarang P.

    2007-12-10

    The hydrodynamic model used in this study is the Finite Volume Coastal Ocean Model (FVCOM) developed by the University of Massachusetts at Dartmouth. The unstructured grid and finite volume framework, as well as the capability of wetting/drying simulation and baroclinic simulation, makes FVCOM a good fit to the modeling needs for nearshore restoration in Puget Sound. The model domain covers the entire Puget Sound, Strait of Juan de Fuca, San Juan Passages, and Georgia Strait at the United States-Canada Border. The model is driven by tide, freshwater discharge, and surface wind. Preliminary model validation was conducted for tides at various locations in the straits and Puget Sound using National Oceanic and Atmospheric Administration (NOAA) tide data. The hydrodynamic model was successfully linked to the NOAA oil spill model General NOAA Operational Modeling Environment model (GNOME) to predict particle trajectories at various locations in Puget Sound. Model results demonstrated that the Puget Sound GNOME model is a useful tool to obtain first-hand information for emergency response such as oil spill and fish migration pathways.

  2. Reconstruction of a meteotsunami in Lake Erie on 27 May 2012: Roles of atmospheric conditions on hydrodynamic response in enclosed basins

    Science.gov (United States)

    Anderson, Eric J.; Bechle, Adam J.; Wu, Chin H.; Schwab, David J.; Mann, Greg E.; Lombardy, Kirk A.

    2015-12-01

    On 27 May 2012, atmospheric conditions gave rise to two convective systems that generated a series of waves in the meteotsunami band on Lake Erie. The resulting waves swept three swimmers a 0.5 mi offshore, inundated a marina, and may have led to a capsized boat along the southern shoreline. Analysis of radial velocities from a nearby radar tower in combination with coastal meteorological observation indicates that the convective systems produced a series of outflow bands that were the likely atmospheric cause of the meteotsunami. In order to explain the processes that led to meteotsunami generation, we model the hydrodynamic response to three meteorological forcing scenarios: (i) the reconstructed atmospheric disturbance from radar analysis, (ii) simulated conditions from a high-resolution weather model, and (iii) interpolated meteorological conditions from the NOAA Great Lakes Coastal Forecasting System. The results reveal that the convective systems generated a series of waves incident to the southern shore of the lake that reflected toward the northern shoreline and reflected again to the southern shore, resulting in spatial wave focusing and edge wave formation that combined to impact recreational users near Cleveland, OH. This study illustrates the effects of meteotsunami development in an enclosed basin, including wave reflection, focusing, and edge wave formation as well as temporal lags between the causative atmospheric conditions and arrival of dangerous wave conditions. As a result, the ability to detect these extreme storms and predict the hydrodynamic response is crucial to reducing risk and building resilient coastal communities.

  3. Use of hydrologic and hydrodynamic modeling for ecosystem restoration

    Science.gov (United States)

    Obeysekera, J.; Kuebler, L.; Ahmed, S.; Chang, M.-L.; Engel, V.; Langevin, C.; Swain, E.; Wan, Y.

    2011-01-01

    Planning and implementation of unprecedented projects for restoring the greater Everglades ecosystem are underway and the hydrologic and hydrodynamic modeling of restoration alternatives has become essential for success of restoration efforts. In view of the complex nature of the South Florida water resources system, regional-scale (system-wide) hydrologic models have been developed and used extensively for the development of the Comprehensive Everglades Restoration Plan. In addition, numerous subregional-scale hydrologic and hydrodynamic models have been developed and are being used for evaluating project-scale water management plans associated with urban, agricultural, and inland costal ecosystems. The authors provide a comprehensive summary of models of all scales, as well as the next generation models under development to meet the future needs of ecosystem restoration efforts in South Florida. The multiagency efforts to develop and apply models have allowed the agencies to understand the complex hydrologic interactions, quantify appropriate performance measures, and use new technologies in simulation algorithms, software development, and GIS/database techniques to meet the future modeling needs of the ecosystem restoration programs. Copyright ?? 2011 Taylor & Francis Group, LLC.

  4. Modeling electrokinetic flows by consistent implicit incompressible smoothed particle hydrodynamics

    Science.gov (United States)

    Pan, Wenxiao; Kim, Kyungjoo; Perego, Mauro; Tartakovsky, Alexandre M.; Parks, Michael L.

    2017-04-01

    We present a consistent implicit incompressible smoothed particle hydrodynamics (I2SPH) discretization of Navier-Stokes, Poisson-Boltzmann, and advection-diffusion equations subject to Dirichlet or Robin boundary conditions. It is applied to model various two and three dimensional electrokinetic flows in simple or complex geometries. The accuracy and convergence of the consistent I2SPH are examined via comparison with analytical solutions, grid-based numerical solutions, or empirical models. The new method provides a framework to explore broader applications of SPH in microfluidics and complex fluids with charged objects, such as colloids and biomolecules, in arbitrary complex geometries.

  5. Modeling electrokinetic flows by consistent implicit incompressible smoothed particle hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wenxiao; Kim, Kyungjoo; Perego, Mauro; Tartakovsky, Alexandre M.; Parks, Michael L.

    2017-04-01

    We present an efficient implicit incompressible smoothed particle hydrodynamics (I2SPH) discretization of Navier-Stokes, Poisson-Boltzmann, and advection-diffusion equations subject to Dirichlet or Robin boundary conditions. It is applied to model various two and three dimensional electrokinetic flows in simple or complex geometries. The I2SPH's accuracy and convergence are examined via comparison with analytical solutions, grid-based numerical solutions, or empirical models. The new method provides a framework to explore broader applications of SPH in microfluidics and complex fluids with charged objects, such as colloids and biomolecules, in arbitrary complex geometries.

  6. Hydrodynamics of embedded planets' first atmospheres - III. The role of radiation transport for super-Earth planets

    Science.gov (United States)

    Cimerman, Nicolas P.; Kuiper, Rolf; Ormel, Chris W.

    2017-11-01

    The population of close-in super-Earths, with gas mass fractions of up to 10 per cent represents a challenge for planet formation theory: how did they avoid runaway gas accretion and collapsing to hot Jupiters despite their core masses being in the critical range of Mc ≃ 10 M⊕? Previous three-dimensional (3D) hydrodynamical simulations indicate that atmospheres of low-mass planets cannot be considered isolated from the protoplanetary disc, contrary to what is assumed in 1D-evolutionary calculations. This finding is referred to as the recycling hypothesis. In this paper, we investigate the recycling hypothesis for super-Earth planets, accounting for realistic 3D radiation hydrodynamics. Also, we conduct a direct comparison in terms of the evolution of the entropy between 1D and 3D geometries. We clearly see that 3D atmospheres maintain higher entropy: although gas in the atmosphere loses entropy through radiative cooling, the advection of high-entropy gas from the disc into the Bondi/Hill sphere slows down Kelvin-Helmholtz contraction, potentially arresting envelope growth at a sub-critical gas mass fraction. Recycling, therefore, operates vigorously, in line with results by previous studies. However, we also identify an `inner core' - in size ≈25 per cent of the Bondi radius - where streamlines are more circular and entropies are much lower than in the outer atmosphere. Future studies at higher resolutions are needed to assess whether this region can become hydrodynamically isolated on long time-scales.

  7. Validation of a Global Hydrodynamic Flood Inundation Model

    Science.gov (United States)

    Bates, P. D.; Smith, A.; Sampson, C. C.; Alfieri, L.; Neal, J. C.

    2014-12-01

    In this work we present first validation results for a hyper-resolution global flood inundation model. We use a true hydrodynamic model (LISFLOOD-FP) to simulate flood inundation at 1km resolution globally and then use downscaling algorithms to determine flood extent and depth at 90m spatial resolution. Terrain data are taken from a custom version of the SRTM data set that has been processed specifically for hydrodynamic modelling. Return periods of flood flows along the entire global river network are determined using: (1) empirical relationships between catchment characteristics and index flood magnitude in different hydroclimatic zones derived from global runoff data; and (2) an index flood growth curve, also empirically derived. Bankful return period flow is then used to set channel width and depth, and flood defence impacts are modelled using empirical relationships between GDP, urbanization and defence standard of protection. The results of these simulations are global flood hazard maps for a number of different return period events from 1 in 5 to 1 in 1000 years. We compare these predictions to flood hazard maps developed by national government agencies in the UK and Germany using similar methods but employing detailed local data, and to observed flood extent at a number of sites including St. Louis, USA and Bangkok in Thailand. Results show that global flood hazard models can have considerable skill given careful treatment to overcome errors in the publicly available data that are used as their input.

  8. Dynamic mesoscale model of dipolar fluids via fluctuating hydrodynamics.

    Science.gov (United States)

    Persson, Rasmus A X; Voulgarakis, Nikolaos K; Chu, Jhih-Wei

    2014-11-07

    Fluctuating hydrodynamics (FHD) is a general framework of mesoscopic modeling and simulation based on conservational laws and constitutive equations of linear and nonlinear responses. However, explicit representation of electrical forces in FHD has yet to appear. In this work, we devised an Ansatz for the dynamics of dipole moment densities that is linked with the Poisson equation of the electrical potential ϕ in coupling to the other equations of FHD. The resulting ϕ-FHD equations then serve as a platform for integrating the essential forces, including electrostatics in addition to hydrodynamics, pressure-volume equation of state, surface tension, and solvent-particle interactions that govern the emergent behaviors of molecular systems at an intermediate scale. This unique merit of ϕ-FHD is illustrated by showing that the water dielectric function and ion hydration free energies in homogeneous and heterogenous systems can be captured accurately via the mesoscopic simulation. Furthermore, we show that the field variables of ϕ-FHD can be mapped from the trajectory of an all-atom molecular dynamics simulation such that model development and parametrization can be based on the information obtained at a finer-grained scale. With the aforementioned multiscale capabilities and a spatial resolution as high as 5 Å, the ϕ-FHD equations represent a useful semi-explicit solvent model for the modeling and simulation of complex systems, such as biomolecular machines and nanofluidics.

  9. Dynamic mesoscale model of dipolar fluids via fluctuating hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Rasmus A. X.; Chu, Jhih-Wei, E-mail: jwchu@nctu.edu.tw [Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu 30068, Taiwan (China); Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30068, Taiwan (China); Voulgarakis, Nikolaos K. [Department of Mathematics, Washington State University, Richland, Washington 99372 (United States)

    2014-11-07

    Fluctuating hydrodynamics (FHD) is a general framework of mesoscopic modeling and simulation based on conservational laws and constitutive equations of linear and nonlinear responses. However, explicit representation of electrical forces in FHD has yet to appear. In this work, we devised an Ansatz for the dynamics of dipole moment densities that is linked with the Poisson equation of the electrical potential ϕ in coupling to the other equations of FHD. The resulting ϕ-FHD equations then serve as a platform for integrating the essential forces, including electrostatics in addition to hydrodynamics, pressure-volume equation of state, surface tension, and solvent-particle interactions that govern the emergent behaviors of molecular systems at an intermediate scale. This unique merit of ϕ-FHD is illustrated by showing that the water dielectric function and ion hydration free energies in homogeneous and heterogenous systems can be captured accurately via the mesoscopic simulation. Furthermore, we show that the field variables of ϕ-FHD can be mapped from the trajectory of an all-atom molecular dynamics simulation such that model development and parametrization can be based on the information obtained at a finer-grained scale. With the aforementioned multiscale capabilities and a spatial resolution as high as 5 Å, the ϕ-FHD equations represent a useful semi-explicit solvent model for the modeling and simulation of complex systems, such as biomolecular machines and nanofluidics.

  10. New equation of state models for hydrodynamic applications

    Science.gov (United States)

    Young, David A.; Barbee, Troy W.; Rogers, Forrest J.

    1998-07-01

    Two new theoretical methods for computing the equation of state of hot, dense matter are discussed. The ab initio phonon theory gives a first-principles calculation of lattice frequencies, which can be used to compare theory and experiment for isothermal and shock compression of solids. The ACTEX dense plasma theory has been improved to allow it to be compared directly with ultrahigh pressure shock data on low-Z materials. The comparisons with experiment are good, suggesting that these models will be useful in generating global EOS tables for hydrodynamic simulations.

  11. Radiation Hydrodynamical Models for Type I Superluminous Supernovae

    Science.gov (United States)

    Nomoto, Ken'ichi; Sorokina, Elena; Blinnikov, Sergei; Tolstov, Alexey; Bersten, Melina; Quimby, Robert

    The physical origin of Type I superluminous supernovae (SLSNe-I), whose luminosities are 10 to 100 times brighter than normal core-collapse supernovae, remains still unknown. Radioactive-decays, magnetars, and circumstellar interactions have been proposed for the power source the light curves, although no definitive conclusions have been reached yet. Since most of light curve studies have been based on simplified semi-analytic models, we have constructed detailed light curve models for various mass of stars including very massive ones and large amount of mass loss with radiation hydrodynamical calculations. Here we focus on the magnetar and circumstellar interaction models and compare their rising time, peak luminosity, width, decline rate of the light curves with observations which show quite a large diversities. We then discuss how to discriminate these models, relevant models parameters, their evolutionary origins, possible roles of chemical enrichment of the early universe, and implications for the identifications of first stars.

  12. Hydrodynamics and water quality models applied to Sepetiba Bay

    Science.gov (United States)

    Cunha, Cynara de L. da N.; Rosman, Paulo C. C.; Ferreira, Aldo Pacheco; Carlos do Nascimento Monteiro, Teófilo

    2006-10-01

    A coupled hydrodynamic and water quality model is used to simulate the pollution in Sepetiba Bay due to sewage effluent. Sepetiba Bay has a complicated geometry and bottom topography, and is located on the Brazilian coast near Rio de Janeiro. In the simulation, the dissolved oxygen (DO) concentration and biochemical oxygen demand (BOD) are used as indicators for the presence of organic matter in the body of water, and as parameters for evaluating the environmental pollution of the eastern part of Sepetiba Bay. Effluent sources in the model are taken from DO and BOD field measurements. The simulation results are consistent with field observations and demonstrate that the model has been correctly calibrated. The model is suitable for evaluating the environmental impact of sewage effluent on Sepetiba Bay from river inflows, assessing the feasibility of different treatment schemes, and developing specific monitoring activities. This approach has general applicability for environmental assessment of complicated coastal bays.

  13. An investigation of the thermal response to meteorological forcing in a hydrodynamic model of Lake Superior

    Science.gov (United States)

    Xue, Pengfei; Schwab, David J.; Hu, Song

    2015-07-01

    Lake Superior, the largest lake in the world by surface area and third largest by volume, features strong spatiotemporal thermal variability due to its immense size and complex bathymetry. The objectives of this study are to document our recent modeling experiences on the simulation of the lake thermal structure and to explore underlying dynamic explanations of the observed modeling success. In this study, we use a three-dimensional hydrodynamic model (FVCOM—Finite Volume Community Ocean Model) and an assimilative weather forecasting model (WRF—Weather Research and Forecasting Model) to study the annual heating and cooling cycle of Lake Superior. Model experiments are carried out with meteorological forcing based on interpolation of surface weather observations, on WRF and on Climate Forecast System Reanalysis (CFSR) reanalysis data, respectively. Model performance is assessed through comparison with satellite products and in situ measurements. Accurate simulations of the lake thermal structure are achieved through (1) adapting the COARE algorithm in the hydrodynamic model to derive instantaneous estimates of latent/sensible heat fluxes and upward longwave radiation based on prognostic surface water temperature simulated within the model as opposed to precomputing them with an assumed surface water temperature; (2) estimating incoming solar radiation and downward longwave radiation based on meteorological measurements as opposed to meteorological model-based estimates; (3) using the weather forecasting model to provide high-resolution dynamically constrained wind fields as opposed to wind fields interpolated from station observations. Analysis reveals that the key to the modeling success is to resolve the lake-atmosphere interactions and apply appropriate representations of different meteorological forcing fields, based on the nature of their spatiotemporal variability. The close agreement between model simulation and observations also suggests that the 3-D

  14. Correlation lengths in hydrodynamic models of active nematics.

    Science.gov (United States)

    Hemingway, Ewan J; Mishra, Prashant; Marchetti, M Cristina; Fielding, Suzanne M

    2016-09-28

    We examine the scaling with activity of the emergent length scales that control the nonequilibrium dynamics of an active nematic liquid crystal, using two popular hydrodynamic models that have been employed in previous studies. In both models we find that the chaotic spatio-temporal dynamics in the regime of fully developed active turbulence is controlled by a single active scale determined by the balance of active and elastic stresses, regardless of whether the active stress is extensile or contractile in nature. The observed scaling of the kinetic energy and enstrophy with activity is consistent with our single-length scale argument and simple dimensional analysis. Our results provide a unified understanding of apparent discrepancies in the previous literature and demonstrate that the essential physics is robust to the choice of model.

  15. Floodplain hydrodynamic modelling of the Lower Volta River in Ghana

    Directory of Open Access Journals (Sweden)

    Frederick Yaw Logah

    2017-12-01

    Full Text Available The impacts of dam releases from re-operation scenarios of the Akosombo and Kpong hydropower facilities on downstream communities along the Lower Volta River were examined through hydrodynamic modelling using the HEC-RAS hydraulic model. The model was used to simulate surface water elevation along the river reach for specified discharge hydrographs from proposed re-operation dam release scenarios. The morphology of the river and its flood plains together with cross-sectional profiles at selected river sections were mapped and used in the hydrodynamic modelling. In addition, both suspended and bed-load sediment were sampled and analysed to determine the current sediment load of the river and its potential to carry more sediment. The modelling results indicate that large areas downstream of the dam including its flood plains would be inundated if dam releases came close to or exceeded 2300 m3/s. It is therefore recommended to relocate communities along the banks and in the flood plains of the Lower Volta River when dam releases are to exceed 2300 m3/s. Suspended sediment transport was found to be very low in the Lower Volta River and the predominant soil type in the river banks and bed is sandy soil. Thus, the geomorphology of the river can be expected to change considerably with time, particularly for sustained high releases from the Akosombo and Kpong dams. The results obtained from this study form a basis for assessing future sedimentation problems in the Lower Volta River and for underpinning the development of sediment control and management strategies for river basins in Ghana. Keywords: Geomorphology, HEC-RAS model, Dam release, Floodplain, Lower Volta River, Ghana

  16. Lagrangian Modeling of the Atmosphere

    Science.gov (United States)

    Schultz, Colin

    2013-08-01

    Like watching a balloon borne by the breeze, a Lagrangian model tracks a parcel of air as it flows through the atmosphere. Whether running forward or backward in time, Lagrangian models offer a powerful tool for tracking and understanding the fates, or origins, of atmospheric flows. In the AGU monograph Lagrangian Modeling of the Atmosphere, editors John Lin, Dominik Brunner, Christoph Gerbig, Andreas Stohl, Ashok Luhar, and Peter Webley explore the nuances of the modeling technique. In this interview Eos talks to Lin about the growing importance of Lagrangian modeling as the world settles on climate change mitigation strategies, the societal value of operational modeling, and how recent advances are making it possible to run these complex calculations at home.

  17. Challenges of citizen science contributions to modelling hydrodynamics of floods

    Science.gov (United States)

    Assumpção, Thaine Herman; Popescu, Ioana; Jonoski, Andreja; Solomatine, Dimitri P.

    2017-04-01

    Citizen science is an established mechanism in many fields of science, including ecology, biology and astronomy. Citizen participation ranges from collecting and interpreting data towards designing experiments with scientists and cooperating with water management authorities. In the environmental sciences, its potential has begun to be explored in the past decades and many studies on the applicability to water resources have emerged. Citizen Observatories are at the core of several EU-funded projects such as WeSenseIt, GroundTruth, GroundTruth 2.0 and SCENT (Smart Toolbox for Engaging Citizens into a People-Centric Observation Web) that already resulted in valuable contributions to the field. Buytaert et al. (2014) has already reviewed the role of citizen science in hydrology. The work presented here aims to complement it, reporting and discussing the use of citizen science for modelling the hydrodynamics of floods in a variety of studies. Additionally, it highlights the challenges that lie ahead to utilize more fully the citizen science potential contribution. In this work, focus is given to each component of hydrodynamic models: water level, velocity, flood extent, roughness and topography. It is addressed how citizens have been contributing to each aspect, mainly considering citizens as sensors and citizens as data interpreters. We consider to which kind of model (1D or 2D) the discussed approaches contribute and what their limitations and potential uses are. We found that although certain mechanisms are well established (e.g. the use of Volunteer Geographic Information for soft validation of land-cover and land-use maps), the applications in a modelling context are rather modest. Also, most studies involving models are limited to replacing traditional data with citizen data. We recommend that citizen science continue to be explored in modelling frameworks, in different case studies, taking advantage of the discussed mechanisms and of new sensor technologies

  18. A Tightly Coupled Non-Equilibrium Magneto-Hydrodynamic Model for Inductively Coupled RF Plasmas

    Science.gov (United States)

    2016-02-29

    Journal Article 3. DATES COVERED (From - To) 12 May 2015 – 06 Oct 2015 4. TITLE AND SUBTITLE A Tightly Coupled Non-Equilibrium Magneto- Hydrodynamic ...development a tightly coupled magneto- hydrodynamic model for Inductively Coupled Radio- Frequency (RF) Plasmas. Non Local Thermodynamic Equilibrium (NLTE... hydrodynamic model for Inductively Coupled RF Plasmas A. Munafò,1, a) S. A. Alfuhaid,1, b) J.-L. Cambier,2, c) and M. Panesi1, d) 1)Department of

  19. ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Workman, Jared, E-mail: kevin.heng@csh.unibe.ch, E-mail: jworkman@coloradomesa.edu [Colorado Mesa University, 1260 Kennedy Avenue, Grand Junction, CO 81501 (United States)

    2014-08-01

    Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

  20. A hydrodynamic model for granular material flows including segregation effects

    Science.gov (United States)

    Gilberg, Dominik; Klar, Axel; Steiner, Konrad

    2017-06-01

    The simulation of granular flows including segregation effects in large industrial processes using particle methods is accurate, but very time-consuming. To overcome the long computation times a macroscopic model is a natural choice. Therefore, we couple a mixture theory based segregation model to a hydrodynamic model of Navier-Stokes-type, describing the flow behavior of the granular material. The granular flow model is a hybrid model derived from kinetic theory and a soil mechanical approach to cover the regime of fast dilute flow, as well as slow dense flow, where the density of the granular material is close to the maximum packing density. Originally, the segregation model has been formulated by Thornton and Gray for idealized avalanches. It is modified and adapted to be in the preferred form for the coupling. In the final coupled model the segregation process depends on the local state of the granular system. On the other hand, the granular system changes as differently mixed regions of the granular material differ i.e. in the packing density. For the modeling process the focus lies on dry granular material flows of two particle types differing only in size but can be easily extended to arbitrary granular mixtures of different particle size and density. To solve the coupled system a finite volume approach is used. To test the model the rotational mixing of small and large particles in a tumbler is simulated.

  1. Atmospheric Deposition Modeling Results

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset provides data on model results for dry and total deposition of sulfur, nitrogen and base cation species. Components include deposition velocities, dry...

  2. Numerical modelling of extreme waves by Smoothed Particle Hydrodynamics

    Directory of Open Access Journals (Sweden)

    M. H. Dao

    2011-02-01

    Full Text Available The impact of extreme/rogue waves can lead to serious damage of vessels as well as marine and coastal structures. Such extreme waves in deep water are characterized by steep wave fronts and an energetic wave crest. The process of wave breaking is highly complex and, apart from the general knowledge that impact loadings are highly impulsive, the dynamics of the breaking and impact are still poorly understood. Using an advanced numerical method, the Smoothed Particle Hydrodynamics enhanced with parallel computing is able to reproduce well the extreme waves and their breaking process. Once the waves and their breaking process are modelled successfully, the dynamics of the breaking and the characteristics of their impact on offshore structures could be studied. The computational methodology and numerical results are presented in this paper.

  3. Modelling of hydrodynamics and mecury transport in lake Velenje. Part 2, Modelling and model verification

    OpenAIRE

    Kotnik, Jože; Žagar, Dušan; Rajar, Rudi; Horvat, Milena

    2004-01-01

    PCFLOW3D - a three-dimensional mathematical model that was developed at the Chair of Fluid Mechanics of the Faculty of Civil and Geodetic Engineering, University of Ljubljana, was used for hydrodynamic and Hg transport simulations in Lake Velenje. The model is fully non-linear and computes three velocity components, water elevation and pressure. Transport-dispersion equations for salinity and heat (and/or any pollutant) are further used to compute the distributions of these par...

  4. GLOFRIM v1.0 – A globally applicable computational framework for integrated hydrological–hydrodynamic modelling

    NARCIS (Netherlands)

    Hoch, J.M.; Neal, Jeffrey; Baart, Fedor; van Beek, L.P.H.; Winsemius, Hessel; Bates, Paul; Bierkens, M.F.P.

    2017-01-01

    We here present GLOFRIM, a globally applicable computational framework for integrated hydrological–hydrodynamic modelling. GLOFRIM facilitates spatially explicit coupling of hydrodynamic and hydrologic models and caters for an ensemble of models to be coupled. It currently encompasses the global

  5. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    related to inaccurate land surface modelling, e.g. enhanced warm bias in warm dry summer months. Coupling the regional climate model to a hydrological model shows the potential of improving the surface flux simulations in dry periods and the 2 m air temperature in general. In the dry periods......The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...

  6. Hydrodynamic modelling of small upland lakes under strong wind forcing

    Science.gov (United States)

    Morales, L.; French, J.; Burningham, H.

    2012-04-01

    Small lakes (Area Stokes equations using a 3D unstructured mesh and a finite volume scheme. The model is forced by meteorological boundary conditions. Improvements made to the FVCOM code include a new graphical user interface to pre- and post process the model input and results respectively, and a JONSWAT wave model to include the effects of wind-wave induced bottom stresses on lake sediment dynamics. Modelled internal scale waves are validated against summer temperature measurements acquired from a thermistor chain deployed at the deepest part of the lake. Seiche motions were validated using data recorded by high-frequency level sensors around the lake margins, and the velocity field and the circulation patterns were validated using the data recorded by an ADCP and GPS drifters. The model is shown to reproduce the lake hydrodynamics and reveals well-developed seiches at different frequencies superimposed on wind-driven circulation patterns that appear to control the distribution of bottom sediments in this small upland lake.

  7. Using radiotracer techniques for coastal hydrodynamic model evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, C.E. E-mail: ceh@ansto.gov.au; Airey, P.L.; Duran, E.B.; Miller, B.M.; Sombrito, E

    2004-07-01

    A three-dimensional (3D) water circulation and contaminant transport model of Manila Bay has been developed with the aim of better understanding the formation and movement of harmful algal blooms. Radiotracer techniques were used to evaluate the model by recording the dispersion of a tracer at depths of 2 and 15 m near the injection point. The selected tracer was {sup 99m}Tc eluted from a molybdenum/technetium medical generator. The rationale for the choice of the tracer and the location of the injection is discussed. At 2 m the transport was dominated by the prevailing winds, and at 15 m by tidally induced currents. The development of the hydrodynamic model and its experimental evaluation were iterative processes. The experimental study confirmed the need for full 3D modelling of Manila Bay; quantified the impact of the prevailing wind field on contaminant dispersion near the injection point; and allowed the calculation of transverse dispersivity to guide the selection of parameter values used in the overall model.

  8. Simulations of Model Microswimmers with Fully Resolved Hydrodynamics

    Science.gov (United States)

    Oyama, Norihiro; Molina, John J.; Yamamoto, Ryoichi

    2017-10-01

    Swimming microorganisms, which include bacteria, algae, and spermatozoa, play a fundamental role in most biological processes. These swimmers are a special type of active particle, that continuously convert local energy into propulsive forces, thereby allowing them to move through their surrounding fluid medium. While the size, shape, and propulsion mechanism vary from one organism to the next, they share certain general characteristics: they exhibit force-free motion and they swim at a small Reynolds number. To study the dynamics of such systems, we use the squirmer model, which provides an ideal representation of swimmers as spheroidal particles that propel owing to a modified boundary condition at their surface. We have considered the single-particle and many-particle dynamics of swimmers in bulk and confined systems using the smoothed profile method, which allows us to efficiently solve the coupled particle-fluid problem. For the single-particle dynamics, we studied the diffusive behavior caused by the swimming of the particles. At short-time scales, the diffusion is caused by the hydrodynamic interactions, whereas at long-time scales, it is determined by the particle-particle collisions. Thus, the short-time diffusion will be the same for both swimmers and inert tracer particles. We then investigated the dynamics of confined microswimmers using cylindrical and parallel-plate confining walls. For the cylindrical confinement, we find evidence of an order/disorder phase transition which depends on the specific type of swimmers and the size of the cylinder. Under parallel-plane walls, some swimmers exhibit wavelike modes, which lead to traveling density waves that bounce back and forth between the walls. From an analysis of the bulk systems, we can show that this wavelike motion can be understood as a pseudoacoustic mode and is a consequence of the intrinsic swimming properties of the particles. The results presented here, together with the simulation method that

  9. Recent advances in non-LTE stellar atmosphere models

    Science.gov (United States)

    Sander, Andreas A. C.

    2017-11-01

    In the last decades, stellar atmosphere models have become a key tool in understanding massive stars. Applied for spectroscopic analysis, these models provide quantitative information on stellar wind properties as well as fundamental stellar parameters. The intricate non-LTE conditions in stellar winds dictate the development of adequate sophisticated model atmosphere codes. The increase in both, the computational power and our understanding of physical processes in stellar atmospheres, led to an increasing complexity in the models. As a result, codes emerged that can tackle a wide range of stellar and wind parameters. After a brief address of the fundamentals of stellar atmosphere modeling, the current stage of clumped and line-blanketed model atmospheres will be discussed. Finally, the path for the next generation of stellar atmosphere models will be outlined. Apart from discussing multi-dimensional approaches, I will emphasize on the coupling of hydrodynamics with a sophisticated treatment of the radiative transfer. This next generation of models will be able to predict wind parameters from first principles, which could open new doors for our understanding of the various facets of massive star physics, evolution, and death.

  10. Hydrodynamics beyond Navier-Stokes: The slip flow model

    Science.gov (United States)

    Yudistiawan, Wahyu P.; Ansumali, Santosh; Karlin, Iliya V.

    2008-07-01

    Recently, analytical solutions for the nonlinear Couette flow demonstrated the relevance of the lattice Boltzmann (LB) models to hydrodynamics beyond the continuum limit [S. Ansumali , Phys. Rev. Lett. 98, 124502 (2007)]. In this paper, we present a systematic study of the simplest LB kinetic equation—the nine-bit model in two dimensions—in order to quantify it as a slip flow approximation. Details of the aforementioned analytical solution are presented, and results are extended to include a general shear- and force-driven unidirectional flow in confined geometry. Exact solutions for the velocity, as well as for pertinent higher-order moments of the distribution functions, are obtained in both Couette and Poiseuille steady-state flows for all values of rarefaction parameter (Knudsen number). Results are compared with the slip flow solution by Cercignani, and a good quantitative agreement is found for both flow situations. Thus, the standard nine-bit LB model is characterized as a valid and self-consistent slip flow model for simulations beyond the Navier-Stokes approximation.

  11. Hydrodynamic Modeling of Nokoué Lake in Benin

    Directory of Open Access Journals (Sweden)

    Josué Zandagba

    2016-12-01

    Full Text Available Nokoué Lake is a complex ecosystem, the understanding of which requires control of physical processes that have occurred. For this, the Surface Water Modeling System (SMS hydrodynamic model was calibrated and validated on the water depth data. The results of these simulations show a good match between the simulated and observed data for bottom roughness and turbulent exchange coefficients, of 0.02 m−1/3·s and 20 m2/s respectively. Once the ability of the model to simulate the hydrodynamics of the lake is testified, the model is used to simulate water surface elevation, exchanged flows and velocities. The simulation shows that the tidal amplitude is maximum at the inlet of the channel and decreases gradually from the inlet towards the lagoon’s main body. The propagation of the tidal wave is characterized by the dephasing and the flattening of the amplitude tide, which increases as we move away from the channel. This dephasing is characterized by a high and low tides delay of about 1 or 4 h and also depends on the tide amplitude and location. The velocities inside the lake are very low and do not exceed 0.03 m/s. The highest are obtained at the entrance of the channel. In a flood period, in contrast with the low-water period, incoming flows are higher than outflows, reinforced by the amplitude of the tide. An average renewal time of the lake has been estimated and corresponds during a flood period to 30 days for an average amplitude tide and 26.3 days on a high amplitude tide. In a low water period it is 40.2 days for an average amplitude tide and 30 days for a high amplitude tide. From the results obtained, several measures must be taken into account for the rational management of the lake water resources. These include a dam construction at the lake upstream, to control the river flows, and the dredging of the channel to facilitate exchanges with the sea.

  12. Hydrodynamic Modeling of Oxidizer-Rich Staged Combustion Injector Flow

    Science.gov (United States)

    Harper, Brent (Technical Monitor); Canino, J. V.; Heister, S. D.; Garrison, L. A.

    2004-01-01

    The main objective of this work is to determine the unsteady hydrodynamic characteristics of coaxial swirl atomizers of interest in oxidizer-rich staged combustion (ORSC) liquid rocket engines. To this end, the pseudo-density (homogeneous flow) treatment combined with the Marker-and-Cell (MAC) numerical algorithm has been used to develop an axisymmetric with swirl, two-phase, unsteady model. The numerical model is capable of assessing the time-dependent orifice exit conditions and internal mixing for arbitrary fuel and oxidizer gas injection conditions. Parametric studies have been conducted to determine the effect of geometry, gas properties, and liquid properties on the exit massflow rate and velocity. It has been found that the frequency at which the liquid film oscillates increases as the density ratio and thickness increase, decreases as film thickness and liquid swirl velocity increase, and is unaffected by the mixing length. Additionally, it has been determined that the variation in the massflow rate increases as the liquid swirl velocity and liquid film thickness increase, and decreases as the density ratio, collar thickness, and mixing length increase.

  13. Galaxy protoclusters in semi-analytic and hydrodynamic models

    Science.gov (United States)

    Lovell, Christopher; Thomas, Peter; Wilkins, Stephen

    2018-01-01

    We present an analysis of galaxy protoclusters in the L-Galaxies semi-analytic model and C-Eagle hydrodynamic simulations. Searching for protoclusters on a scale of ~ 10 cMpc gives an excellent compromise between the completeness and purity of their galaxy populations, leads to high distinction from the field in overdensity space, and allows accurate determination of the descendant cluster mass. This scale is valid over a range of redshifts and selection criteria. We present a procedure for estimating, given a measured galaxy overdensity, the protocluster probability and its descendant cluster mass for a range of modelling assumptions, particularly taking into account the shape of the measurement aperture. This procedure produces lower protocluster probabilities compared to previous estimates using fixed size apertures. The relationship between AGN and protoclusters is also investigated, and shows significant evolution with redshift; at $z \\sim 2$ the fraction of protoclusters traced by AGN is high, but the fraction of all AGN in protoclusters is low, whereas at $z \\geqslant 5$ the fraction of protoclusters containing AGN is low, but most AGN are in protoclusters.We also find evidence for the emergence of a passive sequence in protoclusters at $z \\sim 2$.

  14. Discussion of Stokes' hypothesis through the smoothed particle hydrodynamics model

    Science.gov (United States)

    Colagrossi, Andrea; Durante, Danilo; Bonet Avalos, Josep; Souto-Iglesias, Antonio

    2017-08-01

    Stokes' hypothesis, the zeroing of the bulk viscosity in a Newtonian fluid, is discussed in this paper. To this aim, a continuum macroscopic fluid domain is initially modeled as a Hamiltonian system of discrete particles, for which the interparticle dissipative forces are required to be radial in order to conserve the angular momentum. The resulting system of particles is then reconverted to the continuum domain via the framework of the smoothed particle hydrodynamics (SPH) model. Since an SPH-consistent approximation of the Newtonian viscous term in the momentum equation incorporates interparticle radial as well as nonradial terms, it is postulated that the latter must be null. In the present work it is shown that this constraint implies that first and second viscosities are equal, resulting in a positive value for the bulk viscosity, in contradiction to the cited Stokes' hypothesis. Moreover, it is found that this postulate leads to bulk viscosity coefficients close to values found in the experimental literature for monoatomic gases and common liquids such as water.

  15. Combined Modeling of Acceleration, Transport, and Hydrodynamic Response in Solar Flares. 1; The Numerical Model

    Science.gov (United States)

    Liu, Wei; Petrosian, Vahe; Mariska, John T.

    2009-01-01

    Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares, but for convenience and simplicity they were artificially separated in the past. We present here self consistently combined Fokker-Planck modeling of particles and hydrodynamic simulation of flare plasma. Energetic electrons are modeled with the Stanford unified code of acceleration, transport, and radiation, while plasma is modeled with the Naval Research Laboratory flux tube code. We calculated the collisional heating rate directly from the particle transport code, which is more accurate than those in previous studies based on approximate analytical solutions. We repeated the simulation of Mariska et al. with an injection of power law, downward-beamed electrons using the new heating rate. For this case, a -10% difference was found from their old result. We also used a more realistic spectrum of injected electrons provided by the stochastic acceleration model, which has a smooth transition from a quasi-thermal background at low energies to a non thermal tail at high energies. The inclusion of low-energy electrons results in relatively more heating in the corona (versus chromosphere) and thus a larger downward heat conduction flux. The interplay of electron heating, conduction, and radiative loss leads to stronger chromospheric evaporation than obtained in previous studies, which had a deficit in low-energy electrons due to an arbitrarily assumed low-energy cutoff. The energy and spatial distributions of energetic electrons and bremsstrahlung photons bear signatures of the changing density distribution caused by chromospheric evaporation. In particular, the density jump at the evaporation front gives rise to enhanced emission, which, in principle, can be imaged by X-ray telescopes. This model can be applied to investigate a variety of high-energy processes in solar, space, and astrophysical plasmas.

  16. Computational modeling and analysis of the hydrodynamics of human swimming

    Science.gov (United States)

    von Loebbecke, Alfred

    Computational modeling and simulations are used to investigate the hydrodynamics of competitive human swimming. The simulations employ an immersed boundary (IB) solver that allows us to simulate viscous, incompressible, unsteady flow past complex, moving/deforming three-dimensional bodies on stationary Cartesian grids. This study focuses on the hydrodynamics of the "dolphin kick". Three female and two male Olympic level swimmers are used to develop kinematically accurate models of this stroke for the simulations. A simulation of a dolphin undergoing its natural swimming motion is also presented for comparison. CFD enables the calculation of flow variables throughout the domain and over the swimmer's body surface during the entire kick cycle. The feet are responsible for all thrust generation in the dolphin kick. Moreover, it is found that the down-kick (ventral position) produces more thrust than the up-kick. A quantity of interest to the swimming community is the drag of a swimmer in motion (active drag). Accurate estimates of this quantity have been difficult to obtain in experiments but are easily calculated with CFD simulations. Propulsive efficiencies of the human swimmers are found to be in the range of 11% to 30%. The dolphin simulation case has a much higher efficiency of 55%. Investigation of vortex structures in the wake indicate that the down-kick can produce a vortex ring with a jet of accelerated fluid flowing through its center. This vortex ring and the accompanying jet are the primary thrust generating mechanisms in the human dolphin kick. In an attempt to understand the propulsive mechanisms of surface strokes, we have also conducted a computational analysis of two different styles of arm-pulls in the backstroke and the front crawl. These simulations involve only the arm and no air-water interface is included. Two of the four strokes are specifically designed to take advantage of lift-based propulsion by undergoing lateral motions of the hand

  17. Modeling Free-surface Solitary Waves with Smoothed Particle Hydrodynamics

    National Research Council Canada - National Science Library

    Balázs Tóth

    2017-01-01

    A three-dimensional weakly compressible Smoothed Particle Hydrodynamics (SPH) solver is presented and applied to simulate free-surface solitary waves generated in a quasi two dimensional dam-break experiment...

  18. Model for Simulation Atmospheric Turbulence

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik

    1976-01-01

    A method that produces realistic simulations of atmospheric turbulence is developed and analyzed. The procedure makes use of a generalized spectral analysis, often called a proper orthogonal decomposition or the Karhunen-Loève expansion. A set of criteria, emphasizing a realistic appearance......, a correct spectral shape, and non-Gaussian statistics, is selected in order to evaluate the model turbulence. An actual turbulence record is analyzed in detail providing both a standard for comparison and input statistics for the generalized spectral analysis, which in turn produces a set of orthonormal....... The method is unique in modeling the three velocity components simultaneously, and it is found that important cross-statistical features are reasonably well-behaved. It is concluded that the model provides a practical, operational simulator of atmospheric turbulence....

  19. Gold-standard performance for 2D hydrodynamic modeling

    Science.gov (United States)

    Pasternack, G. B.; MacVicar, B. J.

    2013-12-01

    Two-dimensional, depth-averaged hydrodynamic (2D) models are emerging as an increasingly useful tool for environmental water resources engineering. One of the remaining technical hurdles to the wider adoption and acceptance of 2D modeling is the lack of standards for 2D model performance evaluation when the riverbed undulates, causing lateral flow divergence and convergence. The goal of this study was to establish a gold-standard that quantifies the upper limit of model performance for 2D models of undulating riverbeds when topography is perfectly known and surface roughness is well constrained. A review was conducted of published model performance metrics and the value ranges exhibited by models thus far for each one. Typically predicted velocity differs from observed by 20 to 30 % and the coefficient of determination between the two ranges from 0.5 to 0.8, though there tends to be a bias toward overpredicting low velocity and underpredicting high velocity. To establish a gold standard as to the best performance possible for a 2D model of an undulating bed, two straight, rectangular-walled flume experiments were done with no bed slope and only different bed undulations and water surface slopes. One flume tested model performance in the presence of a porous, homogenous gravel bed with a long flat section, then a linear slope down to a flat pool bottom, and then the same linear slope back up to the flat bed. The other flume had a PVC plastic solid bed with a long flat section followed by a sequence of five identical riffle-pool pairs in close proximity, so it tested model performance given frequent undulations. Detailed water surface elevation and velocity measurements were made for both flumes. Comparing predicted versus observed velocity magnitude for 3 discharges with the gravel-bed flume and 1 discharge for the PVC-bed flume, the coefficient of determination ranged from 0.952 to 0.987 and the slope for the regression line was 0.957 to 1.02. Unsigned velocity

  20. Models of the Solar Atmospheric Response to Flare Heating

    Science.gov (United States)

    Allred, Joel

    2011-01-01

    I will present models of the solar atmospheric response to flare heating. The models solve the equations of non-LTE radiation hydrodynamics with an electron beam added as a flare energy source term. Radiative transfer is solved in detail for many important optically thick hydrogen and helium transitions and numerous optically thin EUV lines making the models ideally suited to study the emission that is produced during flares. I will pay special attention to understanding key EUV lines as well the mechanism for white light production. I will also present preliminary results of how the model solar atmosphere responds to Fletcher & Hudson type flare heating. I will compare this with the results from flare simulations using the standard thick target model.

  1. Development of a Hydrodynamic and Transport model of Bellingham Bay in Support of Nearshore Habitat Restoration

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Taiping; Yang, Zhaoqing; Khangaonkar, Tarang

    2010-04-22

    In this study, a hydrodynamic model based on the unstructured-grid finite volume coastal ocean model (FVCOM) was developed for Bellingham Bay, Washington. The model simulates water surface elevation, velocity, temperature, and salinity in a three-dimensional domain that covers the entire Bellingham Bay and adjacent water bodies, including Lummi Bay, Samish Bay, Padilla Bay, and Rosario Strait. The model was developed using Pacific Northwest National Laboratory’s high-resolution Puget Sound and Northwest Straits circulation and transport model. A sub-model grid for Bellingham Bay and adjacent coastal waters was extracted from the Puget Sound model and refined in Bellingham Bay using bathymetric light detection and ranging (LIDAR) and river channel cross-section data. The model uses tides, river inflows, and meteorological inputs to predict water surface elevations, currents, salinity, and temperature. A tidal open boundary condition was specified using standard National Oceanic and Atmospheric Administration (NOAA) predictions. Temperature and salinity open boundary conditions were specified based on observed data. Meteorological forcing (wind, solar radiation, and net surface heat flux) was obtained from NOAA real observations and National Center for Environmental Prediction North American Regional Analysis outputs. The model was run in parallel with 48 cores using a time step of 2.5 seconds. It took 18 hours of cpu time to complete 26 days of simulation. The model was calibrated with oceanographic field data for the period of 6/1/2009 to 6/26/2009. These data were collected specifically for the purpose of model development and calibration. They include time series of water-surface elevation, currents, temperature, and salinity as well as temperature and salinity profiles during instrument deployment and retrieval. Comparisons between model predictions and field observations show an overall reasonable agreement in both temporal and spatial scales. Comparisons of

  2. Hydrodynamic model of the open-pit mine “Buvač” (Republic of Srpska

    Directory of Open Access Journals (Sweden)

    Papić Petar

    2013-09-01

    Full Text Available Projecting of the dewatering system of the open-pit mine “Buvač” (Republic of Srpska, Bosnia and Herzegovina is based on the use of hydrodynamic model of groundwater regime. Creating the hydrodynamic model of the open-pit mine “Buvač“ was made in phases, which began by basic interpretation of collected data, along with schematization of the groundwater flow and flow conditions, and finally, forming and calibration of model. Hydrodynamic model was created as multilayer model with eight layers. Calibration of the hydrodynamic model is the starting point for making prognosis calculation in order to create the most optimal system of open-pit mine protection from groundwater. The results of model calibration indicated that the rivers Gomjenica and Bistrica, precipitation and inflow from karstified rocks are the primary sources of recharge of the limonite ore body “Buvač”.

  3. Hydrodynamic modeling of accretion shocks on a star with radiative transport and a chromospheric model

    Science.gov (United States)

    de Sá, L.; Chièze, J.-P.; Stehlé, C.; Hubeny, I.; Delahaye, F.; Lanz, T.

    2012-12-01

    The aim of the project (ANR STARSHOCK) is to understand the dynamics and the radiative properties of accretion columns, linking the circumstellar disk to the surface photosphere of Young Stellar Objects. The hydrodynamics is computed first, using a high resolution hydrodynamic 1D ALE code (ASTROLABE) coupled to radiative transfer and line cooling, along with a model for the acoustic heating of the chromospheric plasma. Spectra are then post-processed with a 1D radiative transfer code (SYNSPEC), using DFE solver and an extended atomic database covering a wavelength range from X rays to visible.

  4. Data assimilation in hydrodynamic modelling: on the treatment of non-linearity and bias

    DEFF Research Database (Denmark)

    Sørensen, Jacob Viborg Tornfeldt; Madsen, Henrik

    2004-01-01

    The state estimation problem in hydrodynamic modelling is formulated. The three-dimensional hydrodynamic model MIKE 3 is extended to provide a stochastic state space description of the system and observations are related to the state through the measurement equation. Two state estimators, the max......The state estimation problem in hydrodynamic modelling is formulated. The three-dimensional hydrodynamic model MIKE 3 is extended to provide a stochastic state space description of the system and observations are related to the state through the measurement equation. Two state estimators...... oceanic models. Three measures of non-linearity and one bias measure have been implemented to assess the validity of these assumptions for a given model set-up. Two of these measures further express the non-Gaussianity and thus guide the proper statistical interpretation of the results. The applicability...

  5. Monitoring Mediterranean marine pollution using remote sensing and hydrodynamic modelling

    Science.gov (United States)

    La Loggia, Goffredo; Capodici, Fulvio; Ciraolo, Giuseppe; Drago, Aldo; Maltese, Antonino

    2011-11-01

    Human activities contaminate both coastal areas and open seas, even though impacts are different in terms of pollutants, ecosystems and recovery time. In particular, Mediterranean offshore pollution is mainly related to maritime transport of oil, accounting for 25% of the global maritime traffic and, during the last 25 years, for nearly 7% of the world oil accidents, thus causing serious biological impacts on both open sea and coastal zone habitats. This paper provides a general review of maritime pollution monitoring using integrated approaches of remote sensing and hydrodynamic modeling; focusing on the main results of the MAPRES (Marine pollution monitoring and detection by aerial surveillance and satellite images) research project on the synergistic use of remote sensing, forecasting, cleanup measures and environmental consequences. The paper also investigates techniques of oil spill detection using SAR images, presenting the first results of "Monitoring of marine pollution due to oil slick", a COSMO-SkyMed funded research project where X-band SAR constellation images provided by the Italian Space Agency are used. Finally, the prospect of using real time observations of marine surface conditions is presented through CALYPSO project (CALYPSO-HF Radar Monitoring System and Response against Marine Oil Spills in the Malta Channel), partly financed by the EU under the Operational Programme Italia-Malta 2007-2013. The project concerns the setting up of a permanent and fully operational HF radar observing system, capable of recording surface currents (in real-time with hourly updates) in the stretch of sea between Malta and Sicily. A combined use of collected data and numerical models, aims to optimize intervention and response in the case of marine oil spills.

  6. Improving 1D Stellar Models with 3D Atmospheres

    Science.gov (United States)

    Rørsted Mosumgaard, Jakob; Silva Aguirre, Víctor; Weiss, Achim; Christensen-Dalsgaard, Jørgen; Trampedach, Regner

    2017-10-01

    Stellar evolution codes play a major role in present-day astrophysics, yet they share common issues. In this work we seek to remedy some of those by the use of results from realistic and highly detailed 3D hydrodynamical simulations of stellar atmospheres. We have implemented a new temperature stratification extracted directly from the 3D simulations into the Garching Stellar Evolution Code to replace the simplified atmosphere normally used. Secondly, we have implemented the use of a variable mixing-length parameter, which changes as a function of the stellar surface gravity and temperature - also derived from the 3D simulations. Furthermore, to make our models consistent, we have calculated new opacity tables to match the atmospheric simulations. Here, we present the modified code and initial results on stellar evolution using it.

  7. Hydrodynamics in a cold-model jetting fluidized-bed gasifier with a binary mixture

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K.; Zhang, J.; Zhang, B. [University of Petroleum, Beijing (China)

    2004-12-01

    The average properties of binary system defined by Goossens and others are incorporated into an Eulerian-Eulerian Computational Fluid Dynamics (CFD) model for simulating the hydrodynamics in a cold model of jetting fluidized bed gasifiers. Some of the essential hydrodynamic parameters, including gas - and solid-velocity profiles, time-averaged voidage profiles, and jet penetration height, are investigated in this paper. These results show the CFD approach is an effective tool for predicting hydrodynamics in jetting fluidized beds with multi-component mixture. 15 refs., 6 figs., 3 tabs.

  8. Coupling hydrodynamic and wave models: first step and sensitivity experiments in the Mediterranean Sea

    Science.gov (United States)

    Clementi, Emanuela; Oddo, Paolo; Drudi, Massimiliano; Pinardi, Nadia; Korres, Gerasimos; Grandi, Alessandro

    2017-10-01

    This work describes the first step towards a fully coupled modelling system composed of an ocean circulation and a wind wave model. Sensitivity experiments are presented for the Mediterranean Sea where the hydrodynamic model NEMO is coupled with the third-generation wave model WaveWatchIII (WW3). Both models are implemented at 1/16° horizontal resolution and are forced by ECMWF 1/4° horizontal resolution atmospheric fields. The models are two-way coupled at hourly intervals exchanging the following fields: sea surface currents and temperature are transferred from NEMO to WW3 by modifying the mean momentum transfer of waves and the wind speed stability parameter, respectively. The neutral drag coefficient computed by WW3 is then passed to NEMO, which computes the surface stress. Five-year (2009-2013) numerical experiments were carried out in both uncoupled and coupled mode. In order to validate the modelling system, numerical results were compared with coastal and drifting buoys and remote sensing data. The results show that the coupling of currents with waves improves the representation of the wave spectrum. However, the wave-induced drag coefficient shows only minor improvements in NEMO circulation fields, such as temperature, salinity, and currents.

  9. [Expression of Hydrodynamic Injection-mediated PD-L1 in Myeloablative Conditioning Mouse Model].

    Science.gov (United States)

    Li, Xiao-Fan; Li, Nai-Nong; Yang, Feng-E; Chen, Yuan-Zhong

    2015-10-01

    To establish the mouse model for the expression of PD-L1 by hydrodynamic injection and to study the effects of myeloablative conditioning on hydrodynamic injection-mediated PD-L1 expression. Plasmid amplification, hydrodynamic injection, collagenase perfusion, real time PCR, ELISA and flow cytometry were applied to test the expression and function of PD-L1. Also, animal models were set up to test the effects of chemical or radiactive myeloablative conditioning on hydrodynamic injection-mediated PD-L1 expression. The expression of PD-L1 mRNA and protein could be detected as early as 8 h after hyrodynamic injection and reached peak expression by 24 h, and returned to baseline level by 7 d after injection. Serum PD-L1 level reached to 100 µg/ml as early as 24 h after injection and plateaued at 7 d after injection. Serum PD-L1 persisted for 3 weeks and declined to baseline after 1 month of hydrodynamic injection. The PD-L1 function induced by hydrodynamic injection was consistent with literature reports. At each time point, the PD-L1 expression was not different significantly between the myeloablative conditioning group and control group; the mice transfected with PD-L1 showed a higher survival rate than that in control group. Myeloablative conditioning does not affect hydrodynamic injection-mediated PD-L1 expression, indicating that the PD-L1 can be used in HSCT mouse model.

  10. Mixed boundary-value problems for quantum hydrodynamic models with semiconductors in thermal equilibrium

    Directory of Open Access Journals (Sweden)

    Jianwei Dong

    2005-11-01

    Full Text Available We show the existence of solutions for mixed boundary-value problems that model quantum hydrodynamics in thermal equilibrium. Also we find the semi-classical limit of the solutions.

  11. Hydrodynamic modeling of the mouth of the Columbia River, Oregon and Washington, 2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A process-based numerical model of the mouth of the Columbia River (MCR) and estuary, Oregon and Washington, was applied to simulate hydrodynamic conditions for the...

  12. Modeling Hydrodynamic State of Oil and Gas Condensate Mixture in a Pipeline

    Directory of Open Access Journals (Sweden)

    Dudin Sergey

    2016-01-01

    Based on the developed model a calculation method was obtained which is used to analyze hydrodynamic state and composition of hydrocarbon mixture in each ith section of the pipeline when temperature-pressure and hydraulic conditions change.

  13. Fractionation of terrestrial neon by hydrodynamic hydrogen escape from ancient steam atmospheres

    Science.gov (United States)

    Zahnle, K.

    Atmospheric neon is isotopically heavier than mantle neon. By contrast, nonradiogenic mantle Ar, Kr, and Xe are not known to differ from the atmosphere. These observations are most easily explained by selective neon loss to space; however, neon is much too massive to escape from the modern atmosphere. Steam atmospheres are a likely, if intermittent, feature of the accreting Earth. They occur because, on average, the energy liberated during accretion places Earth above the runaway greenhouse threshold, so that liquid water is not stable at the surface. It is found that steam atmospheres should have lasted some ten to fifty million years. Hydrogen escape would have been vigorous, but abundant heavy constituents would have been retained. There is no lack of plausible candidates; CO2, N2, or CO could all suffice. Neon can escape because it is less massive than any of the likely pollutants. Neon fractionation would have been a natural byproduct. Assuming that the initial Ne-20/Ne-22 ratio was solar, it was found that it would have taken some ten million years to effect the observed neon fractionation in a 30 bar steam atmosphere fouled with 10 bars of CO. Thicker atmospheres would have taken longer; less CO, shorter. This mechanism for fractionating neon has about the right level of efficiency. Because the lighter isotope escapes much more readily, total neon loss is pretty minimal; less than half of the initial neon endowment escapes.

  14. Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Khangaonkar, Tarang; Labiosa, Rochelle G.; Kim, Taeyun

    2010-11-30

    The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or dominate human impacts to dissolved oxygen levels in the sensitive areas. In this study, an intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model. The overall model grid resolution within Puget Sound in its present configuration is about 880 m. The model was driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulated tidal circulations, temperature, and salinity distributions in Puget Sound. The model was validated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model validation indicated that the model simulates tidal elevations and currents in Puget Sound well and reproduces the general patterns of the temperature and salinity distributions.

  15. A hydrodynamic mechanism of meteor ablation. The melt-spraying model

    Science.gov (United States)

    Girin, Oleksandr G.

    2017-10-01

    Context. Hydrodynamic conditions are similar in a molten meteoroid and a liquid drop in a high-speed airflow. Despite the fact that the latter is well-studied, both experimentally and theoretically, hydrodynamic instability theory has not been applied to study the fragmentation of molten meteoroids. Aims: We aim to treat quasi-continuous spraying of meteoroid melt due to hydrodynamic instability as a possible mechanism of ablation. Our objectives are to calculate the time development of particle release, the released particle sizes and their distribution by sizes, as well as the meteoroid mass loss law. Methods: We have applied gradient instability theory to model the behaviour of the meteoroid melt layer and its interaction with the atmosphere. We have assumed a spherical meteoroid and that the meteoroid has a shallow entry angle, such that the density of the air stream interacting with the meteoroid is nearly constant. Results: High-frequency spraying of the molten meteoroid is numerically simulated. The intermediate and final size distributions of released particles are calculated, as well as the meteoroid mass loss law. Fast and slow meteoroids of iron and stone compositions are modelled, resulting in significant differences in the size distribution of melt particles sprayed from each meteoroid. Less viscous iron melt produces finer particles and a denser aerosol wake than a stony one does. Conclusions: Analysis of the critical conditions for the gradient instability mechanism shows that the dynamic pressure of the air-stream at heights up to 100 km is sufficient to overcome surface tension forces and pull out liquid particles from the meteoroid melt by means of unstable disturbances. Hence, the proposed melt-spraying model is able to explain quasi-continuous mode of meteoroid fragmentation at large heights and low dynamic pressures. A closed-form solution of the meteoroid ablation problem is obtained due to the melt-spraying model usage, at the meteoroid

  16. A Full Hydrodynamic Modelling of 2D Breaker Bar Development

    DEFF Research Database (Denmark)

    Jacobsen, Niels Gjøl; Fredsøe, Jørgen

    2011-01-01

    zone. The temporal change of a cross shore beach profile under both regular and bichromatic waves is considered. The dependency on the morphological time scale on the regularity of the incident waves is discussed. The feedback onto the hydrodynamics due to a changing bed level is discussed in the case...

  17. Hydrodynamic model for picosecond propagation of laser-created nanoplasmas

    CERN Document Server

    Saxena, Vikrant; Ziaja, Beata; Santra, Robin

    2015-01-01

    The interaction of a free-electron-laser pulse with a moderate or large size cluster is known to create a quasi-neutral nanoplasma, which then expands on hydrodynamic timescale, i.e., $>1$ ps. To have a better understanding of ion and electron data from experiments derived from laser-irradiated clusters, one needs to simulate cluster dynamics on such long timescales for which the molecular dynamics approach becomes inefficient. We therefore propose a two-step Molecular Dynamics-Hydrodynamic scheme. In the first step we use molecular dynamics code to follow the dynamics of an irradiated cluster until all the photo-excitation and corresponding relaxation processes are finished and a nanoplasma, consisting of ground-state ions and thermalized electrons, is formed. In the second step we perform long-timescale propagation of this nanoplasma with a computationally efficient hydrodynamic approach. In the present paper we examine the feasibility of a hydrodynamic two-fluid approach to follow the expansion of spherica...

  18. Stochastic models for atmospheric dispersion

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2003-01-01

    Simple stochastic differential equation models have been applied by several researchers to describe the dispersion of tracer particles in the planetary atmospheric boundary layer and to form the basis for computer simulations of particle paths. To obtain the drift coefficient, empirical vertical...... velocity distributions that depend on height above the ground both with respect to standard deviation and skewness are substituted into the stationary Fokker/Planck equation. The particle position distribution is taken to be uniform *the well/mixed condition( and also a given dispersion coefficient...

  19. Frontiers in Atmospheric Chemistry Modelling

    Science.gov (United States)

    Colette, Augustin; Bessagnet, Bertrand; Meleux, Frederik; Rouïl, Laurence

    2013-04-01

    The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry-transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, which demonstrated the robustness of the selected air quality model, we discuss the added value in terms of air pollution modelling and decision support. The comparison with in-situ observations shows that model biases are significantly improved despite some spurious added spatial variability attributed to shortcomings in the emission downscaling process and coarse resolution of the meteorological fields. The increased spatial resolution is clearly beneficial for the detection of exceedances and exposure modelling. We reveal small scale air pollution patterns that highlight the contribution of city plumes to background air pollution levels. Up to a factor 5 underestimation of the fraction of population exposed to detrimental levels of pollution can be obtained with a coarse simulation if subgrid scale correction such as urban increments are ignored. This experiment opens new perspectives for environmental decision making. After two decades of efforts to reduce air pollutant emissions across Europe, the challenge is now to find the optimal trade-off between national and local air quality management strategies. While the first approach is based on sectoral strategies and energy policies, the later builds upon new alternatives such as urban development. The strategies, the decision pathways and the involvement of individual citizen differ, and a compromise based on cost and efficiency must be found. We illustrated how high performance computing in atmospheric science can contribute to this

  20. Advanced Atmospheric Ensemble Modeling Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Chiswell, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Kurzeja, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Maze, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Viner, B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Werth, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-29

    Ensemble modeling (EM), the creation of multiple atmospheric simulations for a given time period, has become an essential tool for characterizing uncertainties in model predictions. We explore two novel ensemble modeling techniques: (1) perturbation of model parameters (Adaptive Programming, AP), and (2) data assimilation (Ensemble Kalman Filter, EnKF). The current research is an extension to work from last year and examines transport on a small spatial scale (<100 km) in complex terrain, for more rigorous testing of the ensemble technique. Two different release cases were studied, a coastal release (SF6) and an inland release (Freon) which consisted of two release times. Observations of tracer concentration and meteorology are used to judge the ensemble results. In addition, adaptive grid techniques have been developed to reduce required computing resources for transport calculations. Using a 20- member ensemble, the standard approach generated downwind transport that was quantitatively good for both releases; however, the EnKF method produced additional improvement for the coastal release where the spatial and temporal differences due to interior valley heating lead to the inland movement of the plume. The AP technique showed improvements for both release cases, with more improvement shown in the inland release. This research demonstrated that transport accuracy can be improved when models are adapted to a particular location/time or when important local data is assimilated into the simulation and enhances SRNL’s capability in atmospheric transport modeling in support of its current customer base and local site missions, as well as our ability to attract new customers within the intelligence community.

  1. Coupling hydrodynamic and wave propagation modeling for waveform modeling of SPE.

    Science.gov (United States)

    Larmat, C. S.; Steedman, D. W.; Rougier, E.; Delorey, A.; Bradley, C. R.

    2015-12-01

    The goal of the Source Physics Experiment (SPE) is to bring empirical and theoretical advances to the problem of detection and identification of underground nuclear explosions. This paper presents effort to improve knowledge of the processes that affect seismic wave propagation from the hydrodynamic/plastic source region to the elastic/anelastic far field thanks to numerical modeling. The challenge is to couple the prompt processes that take place in the near source region to the ones taking place later in time due to wave propagation in complex 3D geologic environments. In this paper, we report on results of first-principles simulations coupling hydrodynamic simulation codes (Abaqus and CASH), with a 3D full waveform propagation code, SPECFEM3D. Abaqus and CASH model the shocked, hydrodynamic region via equations of state for the explosive, borehole stemming and jointed/weathered granite. LANL has been recently employing a Coupled Euler-Lagrange (CEL) modeling capability. This has allowed the testing of a new phenomenological model for modeling stored shear energy in jointed material. This unique modeling capability has enabled highfidelity modeling of the explosive, the weak grout-filled borehole, as well as the surrounding jointed rock. SPECFEM3D is based on the Spectral Element Method, a direct numerical method for full waveform modeling with mathematical accuracy (e.g. Komatitsch, 1998, 2002) thanks to its use of the weak formulation of the wave equation and of high-order polynomial functions. The coupling interface is a series of grid points of the SEM mesh situated at the edge of the hydrodynamic code domain. Displacement time series at these points are computed from output of CASH or Abaqus (by interpolation if needed) and fed into the time marching scheme of SPECFEM3D. We will present validation tests and waveforms modeled for several SPE tests conducted so far, with a special focus on effect of the local topography.

  2. Simulation of Tailrace Hydrodynamics Using Computational Fluid Dynamics Models

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Christopher B.; Richmond, Marshall C.

    2001-05-01

    This report investigates the feasibility of using computational fluid dynamics (CFD) tools to investigate hydrodynamic flow fields surrounding the tailrace zone below large hydraulic structures. Previous and ongoing studies using CFD tools to simulate gradually varied flow with multiple constituents and forebay/intake hydrodynamics have shown that CFD tools can provide valuable information for hydraulic and biological evaluation of fish passage near hydraulic structures. These studies however are incapable of simulating the rapidly varying flow fields that involving breakup of the free-surface, such as those through and below high flow outfalls and spillways. Although the use of CFD tools for these types of flow are still an active area of research, initial applications discussed in this report show that these tools are capable of simulating the primary features of these highly transient flow fields.

  3. Reduction of Waste Water in Erhai Lake Based on MIKE21 Hydrodynamic and Water Quality Model

    OpenAIRE

    Changjun Zhu; Qinag Liang; Feng Yan; Wenlong Hao

    2013-01-01

    In order to study the ecological water environment in Erhai Lake, different monitoring sections were set to research the change of hydrodynamics and water quality. According to the measured data, MIKE21 Ecolab, the water quality simulation software developed by DHI, is applied to simulate the water quality in Erhai Lake. The hydrodynamics model coupled with water quality is established by MIKE21FM software to simulate the current situation of Erhai Lake. Then through the comparison with the m...

  4. Effects of hydrodynamics and thermal radiation in the atmosphere after comet impacts

    Science.gov (United States)

    Nemchinov, I. V.; Popova, M. P.; Shubadeeva, L. P.; Shuvalov, V. V.; Svetsov, V. V.

    1993-01-01

    Radiation phenomena in the atmosphere after impacts of cosmic bodies have special features in comparison with the surface nuclear explosions. First, initial concentration of energy after the impact is lower, and second, a wake after the passage of the meteoroid through the atmosphere has a dramatic effect on the atmospheric flow and radiation transfer. Consequently, scaling laws can not be employed for prediction of the flow in the atmosphere and the light flux on the Earth's surface. If a density of high-velocity impactor is low relative to the ground, as in a case of a comet impact on rocks, a major part of the kinetic energy is converted to internal energy of dense hot vapors. But radiation effects can be essential even for fairly low velocities of the impactor. To clarify this issue we have undertaken calculations of 100-Mt explosions at the Earth's surface caused by small comets with velocities from 10 to 70 km/sec. That is, the initial concentration of energy has been varied. The calculations have shown that for velocities of the comet greater or about 20 km/sec a portion of energy emitted from the fireball exceeds 20% of the total energy of the explosion and this quantity does not change very much with the velocity. Other aspects of this investigation are discussed.

  5. Activity-induced clustering in model dumbbell swimmers: the role of hydrodynamic interactions.

    Science.gov (United States)

    Furukawa, Akira; Marenduzzo, Davide; Cates, Michael E

    2014-08-01

    Using a fluid-particle dynamics approach, we numerically study the effects of hydrodynamic interactions on the collective dynamics of active suspensions within a simple model for bacterial motility: each microorganism is modeled as a stroke-averaged dumbbell swimmer with prescribed dipolar force pairs. Using both simulations and qualitative arguments, we show that, when the separation between swimmers is comparable to their size, the swimmers' motions are strongly affected by activity-induced hydrodynamic forces. To further understand these effects, we investigate semidilute suspensions of swimmers in the presence of thermal fluctuations. A direct comparison between simulations with and without hydrodynamic interactions shows these to enhance the dynamic clustering at a relatively small volume fraction; with our chosen model the key ingredient for this clustering behavior is hydrodynamic trapping of one swimmer by another, induced by the active forces. Furthermore, the density dependence of the motility (of both the translational and rotational motions) exhibits distinctly different behaviors with and without hydrodynamic interactions; we argue that this is linked to the clustering tendency. Our study illustrates the fact that hydrodynamic interactions not only affect kinetic pathways in active suspensions, but also cause major changes in their steady state properties.

  6. Observations and Modeling of Atmospheric Radiance Structure

    National Research Council Canada - National Science Library

    Wintersteiner, Peter

    2001-01-01

    The overall purpose of the work that we have undertaken is to provide new capabilities for observing and modeling structured radiance in the atmosphere, particularly the non-LTE regions of the atmosphere...

  7. Hydrodynamic properties of San Quintin Bay, Baja California: Merging models and observations.

    Science.gov (United States)

    Melaku Canu, Donata; Aveytua-Alcázar, Leslie; Camacho-Ibar, Victor F; Querin, Stefano; Solidoro, Cosimo

    2016-07-15

    We investigated the physical dynamics of San Quintin Bay, a coastal lagoon located on the Pacific coast of northern Baja California, Mexico. We implemented, validated and used a finite element 2-D hydrodynamic model to characterize the spatial and temporal variability of the hydrodynamic of the bay in response to variability in the tidal regime and in meteorological forcing patterns. Our analysis of general circulation, residual currents, residence times, and tidal propagation delays allowed us to characterize spatial variability in the hydrodynamic basin features. The eulerian water residence time is -on average and under reference conditions- approximately 7days, although this can change significantly by region and season and under different tidal and meteorological conditions. Ocean upwelling events that bring colder waters into the bay mouth affect hydrodynamic properties in all areas of the lagoon and may affect ecological dynamics. A return to pre-upwelling conditions would take approximately 10days. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Modelling centrifugal partition chromatography separation behavior to characterize influencing hydrodynamic effects on separation efficiency.

    Science.gov (United States)

    Schwienheer, C; Krause, J; Schembecker, G; Merz, J

    2017-04-07

    In addition to the selection or adjustment of phase systems to gain a suitable partition coefficient for the target molecule, the separation efficiency in centrifugal partition chromatography (CPC) is strongly influenced by the hydrodynamic interactions of the mobile and the stationary phase in the chambers. Thus, the hydrodynamic interactions must be investigated and understood in order to enhance a CPC separation run. Different hydrodynamic effects like mass transfer, back mixing and the non-ideal behavior of stationary phase, which cannot be determined directly, are known, but quantifying these effects and their influence on separation performance is barely achieved. In order to understand their influence, a physically detailed mathematical model of a CPC chamber was developed. The model includes a parameter representing the hydrodynamic effects mentioned above and is able to determine the parameters significance by fitting them to separation experiment data. The acquired knowledge is used to correlate the effects of the hydrodynamic influences on the separation performance and can be used to forecast hydrodynamic and separation behavior in a CPC device. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Coupled 1D-2D hydrodynamic inundation model for sewer overflow: Influence of modeling parameters

    Directory of Open Access Journals (Sweden)

    Adeniyi Ganiyu Adeogun

    2015-10-01

    Full Text Available This paper presents outcome of our investigation on the influence of modeling parameters on 1D-2D hydrodynamic inundation model for sewer overflow, developed through coupling of an existing 1D sewer network model (SWMM and 2D inundation model (BREZO. The 1D-2D hydrodynamic model was developed for the purpose of examining flood incidence due to surcharged water on overland surface. The investigation was carried out by performing sensitivity analysis on the developed model. For the sensitivity analysis, modeling parameters, such as mesh resolution Digital Elevation Model (DEM resolution and roughness were considered. The outcome of the study shows the model is sensitive to changes in these parameters. The performance of the model is significantly influenced, by the Manning's friction value, the DEM resolution and the area of the triangular mesh. Also, changes in the aforementioned modeling parameters influence the Flood characteristics, such as the inundation extent, the flow depth and the velocity across the model domain.

  10. Hydrodynamic modelling in the Polish Zone of the Baltic Sea - an overview of Polish achievements

    Directory of Open Access Journals (Sweden)

    Ewa Jasińska

    2003-03-01

    Full Text Available This paper gives a general overview of Polish experience and achievements with regard to hydrodynamic modelling in the Polish zone of the Baltic Sea. The first work started already at the end of the sixties when the first 1D and 2D hydrodynamic models were set up. With the development of numerical methods and increasing computational power a number of 1D, 2D and 3D models were set up and tested. Global, regional and local models cover the most important water bodies,i.e. the Pomeranian Bay - Szczecin Lagoon and Gulf of Gdansk - Vistula Lagoon systems.

  11. Sensitivity analysis of a coupled hydrodynamic-vegetation model using the effectively subsampled quadratures method

    Science.gov (United States)

    Kalra, Tarandeep S.; Aretxabaleta, Alfredo; Seshadri, Pranay; Ganju, Neil K.; Beudin, Alexis

    2017-01-01

    Coastal hydrodynamics can be greatly affected by the presence of submerged aquatic vegetation. The effect of vegetation has been incorporated into the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System. The vegetation implementation includes the plant-induced three-dimensional drag, in-canopy wave-induced streaming, and the production of turbulent kinetic energy by the presence of vegetation. In this study, we evaluate the sensitivity of the flow and wave dynamics to vegetation parameters using Sobol' indices and a least squares polynomial approach referred to as Effective Quadratures method. This method reduces the number of simulations needed for evaluating Sobol' indices and provides a robust, practical, and efficient approach for the parameter sensitivity analysis. The evaluation of Sobol' indices shows that kinetic energy, turbulent kinetic energy, and water level changes are affected by plant density, height, and to a certain degree, diameter. Wave dissipation is mostly dependent on the variation in plant density. Performing sensitivity analyses for the vegetation module in COAWST provides guidance for future observational and modeling work to optimize efforts and reduce exploration of parameter space.

  12. Recent extensions of the residence time distribution concept: unsteady state conditions and hydrodynamic model developments

    Directory of Open Access Journals (Sweden)

    Claudel S.

    2000-01-01

    Full Text Available Two recent extensions of the residence time distribution concept are developed. The first one concerns the use of this method under transient conditions, a concept theoretically treated but rarely confirm by relevant experiments. In the present work, two experimental set-ups have been used to verify some limits of the concept. The second extension is devoted to the development of hydrodynamic models. Up to now, the hydrodynamics of the process are either determined by simple models (mixing cells in series, plug flow reactor with axial dispersion or by the complex calculation of the velocity profile obtained via the Navier-Stokes equations. An alternative is to develop a hydrodynamic model by use of a complex network of interconnected elementary reactors. Such models should be simple enough to be derived easily and sufficiently complex to give a good representation of the behavior of the process.

  13. Development of Fully Coupled Aeroelastic and Hydrodynamic Models for Offshore Wind Turbines: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jonkman, J. M.; Sclavounos, P. D.

    2006-01-01

    Aeroelastic simulation tools are routinely used to design and analyze onshore wind turbines, in order to obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These tools employ sophisticated models of wind-inflow; aerodynamic, gravitational, and inertial loading of the rotor, nacelle, and tower; elastic effects within and between components; and mechanical actuation and electrical responses of the generator and of control and protection systems. For offshore wind turbines, additional models of the hydrodynamic loading in regular and irregular seas, the dynamic coupling between the support platform motions and wind turbine motions, and the dynamic characterization of mooring systems for compliant floating platforms are also important. Hydrodynamic loading includes contributions from hydrostatics, wave radiation, and wave scattering, including free surface memory effects. The integration of all of these models into comprehensive simulation tools, capable of modeling the fully coupled aeroelastic and hydrodynamic responses of floating offshore wind turbines, is presented.

  14. Thermo-hydrodynamic lubrication in hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the thermo-hydrodynamic and the thermo-elasto-hydrodynamic lubrication. The algorithms are methodically detailed and each section is thoroughly illustrated.

  15. Concurrent Modeling of Hydrodynamics and Interaction Forces Improves Particle Deposition Predictions.

    Science.gov (United States)

    Jin, Chao; Ren, Carolyn L; Emelko, Monica B

    2016-04-19

    It is widely believed that media surface roughness enhances particle deposition-numerous, but inconsistent, examples of this effect have been reported. Here, a new mathematical framework describing the effects of hydrodynamics and interaction forces on particle deposition on rough spherical collectors in absence of an energy barrier was developed and validated. In addition to quantifying DLVO force, the model includes improved descriptions of flow field profiles and hydrodynamic retardation functions. This work demonstrates that hydrodynamic effects can significantly alter particle deposition relative to expectations when only the DLVO force is considered. Moreover, the combined effects of hydrodynamics and interaction forces on particle deposition on rough, spherical media are not additive, but synergistic. Notably, the developed model's particle deposition predictions are in closer agreement with experimental observations than those from current models, demonstrating the importance of inclusion of roughness impacts in particle deposition description/simulation. Consideration of hydrodynamic contributions to particle deposition may help to explain discrepancies between model-based expectations and experimental outcomes and improve descriptions of particle deposition during physicochemical filtration in systems with nonsmooth collector surfaces.

  16. A data assimilation system combining CryoSat-2 data and hydrodynamic river models

    DEFF Research Database (Denmark)

    Schneider, Raphael; Ridler, Marc-Etienne; Godiksen, Peter Nygaard

    2017-01-01

    There are numerous hydrologic studies using satellite altimetry data from repeat-orbit missions such as Envisat or Jason over rivers. This study is one of the first examples for the combination of altimetry from drifting-ground track satellite missions, namely CryoSat-2, with a river model. Cryo......Sat-2 SARIn Level 2 data is used to improve a 1D hydrodynamic model of the Brahmaputra River in South Asia, which is based on the Saint-Venant equations for unsteady flow and set up in the MIKE HYDRO River software. After calibration of discharge and water level the hydrodynamic model can accurately...

  17. Numerical modeling of ocean hydrodynamics with variational assimilation of observational data

    Science.gov (United States)

    Zalesny, V. B.; Agoshkov, V. I.; Shutyaev, V. P.; Le Dimet, F.; Ivchenko, B. O.

    2016-07-01

    Models and methods of the numerical modeling of ocean hydrodynamics dating back to the pioneering works of A.S. Sarkisyan are considered, with emphasis on the formulation of problems and algorithms of mathematical modeling and the four-dimensional variational assimilation of observational data. An algorithm is proposed for studying the sensitivity of the optimal solution to observational data errors in a seasurface temperature assimilation problem in order to retrieve heat fluxes on the surface. An example of a solution of the optimal problem of the World Ocean hydrodynamics with the assimilation of climatic temperature and salinity observations is offered.

  18. Integrated methodology for constructing a quantified hydrodynamic model for application to clastic petroleum reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Honarpour, M. M.; Schatzinger, R. A.; Szpakiewicz, M. J.; Jackson, S. R.; Sharma, B.; Tomutsa, L.; Chang, M. M.

    1990-01-01

    A comprehensive, multidisciplinary, stepwise methodology is developed for constructing and integration geological and engineering information for predicting petroleum reservoir performance. This methodology is based on our experience in characterizing shallow marine reservoirs, but it should also apply to other deposystems. The methodology is presented as Part 1 of this report. Three major tasks that must be studied to facilitate a systematic approach for constructing a predictive hydrodynamic model for petroleum reservoirs are addressed: (1) data collection, organization, evaluation, and integration; (2) hydrodynamic model construction and verification; and (3) prediction and ranking of reservoir parameters by numerical simulation using data derived from the model. 39 refs., 62 figs., 13 tabs.

  19. Slow hydrodynamic regime to model B supergiant winds

    Science.gov (United States)

    Venero, R. O. J.; Cidale, L. S.; Cure, M.; Haucke, M.

    2017-10-01

    Current hydrodynamic solutions for the winds of early-type stars are obtained from the theory of rotating stars with radiation-driven winds. These solutions are separated into two main branches: the fast solution and the slow solutions. The first set is the standard CAK solution, while the second set corresponds to a group of solutions with still poorly known properties. In this work we study the properties of the slow wind regime derived for different values of the line force parameters, and compute the resulting line profiles. Then we fit our synthetic line profiles with observed ones, in order to evaluate the ability of the slow solution to represent the variety of features observed in line profiles originated along the winds. We find that the winds of B supergiants can be well-represented by the slow regime, a result that could give new insights into the true nature of the outflows in early-type stars.

  20. Modelling free surface flows with smoothed particle hydrodynamics

    Directory of Open Access Journals (Sweden)

    L.Di G.Sigalotti

    2006-01-01

    Full Text Available In this paper the method of Smoothed Particle Hydrodynamics (SPH is extended to include an adaptive density kernel estimation (ADKE procedure. It is shown that for a van der Waals (vdW fluid, this method can be used to deal with free-surface phenomena without difficulties. In particular, arbitrary moving boundaries can be easily handled because surface tension is effectively simulated by the cohesive pressure forces. Moreover, the ADKE method is seen to increase both the accuracy and stability of SPH since it allows the width of the kernel interpolant to vary locally in a way that only the minimum necessary smoothing is applied at and near free surfaces and sharp fluid-fluid interfaces. The method is robust and easy to implement. Examples of its resolving power are given for both the formation of a circular liquid drop under surface tension and the nonlinear oscillation of excited drops.

  1. Smoothed particle hydrodynamics model for phase separating fluid mixtures. I. General equations

    NARCIS (Netherlands)

    Thieulot, C; Janssen, LPBM; Espanol, P

    We present a thermodynamically consistent discrete fluid particle model for the simulation of a recently proposed set of hydrodynamic equations for a phase separating van der Waals fluid mixture [P. Espanol and C.A.P. Thieulot, J. Chem. Phys. 118, 9109 (2003)]. The discrete model is formulated by

  2. Hydrodynamic Modeling Analysis of Union Slough Restoration Project in Snohomish River, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Wang, Taiping

    2010-12-20

    A modeling study was conducted to evaluate additional project design scenarios at the Union Slough restoration/mitigation site during low tide and to provide recommendations for finish-grade elevations to achieve desired drainage. This was accomplished using the Snohomish River hydrodynamic model developed previously by PNNL.

  3. Hydrodynamic evaluation of a hydraulic clarifier through hydraulic behaviour indicators and simplified flow models

    Directory of Open Access Journals (Sweden)

    Paola Patiño

    2012-04-01

    Full Text Available Hydrodynamic phenomena take place within water treatment plants associated with physical, operational and environmental factors which can affect the water quality. This study evaluated a hydraulic clarifier’s hydrodynamic pattern using sludge recirculation through continuous tracer test leading to determining hydraulic behaviour indicators and simplified flow models. The clarifier had dual flow with a predominantly complete mixture during the hours in which higher temperatures were reported for affluent water compared to those reported inside the reactor, causing the formation of density currents promoting mixing in the reactor and increased turbidity in the effluent. The hydraulic indicators and the Wolf-Resnick model had higher sensitivity to the influence of temperature on reactor hydrodynamics.

  4. Hybrid polygon and hydrodynamic nebula modeling with multi-waveband radiation transfer in astrophysics

    Science.gov (United States)

    Steffen, W.; Koning, N.

    2017-07-01

    We demonstrate the potential for research and outreach of mixed polygon and hydrodynamic modeling and multi-waveband rendering in the interactive 3-D astrophysical virtual laboratory Shape. In 3-D special effects and animation software for the mass media, computer graphics techniques that mix polygon and numerical hydrodynamics have become common place. In astrophysics, however, interactive modeling with polygon structures has only become available with the software Shape. Numerical hydrodynamic simulations and their visualization are usually separate, while in Shape it is integrated with the polygon modeling approach that requires no programming by the user. With two generic examples, we demonstrate that research and outreach modeling can be achieved with techniques similar to those used in the media industry with the added capability for physical rendering at any wavelength band, yielding more realistic radiation modeling. Furthermore, we show how the hydrodynamics and the polygon mesh modeling can be mixed to achieve results that are superior to those obtained using either one of these modeling techniques alone.

  5. A first computational framework for integrated hydrologic-hydrodynamic inundation modelling

    Science.gov (United States)

    Hoch, Jannis; Baart, Fedor; Neal, Jeffrey; van Beek, Rens; Winsemius, Hessel; Bates, Paul; Bierkens, Marc

    2017-04-01

    To provide detailed flood hazard and risk estimates for current and future conditions, advanced modelling approaches are required. Currently, many approaches are however built upon specific hydrologic or hydrodynamic model routines. By applying these routines in stand-alone mode important processes cannot accurately be described. For instance, global hydrologic models (GHM) run at coarse spatial resolution which does not identify locally relevant flood hazard information. Moreover, hydrologic models generally focus on correct computations of water balances, but employ less sophisticated routing schemes such as the kinematic wave approximation. Hydrodynamic models, on the other side, excel in the computations of open water flow dynamics, but are highly dependent on specific runoff or observed discharge for their input. In most cases hydrodynamic models are forced by applying discharge at the boundaries and thus cannot account for water sources within the model domain. Thus, discharge and inundation dynamics at reaches not fed by upstream boundaries cannot be modelled. In a recent study, Hoch et al. (HESS, 2017) coupled the GHM PCR-GLOBWB with the hydrodynamic model Delft3D Flexible Mesh. A core element of this study was that both models were connected on a cell-by-cell basis which allows for direct hydrologic forcing within the hydrodynamic model domain. The means for such model coupling is the Basic Model Interface (BMI) which provides a set of functions to directly access model variables. Model results showed that discharge simulations can profit from model coupling as their accuracy is higher compared to stand-alone runs. Model results of a coupled simulation clearly depend on the quality of the individual models. Depending on purpose, location or simply the models at hand, it would be worthwhile to allow a wider range of models to be coupled. As a first step, we present a framework which allows coupling of PCR-GLOBWB to both Delft3D Flexible Mesh and LISFLOOD

  6. Hybrid fluid/kinetic modeling of Pluto’s escaping atmosphere

    Science.gov (United States)

    Erwin, Justin; Tucker, O. J.; Johnson, Robert E.

    2013-09-01

    Predicting the rate of escape and thermal structure of Pluto’s upper atmosphere in preparation for the New Horizons Spacecraft encounter in 2015 is important for planning and interpreting the expected measurements. Having a moderate Jeans parameter Pluto’s atmosphere does not fit the classic definition of Jeans escape for light species escaping from the terrestrial planets, nor does it fit the hydrodynamic outflow from comets and certain exoplanets. It has been proposed for some time that Pluto lies in the region of slow hydrodynamic escape. Using a hybrid fluid/molecular-kinetic model, we previously demonstrated the typical implementation of this model fails to correctly describe the appropriate temperature structure for the upper atmosphere for solar minimum conditions. Here we use a time-dependent solver to allow us to extend those simulations to higher heating rates and we examine fluid models in which Jeans-like escape expressions are used for the upper boundary conditions. We compare these to hybrid simulations of the atmosphere under heating conditions roughly representative of solar minimum and mean conditions as these bracket conditions expected during the New Horizon encounter. Although we find escape rates comparable to those previously estimated by the slow hydrodynamic escape model, and roughly consistent with energy limited escape, our model produces a much more extended atmosphere with higher temperatures roughly consistent with recent observations of CO. Such an extended atmosphere will be affected by Charon and will affect Pluto’s interaction with the solar wind at the New Horizon encounter. For the parameter space covered, we also find an inverse relationship between exobase temperature and altitude and the Jeans escape rate that is consistent with the energy limited escape rate. Since we have previously shown that such models can be scaled, these results have implications for modeling exoplanet atmospheres for which the energy limited

  7. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  8. A high resolution hydrodynamic 3-D model simulation of the malta shelf area

    Directory of Open Access Journals (Sweden)

    A. F. Drago

    Full Text Available The seasonal variability of the water masses and transport in the Malta Channel and proximity of the Maltese Islands have been simulated by a high resolution (1.6 km horizontal grid on average, 15 vertical sigma layers eddy resolving primitive equation shelf model (ROSARIO-I. The numerical simulation was run with climatological forcing and includes thermohaline dynamics with a turbulence scheme for the vertical mixing coefficients on the basis of the Princeton Ocean Model (POM. The model has been coupled by one-way nesting along three lateral boundaries (east, south and west to an intermediate coarser resolution model (5 km implemented over the Sicilian Channel area. The fields at the open boundaries and the atmospheric forcing at the air-sea interface were applied on a repeating "perpetual" year climatological cycle.

    The ability of the model to reproduce a realistic circulation of the Sicilian-Maltese shelf area has been demonstrated. The skill of the nesting procedure was tested by model-modelc omparisons showing that the major features of the coarse model flow field can be reproduced by the fine model with additional eddy space scale components. The numerical results included upwelling, mainly in summer and early autumn, along the southern coasts of Sicily and Malta; a strong eastward shelf surface flow along shore to Sicily, forming part of the Atlantic Ionian Stream, with a presence throughout the year and with significant seasonal modulation, and a westward winter intensified flow of LIW centered at a depth of around 280 m under the shelf break to the south of Malta. The seasonal variability in the thermohaline structure of the domain and the associated large-scale flow structures can be related to the current knowledge on the observed hydrography of the area. The level of mesoscale resolution achieved by the model allowed the spatial and temporal evolution of the changing flow patterns, triggered by

  9. A high resolution hydrodynamic 3-D model simulation of the malta shelf area

    Directory of Open Access Journals (Sweden)

    A. F. Drago

    2003-01-01

    Full Text Available The seasonal variability of the water masses and transport in the Malta Channel and proximity of the Maltese Islands have been simulated by a high resolution (1.6 km horizontal grid on average, 15 vertical sigma layers eddy resolving primitive equation shelf model (ROSARIO-I. The numerical simulation was run with climatological forcing and includes thermohaline dynamics with a turbulence scheme for the vertical mixing coefficients on the basis of the Princeton Ocean Model (POM. The model has been coupled by one-way nesting along three lateral boundaries (east, south and west to an intermediate coarser resolution model (5 km implemented over the Sicilian Channel area. The fields at the open boundaries and the atmospheric forcing at the air-sea interface were applied on a repeating "perpetual" year climatological cycle. The ability of the model to reproduce a realistic circulation of the Sicilian-Maltese shelf area has been demonstrated. The skill of the nesting procedure was tested by model-modelc omparisons showing that the major features of the coarse model flow field can be reproduced by the fine model with additional eddy space scale components. The numerical results included upwelling, mainly in summer and early autumn, along the southern coasts of Sicily and Malta; a strong eastward shelf surface flow along shore to Sicily, forming part of the Atlantic Ionian Stream, with a presence throughout the year and with significant seasonal modulation, and a westward winter intensified flow of LIW centered at a depth of around 280 m under the shelf break to the south of Malta. The seasonal variability in the thermohaline structure of the domain and the associated large-scale flow structures can be related to the current knowledge on the observed hydrography of the area. The level of mesoscale resolution achieved by the model allowed the spatial and temporal evolution of the changing flow patterns, triggered by internal dynamics, to be followed in

  10. Application of Scaling-Law and CFD Modeling to Hydrodynamics of Circulating Biomass Fluidized Bed Gasifier

    Directory of Open Access Journals (Sweden)

    Mazda Biglari

    2016-06-01

    Full Text Available Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.

  11. Hydrodynamic Hunters.

    Science.gov (United States)

    Jashnsaz, Hossein; Al Juboori, Mohammed; Weistuch, Corey; Miller, Nicholas; Nguyen, Tyler; Meyerhoff, Viktoria; McCoy, Bryan; Perkins, Stephanie; Wallgren, Ross; Ray, Bruce D; Tsekouras, Konstantinos; Anderson, Gregory G; Pressé, Steve

    2017-03-28

    The Gram-negative Bdellovibrio bacteriovorus (BV) is a model bacterial predator that hunts other bacteria and may serve as a living antibiotic. Despite over 50 years since its discovery, it is suggested that BV probably collides into its prey at random. It remains unclear to what degree, if any, BV uses chemical cues to target its prey. The targeted search problem by the predator for its prey in three dimensions is a difficult problem: it requires the predator to sensitively detect prey and forecast its mobile prey's future position on the basis of previously detected signal. Here instead we find that rather than chemically detecting prey, hydrodynamics forces BV into regions high in prey density, thereby improving its odds of a chance collision with prey and ultimately reducing BV's search space for prey. We do so by showing that BV's dynamics are strongly influenced by self-generated hydrodynamic flow fields forcing BV onto surfaces and, for large enough defects on surfaces, forcing BV in orbital motion around these defects. Key experimental controls and calculations recapitulate the hydrodynamic origin of these behaviors. While BV's prey (Escherichia coli) are too small to trap BV in hydrodynamic orbit, the prey are also susceptible to their own hydrodynamic fields, substantially confining them to surfaces and defects where mobile predator and prey density is now dramatically enhanced. Colocalization, driven by hydrodynamics, ultimately reduces BV's search space for prey from three to two dimensions (on surfaces) even down to a single dimension (around defects). We conclude that BV's search for individual prey remains random, as suggested in the literature, but confined, however-by generic hydrodynamic forces-to reduced dimensionality. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  12. Continuum modeling of hydrodynamic particle–particle interactions in microfluidic high-concentration suspensions

    DEFF Research Database (Denmark)

    Ley, Mikkel Wennemoes Hvitfeld; Bruus, Henrik

    2016-01-01

    -concentration field coupled to the continuity and Navier–Stokes equation for the solution. The hydrodynamic interactions are accounted for through the concentration dependence of the suspension viscosity, of the single-particle mobility, and of the momentum transfer from the particles to the suspension. The model...... is applied on a magnetophoretic and an acoustophoretic system, respectively, and based on the results, we illustrate three main points: (1) for relative particle-to-fluid volume fractions greater than 0.01, the hydrodynamic interaction effects become important through a decreased particle mobility...

  13. Application of the Geophysical Scale Multi-Block Transport Modeling System to Hydrodynamic Forcing of Dredged Material Placement Sediment Transport within the James River Estuary

    Science.gov (United States)

    Kim, S. C.; Hayter, E. J.; Pruhs, R.; Luong, P.; Lackey, T. C.

    2016-12-01

    The geophysical scale circulation of the Mid Atlantic Bight and hydrologic inputs from adjacent Chesapeake Bay watersheds and tributaries influences the hydrodynamics and transport of the James River estuary. Both barotropic and baroclinic transport govern the hydrodynamics of this partially stratified estuary. Modeling the placement of dredged sediment requires accommodating this wide spectrum of atmospheric and hydrodynamic scales. The Geophysical Scale Multi-Block (GSMB) Transport Modeling System is a collection of multiple well established and USACE approved process models. Taking advantage of the parallel computing capability of multi-block modeling, we performed one year three-dimensional modeling of hydrodynamics in supporting simulation of dredged sediment placements transport and morphology changes. Model forcing includes spatially and temporally varying meteorological conditions and hydrological inputs from the watershed. Surface heat flux estimates were derived from the National Solar Radiation Database (NSRDB). The open water boundary condition for water level was obtained from an ADCIRC model application of the U. S. East Coast. Temperature-salinity boundary conditions were obtained from the Environmental Protection Agency (EPA) Chesapeake Bay Program (CBP) long-term monitoring stations database. Simulated water levels were calibrated and verified by comparison with National Oceanic and Atmospheric Administration (NOAA) tide gage locations. A harmonic analysis of the modeled tides was performed and compared with NOAA tide prediction data. In addition, project specific circulation was verified using US Army Corps of Engineers (USACE) drogue data. Salinity and temperature transport was verified at seven CBP long term monitoring stations along the navigation channel. Simulation and analysis of model results suggest that GSMB is capable of resolving the long duration, multi-scale processes inherent to practical engineering problems such as dredged material

  14. Temperature Dynamics Investigation At Small And Shallow Lakes Using Hydrodynamic Model

    NARCIS (Netherlands)

    Abbasi, A.; van de Giesen, N.C.; Piasecki, M

    2014-01-01

    A three-dimensional time-dependent hydrodynamic and heat transport model of Lake Binaba, a shallow and small dam reservoir in Ghana, emphasizing the simulation of dynamics and thermal structure has been developed. Most numerical studies of temperature dynamics in reservoirs are based on one- or

  15. Hydrodynamic model approach to the formation of plasmonic wakes in graphene

    DEFF Research Database (Denmark)

    Chaves, A. J.; Peres, N. M. R.; Smirnov, G.

    2017-01-01

    Using the hydrodynamic model in the electrostatic approximation, we describe the formation of graphene surface plasmons when a nearby charge is in motion either perpendicular or parallel to a graphene sheet. In the first case, the electron-energy loss (EEL) spectrum of the electron is computed...

  16. ONE-DIMENSIONAL HYDRODYNAMIC/SEDIMENT TRANSPORT MODEL FOR STREAM NETWORKS: TECHNICAL REPORT

    Science.gov (United States)

    This technical report describes a new sediment transport model and the supporting post-processor, and sampling procedures for sediments in streams. Specifically, the following items are described herein: EFDC1D - This is a new one-dimensional hydrodynamic and sediment tr...

  17. Ballistic transport in the one-dimensional Hubbard model: The hydrodynamic approach

    Science.gov (United States)

    Ilievski, Enej; De Nardis, Jacopo

    2017-08-01

    We outline a general formalism of hydrodynamics for quantum systems with multiple particle species which undergo completely elastic scattering. In the thermodynamic limit, the complete kinematic data of the problem consist of the particle content, the dispersion relations, and a universal dressing transformation which accounts for interparticle interactions. We consider quantum integrable models and we focus on the one-dimensional fermionic Hubbard model. By linearizing hydrodynamic equations, we provide exact closed-form expressions for Drude weights, generalized static charge susceptibilities, and charge-current correlators valid on the hydrodynamic scale, represented as integral kernels operating diagonally in the space of mode numbers of thermodynamic excitations. We find that, on hydrodynamic scales, Drude weights manifestly display Onsager reciprocal relations even for generic (i.e., noncanonical) equilibrium states, and establish a generalized detailed balance condition for a general quantum integrable model. We present exact analytic expressions for the general Drude weights in the Hubbard model, and explain how to reconcile different approaches for computing Drude weights from the previous literature.

  18. Smoothed particle hydrodynamics model for phase separating fluid mixtures. II. Diffusion in a binary mixture

    NARCIS (Netherlands)

    Thieulot, C; Janssen, LPBM; Espanol, P

    A previously formulated smoothed particle hydrodynamics model for a phase separating mixture is tested for the case when viscous processes are negligible and only mass and energy diffusive processes take place. We restrict ourselves to the case of a binary mixture that can exhibit liquid-liquid

  19. Numerical modelling of micro-plasto-hydrodynamic lubrication in plane strip drawing

    DEFF Research Database (Denmark)

    Carretta, Y.; Bech, Jakob Ilsted; Legrand, N.

    2017-01-01

    This paper presents a new finite element model capable of predicting the onset of micro-plasto-hydrodynamic (MPH) lubrication and the amount of lubricant escaping from surface pockets in metal forming.The present approach is divided in two steps. First, a simulation at the macroscopic level is co...

  20. METHODS OF PHYSICAL MODELING OF HYDRODYNAMIC PROCESSES AT CASTING OF ALLOYS

    Directory of Open Access Journals (Sweden)

    V. Ju. Stetsenko

    2012-01-01

    Full Text Available The method of physical modeling of hydrodynamic processes of alloys molding is developed. It is shown that as a liquid it is necessary to use water and diethyl ether at molding of steel, silumins, tin-base bronzes and waterglycerine solutions.

  1. A 3D model of Pluto's atmosphere

    Science.gov (United States)

    Vangvichith, M.; Forget, F.; Wordsworth, R.

    2011-10-01

    For the first time, we have built a GCM of Pluto's atmosphere, adapted from the model of Triton's, recently developed[9] . In fact, Pluto and Triton have a lot of similarities (atmospheric, orbital). This GCM will allow to better understand the complex mechanism of the planet and to study the variation of the thermal profile during time.

  2. A linked hydrodynamic and water quality model for the Salton Sea

    Science.gov (United States)

    Chung, E.G.; Schladow, S.G.; Perez-Losada, J.; Robertson, Dale M.

    2008-01-01

    A linked hydrodynamic and water quality model was developed and applied to the Salton Sea. The hydrodynamic component is based on the one-dimensional numerical model, DLM. The water quality model is based on a new conceptual model for nutrient cycling in the Sea, and simulates temperature, total suspended sediment concentration, nutrient concentrations, including PO4-3, NO3-1 and NH4+1, DO concentration and chlorophyll a concentration as functions of depth and time. Existing water temperature data from 1997 were used to verify that the model could accurately represent the onset and breakup of thermal stratification. 1999 is the only year with a near-complete dataset for water quality variables for the Salton Sea. The linked hydrodynamic and water quality model was run for 1999, and by adjustment of rate coefficients and other water quality parameters, a good match with the data was obtained. In this article, the model is fully described and the model results for reductions in external phosphorus load on chlorophyll a distribution are presented. ?? 2008 Springer Science+Business Media B.V.

  3. Soil-vegetation-atmosphere transfer modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)

    1996-12-31

    In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

  4. Hydrodynamics challenge problem

    Energy Technology Data Exchange (ETDEWEB)

    Hornung, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Keasler, J. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gokhale, M. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-06-09

    The hydrodynamics challenge problem represents a classical HPC physics problem, namely high deformation event modeling via Lagrangian shock hydrodynamics. This challenge problem solves the Sedov blast wave problem for one material in three dimensions. The problem has an analytic solution, and can be scaled to arbitrarily large problem sizes. The reference code is drawn from a production LLNL hydrodynamics code.

  5. Parametric geometric model and hydrodynamic shape optimization of a flying-wing structure underwater glider

    Science.gov (United States)

    Wang, Zhen-yu; Yu, Jian-cheng; Zhang, Ai-qun; Wang, Ya-xing; Zhao, Wen-tao

    2017-12-01

    Combining high precision numerical analysis methods with optimization algorithms to make a systematic exploration of a design space has become an important topic in the modern design methods. During the design process of an underwater glider's flying-wing structure, a surrogate model is introduced to decrease the computation time for a high precision analysis. By these means, the contradiction between precision and efficiency is solved effectively. Based on the parametric geometry modeling, mesh generation and computational fluid dynamics analysis, a surrogate model is constructed by adopting the design of experiment (DOE) theory to solve the multi-objects design optimization problem of the underwater glider. The procedure of a surrogate model construction is presented, and the Gaussian kernel function is specifically discussed. The Particle Swarm Optimization (PSO) algorithm is applied to hydrodynamic design optimization. The hydrodynamic performance of the optimized flying-wing structure underwater glider increases by 9.1%.

  6. Pairwise Force Smoothed Particle Hydrodynamics model for multiphase flow: Surface tension and contact line dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Tartakovsky, Alexandre M.; Panchenko, Alexander

    2016-01-01

    We present a novel formulation of the Pairwise Force Smoothed Particle Hydrodynamics Model (PF-SPH) and use it to simulate two- and three-phase flows in bounded domains. In the PF-SPH model, the Navier-Stokes equations are discretized with the Smoothed Particle Hydrodynamics (SPH) method and the Young-Laplace boundary condition at the fluid-fluid interface and the Young boundary condition at the fluid-fluid-solid interface are replaced with pairwise forces added into the Navier-Stokes equations. We derive a relationship between the parameters in the pairwise forces and the surface tension and static contact angle. Next, we demonstrate the accuracy of the model under static and dynamic conditions. Finally, to demonstrate the capabilities and robustness of the model we use it to simulate flow of three fluids in a porous material.

  7. Depth-Averaged Non-Hydrostatic Hydrodynamic Model Using a New Multithreading Parallel Computing Method

    Directory of Open Access Journals (Sweden)

    Ling Kang

    2017-03-01

    Full Text Available Compared to the hydrostatic hydrodynamic model, the non-hydrostatic hydrodynamic model can accurately simulate flows that feature vertical accelerations. The model’s low computational efficiency severely restricts its wider application. This paper proposes a non-hydrostatic hydrodynamic model based on a multithreading parallel computing method. The horizontal momentum equation is obtained by integrating the Navier–Stokes equations from the bottom to the free surface. The vertical momentum equation is approximated by the Keller-box scheme. A two-step method is used to solve the model equations. A parallel strategy based on block decomposition computation is utilized. The original computational domain is subdivided into two subdomains that are physically connected via a virtual boundary technique. Two sub-threads are created and tasked with the computation of the two subdomains. The producer–consumer model and the thread lock technique are used to achieve synchronous communication between sub-threads. The validity of the model was verified by solitary wave propagation experiments over a flat bottom and slope, followed by two sinusoidal wave propagation experiments over submerged breakwater. The parallel computing method proposed here was found to effectively enhance computational efficiency and save 20%–40% computation time compared to serial computing. The parallel acceleration rate and acceleration efficiency are approximately 1.45% and 72%, respectively. The parallel computing method makes a contribution to the popularization of non-hydrostatic models.

  8. On Evaluating circulation and temperature stratification under changing water levels in Lake Mead with a 3D hydrodynamic model

    Science.gov (United States)

    Li, Y.; Acharya, K.; Chen, D.; Stone, M.; Yu, Z.; Young, M.; Zhu, J.; Shafer, D. S.; Warwick, J. J.

    2009-12-01

    Sustained drought in the western United States since 2000 has led to a significant drop (about 35 meters) in the water level of Lake Mead, the largest reservoir by volume in United States. The drought combined with rapid urban development in southern Nevada and emergence of invasive species has threatened the water quality and ecological processes in Lake Mead. A three-dimensional hydrodynamic model, Environmental Fluid Dynamics Code (EFDC), was applied to investigate lake circulation and temperature stratification in parts of Lake Mead (Las Vegas Bay and Boulder Basin) under changing water levels. Besides the inflow from Las Vegas Wash and the Colorado River, the model considered atmospheric changes as well as the boundary conditions restricted by the operation of Hoover Dam. The model was calibrated and verified by using observed data including water level, velocity, and temperature from 2003 and 2005. The model was applied to study the hydrodynamic processes at water level 366.8 m (year 2000) and at water level 338.2 m (year 2008). The high-stage simulation described the pre-drought lake hydrodynamic processes while the low-stage simulation highlighted the drawdown impact on such processes. The results showed that both inflow and wind-driven mixing process played major roles in the thermal stratification and lake circulation in both cases. However, the atmospheric boundary played a more important role than inflow temperature on thermal stratification of Lake Mead during water level decline. Further, the thermal stratification regime and flow circulation pattern in shallow lake regions (e.g.., the Boulder Basin area) were most impacted. The temperature of the lake at the high-stage was more sensitive to inflow temperatures than at low-stage. Furthermore, flow velocities decreased with the decreasing water level due to reduction in wind impacts, particularly in shallow areas of the lake. Such changes in temperature and lake current due to present drought have a

  9. Modeling hydrodynamic instabilities of double ablation fronts in inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    Yanez C.

    2013-11-01

    Full Text Available A linear Rayleigh-Taylor instability theory of double ablation (DA fronts is developed for direct-drive inertial confinement fusion. Two approaches are discussed: an analytical discontinuity model for the radiation dominated regime of very steep DA front structure, and a numerical self-consistent model that covers more general hydrodynamic profiles behaviours. Dispersion relation results are compared to 2D simulations.

  10. Validation of Hydrodynamic Numerical Model of a Pitching Wave Energy Converter

    DEFF Research Database (Denmark)

    López, Maria del Pilar Heras; Thomas, Sarah; Kramer, Morten Mejlhede

    2017-01-01

    Validation of numerical model is essential in the development of new technologies. Commercial software and codes available simulating wave energy converters (WECs) have not been proved to work for all the available and upcoming technologies yet. The present paper presents the first stages...... of the validation process of a hydrodynamic numerical model for a pitching wave energy converter. The development of dry tests, wave flume and wave basin experiments are going to be explained, lessons learned shared and results presented....

  11. Hydrodynamic models for slurry bubble column reactors. Seventh technical progress report, January--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D.

    1996-04-01

    The objective of this investigation is to convert our ``learning gas solid-liquid`` fluidization model into a predictive design model. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid and particulate phase. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. A hydrodynamic model for multiphase flows, based on the principles of mass, momentum and energy conservation for each phase, was developed and applied to model gas-liquid, gas-liquid-solid fluidization and gas-solid-solid separation. To simulate the industrial slurry bubble column reactors, a computer program based on the hydrodynamic model was written with modules for chemical reactions (e.g. the synthesis of methanol), phase changes and heat exchangers. In the simulations of gas-liquid two phases flow system, the gas hold-ups, computed with a variety of operating conditions such as temperature, pressure, gas and liquid velocities, agree well with the measurements obtained at Air Products` pilot plant. The hydrodynamic model has more flexible features than the previous empirical correlations in predicting the gas hold-up of gas-liquid two-phase flow systems. In the simulations of gas-liquid-solid bubble column reactors with and without slurry circulation, the code computes volume fractions, temperatures and velocity distributions for the gas, the liquid and the solid phases, as well as concentration distributions for the species (CO, H{sub 2}, CH{sub 3}0H, ... ), after startup from a certain initial state. A kinetic theory approach is used to compute a solid viscosity due to particle collisions. Solid motion and gas-liquid-solid mixing are observed on a color PCSHOW movie made from computed time series data. The steady state and time average catalyst concentration profiles, the slurry height and the rates of methanol production agree well with the measurements obtained at an Air Products` pilot plant.

  12. Air-Sea Exchange of Legacy POPs in the North Sea Based on Results of Fate and Transport, and Shelf-Sea Hydrodynamic Ocean Models

    OpenAIRE

    Kieran O'Driscoll

    2014-01-01

    The air-sea exchange of two legacy persistent organic pollutants (POPs), γ-HCH and PCB 153, in the North Sea, is presented and discussed using results of regional fate and transport and shelf-sea hydrodynamic ocean models for the period 1996–2005. Air-sea exchange occurs through gas exchange (deposition and volatilization), wet deposition and dry deposition. Atmospheric concentrations are interpolated into the model domain from results of the EMEP MSC-East multi-compartmental model (Gusev et ...

  13. Stochastic-hydrodynamic model of halo formation in charged particle beams

    Directory of Open Access Journals (Sweden)

    Nicola Cufaro Petroni

    2003-03-01

    Full Text Available The formation of the beam halo in charged particle accelerators is studied in the framework of a stochastic-hydrodynamic model for the collective motion of the particle beam. In such a stochastic-hydrodynamic theory the density and the phase of the charged beam obey a set of coupled nonlinear hydrodynamic equations with explicit time-reversal invariance. This leads to a linearized theory that describes the collective dynamics of the beam in terms of a classical Schrödinger equation. Taking into account space-charge effects, we derive a set of coupled nonlinear hydrodynamic equations. These equations define a collective dynamics of self-interacting systems much in the same spirit as in the Gross-Pitaevskii and Landau-Ginzburg theories of the collective dynamics for interacting quantum many-body systems. Self-consistent solutions of the dynamical equations lead to quasistationary beam configurations with enhanced transverse dispersion and transverse emittance growth. In the limit of a frozen space-charge core it is then possible to determine and study the properties of stationary, stable core-plus-halo beam distributions. In this scheme the possible reproduction of the halo after its elimination is a consequence of the stationarity of the transverse distribution which plays the role of an attractor for every other distribution.

  14. Modeling the hydrodynamic responses to land reclamation in different regions of a semi-enclosed bay

    Science.gov (United States)

    Yang, Y.; Chui, T. F. M.

    2016-12-01

    Water area in bays has been reclaimed to meet the increasing land demand for development. Numbers of studies have examined the hydrodynamic impacts induced by land reclamations in semi-enclosed bays such as San Francisco Bay in the U.S., Tokyo Bay in Japan, and Jiaozhou Bay in China. However, they have not compared the impacts of land reclamations taken place in different regions. The Deep Bay in China was selected as a case study to evaluate and compare the hydrodynamic responses to land reclamations that narrows the bay mouth and that causes water surface loss inside of the bay. A numerical model was employed to simulate the hydrodynamics throughout the bay and to examine the differences in impacts through scenario experiments. The model was validated using the observations of water elevation, currents, and salinity. To indicate the changes in hydrodynamics, tidal prism, current field, tidal energy flux, and water age were computed. Simulation results show that narrowing the bay mouth length by 30% with ??% loss of its original water surface area would increase the total energy flux entering the bay by 26 %, while 14% loss of its original water surface area in middle bay would decrease the total energy entering the bay by 23%. The two regions of reclamations have both resulted in substantial but different changes in current field, the spatial distribution of tidal energy flux and water age. For example, the reclamation at bay mouth has increased the current velocity and tidal energy flux at the bay mouth while that inside of the bay has streamlined the current field and increased the velocity in the inner bay. The water age throughout the bay has been reduced by 5.1% and 13.7% respectively in the two scenarios, increasing the water exchange ability of the bay with the adjacent sea. This study is beneficial to other semi-enclosed bays considering land reclamations, facilitating quick and preliminary estimations of hydrodynamic impacts for planning and management.

  15. Hydrodynamic Instability in an Extended Landau/Levich Model of Liquid-Propellant Combustion

    Science.gov (United States)

    Margolis, Stephen B.; Sackesteder, Kurt (Technical Monitor)

    1998-01-01

    The classical Landau/Levich models of liquid propellant combustion, which serve as seminal examples of hydrodynamic instability in reactive systems, have been combined and extended to account for a dynamic dependence, absent in the original formulations, of the local burning rate on the local pressure and/or temperature fields. The resulting model admits an extremely rich variety of both hydrodynamic and reactive/diffusive instabilities that can be analyzed in various limiting parameter regimes. In the present work, a formal asymptotic analysis, based on the realistic smallness of the gas-to-liquid density ratio, is developed to investigate the combined effects of gravity, surface tension and viscosity on the hydrodynamic instability of the propagating liquid/gas interface. In particular, a composite asymptotic expression, spanning three distinguished wavenumber regimes, is derived for both cellular and pulsating hydrodynamic neutral stability boundaries A(sub p)(k), where A(sub p) is the pressure sensitivity of the burning rate and k is the disturbance wavenumber. For the case of cellular (Landau) instability, the results demonstrate explicitly the stabilizing effect of gravity on long-wave disturbances, the stabilizing effect of viscosity and surface tension on short-wave perturbations, and the instability associated with intermediate wavenumbers for critical negative values of A(sub p). In the limiting case of weak gravity, it is shown that cellular hydrodynamic instability in this context is a long-wave instability phenomenon, whereas at normal gravity, this instability is first manifested through O(l) wavenumber disturbances. It is also demonstrated that, in the large wavenumber regime, surface tension and both liquid and gas viscosity all produce comparable stabilizing effects in the large-wavenumber regime, thereby providing significant modifications to previous analyses of Landau instability in which one or more of these effects were neglected. In contrast

  16. A Hydrodynamic Model of The Human Leg Circulation.

    Science.gov (United States)

    Klabunde, Richard E.; McDowell, Donald E.

    1984-01-01

    Describes the construction and use of a life-size model which shows blood flow under normal and pathological conditions. Four experimental procedures (single vessel occlusion, dilation of distal vascular bed, single artery stenosis, and multiple artery stenoses) typical of those demonstrated by the model are discussed and diagrammed. (DH)

  17. Validation Hydrodynamic Models of Three Topological Models of Secondary Facultative Ponds

    Directory of Open Access Journals (Sweden)

    Aponte-Reyes Alxander

    2014-10-01

    Full Text Available A methodology was developed to analyze boundary conditions, the size of the mesh and the turbulence of a mathematical model of CFD, which could explain hydrodynamic behavior on facultative stabilization ponds, FSP, built to pilot scale: conventional pond, CP, baffled pond, BP, and baffled-mesh pond, BMP. Models dispersion studies were performed in field for validation, taking samples into and out of the FSP, the information was used to carry out CFD model simulations of the three topologies. Evaluated mesh sizes ranged from 500,000 to 2,000,000 elements. The boundary condition in Pared surface-free slip showed good qualitative behavior and the turbulence model κ–ε Low Reynolds yielded good results. The biomass contained in LFS generates interference on dispersion studies and should be taken into account in assessing the CFD modeling, the tracer injection times, its concentration at the entrance, the effect of wind on CFD, and the flow models adopted as a basis for modeling are parameters to be taken into account for the CFD model validation and calibration.

  18. A viscous quantum hydrodynamics model based on dynamic density functional theory.

    Science.gov (United States)

    Diaw, Abdourahmane; Murillo, Michael S

    2017-11-10

    Dynamic density functional theory (DDFT) is emerging as a useful theoretical technique for modeling the dynamics of correlated systems. We extend DDFT to quantum systems for application to dense plasmas through a quantum hydrodynamics (QHD) approach. The DDFT-based QHD approach includes correlations in the the equation of state self-consistently, satisfies sum rules and includes irreversibility arising from collisions. While QHD can be used generally to model non-equilibrium, heterogeneous plasmas, we employ the DDFT-QHD framework to generate a model for the electronic dynamic structure factor, which offers an avenue for measuring hydrodynamic properties, such as transport coefficients via x-ray Thomson scattering.

  19. A Possible Universe in Pulsation by Using a Hydro-Dynamical Model for Gravity

    Directory of Open Access Journals (Sweden)

    Corneliu BERBENTE

    2016-12-01

    Full Text Available By using a hydro-dynamical model for gravity previously given by the author, a pulsating universe is possible to describe. This is possible because two hydro-dynamical sources are in attraction both when they are emitting and absorbing fluid. In our model, bodies (matter and energy are interacting via an incompressible fluid made of gravitons (photon-like particles having a wave length of the order of magnitude of the radius of universe. One considers the universe uniform at large scale, the effects of general relativity type being local and negligible at global scale. An “elastic sphere” model for the universe is suggested to describe the possible inversion. The expansion of the universe stops when the “elastic energy” overcomes the kinetic one; this takes place near the point of maximal emission speed of the fluid of gravitons. The differential equation for the universe in expansion is adapted to contraction. Analytical solutions are given.

  20. A 3D Hydrodynamic Model for Cytokinesis of Eukaryotic Cells

    Science.gov (United States)

    2014-08-01

    proposed a mathematical model for cell cleavage for the sea urchin by considering chemotactic motion of the centro- somes. In [23], the author...approach to study the cellular morphological change during cytokinesis. In this model, the force along the contracting ring or cytokinetic ring induced by...during cytokinesis, surface tension of the cell membrane also contributes to this process by retaining the morphological integrity of the offspring

  1. Detailed modeling of hydrodynamics mass transfer and chemical reactions in a bubble column using a discrete bubble model

    NARCIS (Netherlands)

    Darmana, D.; Deen, N.G.; Kuipers, J.A.M.

    2005-01-01

    A 3D discrete bubble model is adopted to investigate complex behavior involving hydrodynamics, mass transfer and chemical reactions in a gas¿liquid bubble column reactor. In this model a continuum description is adopted for the liquid phase and additionally each individual bubble is tracked in a

  2. Assessment of Energy Removal Impacts on Physical Systems: Hydrodynamic Model Domain Expansion and Refinement, and Online Dissemination of Model Results

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Khangaonkar, Tarang; Wang, Taiping

    2010-08-01

    In this report we describe the 1) the expansion of the PNNL hydrodynamic model domain to include the continental shelf along the coasts of Washington, Oregon, and Vancouver Island; and 2) the approach and progress in developing the online/Internet disseminations of model results and outreach efforts in support of the Puget Sound Operational Forecast System (PS-OPF). Submittal of this report completes the work on Task 2.1.2, Effects of Physical Systems, Subtask 2.1.2.1, Hydrodynamics, for fiscal year 2010 of the Environmental Effects of Marine and Hydrokinetic Energy project.

  3. Thermal and hydrodynamic modelling of active catheters for interventional radiology.

    Science.gov (United States)

    Marchandise, Emilie; Flaud, Patrice; Royon, Laurent; Blanc, Raphaël; Szewczyk, Jérome

    2011-07-01

    Interventional radiologists desire to improve their operating tools such as catheters. Active catheters in which the tip is moved using shape memory alloy actuators activated using the Joule effect present a promising approach for easier navigation in the small vessels. However, the increase in temperature caused by this Joule effect must be controlled in order to prevent damage to blood cells and tissues. This paper is devoted to the simulation and experimental validation of a fluid-thermal model of an active catheter prototype. Comparisons between computer-predicted and experimentally measured temperatures are presented for both experiments in air and water at 37°C. Good agreement between the computational and experimental results is found, demonstrating the validity of the developed computer model. These comparisons enable us to highlight some important issues in the modelling process and to determine the optimal current for the activation of the catheter.

  4. The application of single particle hydrodynamics in continuum models of multiphase flow

    Science.gov (United States)

    Decker, Rand

    1988-01-01

    A review of the application of single particle hydrodynamics in models for the exchange of interphase momentum in continuum models of multiphase flow is presented. Considered are the equations of motion for a laminar, mechanical two phase flow. Inherent to this theory is a model for the interphase exchange of momentum due to drag between the dispersed particulate and continuous fluid phases. In addition, applications of two phase flow theory to de-mixing flows require the modeling of interphase momentum exchange due to lift forces. The applications of single particle analysis in deriving models for drag and lift are examined.

  5. Integrated hydrologic and hydrodynamic modeling to assess water exchange in a data-scarce reservoir

    Science.gov (United States)

    Wu, Binbin; Wang, Guoqiang; Wang, Zhonggen; Liu, Changming; Ma, Jianming

    2017-12-01

    Integrated hydrologic and hydrodynamic modeling is useful in evaluating hydrodynamic characteristics (e.g. water exchange processes) in data-scarce water bodies, however, most studies lack verification of the hydrologic model. Here, water exchange (represented by water age) was investigated through integrated hydrologic and hydrodynamic modeling of the Hongfeng Reservoir, a poorly gauged reservoir in southwest China. The performance of the hydrologic model and parameter replacement among sub-basins with hydrological similarity was verified by historical data. Results showed that hydrological similarity based on the hierarchical cluster analysis and topographic index probability density distribution was reliable with satisfactory performance of parameter replacement. The hydrodynamic model was verified using daily water levels and water temperatures from 2009 and 2010. The water exchange processes in the Hongfeng Reservoir are very complex with temporal, vertical, and spatial variations. The temporal water age was primarily controlled by the variable inflow and outflow, and the maximum and minimum ages for the site near the dam were 406.10 d (15th June) and 90.74 d (3rd August), respectively, in 2010. Distinct vertical differences in water age showed that surface flow, interflow, and underflow appeared alternately, depending on the season and water depth. The worst water exchange situation was found in the central areas of the North Lake with the highest water ages in the bottom on both 15th June and 3rd August, in 2010. Comparison of the spatial water ages revealed that the more favorable hydraulic conditions on 3rd August mainly improved the water exchange in the dam areas and most areas of the South Lake, but had little effect on the bottom layers of the other deepest areas in the South and North Lakes. The presented framework can be applied in other data-scarce waterbodies worldwide to provide better understanding of water exchange processes.

  6. Reshocks, rarefactions, and the generalized Layzer model for hydrodynamic instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Mikaelian, K O

    2008-06-10

    We report numerical simulations and analytic modeling of shock tube experiments on Rayleigh-Taylor and Richtmyer-Meshkov instabilities. We examine single interfaces of the type A/B where the incident shock is initiated in A and the transmitted shock proceeds into B. Examples are He/air and air/He. In addition, we study finite-thickness or double-interface A/B/A configurations like air/SF{sub 6}/air gas-curtain experiments. We first consider conventional shock tubes that have a 'fixed' boundary: A solid endwall which reflects the transmitted shock and reshocks the interface(s). Then we focus on new experiments with a 'free' boundary--a membrane disrupted mechanically or by the transmitted shock, sending back a rarefaction towards the interface(s). Complex acceleration histories are achieved, relevant for Inertial Confinement Fusion implosions. We compare our simulation results with a generalized Layzer model for two fluids with time-dependent densities, and derive a new freeze-out condition whereby accelerating and compressive forces cancel each other out. Except for the recently reported failures of the Layzer model, the generalized Layzer model and hydrocode simulations for reshocks and rarefactions agree well with each other, and remain to be verified experimentally.

  7. Hydrodynamic And Water Quality Surrogate Modeling For Reservoir Operation

    NARCIS (Netherlands)

    Aguilar Lopez, J.P.; Andel, Schalk Jan Van; Werner, M; Solomatine, D.P.; Piasecki, M

    2014-01-01

    Data for water management is increasingly easy to access, it has finer spatial and temporal resolution, and it is available from various sources. Precipitation data can be obtained from meteorological stations, radar, satellites and weather models. Land use data is also available from different

  8. Hydrodynamic Modelling and Experimental Analysis of FE-DMFC Stacks

    Science.gov (United States)

    Kablou, Yashar

    Direct methanol fuel cells (DMFCs) present some unique features such as having liquid fuel, quick refueling process, compact design and high energy density. These characteristics make them incredibly suitable as a promising power source for portable electronic applications, such as cell phones or laptop computers. Despite of these positive aspects, the commercial development of DMFCs has nevertheless been hindered by some important issues such as, carbon dioxide formation at the anode compartment and, methanol crossover through the membrane. Many researchers have tried to model the two-phase flow behavior inside the DMFC anode compartment using the "homogenous flow modelling" approach, which has proven to be inaccurate specially when dealing with DMFC stacks. On the other hand, several strategies to prevent methanol crossover have been suggested in the literature, including the use of a flowing electrolyte between the DMFC anode and cathode compartments. Preliminary tests on flowing electrolyte direct methanol fuel cells (FE-DMFCs) have shown promising results; however, further investigation should be carried out on the stack level. In the first part of this study, a quasi two-dimensional numerical model was developed, to predict the two-phase flow behavior within the DMFC anode compartment, both in single cell and stack levels. Various types of flow modelling approaches and void fraction correlations were utilized to estimate the pressure drop across the anode compartment. It was found that the "separated flow modelling" approach, as well as CISE correlation for void fraction (developed at the CISE labs in Milan), yield the best results. In the second part, a five-cell FE-DMFC stack unit with a parallel serpentine flow bed design and U-type manifold configuration, was developed and tested at various operating conditions. It was found that, the flowing electrolyte effectively reduced methanol crossover and, improved the stack performance.

  9. Development of hydrodynamic analysis model for IRWST/Sparger

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Nyung; Lee, Kyung Won; Yum, Sang Hoo; Yoon, Sung Sik [Kyung Hee University, Seoul (Korea)

    2001-04-01

    One of the design improvements of the KNGR(Korean Next Generation Reactor) which is advanced to safety and economy is the adoption of IRWST(In-Containment Refueling Water Storage Tank). The IRWST, installed inside of the containment building, has more designed purpose than merely the location change of the tank. Since the design functions of the IRWST is similar to these of the BWR's suppression pool, theoretical models applicable to BWR's suppression pool can be mostly applied to the IRWST. But for the PWR, the geometry of the sparger, the operation mode and the steam quantity and temperature and pressure of discharged fluid from primary system to IRWST through PSV or SDV may be different from those of BWR. Also there is some defects in detailed parts of condensation model. Therefore we, as the first nation to construct PWR with IRWST, must carry out profound research for there problems such that the results can be utilized and localized as an exclusive technology. To analyze steam condensation in IRWST, BWR operating experience, experimental data, design parameter of IRWST and wide range of literature review were consulted. Through the review, the point at issue in operating experience, every condensation and thermal-hydrolic phenomena in IRWST are throughly analyzed and the dominant parameters are found to be subcooled temperature and mass flow rate. This research has been understood the various theoretical and experimental models related to the phenomena and investigated the references about the concept and the design of KNGR's IRWST. The research has covered details of pipe clearing and boundary conditions, numerical method, bubble behavior and analytical method, distribution of velocity and pressure in sparger, load effect on structures, model of chugging and thermal stratification. These models were qualified for design and safety evaluation of Nuclear Power Plant. 15 refs., 22 figs., 4 tabs. (Author)

  10. Thermal equilibrium solution to new model of bipolar hybrid quantum hydrodynamics

    Science.gov (United States)

    Di Michele, Federica; Mei, Ming; Rubino, Bruno; Sampalmieri, Rosella

    2017-08-01

    In this paper we study the hybrid quantum hydrodynamic model for nano-sized bipolar semiconductor devices in thermal equilibrium. By introducing a hybrid version of the Bhom potential, we derive a bipolar hybrid quantum hydrodynamic model, which is able to account for quantum effects in a localized region of the device for both electrons and holes. Coupled with Poisson equation for the electric potential, the steady-state system is regionally degenerate in its ellipticity, due to the quantum effect only in part of the device. This regional degeneracy of ellipticity makes the study more challenging. The main purpose of the paper is to investigate the existence and uniqueness of the weak solutions to this new type of equations. We first establish the uniform boundedness of the smooth solutions to the modified bipolar quantum hydrodynamic model by the variational method, then we use the compactness technique to prove the existence of weak solutions to the original hybrid system by taking hybrid limit. In particular, we account for two different kinds of hybrid behaviour. We perform the first hybrid limit when both electrons and holes behave quantum in a given region of the device, and the second one when only one carrier exhibits hybrid behaviour, whereas the other one is presented classically in the whole domain. The semi-classical limit results are also obtained. Finally, the theoretical results are tested numerically on a simple toy model.

  11. Numerical analysis of a two-pion correlation function based on a hydrodynamical model

    CERN Document Server

    Morita, K; Nakamura, H; Nonaka, C; Morita, Kenji; Muroya, Shin; Nakamura, Hiroki; Nonaka, Chiho

    2000-01-01

    We will numerically investgate two-particle correlation function of CERN--SPS 158 A GeV Pb+Pb central collisions in detail based on a (3+1)-dimensional relativistic hydrodynamical model with first order phase transition. We use the Yano-Koonin-Podgoretski\\u{\\i} parametrization as well as the usual Cartesian parametrization and analyze the pair momentum dependence of HBT radii extracted from the parametrizations. We find that the interpretation of the temporal radius parameters as the time duration in YKP parametrization is not available for the hydrodynamical model where the source became opaque naturally because of expansion and surface dominant freeze-out. Finally, effect of the phase transition on the source opacity is also discussed.

  12. Dissipative quantum hydrodynamics model of x-ray Thomson scattering in dense plasmas

    Science.gov (United States)

    Diaw, Abdourahmane; Murillo, Michael

    2017-10-01

    X-ray Thomson scattering (XRTS) provides detailed diagnostic information about dense plasma experiments. The inferences made rely on an accurate model for the form factor, which is typically expressed in terms of a well-known response function. Here, we develop an alternate approach based on quantum hydrodynamics using a viscous form of dynamical density functional theory. This approach is shown to include the equation of state self-consistently, including sum rules, as well as irreversibility arising from collisions. This framework is used to generate a model for the scattering spectrum, and it offers an avenue for measuring hydrodynamic properties, such as transport coefficients, using XRTS. This work was supported by the Air Force Office of Scientific Research (Grant No. FA9550-12-1-0344).

  13. Finite Element Modelling of the Hydrodynamic Environment of a Small ROV

    Directory of Open Access Journals (Sweden)

    Ren Guang

    1993-07-01

    Full Text Available This paper addresses a practical problem, namely, modeling the hydrodynamic environment of a small ROV. This has become the problem of solving time-dependent incompressible Navier-Stokes equations with moving boundaries and a new method is developed to solve it. Navier-Stokes equations expressed in a moving-body-fixed coordinate frame with moving boundaries are derived and solved by a proposed finite element method which is a modified velocity correction procedure (Ren and Utnes 1993. The present method is implemented in the C language on a SUN/Sparc Station. The algorithm and program are demonstrated by solving a classic driven cavity flow problem and a simplified model of the hydrodynamic environment of a small ROV, which is a moving boundary problem. The results from the driven cavity flow problem are compared to previous work. A definition is also given of the moving boundary problem (MBP related to the solution of Navier-Stokes equations.

  14. Validation of Hydrodynamic Load Models Using CFD for the OC4-DeepCwind Semisubmersible: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Benitz, M. A.; Schmidt, D. P.; Lackner, M. A.; Stewart, G. M.; Jonkman, J.; Robertson, A.

    2015-03-01

    Computational fluid dynamics (CFD) simulations were carried out on the OC4-DeepCwind semi-submersible to obtain a better understanding of how to set hydrodynamic coefficients for the structure when using an engineering tool such as FAST to model the system. The focus here was on the drag behavior and the effects of the free-surface, free-ends and multi-member arrangement of the semi-submersible structure. These effects are investigated through code-to-code comparisons and flow visualizations. The implications on mean load predictions from engineering tools are addressed. The work presented here suggests that selection of drag coefficients should take into consideration a variety of geometric factors. Furthermore, CFD simulations demonstrate large time-varying loads due to vortex shedding, which FAST's hydrodynamic module, HydroDyn, does not model. The implications of these oscillatory loads on the fatigue life needs to be addressed.

  15. van der Waals normal form for a one-dimensional hydrodynamic model.

    Science.gov (United States)

    Cartes, C; Clerc, M G; Soto, R

    2004-09-01

    Phase separation in a fluidized granular system is studied. We consider a one-dimensional hydrodynamic model that mimics a two-dimensional fluidized granular system with a vibrating wall and without gravity, which exhibits a phase separation. Close to the critical point, by means of an adiabatic elimination of the temperature, we deduce the van der Waals normal form, which is the equation that describes the slow dynamics of the system and predicts the qualitative behavior in different regions of parameters. This allows us to understand the origin of the effective viscosity and the spatial saturation at the onset of the bifurcation. The hydrodynamic model and van der Waals normal form exhibit a behavior similar to the one observed in molecular dynamics simulations.

  16. CISOCUR - Hydrodynamic circulation in the Curonian Lagoon inferred through stable isotope measurements and numerical modelling

    Science.gov (United States)

    Umgiesser, Georg; Razinkovas-Baziukas, Arturas; Barisevičiūtė, Ruta; Baziukė, Dalia; Ertürk, Ali; Gasiūnaitė, Jovita; Gulbinskas, Saulius; Lubienė, Irma; Maračkinaite, Jurgita; Petkuvienė, Jolita; Pilkaitytė, Renata; Ruginis, Tomas; Zemlys, Petras; Žilius, Mindaugas

    2013-04-01

    The spatial pattern of the hydrodynamic circulation of the Curonian lagoon, the largest European coastal lagoon, is still little understood. In absence of automatic current registration data all the existing models relied mostly on such data as water levels leaving high level of uncertainty. Here we present CISOCUR, a new project financed by the European Social Fund under the Global Grant measure. The project applies a new methodology that uses the carbon stable isotope (SI) ratio of C12 and C13 that characterize different water sources entering the lagoon and may be altered by internal kinetic processes. Through the tracing of these isotope ratios different water masses can be identified. This gives the possibility to validate several hypotheses of water circulation and validate hydrodynamic models. In particular it will be possible to 1) trace water masses entering the lagoon through the Nemunas and the Klaipeda strait; 2) test the hypothesis of sediment transport mechanisms inside the lagoon; 3) evaluate the importance of physical forcing on the lagoon circulation. The use of a hydrodynamic finite element model, coupled with the SI method, will allow for a realistic description of the transport processes inside the Curonian lagoon. So the main research goal is to apply the stable isotope tracers and a finite element model to determine the circulation patterns in the Curonian lagoon. Overall, the project will develop according to 4 main phases: 1) A pilot study to measure the isotope composition of different carbon compounds (dissolved and suspended) in different water bodies that feed water into the central lagoon. Through this pilot study the optimal study sites for the seasonal campaign will be identified as well. 2) Seasonal field campaigns in the monitoring stations identified in phase 1 to measure the carbon isotope ratio. 3) Development of a model that describes the kinetics of carbon isotopes and its transformation. 4) Application of a hydrodynamic model

  17. Flood hazard maps from SAR data and global hydrodynamic models

    Science.gov (United States)

    Giustarini, Laura; Chini, Marci; Hostache, Renaud; Matgen, Patrick; Pappenberger, Florian; Bally, Phillippe

    2015-04-01

    With flood consequences likely to amplify because of growing population and ongoing accumulation of assets in flood-prone areas, global flood hazard and risk maps are greatly needed for improving flood preparedness at large scale. At the same time, with the rapidly growing archives of SAR images of floods, there is a high potential of making use of these images for global and regional flood management. In this framework, an original method is presented to integrate global flood inundation modeling and microwave remote sensing. It takes advantage of the combination of the time and space continuity of a global inundation model with the high spatial resolution of satellite observations. The availability of model simulations over a long time period offers the opportunity to estimate flood non-exceedance probabilities in a robust way. The probabilities can later be attributed to historical satellite observations. SAR-derived flood extent maps with their associated non-exceedance probabilities are then combined to generate flood hazard maps with a spatial resolution equal to that of the satellite images, which is most of the time higher than that of a global inundation model. The method can be applied to any area of interest in the world, provided that a sufficient number of relevant remote sensing images are available. We applied the method on the Severn River (UK) and on the Zambezi River (Mozambique), where large archives of Envisat flood images can be exploited. The global ECMWF flood inundation model is considered for computing the statistics of extreme events. A comparison with flood hazard maps estimated with in situ measured discharge is carried out. An additional analysis has been performed on the Severn River, using high resolution SAR data from the COSMO-SkyMed SAR constellation, acquired for a single flood event (one flood map per day between 27/11/2012 and 4/12/2012). The results showed that it is vital to observe the peak of the flood. However, a single

  18. Hydrodynamic Modelling and Layout Optimisation of Wave Energy Converter Arrays

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé

    2017-01-01

    This PhD thesis explores mathematical models for recreation of small-amplitude ocean waves and their interaction with assemblies of oscillating wave energy converters. Underpinned by the simulation capabilities associated with these models, algorithms seeking optimal arrangements between devices...... in various positions and orientations are finally investigated. This thesis intends in this way to offer a practical approach to the analysis of wave energy converters when they operate together as an array and the optimal design of array layouts. The topics covered by the text include propagation of waves...... around solid bodies, generation of waves by oscillating bodies, wave transformation due to slowly-varying water depth conditions, basic principles of wave power extraction by oscillating bodies, and optimal formation of arrays of wave energy converters....

  19. Boussinesq modeling of wave-induced hydrodynamics in coastal wetlands

    Science.gov (United States)

    Chakrabarti, Agnimitro; Brandt, Steven R.; Chen, Qin; Shi, Fengyan

    2017-05-01

    In this paper, an improved formulation of the vegetation drag force, applicable for the fully nonlinear Boussinesq equations and based on the use of the depth-varying, higher-order expansion of the horizontal velocity, in the quadratic vegetation drag law has been presented. The model uses the same numerical schemes as FUNWAVE TVD but is based on the CACTUS framework. The model is validated for wave height and setup, against laboratory experiments with and without vegetation cover. The wave attenuation results using the improved formulation were compared with those using the first-order reference velocity as well as with analytical solutions using linear wave theory. The analytical solution using the depth-varying velocity, predicted by the linear wave theory, was shown to match the model results with the fully expanded velocity approach very well for all wave cases, except under near-emergent and emergent conditions (when the ratio of stem height to water depth is greater than 0.75) and when the Ursell (Ur) number is less than 5. Simulations during peak storm waves, during Hurricane Isaac, showed that vegetation is very effective in reducing setup on platforms and in reducing the wave energy within the first few hundred meters.

  20. Hydrodynamic Instability and Thermal Coupling in a Dynamic Model of Liquid-Propellant Combustion

    Science.gov (United States)

    Margolis, S. B.

    1999-01-01

    For liquid-propellant combustion, the Landau/Levich hydrodynamic models have been combined and extended to account for a dynamic dependence of the burning rate on the local pressure and temperature fields. Analysis of these extended models is greatly facilitated by exploiting the realistic smallness of the gas-to-liquid density ratio rho. Neglecting thermal coupling effects, an asymptotic expression was then derived for the cellular stability boundary A(sub p)(k) where A(sub p) is the pressure sensitivity of the burning rate and k is the disturbance wavenumber. The results explicitly indicate the stabilizing effects of gravity on long-wave disturbances, and those of viscosity and surface tension on short-wave perturbations, and the instability associated with intermediate wavenumbers for critical negative values of A(sub p). In the limit of weak gravity, hydrodynamic instability in liquid-propellant combustion becomes a long-wave, instability phenomenon, whereas at normal gravity, this instability is first manifested through O(1) wavenumbers. In addition, surface tension and viscosity (both liquid and gas) each produce comparable effects in the large-wavenumber regime, thereby providing important modifications to the previous analyses in which one or more of these effects was neglected. For A(sub p)= O, the Landau/Levich results are recovered in appropriate limiting cases, although this typically corresponds to a hydrodynamically unstable parameter regime for p combustion have been observed at low pressures in hydroxylammonium nitrate (HAN)-based liquid propellants, which often exhibit negative pressure sensitivities. While nonsteady combustion may correspond to secondary and higher-order bifurcations above the cellular boundary, it may also be a manifestation of this pulsating type of hydrodynamic instability. In the present work, a nonzero temperature sensitivity is incorporated into our previous asymptotic analyses. This entails a coupling of the energy equation

  1. Vertical structures induced by propeller moonlets: Comparison of hydrodynamical model and N-body box simulations

    Science.gov (United States)

    Hoffmann, H.; Seiß, M.; Salo, H.; Spahn, F.

    2014-04-01

    Small moonlets in Saturn's rings induce propeller called structures into the surrounding ring material. Images of Saturn's rings, taken by the Cassini spacecraft near Saturn's equinox in 2009, show shadows cast by these propellers [1], offering the opportunity to study their vertical structure. We compare results from an extended hydrodynamical propeller model with results from local N-body box simulations of propeller structures. In the hydrodynamical model, maximal propeller heights are determined from the gravitational scattering of the ring particles by the moonlet. Afterwards the disturbed balance of viscous heating and collisional cooling is considered as main mechanism of the propeller height relaxation [2]. For the N-body box simulations we use the code by Salo [3], which was also applied in the propeller simulations of [4] and [5]. We find that the exponential height relaxation predicted by the hydrodynamical modelling is confirmed by N-body simulations of non-self gravitating ring particles. By projecting the propeller height evolution of the hydrodynamical model into observations of the shadows cast by the Earhart propeller, we determine the exponential cooling constant of the height relaxation. With this cooling constant we estimate collision frequencies of about 6 collisions per particle per orbit in the propeller gap region or about 11 collisions per particle per orbit in the propeller wake region of the Earhart propeller. The N-body simulations lead to maximal propeller heights between 60 to 70 percent of the Hill radius of the corresponding moonlet. Moonlet sizes estimated by this relation are in fair agreement with size estimates from radial propeller scalings [5, 6] for propeller structures with observed shadows.

  2. Performance analysis of coupled and uncoupled hydrodynamic and wave models in the northern Adriatic Sea

    Science.gov (United States)

    Busca, Claudia; Coluccelli, Alessandro; Valentini, Andrea; Benetazzo, Alvise; Bonaldo, Davide; Bortoluzzi, Giovanni; Carniel, Sandro; Falcieri, Francesco; Paccagnella, Tiziana; Ravaioli, Mariangela; Riminucci, Francesco; Sclavo, Mauro; Russo, Aniello

    2014-05-01

    The complex dynamics of the Adriatic Sea are the result of geographical position, orography and bathymetry, as well as rivers discharge and meteorological conditions that influence, more strongly, the shallow northern part. Such complexity requires a constant monitoring of marine conditions in order to support several activities (marine resources management, naval operations, emergency management, shipping, tourism, as well as scientific ones). Platforms, buoys and mooring located in Adriatic Sea supply almost continuously real time punctual information, which can be spatially extended, with some limitations, by drifters and remote sensing. Operational forecasting systems represent valid tools to provide a complete tridimensional coverage of the area, with a high spatial and temporal resolution. The Hydro-Meteo-Clima Service of the Emilia-Romagna Environmental Agency (ARPA-SIMC, Bologna, Italy) and the Dept. of Life and Environmental Sciences of Università Politecnica delle Marche (DISVA-UNIVPM, Ancona, Italy), in collaboration with the Institute of Marine Science of the National Research Council (ISMAR-CNR, Italy) operationally run several wave and hydrodynamic models on the Adriatic Sea. The main implementations are based on the Regional Ocean Modeling System (ROMS), the wave model Simulating WAves Nearshore (SWAN), and the coupling of the former two models in the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) system. Horizontal resolutions of the different systems range from the 2 km of AdriaROMS to the 0.5 km of the recently implemented northern Adriatic COAWST. Forecasts are produced every day for the subsequent 72 hour with hourly resolution. All the systems compute the fluxes exchanged through the interface with the atmosphere from the numerical weather prediction system named COSMO-I7, an implementation for Italy of the Consortium for Small-scale Modeling (COSMO) model, at 7 km horizontal resolution. Considering the several operational

  3. Hydrodynamic Modeling Analysis to Support Nearshore Restoration Projects in a Changing Climate

    Directory of Open Access Journals (Sweden)

    Zhaoqing Yang

    2014-01-01

    Full Text Available To re-establish the intertidal wetlands with full tidal exchange and improve salmonid rearing habitat in the Skagit River estuary, State of Washington, USA, a diked agriculture farm land along the Skagit Bay front is proposed to be restored to a fully functional tidal wetland. The complex and dynamic Skagit River estuarine system calls for the need of a multi-facet and multi-dimensional analysis using observed data, numerical and analytical methods. To assist the feasibility study of the restoration project, a hydrodynamic modeling analysis was conducted using a high-resolution unstructured-grid coastal ocean model to evaluate the hydrodynamic response to restoration alternatives and to provide guidance to the engineering design of a new levee in the restoration site. A set of parameters were defined to quantify the hydrodynamic response of the nearshore restoration project, such as inundation area, duration of inundation, water depth and salinity of the inundated area. To assist the design of the new levee in the restoration site, the maximum water level near the project site was estimated with consideration of extreme high tide, wind-induced storm surge, significant wave height and future sea-level rise based on numerical model results and coastal engineering calculation.

  4. Modified-Gravity-GADGET: a new code for cosmological hydrodynamical simulations of modified gravity models

    Science.gov (United States)

    Puchwein, Ewald; Baldi, Marco; Springel, Volker

    2013-11-01

    We present a new massively parallel code for N-body and cosmological hydrodynamical simulations of modified gravity models. The code employs a multigrid-accelerated Newton-Gauss-Seidel relaxation solver on an adaptive mesh to efficiently solve for perturbations in the scalar degree of freedom of the modified gravity model. As this new algorithm is implemented as a module for the P-GADGET3 code, it can at the same time follow the baryonic physics included in P-GADGET3, such as hydrodynamics, radiative cooling and star formation. We demonstrate that the code works reliably by applying it to simple test problems that can be solved analytically, as well as by comparing cosmological simulations to results from the literature. Using the new code, we perform the first non-radiative and radiative cosmological hydrodynamical simulations of an f (R)-gravity model. We also discuss the impact of active galactic nucleus feedback on the matter power spectrum, as well as degeneracies between the influence of baryonic processes and modifications of gravity.

  5. Three-dimensional modelling of the hydrodynamics of the Southern Bight of the North Sea: first results

    Science.gov (United States)

    Ivanov, Evgeny; Capet, Arthur; Barth, Alexander; Delhez, Eric; Soetaert, Karline; Grégoire, Marilaure

    2017-04-01

    In the frame of the Belgian research project FaCE-It (Functional biodiversity in a Changing sedimentary Environment: Implications for biogeochemistry and food webs in a managerial setting), the impact of dredging activities and offshore wind farm installation on the spatial distribution of sediment grain size, biodiversity and biogeochemistry will be estimated in the Southern Bight of the North Sea (SBNS) with a focus on the Belgian Coastal Zone (BCZ). To reach this goal, the three-dimensional hydrodynamical model ROMS-COAWST is implemented in the SBNS in order to simulate the complex hydrodynamics and sediment transport. Two levels of nesting are used to reach a resolution of 250 m in the BCZ. The model is forced at the air-sea interface by the 6-hourly ECMWF ERA-interim atmospheric dataset and at the open boundaries by the coarse resolution model results available from CMEMS (Copernicus Marine Environment Monitoring Service), and also considers tides and 4 main rivers (Scheldt, Rhine with Maas, Thames and Seine). Two types of simulations have been performed: a 10-years climatological simulation and a simulation over 2003-2013 to investigate the interannual dynamics. The model skills are evaluated by comparing its outputs to historical data (e.g. salinity, temperature and currents) from remote sensing and in-situ. The sediment transport module will then be implemented and its outputs compared to historical and newly collected (in the frame of FaCE-iT) observations on grain size distribution as well as with satellite Suspended Particulate Matter (SPM) images. This will allow assessing the impact of substrate modification due to offshore human activities at local and regional scales.

  6. Chemical kinetics and modeling of planetary atmospheres

    Science.gov (United States)

    Yung, Yuk L.

    1990-01-01

    A unified overview is presented for chemical kinetics and chemical modeling in planetary atmospheres. The recent major advances in the understanding of the chemistry of the terrestrial atmosphere make the study of planets more interesting and relevant. A deeper understanding suggests that the important chemical cycles have a universal character that connects the different planets and ultimately link together the origin and evolution of the solar system. The completeness (or incompleteness) of the data base for chemical kinetics in planetary atmospheres will always be judged by comparison with that for the terrestrial atmosphere. In the latter case, the chemistry of H, O, N, and Cl species is well understood. S chemistry is poorly understood. In the atmospheres of Jovian planets and Titan, the C-H chemistry of simple species (containing 2 or less C atoms) is fairly well understood. The chemistry of higher hydrocarbons and the C-N, P-N chemistry is much less understood. In the atmosphere of Venus, the dominant chemistry is that of chlorine and sulfur, and very little is known about C1-S coupled chemistry. A new frontier for chemical kinetics both in the Earth and planetary atmospheres is the study of heterogeneous reactions. The formation of the ozone hole on Earth, the ubiquitous photochemical haze on Venus and in the Jovian planets and Titan all testify to the importance of heterogeneous reactions. It remains a challenge to connect the gas phase chemistry to the production of aerosols.

  7. A Mercury Model of Atmospheric Transport

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Alex B. [Oregon State Univ., Corvallis, OR (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chodash, Perry A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Procassini, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2018-01-19

    Using the particle transport code Mercury, accurate models were built of the two sources used in Operation BREN, a series of radiation experiments performed by the United States during the 1960s. In the future, these models will be used to validate Mercury’s ability to simulate atmospheric transport.

  8. Applying downscaled global climate model data to a hydrodynamic surface-water and groundwater model

    Science.gov (United States)

    Swain, Eric; Stefanova, Lydia; Smith, Thomas

    2014-01-01

    Precipitation data from Global Climate Models have been downscaled to smaller regions. Adapting this downscaled precipitation data to a coupled hydrodynamic surface-water/groundwater model of southern Florida allows an examination of future conditions and their effect on groundwater levels, inundation patterns, surface-water stage and flows, and salinity. The downscaled rainfall data include the 1996-2001 time series from the European Center for Medium-Range Weather Forecasting ERA-40 simulation and both the 1996-1999 and 2038-2057 time series from two global climate models: the Community Climate System Model (CCSM) and the Geophysical Fluid Dynamic Laboratory (GFDL). Synthesized surface-water inflow datasets were developed for the 2038-2057 simulations. The resulting hydrologic simulations, with and without a 30-cm sea-level rise, were compared with each other and field data to analyze a range of projected conditions. Simulations predicted generally higher future stage and groundwater levels and surface-water flows, with sea-level rise inducing higher coastal salinities. A coincident rise in sea level, precipitation and surface-water flows resulted in a narrower inland saline/fresh transition zone. The inland areas were affected more by the rainfall difference than the sea-level rise, and the rainfall differences make little difference in coastal inundation, but a larger difference in coastal salinities.

  9. Modelling large floating bodies in urban area flash-floods via a Smoothed Particle Hydrodynamics model

    Science.gov (United States)

    Albano, Raffaele; Sole, Aurelia; Mirauda, Domenica; Adamowski, Jan

    2016-10-01

    Large debris, including vehicles parked along floodplains, can cause severe damage and significant loss of life during urban area flash-floods. In this study, the authors validated and applied the Smoothed Particle Hydrodynamics (SPH) model, developed in Amicarelli et al. (2015), which reproduces in 3D the dynamics of rigid bodies driven by free surface flows, to the design of flood mitigation measures. To validate the model, the authors compared the model's predictions to the results of an experimental setup, involving a dam breach that strikes two fixed obstacles and three transportable floating bodies. Given the accuracy of the results, in terms of water depth over time and the time history of the bodies' movements, the SPH model explored in this study was used to analyse the mitigation efficiency of a proposed structural intervention - the use of small barriers (groynes) to prevent the transport of floating bodies. Different groynes configurations were examined to identify the most appropriate design and layout for urban area flash-flood damage mitigation. The authors found that groynes positioned upstream and downstream of each floating body can be effective as a risk mitigation measure for damage resulting from their movement.

  10. Coupled atmosphere-wildland fire modelling

    Directory of Open Access Journals (Sweden)

    Jacques Henri Balbi

    2009-10-01

    Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.

  11. Event-plane dependent di-hadron correlations with harmonic vn subtraction in a hydrodynamic model

    Science.gov (United States)

    Castilho, Wagner M.; Qian, Wei-Liang; Hama, Yogiro; Kodama, Takeshi

    2018-02-01

    In this work, a hydrodynamic study of the di-hadron azimuthal correlations for the Au+Au collisions at 200 GeV is carried out. The correlations are evaluated using the ZYAM method for the centrality windows as well as the transverse momentum range in accordance with the existing data. Event-plane dependence of the correlation is obtained after the subtraction of contributions from the most dominant harmonic coefficients. In particular, the contribution from the triangular flow, v3, is removed from the proper correlations following the procedure implemented by the STAR collaboration. The resultant structure observed in the correlations was sometimes attributed to the mini-jet dynamics, but the present calculations show that a pure hydrodynamic model gives a reasonable agreement with the main feature of the published data. A brief discussion on the physical content of the present findings is presented.

  12. Calibration of HEC-Ras hydrodynamic model using gauged discharge data and flood inundation maps

    Science.gov (United States)

    Tong, Rui; Komma, Jürgen

    2017-04-01

    The estimation of flood is essential for disaster alleviation. Hydrodynamic models are implemented to predict the occurrence and variance of flood in different scales. In practice, the calibration of hydrodynamic models aims to search the best possible parameters for the representation the natural flow resistance. Recent years have seen the calibration of hydrodynamic models being more actual and faster following the advance of earth observation products and computer based optimization techniques. In this study, the Hydrologic Engineering River Analysis System (HEC-Ras) model was set up with high-resolution digital elevation model from Laser scanner for the river Inn in Tyrol, Austria. 10 largest flood events from 19 hourly discharge gauges and flood inundation maps were selected to calibrate the HEC-Ras model. Manning roughness values and lateral inflow factors as parameters were automatically optimized with the Shuffled complex with Principal component analysis (SP-UCI) algorithm developed from the Shuffled Complex Evolution (SCE-UA). Different objective functions (Nash-Sutcliffe model efficiency coefficient, the timing of peak, peak value and Root-mean-square deviation) were used in single or multiple way. It was found that the lateral inflow factor was the most sensitive parameter. SP-UCI algorithm could avoid the local optimal and achieve efficient and effective parameters in the calibration of HEC-Ras model using flood extension images. As results showed, calibration by means of gauged discharge data and flood inundation maps, together with objective function of Nash-Sutcliffe model efficiency coefficient, was very robust to obtain more reliable flood simulation, and also to catch up with the peak value and the timing of peak.

  13. Conceptual Site Model for Newark Bay—Hydrodynamics and Sediment Transport

    Directory of Open Access Journals (Sweden)

    Parmeshwar L. Shrestha

    2014-02-01

    Full Text Available A conceptual site model (CSM has been developed for the Newark Bay Study Area (NBSA as part of the Remedial Investigation/Feasibility Study (RI/FS for this New Jersey site. The CSM is an evolving document that describes the influence of physical, chemical and biological processes on contaminant fate and transport. The CSM is initiated at the start of a project, updated during site activities, and used to inform sampling and remediation planning. This paper describes the hydrodynamic and sediment transport components of the CSM for the NBSA. Hydrodynamic processes are influenced by freshwater inflows, astronomical forcing through two tidal straits, meteorological conditions, and anthropogenic activities such as navigational dredging. Sediment dynamics are driven by hydrodynamics, waves, sediment loading from freshwater sources and the tidal straits, sediment size gradation, sediment bed properties, and particle-to-particle interactions. Cohesive sediment transport is governed by advection, dispersion, aggregation, settling, consolidation, and erosion. Noncohesive sediment transport is governed by advection, dispersion, settling, armoring, and transport in suspension and along the bed. The CSM will inform the development and application of a numerical model that accounts for all key variables to adequately describe the NBSA’s historical, current, and future physical conditions.

  14. Using a coupled eco-hydrodynamic model to predict habitat for target species following dam removal

    Science.gov (United States)

    Tomsic, C.A.; Granata, T.C.; Murphy, R.P.; Livchak, C.J.

    2007-01-01

    A habitat suitability index (HSI) model was developed for a water quality sensitive fish (Greater Redhorse) and macroinvertebrate (Plecoptera) species to determine the restoration success of the St. John Dam removal for the Sandusky River (Ohio). An ArcGIS?? model was created for pre- and post-dam removal scenarios. Inputs to the HSI model consist of substrate distributions from river surveys, and water level and velocity time series, outputs from a hydrodynamic model. The ArcGIS?? model predicted habitat suitability indices at 45 river cross-sections in the hydrodynamic model. The model was programmed to produce polygon layers, using graphical user interfaces that were displayed in the ArcGIS?? environment. The results of the model clearly show an increase of habitat suitability from pre- to post-dam removal periods and in the former reservoir. The change in suitability of the model is attributed mostly to the change in depth in the river following the dam removal for both the fish and invertebrate species. The results of the invertebrate model followed the same positive trend as species enumerations from the river basin. ?? 2007 Elsevier B.V. All rights reserved.

  15. Impact of intertidal area characteristics on estuarine tidal hydrodynamics: A modelling study for the Scheldt Estuary

    Science.gov (United States)

    Stark, J.; Smolders, S.; Meire, P.; Temmerman, S.

    2017-11-01

    Marsh restoration projects are nowadays being implemented as ecosystem-based strategies to reduce flood risks and to restore intertidal habitat along estuaries. Changes in estuarine tidal hydrodynamics are expected along with such intertidal area changes. A validated hydrodynamic model of the Scheldt Estuary is used to gain fundamental insights in the role of intertidal area characteristics on tidal hydrodynamics and tidal asymmetry in particular through several geomorphological scenarios in which intertidal area elevation and location along the estuary is varied. Model results indicate that the location of intertidal areas and their storage volume relative to the local tidal prism determine the intensity and reach along the estuary over which tidal hydrodynamics are affected. Our model results also suggest that intertidal storage areas that are located within the main estuarine channel system, and hence are part of the flow-carrying part of the estuary, may affect tidal hydrodynamics differently than intertidal areas that are side-basins of the main estuarine channel, and hence only contribute little to the flow-carrying cross-section of the estuary. If tidal flats contribute to the channel cross-section and exert frictional effects on the tidal propagation, the elevation of intertidal flats influences the magnitude and direction of tidal asymmetry along estuarine channels. Ebb-dominance is most strongly enhanced if tidal flats are around mean sea level or slightly above. Conversely, flood-dominance is enhanced if the tidal flats are situated low in the tidal frame. For intertidal storage areas at specific locations besides the main channel, flood-dominance in the estuary channel peaks in the vicinity of those areas and generally reduces upstream and downstream compared to a reference scenario. Finally, the model results indicate an along-estuary varying impact on the tidal prism as a result of adding intertidal storage at a specific location. In addition to known

  16. Tagging Water Sources in Atmospheric Models

    Science.gov (United States)

    Bosilovich, M.

    2003-01-01

    Tagging of water sources in atmospheric models allows for quantitative diagnostics of how water is transported from its source region to its sink region. In this presentation, we review how this methodology is applied to global atmospheric models. We will present several applications of the methodology. In one example, the regional sources of water for the North American Monsoon system are evaluated by tagging the surface evaporation. In another example, the tagged water is used to quantify the global water cycling rate and residence time. We will also discuss the need for more research and the importance of these diagnostics in water cycle studies.

  17. A Modelling Approach to Multibody Dynamics of Fluid Power Machinery with Hydrodynamic Lubrication

    DEFF Research Database (Denmark)

    Johansen, Per; Rømer, Daniel; Andersen, Torben Ole

    2013-01-01

    The efficiency potential of the digital displacement technology and the increasing interest in hydraulic transmissions in wind and wave energy applications has created an incentive for development of high efficiency fluid power machinery. Modelling and analysis of fluid power machinery loss mecha...... to be coupled with multibody dynamics models. The focus of the current paper is an approach where the transient pressure field in hydrodynamic lubricated joint clearances are modelled by a set of control volumes and coupled with the fluid power machinery mechanics....

  18. Non-relativistic limit of the compressible Navier-Stokes-Fourier-P1 approximation model arising in radiation hydrodynamics

    OpenAIRE

    Jiang, Song; Li, Fucai; Xie, Feng

    2015-01-01

    As is well-known that the general radiation hydrodynamics models include two mainly coupled parts: one is macroscopic fluid part, which is governed by the compressible Navier-Stokes-Fourier equations, another is radiation field part, which is described by the transport equation of photons. Under the two physical approximations: "gray" approximation and P1 approximation, one can derive the so-called Navier-Stokes-Fourier-P1 approximation radiation hydrodynamics model from the general one. In t...

  19. Hydrodynamic and Sediment Modelling within a Macro Tidal Estuary: Port Curtis Estuary, Australia

    Directory of Open Access Journals (Sweden)

    Ryan J. K. Dunn

    2015-07-01

    Full Text Available An understanding of sediment transport processes and resultant concentration dynamics in estuaries is of great importance to engineering design awareness and the management of these environments. Predictive modelling approaches provide an opportunity to investigate and address potential system responses to nominated events, changes, or conditions of interest, often on high temporal and spatial resolution scales. In this study, a three-dimensional hydrodynamic model and wave model were validated and applied to generate forcing conditions for input into a sediment transport model for the period 7 May 2010–30 October 2010 within a macro tidal estuary, Port Curtis estuary (Australia. The hydrodynamic model was verified against surface and near-bottom current measurements. The model accurately reproduced the variations of surface and near-bottom currents at both a mid-estuary and upper-estuary location. Sediment transport model predictions were performed under varying meteorological conditions and tidal forcing over a 180-day period and were validated against turbidity data collected at six stations within Port Curtis estuary. The sediment transport model was able to predict both the magnitudes of the turbidity levels and the modulation induced by the neap and spring tides and wind-wave variations. The model-predicted (converted turbidity levels compared favourably with the measured surface water turbidity levels at all six stations. The study results have useful practical application for Port Curtis estuary, including providing predictive capabilities to support the selection of locations for monitoring/compliance sites.

  20. Application of 3D hydrodynamic and particle tracking models for better environmental management of finfish culture

    Science.gov (United States)

    Moreno Navas, Juan; Telfer, Trevor C.; Ross, Lindsay G.

    2011-04-01

    Hydrographic conditions, and particularly current speeds, have a strong influence on the management of fish cage culture. These hydrodynamic conditions can be used to predict particle movement within the water column and the results used to optimise environmental conditions for effective site selection, setting of environmental quality standards, waste dispersion, and potential disease transfer. To this end, a 3D hydrodynamic model, MOHID, has been coupled to a particle tracking model to study the effects of mean current speed, quiescent water periods and bulk water circulation in Mulroy Bay, Co. Donegal Ireland, an Irish fjard (shallow fjordic system) important to the aquaculture industry. A Lagangrian method simulated the instantaneous release of "particles" emulating discharge from finfish cages to show the behaviour of waste in terms of water circulation and water exchange. The 3D spatial models were used to identify areas of mixed and stratified water using a version of the Simpson-Hunter criteria, and to use this in conjunction with models of current flow for appropriate site selection for salmon aquaculture. The modelled outcomes for stratification were in good agreement with the direct measurements of water column stratification based on observed density profiles. Calculations of the Simpson-Hunter tidal parameter indicated that most of Mulroy Bay was potentially stratified with a well mixed region over the shallow channels where the water is faster flowing. The fjard was characterised by areas of both very low and high mean current speeds, with some areas having long periods of quiescent water. The residual current and the particle tracking animations created through the models revealed an anticlockwise eddy that may influence waste dispersion and potential for disease transfer, among salmon cages and which ensures that the retention time of waste substances from cages is extended. The hydrodynamic model results were incorporated into the ArcView TM GIS

  1. Modeling and design of radiative hydrodynamic experiments with X-ray Thomson Scattering measurements on NIF

    Science.gov (United States)

    Ma, K. H.; Lefevre, H. J.; Belancourt, P. X.; MacDonald, M. J.; Doeppner, T.; Keiter, P. A.; Kuranz, C. C.; Johnsen, E.

    2017-10-01

    Recent experiments at the National Ignition Facility studied the effect of radiation on shock-driven hydrodynamic instability growth. X-ray radiography images from these experiments indicate that perturbation growth is lower in highly radiative shocks compared to shocks with negligible radiation flux. The reduction in instability growth is attributed to ablation from higher temperatures in the foam for highly radiative shocks. The proposed design implements the X-ray Thomson Scattering (XRTS) technique in the radiative shock tube platform to measure electron temperatures and densities in the shocked foam. We model these experiments with CRASH, an Eulerian radiation hydrodynamics code with block-adaptive mesh refinement, multi-group radiation transport and electron heat conduction. Simulations are presented with SiO2 and carbon foams for both the high temperature, radiative shock and the low-temperature, hydrodynamic shock cases. Calculations from CRASH give estimations for shock speed, electron temperature, effective ionization, and other quantities necessary for designing the XRTS diagnostic measurement. This work is funded by the LLNL under subcontract B614207, and was performed under the auspices of the U.S. DOE by LLNL under Contract No. DE-AC52-07NA27344.

  2. Radiation Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Castor, J I

    2003-10-16

    The discipline of radiation hydrodynamics is the branch of hydrodynamics in which the moving fluid absorbs and emits electromagnetic radiation, and in so doing modifies its dynamical behavior. That is, the net gain or loss of energy by parcels of the fluid material through absorption or emission of radiation are sufficient to change the pressure of the material, and therefore change its motion; alternatively, the net momentum exchange between radiation and matter may alter the motion of the matter directly. Ignoring the radiation contributions to energy and momentum will give a wrong prediction of the hydrodynamic motion when the correct description is radiation hydrodynamics. Of course, there are circumstances when a large quantity of radiation is present, yet can be ignored without causing the model to be in error. This happens when radiation from an exterior source streams through the problem, but the latter is so transparent that the energy and momentum coupling is negligible. Everything we say about radiation hydrodynamics applies equally well to neutrinos and photons (apart from the Einstein relations, specific to bosons), but in almost every area of astrophysics neutrino hydrodynamics is ignored, simply because the systems are exceedingly transparent to neutrinos, even though the energy flux in neutrinos may be substantial. Another place where we can do ''radiation hydrodynamics'' without using any sophisticated theory is deep within stars or other bodies, where the material is so opaque to the radiation that the mean free path of photons is entirely negligible compared with the size of the system, the distance over which any fluid quantity varies, and so on. In this case we can suppose that the radiation is in equilibrium with the matter locally, and its energy, pressure and momentum can be lumped in with those of the rest of the fluid. That is, it is no more necessary to distinguish photons from atoms, nuclei and electrons, than it is

  3. Electrical model of cold atmospheric plasma gun

    Science.gov (United States)

    Slutsker, Ya. Z.; Semenov, V. E.; Krasik, Ya. E.; Ryzhkov, M. A.; Felsteiner, J.; Binenbaum, Y.; Gil, Z.; Shtrichman, R.; Cohen, J. T.

    2017-10-01

    We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.

  4. Analytic Modeling of the Hydrodynamic, Thermal, and Structural Behavior of Foil Thrust Bearings

    Science.gov (United States)

    Bruckner, Robert J.; DellaCorte, Christopher; Prahl, Joseph M.

    2005-01-01

    A simulation and modeling effort is conducted on gas foil thrust bearings. A foil bearing is a self acting hydrodynamic device capable of separating stationary and rotating components of rotating machinery by a film of air or other gaseous lubricant. Although simple in appearance these bearings have proven to be complicated devices in analysis. They are sensitive to fluid structure interaction, use a compressible gas as a lubricant, may not be in the fully continuum range of fluid mechanics, and operate in the range where viscous heat generation is significant. These factors provide a challenge to the simulation and modeling task. The Reynolds equation with the addition of Knudsen number effects due to thin film thicknesses is used to simulate the hydrodynamics. The energy equation is manipulated to simulate the temperature field of the lubricant film and combined with the ideal gas relationship, provides density field input to the Reynolds equation. Heat transfer between the lubricant and the surroundings is also modeled. The structural deformations of the bearing are modeled with a single partial differential equation. The equation models the top foil as a thin, bending dominated membrane whose deflections are governed by the biharmonic equation. A linear superposition of hydrodynamic load and compliant foundation reaction is included. The stiffness of the compliant foundation is modeled as a distributed stiffness that supports the top foil. The system of governing equations is solved numerically by a computer program written in the Mathematica computing environment. Representative calculations and comparisons with experimental results are included for a generation I gas foil thrust bearing.

  5. Modeling of hydrodynamics in hollow fiber membrane bioreactor for mammalian cells cultivation

    Directory of Open Access Journals (Sweden)

    N. V. Menshutina

    2016-01-01

    Full Text Available The mathematical modelling in CFD-packages are powerfull instrument for design and calculation of any engineering tasks. CFD-package contains the set of programs that allow to model the different objects behavior based on the mathematical lows. ANSYS Fluent are widely used for modelling of biotechnological and chemical-technological processes. This package is convenient to describe their hydrodynamics. As cell cultivation is one of the actual scientific direction in modern biotechnology ANSYS Fluent was used to create the model of hollow fiber membrane bioreactor. The fibers are hollow cylindrical membrane to be used for cell cultivation. The criterion of process effectiveness for cell growth is full filling of the membrane surface by cells in the bioreactor. While the cell growth the fiber permeability is decreased which effects to feed flow through membrane pores. The specific feature of this process is to ensure such feed flow to deliver the optimal nutrition for the cells on the external membrane surface. The velocity distribution inside the fiber and in all bioreactor as a whole has been calculated based on mass an impulse conservation equations taking into account the mathematical model assumptions. The hydrodynamics analysis in hollow fiber membrane bioreactor is described by the three-dimensional model created in ANSYS Fluent. The specific features of one membrane model are considered and for whole bioreactor too.

  6. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled: Modelling Stable Atmospheric Boundary Layers over Snow H.A.M. Sterk Wageningen, 29th of April, 2015 Summary The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs typically form at night and in polar

  7. Hydrodynamic Cucker-Smale model with normalized communication weights and time delay

    KAUST Repository

    Choi, Young-Pil

    2017-07-17

    We study a hydrodynamic Cucker-Smale-type model with time delay in communication and information processing, in which agents interact with each other through normalized communication weights. The model consists of a pressureless Euler system with time delayed non-local alignment forces. We resort to its Lagrangian formulation and prove the existence of its global in time classical solutions. Moreover, we derive a sufficient condition for the asymptotic flocking behavior of the solutions. Finally, we show the presence of a critical phenomenon for the Eulerian system posed in the spatially one-dimensional setting.

  8. Hydrodynamic modelling and global datasets: Flow connectivity and SRTM data, a Bangkok case study.

    Science.gov (United States)

    Trigg, M. A.; Bates, P. B.; Michaelides, K.

    2012-04-01

    The rise in the global interconnected manufacturing supply chains requires an understanding and consistent quantification of flood risk at a global scale. Flood risk is often better quantified (or at least more precisely defined) in regions where there has been an investment in comprehensive topographical data collection such as LiDAR coupled with detailed hydrodynamic modelling. Yet in regions where these data and modelling are unavailable, the implications of flooding and the knock on effects for global industries can be dramatic, as evidenced by the recent floods in Bangkok, Thailand. There is a growing momentum in terms of global modelling initiatives to address this lack of a consistent understanding of flood risk and they will rely heavily on the application of available global datasets relevant to hydrodynamic modelling, such as Shuttle Radar Topography Mission (SRTM) data and its derivatives. These global datasets bring opportunities to apply consistent methodologies on an automated basis in all regions, while the use of coarser scale datasets also brings many challenges such as sub-grid process representation and downscaled hydrology data from global climate models. There are significant opportunities for hydrological science in helping define new, realistic and physically based methodologies that can be applied globally as well as the possibility of gaining new insights into flood risk through analysis of the many large datasets that will be derived from this work. We use Bangkok as a case study to explore some of the issues related to using these available global datasets for hydrodynamic modelling, with particular focus on using SRTM data to represent topography. Research has shown that flow connectivity on the floodplain is an important component in the dynamics of flood flows on to and off the floodplain, and indeed within different areas of the floodplain. A lack of representation of flow connectivity, often due to data resolution limitations, means

  9. Improved reference models for middle atmosphere ozone

    Science.gov (United States)

    Keating, G. M.; Pitts, M. C.; Chen, C.

    1990-01-01

    This paper describes the improvements introduced into the original version of ozone reference model of Keating and Young (1985, 1987) which is to be incorporated in the next COSPAR International Reference Atmosphere (CIRA). The ozone reference model will provide information on the global ozone distribution (including the ozone vertical structure as a function of month and latitude from 25 to 90 km) combining data from five recent satellite experiments: the Nimbus 7 LIMS, Nimbus 7 SBUV, AE-2 Stratospheric Aerosol Gas Experiment (SAGE), Solar Mesosphere Explorer (SME) UV Spectrometer, and SME 1.27 Micron Airglow. The improved version of the reference model uses reprocessed AE-2 SAGE data (sunset) and extends the use of SAGE data from 1981 to the 1981-1983 time period. Comparisons are presented between the results of this ozone model and various nonsatellite measurements at different levels in the middle atmosphere.

  10. Hybrid methods for simulating hydrodynamics and heat transfer in multiscale (1D-3D) models

    Science.gov (United States)

    Filimonov, S. A.; Mikhienkova, E. I.; Dekterev, A. A.; Boykov, D. V.

    2017-09-01

    The work is devoted to application of different-scale models in the simulation of hydrodynamics and heat transfer of large and/or complex systems, which can be considered as a combination of extended and “compact” elements. The model consisting of simultaneously existing three-dimensional and network (one-dimensional) elements is called multiscale. The paper examines the relevance of building such models and considers three main options for their implementation: the spatial and the network parts of the model are calculated separately; spatial and network parts are calculated simultaneously (hydraulically unified model); network elements “penetrate” the spatial part and are connected through the integral characteristics at the tube/channel walls (hydraulically disconnected model). Each proposed method is analyzed in terms of advantages and disadvantages. The paper presents a number of practical examples demonstrating the application of multiscale models.

  11. The Whole Atmosphere Community Climate Model

    Science.gov (United States)

    Boville, B. A.; Garcia, R. R.; Sassi, F.; Kinnison, D.; Roble, R. G.

    The Whole Atmosphere Community Climate Model (WACCM) is an upward exten- sion of the National Center for Atmospheric Research Community Climate System Model. WACCM simulates the atmosphere from the surface to the lower thermosphere (140 km) and includes both dynamical and chemical components. The salient points of the model formulation will be summarized and several aspects of its performance will be discussed. Comparison with observations indicates that WACCM produces re- alistic temperature and zonal wind distributions. Both the mean state and interannual variability will be summarized. Temperature inversions in the midlatitude mesosphere have been reported by several authors and are also found in WACCM. These inver- sions are formed primarily by planetary wave forcing, but the background state on which they form also requires gravity wave forcing. The response to sea surface temperature (SST) anomalies will be examined by com- paring simulations with observed SSTs for 1950-1998 to a simulation with clima- tological annual cycle of SSTs. The response to ENSO events is found to extend though the winter stratosphere and mesosphere and a signal is also found at the sum- mer mesopause. The experimental framework allows the ENSO signal to be isolated, because no other forcings are included (e.g. solar variability and volcanic eruptions) which complicate the observational record. The temperature and wind variations asso- ciated with ENSO are large enough to generate significant perturbations in the chem- ical composition of the middle atmosphere, which will also be discussed.

  12. MODEL OF HYDRODYNAMIC MIXING OF CARBONIC POWDERS IN VACUUMATOR, USED IN STEEL-MAKING OF RUP “BMZ”

    Directory of Open Access Journals (Sweden)

    A. N. Chichko

    2005-01-01

    Full Text Available The mathematical model of the mixing and dissolving process of carbonic powder in a system '"vacuumator-bowl” under influence of circulating argon is offered. The spatial distribution of hydrodynamic currents at mixing of carbonic powder, received on the basis of computer calculations is presented. The character of distribution of hydrodynamic speeds of melt (circulating currents in industrial bowl and vacuumator for different time slots of mixing is determined. 

  13. Investigation of Two-Phase Flow in AxialCentrifugal Impeller by Hydrodynamic Modeling Methods

    Directory of Open Access Journals (Sweden)

    V. O. Lomakin

    2014-01-01

    Full Text Available The article provides a methodology to study the flow in the wet part of the pump with fundamentally new axial-centrifugal impeller by methods of hydrodynamic modeling in the software package STAR CCM +. The objective of the study was to determine the normal and cavitation characteristics of the pump with a new type of wet part, as well as optimization of the geometrical parameters of the pump. Authors solved this problem using an example of the hot coolant pump, which should meet high requirements for cavitation quality and efficiency (hydraulic efficiency up to 87%, critical value of NPSH to 2.2 m.Also, the article focuses on the methods of numerical solution of two-phase flow simulation in a pump that are needed for a more accurate simulation of cavitation in the pump and research work in liquids with high gas content.Hydrodynamic modeling was performed on a computing cluster at the department E-10 of BMSTU for pump flow simulation in unsteady statement of problem using the computational grid size to 1.5 million cells. Simultaneously, the experimental model of the pump was made by 3D printing and tested at the stand in the BMSTU. Test results, which were compared with the calculated data are also given in the article. Inaccuracy of the calculation of pump head does not exceed 5%.The simulation results may be of interest to specialists in the field of hydrodynamic modeling, and for designers of such pumps. The authors also report production of a full-length prototype of the pump in order to conduct further testing for the verification of the data in the article, primarily in terms of cavitation characteristics.

  14. Atmospheric inverse modeling via sparse reconstruction

    Science.gov (United States)

    Hase, Nils; Miller, Scot M.; Maaß, Peter; Notholt, Justus; Palm, Mathias; Warneke, Thorsten

    2017-10-01

    Many applications in atmospheric science involve ill-posed inverse problems. A crucial component of many inverse problems is the proper formulation of a priori knowledge about the unknown parameters. In most cases, this knowledge is expressed as a Gaussian prior. This formulation often performs well at capturing smoothed, large-scale processes but is often ill equipped to capture localized structures like large point sources or localized hot spots. Over the last decade, scientists from a diverse array of applied mathematics and engineering fields have developed sparse reconstruction techniques to identify localized structures. In this study, we present a new regularization approach for ill-posed inverse problems in atmospheric science. It is based on Tikhonov regularization with sparsity constraint and allows bounds on the parameters. We enforce sparsity using a dictionary representation system. We analyze its performance in an atmospheric inverse modeling scenario by estimating anthropogenic US methane (CH4) emissions from simulated atmospheric measurements. Different measures indicate that our sparse reconstruction approach is better able to capture large point sources or localized hot spots than other methods commonly used in atmospheric inversions. It captures the overall signal equally well but adds details on the grid scale. This feature can be of value for any inverse problem with point or spatially discrete sources. We show an example for source estimation of synthetic methane emissions from the Barnett shale formation.

  15. Atmospheric inverse modeling via sparse reconstruction

    Directory of Open Access Journals (Sweden)

    N. Hase

    2017-10-01

    Full Text Available Many applications in atmospheric science involve ill-posed inverse problems. A crucial component of many inverse problems is the proper formulation of a priori knowledge about the unknown parameters. In most cases, this knowledge is expressed as a Gaussian prior. This formulation often performs well at capturing smoothed, large-scale processes but is often ill equipped to capture localized structures like large point sources or localized hot spots. Over the last decade, scientists from a diverse array of applied mathematics and engineering fields have developed sparse reconstruction techniques to identify localized structures. In this study, we present a new regularization approach for ill-posed inverse problems in atmospheric science. It is based on Tikhonov regularization with sparsity constraint and allows bounds on the parameters. We enforce sparsity using a dictionary representation system. We analyze its performance in an atmospheric inverse modeling scenario by estimating anthropogenic US methane (CH4 emissions from simulated atmospheric measurements. Different measures indicate that our sparse reconstruction approach is better able to capture large point sources or localized hot spots than other methods commonly used in atmospheric inversions. It captures the overall signal equally well but adds details on the grid scale. This feature can be of value for any inverse problem with point or spatially discrete sources. We show an example for source estimation of synthetic methane emissions from the Barnett shale formation.

  16. Envisat/ASAR Images for the Calibration of Wind Drag Action in the Doñana Wetlands 2D Hydrodynamic Model

    Directory of Open Access Journals (Sweden)

    Anaïs Ramos-Fuertes

    2013-12-01

    Full Text Available Doñana National Park wetlands are located in southwest Spain, on the right bank of the Guadalquivir River, near the Atlantic Ocean coast. The wetlands dry out completely every summer and progressively flood again throughout the fall and winter seasons. Given the flatness of Doñana’s topography, the wind drag action can induce the flooding or emergence of extensive areas, detectable in remote sensing images. Envisat/ASAR scenes acquired before and during strong and persistent wind episodes enabled the spatial delineation of the wind-induced water displacement. A two-dimensional hydrodynamic model of Doñana wetlands was built in 2006 with the aim to predict the effect of proposed hydrologic restoration actions within Doñana’s basin. In this work, on-site wind records and concurrent ASAR scenes are used for the calibration of the wind-drag modeling by assessing different formulations. Results show a good adjustment between the modeled and observed wind drag effect. Displacements of up to 2 km in the wind direction are satisfactorily reproduced by the hydrodynamic model, while including an atmospheric stability parameter led to no significant improvement of the results. Such evidence will contribute to a more accurate simulation of hypothetic or design scenarios, when no information is available for the atmospheric stability assessment.

  17. Better Insight Into Water Resources Management With Integrated Hydrodynamic And Water Quality Models

    Science.gov (United States)

    Debele, B.; Srinivasan, R.; Parlange, J.

    2004-12-01

    Models have long been used in water resources management to guide decision making and improve understanding of the system. Numerous models of different scales -spatial and temporal - are available. Yet, very few models manage to bridge simulations of hydrological and water quality parameters from both upland watershed and riverine system. Most water quality models, such as QUAL2E and EPD-RIV1 concentrate on the riverine system while CE-QUAL-W2 and WASP models focus on larger waterbodies, such as lakes and reservoirs. On the other hand, the original SWAT model, HSPF and other upland watershed hydrological models simulate agricultural (diffuse) pollution sources with limited number of processes incorporated to handle point source pollutions that emanate from industrial sectors. Such limitations, which are common in most hydrodynamic and water quality models undermine better understanding that otherwise could be uncovered by employing integrated hydrological and water quality models for both upland watershed and riverine system. The SWAT model is a well documented and verified hydrological and water quality model that has been developed to simulate the effects of various management scenarios on the health of the environment in terms of water quantity and quality. Recently, the SWAT model has been extended to include the simulation of hydrodynamic and water quality parameters in the river system. The extended SWAT model (ESWAT) has been further extended to run using diurnally varying (hourly) weather data and produce outputs at hourly timescales. This and other improvements in the ESWAT model have been documented in the current work. Besides, the results from two case studies in Texas will be reported.

  18. Modeling of bioreactor hydrodynamic environment and its effects on tissue growth.

    Science.gov (United States)

    Bilgen, Bahar; Barabino, Gilda A

    2012-01-01

    The design of optimal bioreactor systems for tissue engineering applications requires a sophisticated understanding of the complexities of the bioreactor environment and the role that it plays in the formation of engineered tissues. To this end, a tissue growth model is developed to characterize the tissue growth and extracellular matrix synthesis by chondrocytes seeded and cultivated on polyglycolic acid scaffolds in a wavy-walled bioreactor for a period of 4 weeks. This model consists of four components: (1) a computational fluid dynamics (CFD) model to characterize the complex hydrodynamic environment in the bioreactor, (2) a kinetic growth model to characterize the cell growth and extracellular matrix production dynamics, (3) an artificial neural network (ANN) that empirically correlates hydrodynamic parameters with kinetic constants, and (4) a second ANN that correlates the biochemical composition of constructs with their material properties. In tandem, these components enable the prediction of the dynamics of tissue growth, as well as the final compositional and mechanical properties of engineered cartilage. The growth model methodology developed in this study serves as a tool to predict optimal bioprocessing conditions required to achieve desired tissue properties.

  19. 2 Dimensional Hydrodynamic Flood Routing Analysis on Flood Forecasting Modelling for Kelantan River Basin

    Directory of Open Access Journals (Sweden)

    Azad Wan Hazdy

    2017-01-01

    Full Text Available Flood disaster occurs quite frequently in Malaysia and has been categorized as the most threatening natural disaster compared to landslides, hurricanes, tsunami, haze and others. A study by Department of Irrigation and Drainage (DID show that 9% of land areas in Malaysia are prone to flood which may affect approximately 4.9 million of the population. 2 Dimensional floods routing modelling demonstrate is turning out to be broadly utilized for flood plain display and is an extremely viable device for evaluating flood. Flood propagations can be better understood by simulating the flow and water level by using hydrodynamic modelling. The hydrodynamic flood routing can be recognized by the spatial complexity of the schematization such as 1D model and 2D model. It was found that most of available hydrological models for flood forecasting are more focus on short duration as compared to long duration hydrological model using the Probabilistic Distribution Moisture Model (PDM. The aim of this paper is to discuss preliminary findings on development of flood forecasting model using Probabilistic Distribution Moisture Model (PDM for Kelantan river basin. Among the findings discuss in this paper includes preliminary calibrated PDM model, which performed reasonably for the Dec 2014, but underestimated the peak flows. Apart from that, this paper also discusses findings on Soil Moisture Deficit (SMD and flood plain analysis. Flood forecasting is the complex process that begins with an understanding of the geographical makeup of the catchment and knowledge of the preferential regions of heavy rainfall and flood behaviour for the area of responsibility. Therefore, to decreases the uncertainty in the model output, so it is important to increase the complexity of the model.

  20. Hydrodynamic and Inundation Modeling of China’s Largest Freshwater Lake Aided by Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2015-04-01

    Full Text Available China’s largest freshwater lake, Poyang Lake, is characterized by rapid changes in its inundation area and hydrodynamics, so in this study, a hydrodynamic model of Poyang Lake was established to simulate these long-term changes. Inundation information was extracted from Moderate Resolution Imaging Spectroradiometer (MODIS remote sensing data and used to calibrate the wetting and drying parameter by assessing the accuracy of the simulated inundation area and its boundary. The bottom friction parameter was calibrated using current velocity measurements from Acoustic Doppler Current Profilers (ADCP. The results show the model is capable of predicting the inundation area dynamic through cross-validation with remotely sensed inundation data, and can reproduce the seasonal dynamics of the water level, and water discharge through a comparison with hydrological data. Based on the model results, the characteristics of the current velocities of the lake in the wet season and the dry season of the lake were explored, and the potential effect of the current dynamic on water quality patterns was discussed. The model is a promising basic tool for prediction and management of the water resource and water quality of Poyang Lake.

  1. Note on the hydrodynamic description of thin nematic films: Strong anchoring model

    KAUST Repository

    Lin, Te-Sheng

    2013-01-01

    We discuss the long-wave hydrodynamic model for a thin film of nematic liquid crystal in the limit of strong anchoring at the free surface and at the substrate. We rigorously clarify how the elastic energy enters the evolution equation for the film thickness in order to provide a solid basis for further investigation: several conflicting models exist in the literature that predict qualitatively different behaviour. We consolidate the various approaches and show that the long-wave model derived through an asymptotic expansion of the full nemato-hydrodynamic equations with consistent boundary conditions agrees with the model one obtains by employing a thermodynamically motivated gradient dynamics formulation based on an underlying free energy functional. As a result, we find that in the case of strong anchoring the elastic distortion energy is always stabilising. To support the discussion in the main part of the paper, an appendix gives the full derivation of the evolution equation for the film thickness via asymptotic expansion. © 2013 AIP Publishing LLC.

  2. Hydrodynamic models of gas-liquid two-phase flow in porous media

    Directory of Open Access Journals (Sweden)

    B GutiérrezR

    2016-09-01

    Full Text Available Equations and models describing the hydrodynamic of gas-liquid two-phase flows in porous media have become increasingly necessary in order to predict their main features throughout porous networks. The main subject of this research was to study the influence of capillary, viscous and inertial forces and flow configurations on the hydrodynamic features of a gas-liquid two-phase flow in a glass micromodel. Experimental results were obtained and compared with those predicted by three published models. The Fundamental Forces Balance and the Fluid-Fluid Interface models did not describe accurately experimental behavior even when the first of them considers particular characteristics of flow patterns. Semi-empirical models such as The Relative Permeability can describe physical flow characteristics and can also be modified to include different effects not initially considered. Traditionally, relative permeabilities have been associated almost exclusively with saturation conditions. However, it was concluded in this research that liquid relative permeability is function of saturation conditions but also depends on flow patterns and Capillary number.

  3. Hydrodynamic modeling of a reservoir used to supply water to Belem (Lake Agua Preta, Para, Brazil

    Directory of Open Access Journals (Sweden)

    Maria Lourdes Souza Santos

    2015-07-01

    Full Text Available Lake Agua Preta is used by the Sanitation Company of Para (Cosanpa to supply water to the Belem Metropolitan Region. This study aims to use the Base System Modeling Program Environmental Hydrodynamics (Sisbahia model to simulate seasonal hydrodynamic conditions in the lake and identify areas with the greatest silting. The model results revealed an identical distribution of the velocity module for each month of the year. However, at the outlet of the lake, a water channel variation speed of 0.28–0.32 m s-1 was observed. Furthermore, at the inlet of the lake, vortex silting tended to occur, as verified by bathymetry. Sedimentation mainly occurred during periods of low rainfall, which is when Cosanpa increases the inflow of water to maintain the reservoir level and this leads to an increase in sediments in suspension. With the model, it was possible to identify locations with higher rates of sedimentation, and in the future, such data can serve as an effective tool for managing this water resource.

  4. Smoothed particle hydrodynamics modelling in continuum mechanics: fluid-structure interaction

    Directory of Open Access Journals (Sweden)

    Groenenboom P. H. L.

    2009-06-01

    Full Text Available Within this study, the implementation of the smoothed particle hydrodynamics (SPH method solving the complex problem of interaction between a quasi-incompressible fluid involving a free surface and an elastic structure is outlined. A brief description of the SPH model for both the quasi-incompressible fluid and the isotropic elastic solid is presented. The interaction between the fluid and the elastic structure is realised through the contact algorithm. The results of numerical computations are confronted with the experimental as well as computational data published in the literature.

  5. Coupling Hydrodynamic and Wave Propagation Codes for Modeling of Seismic Waves recorded at the SPE Test.

    Science.gov (United States)

    Larmat, C. S.; Rougier, E.; Delorey, A.; Steedman, D. W.; Bradley, C. R.

    2016-12-01

    The goal of the Source Physics Experiment (SPE) is to bring empirical and theoretical advances to the problem of detection and identification of underground nuclear explosions. For this, the SPE program includes a strong modeling effort based on first principles calculations with the challenge to capture both the source and near-source processes and those taking place later in time as seismic waves propagate within complex 3D geologic environments. In this paper, we report on results of modeling that uses hydrodynamic simulation codes (Abaqus and CASH) coupled with a 3D full waveform propagation code, SPECFEM3D. For modeling the near source region, we employ a fully-coupled Euler-Lagrange (CEL) modeling capability with a new continuum-based visco-plastic fracture model for simulation of damage processes, called AZ_Frac. These capabilities produce high-fidelity models of various factors believed to be key in the generation of seismic waves: the explosion dynamics, a weak grout-filled borehole, the surrounding jointed rock, and damage creation and deformations happening around the source and the free surface. SPECFEM3D, based on the Spectral Element Method (SEM) is a direct numerical method for full wave modeling with mathematical accuracy. The coupling interface consists of a series of grid points of the SEM mesh situated inside of the hydrodynamic code's domain. Displacement time series at these points are computed using output data from CASH or Abaqus (by interpolation if needed) and fed into the time marching scheme of SPECFEM3D. We will present validation tests with the Sharpe's model and comparisons of waveforms modeled with Rg waves (2-8Hz) that were recorded up to 2 km for SPE. We especially show effects of the local topography, velocity structure and spallation. Our models predict smaller amplitudes of Rg waves for the first five SPE shots compared to pure elastic models such as Denny &Johnson (1991).

  6. Comparison of new generation low-complexity flood inundation mapping tools with a hydrodynamic model

    Science.gov (United States)

    Afshari, Shahab; Tavakoly, Ahmad A.; Rajib, Mohammad Adnan; Zheng, Xing; Follum, Michael L.; Omranian, Ehsan; Fekete, Balázs M.

    2018-01-01

    The objective of this study is to compare two new generation low-complexity tools, AutoRoute and Height Above the Nearest Drainage (HAND), with a two-dimensional hydrodynamic model (Hydrologic Engineering Center-River Analysis System, HEC-RAS 2D). The assessment was conducted on two hydrologically different and geographically distant test-cases in the United States, including the 16,900 km2 Cedar River (CR) watershed in Iowa and a 62 km2 domain along the Black Warrior River (BWR) in Alabama. For BWR, twelve different configurations were set up for each of the models, including four different terrain setups (e.g. with and without channel bathymetry and a levee), and three flooding conditions representing moderate to extreme hazards at 10-, 100-, and 500-year return periods. For the CR watershed, models were compared with a simplistic terrain setup (without bathymetry and any form of hydraulic controls) and one flooding condition (100-year return period). Input streamflow forcing data representing these hypothetical events were constructed by applying a new fusion approach on National Water Model outputs. Simulated inundation extent and depth from AutoRoute, HAND, and HEC-RAS 2D were compared with one another and with the corresponding FEMA reference estimates. Irrespective of the configurations, the low-complexity models were able to produce inundation extents similar to HEC-RAS 2D, with AutoRoute showing slightly higher accuracy than the HAND model. Among four terrain setups, the one including both levee and channel bathymetry showed lowest fitness score on the spatial agreement of inundation extent, due to the weak physical representation of low-complexity models compared to a hydrodynamic model. For inundation depth, the low-complexity models showed an overestimating tendency, especially in the deeper segments of the channel. Based on such reasonably good prediction skills, low-complexity flood models can be considered as a suitable alternative for fast

  7. Source tracking using microbial community fingerprints: Method comparison with hydrodynamic modelling.

    Science.gov (United States)

    McCarthy, D T; Jovanovic, D; Lintern, A; Teakle, I; Barnes, M; Deletic, A; Coleman, R; Rooney, G; Prosser, T; Coutts, S; Hipsey, M R; Bruce, L C; Henry, R

    2017-02-01

    Urban estuaries around the world are experiencing contamination from diffuse and point sources, which increases risks to public health. To mitigate and manage risks posed by elevated levels of contamination in urban waterways, it is critical to identify the primary water sources of contamination within catchments. Source tracking using microbial community fingerprints is one tool that can be used to identify sources. However, results derived from this approach have not yet been evaluated using independent datasets. As such, the key objectives of this investigation were: (1) to identify the major sources of water responsible for bacterial loadings within an urban estuary using microbial source tracking (MST) using microbial communities; and (2) to evaluate this method using a 3-dimensional hydrodynamic model. The Yarra River estuary, which flows through the city of Melbourne in South-East Australia was the focus of this study. We found that the water sources contributing to the bacterial community in the Yarra River estuary varied temporally depending on the estuary's hydrodynamic conditions. The water source apportionment determined using microbial community MST correlated to those determined using a 3-dimensional hydrodynamic model of the transport and mixing of a tracer in the estuary. While there were some discrepancies between the two methods, this investigation demonstrated that MST using bacterial community fingerprints can identify the primary water sources of microorganisms in an estuarine environment. As such, with further optimization and improvements, microbial community MST has the potential to become a powerful tool that could be practically applied in the mitigation of contaminated aquatic systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. The optimization of high resolution topographic data for 1D hydrodynamic models

    Energy Technology Data Exchange (ETDEWEB)

    Ales, Ronovsky, E-mail: ales.ronovsky@vsb.cz; Michal, Podhoranyi [IT4Innovations National Supercomputing Center, VŠB-Technical University of Ostrava, Studentská 6231/1B, 708 33 Ostrava (Czech Republic)

    2016-06-08

    The main focus of our research presented in this paper is to optimize and use high resolution topographical data (HRTD) for hydrological modelling. Optimization of HRTD is done by generating adaptive mesh by measuring distance of coarse mesh and the surface of the dataset and adapting the mesh from the perspective of keeping the geometry as close to initial resolution as possible. Technique described in this paper enables computation of very accurate 1-D hydrodynamic models. In the paper, we use HEC-RAS software as a solver. For comparison, we have chosen the amount of generated cells/grid elements (in whole discretization domain and selected cross sections) with respect to preservation of the accuracy of the computational domain. Generation of the mesh for hydrodynamic modelling is strongly reliant on domain size and domain resolution. Topographical dataset used in this paper was created using LiDAR method and it captures 5.9km long section of a catchment of the river Olše. We studied crucial changes in topography for generated mesh. Assessment was done by commonly used statistical and visualization methods.

  9. Calculation of Hydrodynamic Properties for G-Quadruplex Nucleic Acid Structures from in silico Bead Models

    Science.gov (United States)

    Le, Huy T.; Buscaglia, Robert; Dean, William L.; Chaires, Jonathan B.; Trent, John O.

    2012-01-01

    Nucleic acids enriched in guanine bases can adopt unique quadruple helical tertiary structures known as G-quadruplexes. G-quadruplexes have emerged as attractive drug targets as many G-quadruplex-forming sequences have been discovered in functionally critical sites within the human genome, including the telomere, oncogene promoters, and mRNA processing sites. A single G-quadruplex-forming sequence can adopt one of multiple folding topologies often resulting in a lack of a single definitive atomic-level resolution structure for many of these sequences and a major challenge to the discovery of G-quadruplex-selective small molecule drugs. Low-resolution techniques employed to study G-quadruplex structures (e.g. CD spectroscopy) are often unable to discern between G-quadruplex structural ensembles while high-resolution techniques (e.g. NMR spectroscopy) can be overwhelmed by a highly polymorphic system. Hydrodynamic bead modeling is an approach to studying G-quadruplex structures that could bridge the gap between low-resolution techniques and high-resolution molecular models. Here, we present a discussion of hydrodynamic bead modeling in the context of studying G-quadruplex structures, highlighting recent successes and limitations to this approach, as well as an example featuring a G-quadruplex structure formed from the human telomere. This example can easily be adapted to the investigation of any other G-quadruplex-forming sequences. PMID:22886555

  10. Pollution history of a tropical estuary revealed by combined hydrodynamic modelling and sediment geochemistry

    Science.gov (United States)

    Andrews, J. E.; Greenaway, A. M.; Bigg, G. R.; Webber, D. F.; Dennis, P. F.; Guthrie, G. A.

    1999-01-01

    Hydrodynamic modelling of water movement in Hunts Bay, a protected part of Kingston Harbour, Jamaica, shows that depth averaged tidal flows are very low. In the northeast corner of Hunts Bay, water is essentially stagnant. Even under high flow conditions, much of the Bay bottom water is `bypassed' by buoyant, lower salinity surface flows. The muddy sediments of Hunts Bay reflect these sluggish to stagnant conditions; sediment cores from the northeast corner of the Bay contain progressively higher amounts of organic matter in their upper parts (˜last 15-20 years sedimentation). Combined C/N ratios and stable carbon isotope compositions of this organic matter imply a sewage origin. Both lead and chromium metal concentrations and enrichment factors relative to average crustal shales show geographically related patterns that reflect hydrodynamic circulation predicted by modelling. In particular, metal concentrations and enrichment factors are highest at the northern end of the bay, especially in the northeast corner. Modelling confirms that stagnant conditions would occur in the northeast part of the bay even without the presence of a major causeway. The causeway may contribute to low flow conditions, but is not the principal cause of organic contamination, which is simply an excessive input of sewage.

  11. Hydrodynamic Transfection for Generation of Novel Mouse Models for Liver Cancer Research

    Science.gov (United States)

    Chen, Xin; Calvisi, Diego F.

    2015-01-01

    Primary liver cancers, including hepatocellular carcinoma and intrahepatic cholangiocarcinoma, are leading causes of cancer-related death worldwide. Recent large-scale genomic approaches have identified a wide number of genes whose deregulation is associated with hepatocellular carcinoma and intrahepatic cholangiocarcinoma development. Murine models are critical tools to determine the oncogenic potential of these genes. Conventionally, transgenic or knockout mouse models are used for this purpose. However, several limitations apply to the latter models. Herein, we review a novel approach for stable gene expression in mouse hepatocytes by hydrodynamic injection in combination with Sleeping Beauty–mediated somatic integration. This method represents a flexible, reliable, and cost-effective tool to generate preclinical murine models for liver cancer research. Furthermore, it can be used as an in vivo transfection method to study biochemical cross talks among multiple pathways along hepatocarcinogenesis and to test the therapeutic potential of drugs against liver cancer. PMID:24480331

  12. Investigation of the influence of the open cell foam models geometry on hydrodynamic calculation

    Science.gov (United States)

    Soloveva, O. V.; Solovev, S. A.; Khusainov, R. R.; Popkova, O. S.; Panenko, D. O.

    2018-01-01

    A geometrical model of the open cell foam was created as an ordered set of intersecting spheres. The proposed model closely describes a real porous cellular structure. The hydrodynamics flow was calculated on the basis of a simple model in the ANSYS Fluent software package. A pressure drop was determined, the value of which was compared with the experimental data of other authors. As a result of the conducted studies, we found that a porous structure with smoothed faces provides the smallest pressure drop with the same porosity of the package. Analysis of the calculated data demonstrated that the approximation of an elementary porous cell substantially distorts the flow field. This is undesirable in detailed modeling of the open cell foam.

  13. Sensitivity analysis of a coupled hydrodynamic-vegetation model using the effectively subsampled quadratures method (ESQM v5.2)

    Science.gov (United States)

    Kalra, Tarandeep S.; Aretxabaleta, Alfredo; Seshadri, Pranay; Ganju, Neil K.; Beudin, Alexis

    2017-12-01

    Coastal hydrodynamics can be greatly affected by the presence of submerged aquatic vegetation. The effect of vegetation has been incorporated into the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system. The vegetation implementation includes the plant-induced three-dimensional drag, in-canopy wave-induced streaming, and the production of turbulent kinetic energy by the presence of vegetation. In this study, we evaluate the sensitivity of the flow and wave dynamics to vegetation parameters using Sobol' indices and a least squares polynomial approach referred to as the Effective Quadratures method. This method reduces the number of simulations needed for evaluating Sobol' indices and provides a robust, practical, and efficient approach for the parameter sensitivity analysis. The evaluation of Sobol' indices shows that kinetic energy, turbulent kinetic energy, and water level changes are affected by plant stem density, height, and, to a lesser degree, diameter. Wave dissipation is mostly dependent on the variation in plant stem density. Performing sensitivity analyses for the vegetation module in COAWST provides guidance to optimize efforts and reduce exploration of parameter space for future observational and modeling work.

  14. Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

    Science.gov (United States)

    Sagan, C.

    1974-01-01

    The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

  15. Anisotropic hydrodynamic modeling of 2.76 TeV Pb-Pb collisions

    Science.gov (United States)

    Alqahtani, Mubarak; Nopoush, Mohammad; Ryblewski, Radoslaw; Strickland, Michael

    2017-10-01

    We compare phenomenological results from 3 +1 D quasiparticle anisotropic hydrodynamics (aHydroQP) with experimental data collected in the CERN Large Hadron Collider 2.76 TeV Pb-Pb collisions. In particular, we present comparisons of particle spectra, average transverse momentum, elliptic flow, and Hanbury Brown-Twiss radii. The aHydroQP model relies on the introduction of a single temperature-dependent quasiparticle mass which is fit to lattice QCD data. By taking moments of the resulting Boltzmann equation, we obtain the dynamical equations used in the hydrodynamic stage which include the effects of both shear and bulk viscosities. At freeze-out, we use anisotropic Cooper-Frye freeze-out performed on a fixed-energy-density hypersurface to convert to hadrons. To model the production and decays of the hadrons we use therminator2 which is customized to sample from ellipsoidal momentum-space distribution functions. Using smooth Glauber initial conditions, we find very good agreement with many heavy-ion collision observables.

  16. Hydrodynamic Modelling of Municipal Solid Waste Residues in a Pilot Scale Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    João Cardoso

    2017-11-01

    Full Text Available The present study investigates the hydrodynamics and heat transfer behavior of municipal solid waste (MSW gasification in a pilot scale bubbling fluidized bed reactor. A multiphase 2-D numerical model following an Eulerian-Eulerian approach within the FLUENT framework was implemented. User defined functions (UDFs were coupled to improve hydrodynamics and heat transfer phenomena, and to minimize deviations between the experimental and numerical results. A grid independence study was accomplished through comparison of the bed volume fraction profiles and by reasoning the grid accuracy and computational cost. The standard deviation concept was used to determine the mixing quality indexes. Simulated results showed that UDFs improvements increased the accuracy of the mathematical model. Smaller size ratio of the MSW-dolomite mixture revealed a more uniform mixing, and larger ratios enhanced segregation. Also, increased superficial gas velocity promoted the solid particles mixing. Heat transfer within the fluidized bed showed strong dependence on the MSW solid particles sizes, with smaller particles revealing a more effective process.

  17. A hydrodynamic model of labyrinth to study the stimulation of perilymph compartments by audioprostheses.

    Science.gov (United States)

    Urquiza, R; Oballe, O; Sánchez, J A; Casanova, R; Gago, A; Ciges, M

    2008-04-01

    The hydrodynamic model of the labyrinth spaces (LHM) is a useful tool for research on implantable audioprostheses, in particular to develop suitable actuators using MEMS technology (micro-electromechanic machine system). It has other potential applications for auditory research. The energy reaching the labyrinth fluids is crucial information for developing prostheses to substitute the tympanic-ossicular system because adequate stimulation of the cochlear partition is essential. However, in vivo measurements in human ears are not currently available. Therefore a model of the normal labyrinth resembling its hydrodynamic properties becomes a valuable tool. It could allow comparison of different processing systems, algorithms and transducers, to develop new audioprostheses and improve their effectiveness and efficiency. This work presents one LHM that emulates the conduction of the stimuli from the stapes footplate through the labyrinthine fluids, including its dimensions and physical properties, and some examples of measurements of perilymph stimulation by different audioprostheses and algorithms. RESULTS. As shown in the reported examples, this LHM provided effective measurement of acoustic stimulation across the whole human auditory frequency and intensity spectrum. Air-delivered and direct stimulation methods are possible. This provided convenient information for the actuator development and allowed comparison between different prototypes, stimulation patterns and algorithms.

  18. Radiation Hydrodynamical Turbulence in Protoplanetary Disks: Numerical Models and Observational Constraints

    Science.gov (United States)

    Flock, Mario; Nelson, Richard P.; Turner, Neal J.; Bertrang, Gesa H.-M.; Carrasco-González, Carlos; Henning, Thomas; Lyra, Wladimir; Teague, Richard

    2017-12-01

    Planets are born in protostellar disks, which are now observed with enough resolution to address questions about internal gas flows. Magnetic forces are possibly drivers of the flows, but ionization state estimates suggest that much of the gas mass decouples from magnetic fields. Thus, hydrodynamical instabilities could play a major role. We investigate disk dynamics under conditions typical for a T Tauri system, using global 3D radiation-hydrodynamics simulations with embedded particles and a resolution of 70 cells per scale height. Stellar irradiation heating is included with realistic dust opacities. The disk starts in joint radiative balance and hydrostatic equilibrium. The vertical shear instability (VSI) develops into turbulence that persists up to at least 1600 inner orbits (143 outer orbits). Turbulent speeds are a few percent of the local sound speed at the midplane, increasing to 20%, or 100 m s-1, in the corona. These are consistent with recent upper limits on turbulent speeds from optically thin and thick molecular line observations of TW Hya and HD 163296. The predominantly vertical motions induced by the VSI efficiently lift particles upward. Grains 0.1 and 1 mm in size achieve scale heights greater than expected in isotropic turbulence. We conclude that while kinematic constraints from molecular line emission do not directly discriminate between magnetic and nonmagnetic disk models, the small dust scale heights measured in HL Tau and HD 163296 favor turbulent magnetic models, which reach lower ratios of the vertical kinetic energy density to the accretion stress.

  19. Transient pressure changes in the vertebral canal during whiplash motion--A hydrodynamic modeling approach.

    Science.gov (United States)

    Yao, Hua-Dong; Svensson, Mats Y; Nilsson, Håkan

    2016-02-08

    In vehicle collisions, the occupant's torso is accelerated in a given direction while the unsupported head tends to lag behind. This mechanism results in whiplash motion to the neck. In whiplash experiments conducted for animals, pressure transients have been recorded in the spinal canal. It was hypothesized that the transients caused dorsal root ganglion dysfunction. Neck motion introduces volume changes inside the vertebral canal. The changes require an adaptation which is likely achieved by redistribution of blood volume in the internal vertebral venous plexus (IVVP). Pressure transients then arise from the rapid redistribution. The present study aimed to explore the hypothesis theoretically and analytically. Further, the objectives were to quantify the effect of the neck motion on the pressure generation and to identify the physical factors involved. We developed a hydrodynamic system of tubes that represent the IVVP and its lateral intervertebral vein connections. An analytical model was developed for an anatomical geometrical relation that the venous blood volume changes with respect to the vertebral angular displacement. This model was adopted in the hydrodynamic tube system so that the system can predict the pressure transients on the basis of the neck vertebral motion data from a whiplash experiment. The predicted pressure transients were in good agreement with the earlier experimental data. A parametric study was conducted and showed that the system can be used to assess the influences of anatomical geometrical properties and vehicle collision severity on the pressure generation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. High-resolution modelling of 3D hydrodynamics in coastal archipelagos

    Science.gov (United States)

    Miettunen, Elina; Tuomi, Laura; Ropponen, Janne; Lignell, Risto

    2016-04-01

    Dynamics of the coastal seas are affected by eutrophication, over-fishing, coastal construction and climate change. To enable the sustainable development of these areas, monitoring and modelling of the state of the sea are needed. The Archipelago Sea, located in the northern part of the semi-enclosed and brackish water Baltic Sea, is one of the most complex coastal areas with over 40 000 small islands and islets. It is also very vulnerable area already heavily stressed with eutrophication. Applicable modelling tools are needed to support the decision making and to provide sufficiently reliable information on the effects of the planned actions on the state of the coastal waters. We used 3D hydrodynamic model COHERENS to model the Archipelago Sea area with high spatial resolution of 0.25 nmi. Boundary conditions for this limited area were provided from coarser resolution, 2 nmi, Baltic Sea grid. In order to evaluate the performance of the high-resolution coastal model implementation a comprehensive measurement dataset was gathered, including hydrographic data from three intensive monitoring stations and several more rarely visited monitoring or research stations. The hydrodynamic model was able to simulate the surface temperature and salinity fields and their seasonal variation with good accuracy in this complex area. The sharp depth gradients typical for this area provided some challenges to the modelling. There was some over mixing and related to too strong vertical currents in the steep slopes of the deeper fault lines. Also the water exchange between the more open sea and coastal areas through narrow channels between the islands is not sufficiently well reproduced with the current resolution, leading to too high bottom temperatures.

  1. Generic atmospheric correction models for radar measurements

    Science.gov (United States)

    Li, Zhenhong; Yu, Chen; Crippa, Paola; Penna, Nigel

    2017-04-01

    Atmospheric effects (especially the part due to tropospheric water vapour) represent one of the major error sources of repeat-pass Interferometric Synthetic Aperture Radar (InSAR), and limit the accuracy of InSAR derived surface displacements. The spatio-temporal variations of atmospheric water vapour make it a challenge to measure small-amplitude surface displacements with InSAR. In previous studies, several InSAR atmospheric correction models have been successfully demonstrated: (1) Ground-based correction models such as those using Global Navigation Satellite System (GNSS) and/or surface meteorological observations, (2) Space-based correction models including those involving NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and/or ESA Medium Resolution Imaging Spectrometer (MERIS), and (3) Numerical Weather Model (NWM) based corrections including those using the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim and/or Weather Research and Forecasting (WRF) models. Each model has its own inherited limitations. For example, ground-based correction models are limited by the availability (and distribution) of ground observations, whilst MODIS/MERIS correction models are sensitive to the presence of clouds and there is often a time difference between space-based water vapour and radar observations. Similar to space-based correction models, NWM correction models might be impacted by the time difference between NWM and radar observations. Taking into account the inherent advantages and limitations of GNSS, MODIS and ECMWF water vapour products, we aim to develop a global and near-real-time mode InSAR atmospheric correction model. Tropospheric delays can be routinely retrieved from ground-based GNSS arrays in all-weather conditions and also in real-time. We develop an Iterative Tropospheric Decomposition (ITD) interpolation model that decouples the GNSS-estimated total tropospheric delays into (i) a stratified component highly correlated

  2. Hydrodynamics with strength: scaling-invariant solutions for elastic-plastic cavity expansion models

    Science.gov (United States)

    Albright, Jason; Ramsey, Scott; Baty, Roy

    2017-11-01

    Spherical cavity expansion (SCE) models are used to describe idealized detonation and high-velocity impact in a variety of materials. The common theme in SCE models is the presence of a pressure-driven cavity or void within a domain comprised of plastic and elastic response sub-regions. In past work, the yield criterion characterizing material strength in the plastic sub-region is usually taken for granted and assumed to take a known functional form restrictive to certain classes of materials, e.g. ductile metals or brittle geologic materials. Our objective is to systematically determine a general functional form for the yield criterion under the additional requirement that the SCE admits a similarity solution. Solutions determined under this additional requirement have immediate implications toward development of new compressible flow algorithm verification test problems. However, more importantly, these results also provide novel insight into modeling the yield criteria from the perspective of hydrodynamic scaling.

  3. Data-Driven Radiative Hydrodynamic Modeling of the 2014 March 29 X1.0 Solar Flare

    Science.gov (United States)

    Da Costa, Fatima Rubio; Kleint, Lucia; Petrosian, Vahe; Liu, Wei; Allred, Joel C.

    2016-01-01

    Spectroscopic observations of solar flares provide critical diagnostics of the physical conditions in the flaring atmosphere. Some key features in observed spectra have not yet been accounted for in existing flare models. Here we report a data-driven simulation of the well-observed X1.0 flare on 2014 March 29 that can reconcile some well-known spectral discrepancies. We analyzed spectra of the flaring region from the Interface Region Imaging Spectrograph (IRIS) in Mg II hk, the Interferometric BIdimensional Spectropolarimeter at the Dunn Solar Telescope (DSTIBIS) in H(alpha) 6563A and Ca II 8542A, and the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) in hard X-rays. We constructed a multithreaded flare loop model and used the electron flux inferred from RHESSI data as the input to the radiative hydrodynamic code RADYN to simulate the atmospheric response. We then synthesized various chromospheric emission lines and compared them with the IRIS and IBIS observations. In general, the synthetic intensities agree with the observed ones, especially near the northern footpoint of the flare. The simulated Mg II line profile has narrower wings than the observed one. This discrepancy can be reduced by using a higher microturbulent velocity (27 km/s) in a narrow chromospheric layer. In addition, we found that an increase of electron density in the upper chromosphere within a narrow height range of approx. 800 km below the transition region can turn the simulated Mg II line core into emission and thus reproduce the single peaked profile, which is a common feature in all IRIS flares.

  4. Macroinvertebrate response to flow changes in a subalpine stream: predictions from two-dimensional hydrodynamic models

    Science.gov (United States)

    Waddle, T.J.; Holmquist, J.G.

    2013-01-01

    Two-dimensional hydrodynamic models are being used increasingly as alternatives to traditional one-dimensional instream flow methodologies for assessing adequacy of flow and associated faunal habitat. Two-dimensional modelling of habitat has focused primarily on fishes, but fish-based assessments may not model benthic macroinvertebrate habitat effectively. We extend two-dimensional techniques to a macroinvertebrate assemblage in a high-elevation stream in the Sierra Nevada (Dana Fork of the Tuolumne River, Yosemite National Park, CA, USA). This stream frequently flows at less than 0.03?m3?s?1 in late summer and is representative of a common water abstraction scenario: maximum water abstraction coinciding with seasonally low flows. We used two-dimensional modelling to predict invertebrate responses to reduced flows that might result from increased abstraction. We collected site-specific field data on the macroinvertebrate assemblage, bed topography and flow conditions and then coupled a two-dimensional hydrodynamic model with macroinvertebrate indices to evaluate habitat across a range of low flows. Macroinvertebrate indices were calculated for the wetted area at each flow. A surrogate flow record based on an adjacent watershed was used to evaluate frequency and duration of low flow events. Using surrogate historical records, we estimated that flow should fall below 0.071?m3?s?1 at least 1?day in 82 of 95?years and below 0.028?m3?s?1 in 48 of 95?years. Invertebrate metric means indicated minor losses in response to modelled discharge reductions, but wetted area decreased substantially. Responses of invertebrates to water abstraction will likely be a function of changing habitat quantity rather than quality.

  5. Parameterizing floodplain vegetation roughness using Airborne Light Detection and Ranging (LiDAR) on a 2D hydrodynamic model of the Lower Yuba River, CA

    Science.gov (United States)

    Abu-Aly, T. R.; Pasternack, G. B.; Wyrick, J. R.; Barker, R.; Massa, D.; Johnson, T.

    2011-12-01

    Riparian vegetation in lowland rivers has an important effect on hydrodynamics that needs to be accounted for in predictive hydrodynamic modeling. Present-day 2D hydrodynamic models can spatially distribute vegetation, and often do so using discrete polygons to characterize ostensibly uniform vegetative patches into a small set of different vegetation class types. Then roughness values are empirically assigned to each patch type. In order for 2D models to accurately capture the complex out-of-bank flow interactions, a new methodology is needed to bridge a physical connection between vegetation presence and flow resistance at the reach scale. Airborne Light Detection and Ranging enables mapping the 1-2 m resolution grid of vegetation presence and canopy height. In this study a next-generation algorithm was used to spatially distribute stage-dependent channel roughness at the 1-m scale over ~30-km of gravel-bed river corridor using equations from atmospheric boundary layer theory that reduce the data inputs to just estimated water depth and canopy height. Then 2D models were run for flows ranging from 0.2-20 times bankfull discharge both with and without spatially distributed vegetation. Results were analyzed to gain insight into the stage-dependent effects of vegetation on velocities, flow paths, and sediment transport capacity. At the flood flow of 21,100 cfs, adding vegetation caused an 8.0% increase in the wetted area, a 7.4% increase in the mean depth, and a 17.5% decrease in the mean velocity compared with the unvegetated model. The results showed that vegetation has a strong channelization effect on the flow, increasing mid-channel velocities and diverting flow away from densely vegetated areas. In the floodplain, vegetation stands caused preferential flow paths that were otherwise unaccounted for in the unvegetated model runs.

  6. Hydrodynamic Modeling of the Near-Source Environment at a Jointed Site

    Science.gov (United States)

    Snelson, C. M.; Bradley, C. R.; Steedman, D. W.; Rougier, E.

    2014-12-01

    We perform near source hydrodynamic modeling of an explosive event in granite: the first Source Physics Experiment (SPE-1). The effort includes constitutive material behavior of the rock, the optimal means for representing the granite joint response, and the best modeling approach for including both the high-deformation source region and the complex material response in the near field. Each of these factors contributes to better estimates of explosion to seismic phenomena to help the verification community. We illustrate the transition of results from increasing modeling fidelity from one-dimensional (1-D) modeling which simplifies both the source geometry and the geologic character to full, detailed three-dimensional (3-D) modeling. Both levels of modeling include an accepted explosive source model and a laboratory test-based constitutive mode for the intact granite. But the full 3-D model also explicitly models the cylindrically-shaped explosive in a grout filled borehole as well as explicit representation of rock joints as contact surfaces. These modeling attributes provide for an excellent match to recorded velocity measurements in both amplitude and character. But as explicit modeling of joints is currently impractical for a large rock volume, we modify the laboratory intact properties to implicitly include the effects of joints such as in the method of Hoek and Brown to develop a credible predictive methodology for a large region.

  7. Modeling circumstellar disc fragmentation and episodic protostellar accretion with smoothed particle hydrodynamics in cell

    Science.gov (United States)

    Stoyanovskaya, O. P.; Snytnikov, N. V.; Snytnikov, V. N.

    2017-10-01

    We discuss the ability of the smoothed particle hydrodynamics (SPH) method combined with a grid-based solver for the Poisson equation to model mass accretion onto protostars in gravitationally unstable protostellar discs. We scrutinize important features of coupling the SPH with grid-based solvers and numerical issues associated with (1) large number of SPH neighbors and (2) relation between gravitational softening and hydrodynamic smoothing length. We report results of our simulations of razor-thin disc prone to fragmentation and demonstrate that the algorithm being simple and homogeneous captures the target physical processes - disc gravitational fragmentation and accretion of gas onto the protostar caused by inward migration of dense clumps. In particular, we obtain two types of accretion bursts: a short-duration one caused by a quick inward migration of the clump, previously reported in the literature, and the prolonged one caused by the clump lingering at radial distances on the order of 15-25 au. The latter is culminated with a sharp accretion surge caused by the clump ultimately falling on the protostar.

  8. Application of the hydrodynamic predictive modeling on the example of the pumping station 'Bezdan 1'

    Directory of Open Access Journals (Sweden)

    Polomčić Dušan M.

    2014-01-01

    Full Text Available In the area of Bezdan, the construction of a new pumping station, p.s. 'Bezdan 1', on the location of the existing and nonfunctional pumping station 'Bezdan I', is envisaged. Given the position of the future pump station, a problem of digging the foundation pits in terms of protection from high groundwater levels, was noticed. This paper aims to analyze the possibilities for lowering the groundwater levels below the projected elevation, which will enable unobstructed work on the pumping station. By using the hydrodynamic analysis and its most complex and most applicable methods of three-dimensional hydrodynamic modeling of aquifer regime, based on the numerical method of finite differences, the system of protection and variations of the protection solutions from groundwater at the research location of the future p.s. 'Bezdan 1' was defined. Three variants of solution were given, and characteristics of the system of protection from groundwater were defined for each, the optimal number of drainage wells in the system and their spatial distribution and the time required for maximal effects of the lowering of the groundwater levels below the elevation of the excavation facilities of CS 'Bezdan 1'. Presented paper provides the basis for some of the methods of multicriteria optimization and the selection of the optimal variant of the system of protection from groundwater's, considering, in this way, the weight of various factors that influence the choice of the variant, such as technical, economic, environmental and safety factors.

  9. Vegetation Density, Root Architecture Model, and Hydrodynamic Simulation Rhizophora apiculata Bl. in Bone Bay, South Sulawesi

    Directory of Open Access Journals (Sweden)

    Aswar Rustam

    2017-09-01

    Full Text Available Mangrove is the only ecosistem that grows and develops in the coastal area. This study was conducted to analyze the mangrove forest vegetation to create a simulation of the root sistem of Rhizophora apiculata Bl. related to its ability in the process of hydrodynamic fluid of seawater in the Lompo village, District Awangpone, Bone Regency, South Sulawesi. Criteria that used as a model reference had minimum age approximately five years and minimum height of about 2 m. The variables that measure were height, diameter, and length of the roots. The parameters of the simulation are the average speed of sea level, the dynamic pressure of seawater, as well as drag coefficient of Gulf of Bone. Based on this research, vegetation area with highest density located at second kilometer, medium density located at first kilometer, and the lowest density located at third kilometer. The average velocity of seawater, the lowest is in the natural cropping pattern of highest density, meanwhile the highest is in the parallel cropping pattern of lowest density. Dynamic pressure, the lowest is in the natural cropping pattern of highest density, meanwhile the highest is in the parallel cropping pattern of lowest density. The drag coefficient, the highest is in the natural cropping pattern of highest density, meanwhile the lowest is in the parallel cropping pattern of lowest density. Keywords: drag coefficient, hydrodynamics, mangrove, Rhizophora apiculata Bl., simulation

  10. A data assimilation system combining CryoSat-2 data and hydrodynamic river models

    Science.gov (United States)

    Schneider, Raphael; Ridler, Marc-Etienne; Godiksen, Peter Nygaard; Madsen, Henrik; Bauer-Gottwein, Peter

    2018-02-01

    There are numerous hydrologic studies using satellite altimetry data from repeat-orbit missions such as Envisat or Jason over rivers. This study is one of the first examples for the combination of altimetry from drifting-ground track satellite missions, namely CryoSat-2, with a river model. CryoSat-2 SARIn Level 2 data is used to improve a 1D hydrodynamic model of the Brahmaputra River in South Asia, which is based on the Saint-Venant equations for unsteady flow and set up in the MIKE HYDRO River software. After calibration of discharge and water level the hydrodynamic model can accurately and bias-free represent the spatio-temporal variations of water levels. A data assimilation framework has been developed and linked with the model. It is a flexible framework that can assimilate water level data which are arbitrarily distributed in time and space. The setup has been used to assimilate CryoSat-2 water level observations over the Assam valley for the years 2010-2015, using an Ensemble Transform Kalman Filter (ETKF). Performance improvement in terms of discharge forecasting skill was then evaluated. For experiments with synthetic CryoSat-2 data the continuous ranked probability score (CRPS) was improved by up to 32%, whilst for experiments assimilating real data it could be improved by up to 10%. The developed methods are expected to be transferable to other rivers and altimeter missions. The model setup and calibration is based almost entirely on globally available remote sensing data.

  11. Swimming without a spine: Computational modeling and analysis of the swimming hydrodynamics of the Spanish Dancer.

    Science.gov (United States)

    Zhou, Zhuoyu; Mittal, Rajat

    2017-10-16

    Incompressible flow simulations are used to study the swimming of a Spanish Dancer (Hexabranchus sanguineus), a soft-bodied invertebrate marine gastropod that swims by combining body pitching with undulations of its large mantle. A simple model based on a field video is employed as the basis for the model and coupling of the flow with the body acceleration enables us to examine the free swimming of this animal. Simulations indicate propulsive efficiencies of up to about 57% and terminal swimming speeds of 1.33 body lengths per cycle. Examination of the effect of body planform on the swimming hydrodynamics suggests that the planform of this animal is likely adapted to enhance its swimming performance. © 2017 IOP Publishing Ltd.

  12. Numerical Modeling of Hydrodynamic and Sediment Siltation Due to Typhoon in Estuary Channel Regulation

    Directory of Open Access Journals (Sweden)

    Zhao Hongbo

    2015-09-01

    Full Text Available Oujiang Estuary is a complex tidal estuary with many channels and shoals in the East China Sea, which was affected by typhoon frequently. The navigation channel of Wenzhou Port is located in the north branch of Oujiang Estuary, which happened serious sediment siltation in many times due to typhoon impact. The regulation is considered to decrease siltaion of the channel and protect shoals as well. According to the site survey data, the mathematic model is established and validated, which simulates the hydrodynamic, sediment transport and channel siltation due to typhoon in Oujiang Estuary. The channel regulation scenario is studied by the model simulation after analysis of the silation character. It indicates that the high concentration sediment from shoals north of channel is main sediment source caused siltation in the channel, which can be prevented into the channel by the regulation scenario and decrease siltation efficiently.

  13. Tidal Hydrodynamics in the Lower Columbia River Estuary through Depth Averaged Adaptive Hydraulics Modeling

    Directory of Open Access Journals (Sweden)

    Gaurav Savant

    2014-01-01

    Full Text Available The adaptive hydraulics (AdH numerical code was applied to study tidal propagation in the Lower Columbia River (LCR estuary. The results demonstrate the readiness of this AdH model towards the further study of hydrodynamics in the LCR. The AdH model accurately replicated behavior of the tide as it propagated upstream into the LCR system. Results show that the MSf tidal component and the M4 overtidal component are generated in the middle LCR and contain a substantial amount of tidal energy. An analysis was performed to determine the causes of MSf tide amplification, and it was found that approximately 80% of the amplification occurs due to nonlinear interaction between the M2 and the S2 tidal components.

  14. Applying Contact Angle to a 2D Multiphase Smoothed Particle Hydrodynamics Model

    CERN Document Server

    Farrokhpanah, Amirsaman; Mostaghimi, Javad

    2016-01-01

    Equilibrium contact angle of liquid drops over horizontal surfaces has been modeled using Smoothed Particle Hydrodynamics (SPH). The model is capable of accurate implementation of contact angles to stationary and moving contact lines. In this scheme, the desired value for stationary or dynamic contact angle is used to correct the profile near the triple point. This is achieved by correcting the surface normals near the contact line and also interpolating the drop profile into the boundaries. Simulations show that a close match to the chosen contact angle values can be achieved for both stationary and moving contact lines. This technique has proven to reduce the amount of nonphysical shear stresses near the triple point and to enhance the convergence characteristics of the solver.

  15. Laser-Induced Translative Hydrodynamic Mass Snapshots: Noninvasive Characterization and Predictive Modeling via Mapping at Nanoscale

    Science.gov (United States)

    Wang, X. W.; Kuchmizhak, A. A.; Li, X.; Juodkazis, S.; Vitrik, O. B.; Kulchin, Yu. N.; Zhakhovsky, V. V.; Danilov, P. A.; Ionin, A. A.; Kudryashov, S. I.; Rudenko, A. A.; Inogamov, N. A.

    2017-10-01

    Subwavelength structures (meta-atoms) with artificially engineered permittivity and permeability have shown promising applications for guiding and controlling the flow of electromagnetic energy on the nanoscale. Ultrafast laser nanoprinting emerges as a promising single-step, green and flexible technology in fabricating large-area arrays of meta-atoms through the translative or ablative modification of noble-metal thin films. Ultrafast laser energy deposition in noble-metal films produces irreversible, intricate nanoscale translative mass redistributions after resolidification of the transient thermally assisted hydrodynamic melt perturbations. Such mass redistribution results in the formation of a radially symmetric frozen surface with modified hidden nanofeatures, which strongly affect the optical response harnessed in plasmonic sensing and nonlinear optical applications. Here, we demonstrate that side-view electron microscopy and ion-beam cross sections together with low-energy electron x-ray dispersion microscopy provide exact information about such three-dimensional patterns, enabling an accurate acquisition of their cross-sectional mass distributions. Such nanoscale solidified structures are theoretically modeled, considering the underlying physical processes associated with laser-induced energy absorption, electron-ion energy exchange, acoustic relaxation, and hydrodynamic flows. A theoretical approach, separating slow and fast physical processes and combining hybrid analytical two-temperature calculations, scalable molecular-dynamics simulations, and a semianalytical thin-shell model is synergistically applied. These advanced characterization approaches are required for a detailed modeling of near-field electromagnetic response and pave the way to a fully automated noninvasive in-line control of a high-throughput and large-scale laser fabrication. This theoretical modeling provides an accurate prediction of scales and topographies of the laser

  16. Application of an Ensemble Kalman filter to a 1-D coupled hydrodynamic-ecosystem model of the Ligurian Sea

    NARCIS (Netherlands)

    Lenartz, F.; Raick, C.; Soetaert, K.E.R.; Grégoire, M.

    2007-01-01

    The Ensemble Kalman filter (EnKF) has been applied to a 1-D complex ecosystem model coupled with a hydrodynamic model of the Ligurian Sea. In order to improve the performance of the EnKF, an ensemble subsampling strategy has been used to better represent the covariance matrices and a pre-analysis

  17. Hybrid complexity modelling of changes to estuary morphology, hydrodynamics and tidal surge water levels at 10 to 200 year timescales.

    Science.gov (United States)

    French, J.; Burningham, H.

    2016-12-01

    Extreme coastal flooding is expected to increase with climate change, especially in estuaries susceptible to tidal surges. Estuary hydrodynamics are well understood and models can predict spatial variation in tide and surge water levels with skill. However, estuary morphological change alters the pathway between sources of flood risk (tides, surges) and receptors (humans, assets, activities) in vulnerable areas. Our ability to predict morphological change at timescales relevant to climate change remains limited, and this hinders quantitative assessment of changing flood risk. Reductionist hydrodynamic and sediment transport models tend to perform poorly at longer timescales and estuary morphodynamics are increasingly modelled using more `synthesist' approaches to capture landform behaviour at 10 to 100+ year timescales. However, non-linear interaction between tides and morphology means that it is useful to retain hydrodynamic complexity to resolve feedbacks between morphological change and tide/surge propagation. This paper presents a new approach to estuary morphological evolution that combines 1D simulation of tidal hydrodynamics with parameterised 2D representation of intertidal sedimentation and erosion under the influence of fetch-limited waves (Estuary Spatial Landscape Evolution Model; ESTEEM). ESTEEM is used in combination with a 2D shallow water equation model (Telemac2D) to simulate changes in 100 to 200-year flood levels that include changes in morphology due to continuing natural sedimentary processes and realignment of flood defences to accommodate sea-level rise. Results for two UK estuaries indicate that hydrodynamics and surge levels change only slightly with present defences in place. Flood defence realignment results in step-changes to the morphology and significant effects on tide and surge water levels. Evolution of the altered morphology tends to counter the hydrodynamic impact, but is sensitive to wind climate, which strongly controls

  18. Hydropower Optimization Using Artificial Neural Network Surrogate Models of a High-Fidelity Hydrodynamics and Water Quality Model

    Science.gov (United States)

    Shaw, Amelia R.; Smith Sawyer, Heather; LeBoeuf, Eugene J.; McDonald, Mark P.; Hadjerioua, Boualem

    2017-11-01

    Hydropower operations optimization subject to environmental constraints is limited by challenges associated with dimensionality and spatial and temporal resolution. The need for high-fidelity hydrodynamic and water quality models within optimization schemes is driven by improved computational capabilities, increased requirements to meet specific points of compliance with greater resolution, and the need to optimize operations of not just single reservoirs but systems of reservoirs. This study describes an important advancement for computing hourly power generation schemes for a hydropower reservoir using high-fidelity models, surrogate modeling techniques, and optimization methods. The predictive power of the high-fidelity hydrodynamic and water quality model CE-QUAL-W2 is successfully emulated by an artificial neural network, then integrated into a genetic algorithm optimization approach to maximize hydropower generation subject to constraints on dam operations and water quality. This methodology is applied to a multipurpose reservoir near Nashville, Tennessee, USA. The model successfully reproduced high-fidelity reservoir information while enabling 6.8% and 6.6% increases in hydropower production value relative to actual operations for dissolved oxygen (DO) limits of 5 and 6 mg/L, respectively, while witnessing an expected decrease in power generation at more restrictive DO constraints. Exploration of simultaneous temperature and DO constraints revealed capability to address multiple water quality constraints at specified locations. The reduced computational requirements of the new modeling approach demonstrated an ability to provide decision support for reservoir operations scheduling while maintaining high-fidelity hydrodynamic and water quality information as part of the optimization decision support routines.

  19. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    Science.gov (United States)

    P. Sarrette, J.; Eichwald, O.; Marchal, F.; Ducasse, O.; Yousfi, M.

    2016-05-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air). The simulation involves the electro-dynamics, chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  20. Physical characterization of the Guadiana Estuary using the hydrodynamic model MOHID

    Science.gov (United States)

    Concepción Calero, María; García-Lafuente, Jesús; Garel, Erwan; Delgado-Cabello, Javier; Moreno-Navas, Juan; Martins, Flávio

    2017-04-01

    Guadiana Estuary is an intertidal estuary situated in SW of Iberian Peninsula, the latest 50 Km of which constitutes the natural border between Spain and Portugal. Tidal influence extends to about 80 Km upstream. The Guadiana River presents a high seasonal irregularity with wet winters and dry summers. Recently the river flow has been modified drastically by several dams constructed along the river. One of them is the Alqueva dam, opened in 2002, which is the biggest reservoir in Western Europe. It is placed to 120 Km upstream from the mouth of the estuary and is the last water control in the system being the main dam affecting the flow. A hydrodynamic model based on the MOHID system has been developed to study the hydrodynamics of the Guadiana Estuary. Tidal forcing and fresh water discharges were used in the boundary conditions. The model has been validated by comparing the model outcomes with in situ data measurements in several points along the estuary. Different scenarios have been simulated in order to know tidal progression and asymmetries in the circulation between wet and dry periods. Those phenomena are important because they influence the ecosystem and the distribution of sediments into the estuary and nearest coast. With a discharge of 300 m3/s the friction dominates over the amplification of the tide signal throughout the estuary while with smaller discharges the opposite effect occurs between 30 and 60 km. The difference in duration between floods and ebbs is greater the greater the discharge and the currents do not invert downstream at 50 Km with a discharge of 500 m3/s. Determining a regime of freshwater inputs from the Alqueva dam can be determinant to maintain the natural range of variation between dry and wet periods prior to the inauguration of the dam.

  1. A hydrodynamic model of nearshore waves and wave-induced currents

    Directory of Open Access Journals (Sweden)

    Ahmed Khaled Seif

    2011-09-01

    Full Text Available In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995 and Larson and Kraus (2002. Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF basin and the Hazaki Oceanographical Research Station (HORS. Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

  2. Implementing Numerical Experiments Based on the Coupled Model of Atmospheric General Circulation and Thermohaline Ocean One

    Directory of Open Access Journals (Sweden)

    V. P. Parhomenko

    2015-01-01

    Full Text Available The paper presents a realized hydrodynamic three-dimensional global climatic model, which comprises the model blocks of atmospheric general circulation, thermohaline large-scale circulation of the ocean, and sea ice evolution. Before rather strongly aggregated heat-moisturebalance model of the atmosphere for temperature and humidity of a surface layer was used as a model of the atmosphere. The atmospheric general circulation model is significantly more complicated and allows us to describe processes in the atmosphere more adequately. Functioning of a coupled climatic model is considered in conditions of the seasonal cycle of solar radiation.The paper considers a procedure for coupled calculation of the ocean model and atmospheric general circulation model. Synchronization of a number of parameters in both models is necessary for their joint action. In this regard a procedure of two-dimensional interpolation of data defined on the grids of the ocean model and atmosphere model and back is developed. A feature of this task is discrepancy of grid nodes and continental configurations in models. Coupled model-based long-term calculations for more than 400 years have shown its stable work. Calculation results and comparison with observation data are under discussion.The paper shows distribution of mean global atmosphere temperature versus time in stable conditions to demonstrate that there is inter-annual variability of atmosphere temperature at the steady state of a climate system. It presents distribution of temperature difference of the ocean surface from the observations and from the model of the ocean thermohaline circulation for January. Noticeable deviations of temperature are observed near Antarctica. Apparently, it is because of inaccurate calculation of the sea ice distribution in model. The geographical distribution of the ocean surface temperature for January with coupled calculation shows, in general, a zonal uniform structure of isolines

  3. Preliminary study on performance of a coupled hydrodynamic and sediment transport model on small domain

    Science.gov (United States)

    Rasyif, Teuku M.; Kato, Shigeru; Syamsidik, Okabe, Takumi

    2017-10-01

    Numerical simulation is one of the useful tools to analyze natural phenomena in the earth such as the tsunami disaster. Several numerical models can simulate the tsunami wave from its generation, propagation, and inundation. However, most tsunami models do not include the sediment transport module. The tsunami wave actually induces a lot of sediment during the propagation in the coastal area. In the case of Indian Ocean Tsunami in 2004, massive morphological changes were caused by the tsunami waves around Sumatra coast. In Aceh, some areas eroded by the tsunami wave were living place for a local community. It is indispensable for the resident in the coastal area to estimate the risk of morphological changes due to a tsunami wave. Therefore, a model that can investigate the morphological changes due tsunami wave is necessary. The result of this model can be used to consider a countermeasure for tsunami wave impact in the coastal area, such as land-use management and planning. The COMCOT-SED model had been developed by several researchers. This model combines the hydrodynamic module and the sediment module. The aim of this study is to get general information about performance of the COMCOT-SED model and to modify the model for more accurate results. Firstly, the model was demonstrated in the ideal condition to confirm the model validity. Then, we evaluated the model performance comparing the model results and the laboratory experiment data which was conducted by other researcher. The authors found that the results of water level and bottom profile by the original model in the ideal condition are not suitable. The model modification will give us more suitable results. The modified model will be applied to simulate the tsunami wave and sediment transport in the small area.

  4. Lattice hydrodynamic modeling of two-lane traffic flow with timid and aggressive driving behavior

    Science.gov (United States)

    Sharma, Sapna

    2015-03-01

    In this paper, a new two-lane lattice hydrodynamic traffic flow model is proposed by considering the aggressive or timid characteristics of driver's behavior. The effect of driver's characteristic on the stability of traffic flow is examined through linear stability analysis. It is shown that for both the cases of lane changing or without lane changing the stability region significantly enlarges (reduces) as the proportion of aggressive (timid) drivers increases. To describe the propagation behavior of a density wave near the critical point, nonlinear analysis is conducted and mKdV equation representing kink-antikink soliton is derived. The effect of anticipation parameter with more aggressive (timid) drivers is also investigated and found that it has a positive (negative) effect on the stability of two-lane traffic flow dynamics. Simulation results are found consistent with the theoretical findings which confirm that the driver's characteristics play a significant role in a two-lane traffic system.

  5. AGN Obscuration Through Dusty Infrared Dominated Flows. II. Multidimensional, Radiation-Hydrodynamics Modeling

    Science.gov (United States)

    Dorodnitsyn, Anton; Kallman, Tim; Bisno\\vatyiI-Kogan, Gennadyi

    2011-01-01

    We explore a detailed model in which the active galactic nucleus (AGN) obscuration results from the extinction of AGN radiation in a global ow driven by the pressure of infrared radiation on dust grains. We assume that external illumination by UV and soft X-rays of the dusty gas located at approximately 1pc away from the supermassive black hole is followed by a conversion of such radiation into IR. Using 2.5D, time-dependent radiation hydrodynamics simulations in a ux-limited di usion approximation we nd that the external illumination can support a geometrically thick obscuration via out ows driven by infrared radiation pressure in AGN with luminosities greater than 0:05 L(sub edd) and Compton optical depth, Tau(sub T) approx > & 1.

  6. Three-dimensional Modeling of Tidal Hydrodynamics in the San Francisco Estuary

    Directory of Open Access Journals (Sweden)

    Edward S. Gross

    2010-01-01

    Full Text Available Simulations of circulation in the San Francisco Estuary were performed with the three-dimensional TRIM3D hydrodynamic model using a generic length scale turbulence closure. The model was calibrated to reproduce observed tidal elevations, tidal currents, and salinity observations in the San Francisco Estuary using data collected during 1996-1998, a period of high and variable freshwater flow. It was then validated for 1994-1995, with emphasis on spring of 1994, a period of intensive data collection in the northern estuary. The model predicts tidal elevations and tidal currents accurately, and realistically predicts salinity at both the seasonal and tidal time scales. The model represents salt intrusion into the estuary accurately, and therefore accurately represents the salt balance. The model’s accuracy is adequate for its intended purposes of predicting salinity, analyzing gravitational circulation, and driving a particle-tracking model. Two applications were used to demonstrate the utility of the model. We estimated the components of the longitudinal salt flux and examined their dependence on flow conditions, and compared predicted salt intrusion with estimates from two empirical models.

  7. Wind forcing of upland lake hydrodynamics: implementation and validation of a 3D numerical model

    Science.gov (United States)

    Morales, L.; French, J.; Burningham, H.; Evans, C.; Battarbee, R.

    2010-12-01

    Upland lakes act as important archives of environmental change, yet inferences based on the analysis of sediment cores are frequently compromised by an incomplete understanding of the hydrodynamic processes controlling the distribution and completeness of lake sediment sequences and their linkages to wider environmental factors. Many upland lakes are characterized by complex vertical and horizontal circulation patterns induced by the action of wind on the water surface. Wind forcing is important not only for the resuspension of bottom sediments in shallow marginal areas, but may also control the broader distribution of sediment accumulation. The work presented here represents the first stage of a project aimed at elucidating the linkages between wind forcing and the distribution of bottom sediments in upland lakes and the extent to which simple 'sediment focusing' models provide an adequate basis for predicting optimal locations for the acquisition of core samples for palaeolimnological analysis. As a first step, a 3D numerical hydrodynamic model is implemented for Llyn Conwy, a small oligotrophic upland lake in North Wales, UK. This utilises the community ocean model, FVCOM, that solves the Navier-Stokes equations in 3D on an unstructured triangular mesh using the finite volume method. A new graphical user interface has been developed for FVCOM to facilitate pre- and post-processing of lake modelling problems. At Llyn Conwy, the model is forced using local meteorological data and validated against vertical temperature profiles recorded by a long-term buoy deployment and short-term observations of vertical current structure measured using an upward-looking acoustic doppler profiler and surface circulation obtained from GPS drifters. Challenges in the application of FVCOM to a small lake include the design of a mesh that ensures numerical stability whilst resolving a complex bathymetry, and the need for careful treatment of model 'spin-up'. Once calibrated, the

  8. Modeling the Effects of Hydrodynamic Regimes on Microbial Communities within Fluvial Biofilms: Combining Deterministic and Stochastic Processes.

    Science.gov (United States)

    Li, Yi; Wang, Chao; Zhang, Wenlong; Wang, Peifang; Niu, Lihua; Hou, Jun; Wang, Jing; Wang, Linqiong

    2015-11-03

    To fully understand the effects of hydrodynamics on a microbial community, the roles of niche-based and neutral processes must be considered in a mathematical model. To this end, a two-dimensional model combining mechanisms of immigration, dispersal, and niche differentiation was first established to describe the effects of hydrodynamics on bacterial communities within fluvial biofilms. Deterministic factors of the model were identified via the calculation of Spearman's rank correlation coefficients between parameters of hydrodynamics and the bacterial community. It was found that turbulent kinetic energy and turbulent intensity were considered as a set of reasonable predictors of community composition, whereas flow velocity and turbulent intensity can be combined together to predict biofilm bacterial biomass. According to the modeling result, the bacterial community could get its favorable assembly condition with a flow velocity ranging from 0.041 to 0.061 m/s. However, the driving force for biofilm community assembly changed with the local hydrodynamics. Individuals reproduction within the biofilm was the main driving force with flow velocity less than 0.05 m/s, while cell migration played a much more important role with velocity larger than 0.05 m/s. The developed model could be considered as a useful tool for improving the technologies of water environment protection and remediation.

  9. Comparing the Degree of Land-Atmosphere Interaction in Four Atmospheric General Circulation Models

    Science.gov (United States)

    Koster, Randal D.; Dirmeyer, Paul A.; Hahmann, Andrea N.; Ijpelaar, Ruben; Tyahla, Lori; Cox, Peter; Suarez, Max J.; Houser, Paul R. (Technical Monitor)

    2001-01-01

    Land-atmosphere feedback, by which (for example) precipitation-induced moisture anomalies at the land surface affect the overlying atmosphere and thereby the subsequent generation of precipitation, has been examined and quantified with many atmospheric general circulation models (AGCMs). Generally missing from such studies, however, is an indication of the extent to which the simulated feedback strength is model dependent. Four modeling groups have recently performed a highly controlled numerical experiment that allows an objective inter-model comparison of land-atmosphere feedback strength. The experiment essentially consists of an ensemble of simulations in which each member simulation artificially maintains the same time series of surface prognostic variables. Differences in atmospheric behavior between the ensemble members then indicates the degree to which the state of the land surface controls atmospheric processes in that model. A comparison of the four sets of experimental results shows that feedback strength does indeed vary significantly between the AGCMs.

  10. Hydrodynamic Modeling of Flood Dynamics and Restoration Potential of Lower Missouri River Floodplains

    Science.gov (United States)

    Lindner, G. A.

    2012-12-01

    Lower Missouri River floodplains have the potential to provide multiple ecosystem services including agricultural production, floodwater storage, nutrient processing, and provision of habitats. In this research, a 2-dimensional hydrodynamic model of a representative looped floodplain bottom of approximately 20 km is utilized to explore how floodplain inundation contributes to ecosystem benefits and costs. High resolution 2-dimensional hydrodynamic modeling provides insights into the way velocities, flood stages, residence times, and transported constituents (sediment, nutrients, and fish larvae, for example) are affected by levee geometry, floodplain vegetation patterns, and flood magnitude and duration. The utility of 2-dimensional numerical hydraulic models to represent the channel and floodplain are demonstrated at a scale relevant to understanding processes that control channel/floodplain dynamics. The sensitivity of model response to alternative land use scenarios, including levee setbacks and variable overbank roughness, is quantified using hydraulic parameters such as velocity, water level, conveyance, and residence time. The 2-dimensional models are calibrated to existing 1-dimensional modeling solutions and field measurements of water surface from 1993 and 2007 for the 2-year, 5-year, and 10-year recurrence intervals. Calibration runs with current levee configurations are matched to approximately ±0.1 meters. Simulations of alternative land use scenarios demonstrate the tradeoffs between ecological restoration and flood risk reductions. Levee setbacks with low hydraulic roughness associated with traditional row crop agriculture on the floodplains have the greatest potential for flood stage reductions, while native plant communities with higher roughness can negate the effects of the setbacks by increasing water levels due to enhanced frictional resistance. Residence times, which are presumed to be related to ecosystem services, demonstrate increasingly

  11. From the simplest equations of Hydrodynamics to science and engineering modeling skills

    Directory of Open Access Journals (Sweden)

    Juan Carlos Castro-Palacio

    2017-08-01

    Full Text Available The development of modeling skills is a very important issue in Science teaching nowadays. The present work illustrates how, from the simplest equations of hydrodynamics, it is possible to contribute to this end. Bernoulli and continuity equations are included in Physics syllabi of secondary and university levels, and can be seen as a linking between general and professional education. By means of the proposed project, students are taken through general stages which are usually present in any engineering project or research work based on modeling and simulation. such as the formulation of the problem, the statement of the Physics model, a computational simulation and the comparison between theory and experiments. This kind of project allows for the development of modeling skills and also to some other typical skills of the scientist's and engineer's profiles nowadays, such as  fitting and graphing analysis. It is common to see that secondary and  first year university courses do not contribute much to the formation of modeling skills, instead they rather contribute to particular skills from the perspective of the different subjects. On the other hand, students are usually more motivated for the modeling of real world situations than for idealized ones.

  12. Investigation of the hydrodynamic model test of forced rolling for a barge using PIV

    Directory of Open Access Journals (Sweden)

    WANG Xiaoqiang

    2017-03-01

    Full Text Available In order to study the physical details of viscous flow in ship roll motions and improve the accuracy of ship roll damping numerical simulation, the application of the Particle Image Velocimetry (PIV technique is investigated in model tests of forced ship rolling in calm water. The hydrodynamic force and flow field at the bilge region are simultaneously measured for barges at different amplitudes and frequencies in which the self-made forced rolling facility was used. In the model test, the viscous flow variation with the time around the bilge region was studied during ship rolling motion. The changes in ship roll damping coefficients with the rolling amplitude and period were also investigated. A comparison of the model test results with the Computational Fluid Dynamics(CFDresults shows that the numerical ship roll damping coefficients agree well with the model test results, while the differences in the local flow details exist between the CFD results and model test results. Further research into the model test technique and CFD application is required.

  13. Galaxies in the EAGLE hydrodynamical simulation and in the Durham and Munich semi-analytical models

    Science.gov (United States)

    Guo, Quan; Gonzalez-Perez, Violeta; Guo, Qi; Schaller, Matthieu; Furlong, Michelle; Bower, Richard G.; Cole, Shaun; Crain, Robert A.; Frenk, Carlos S.; Helly, John C.; Lacey, Cedric G.; Lagos, Claudia del P.; Mitchell, Peter; Schaye, Joop; Theuns, Tom

    2016-10-01

    We compare global predictions from the EAGLE hydrodynamical simulation, and two semi-analytic (SA) models of galaxy formation, L-GALAXIES and GALFORM. All three models include the key physical processes for the formation and evolution of galaxies and their parameters are calibrated against a small number of observables at z ≈ 0. The two SA models have been applied to merger trees constructed from the EAGLE dark matter only simulation. We find that at z ≤ 2, both the galaxy stellar mass functions for stellar masses M* 109.5 M⊙ differ in some instances by an order of magnitude, while the stellar mass-size relation in EAGLE is a factor of ≈2 tighter than for the two SA models. Our results suggest the need for a revision of how SA models treat the effect of baryonic self-gravity on the underlying dark matter. The treatment of gas flows in the models needs to be revised based on detailed comparison with observations to understand in particular the evolution of the stellar mass-metallicity relation.

  14. Discrete phase model representation of particulate matter (PM) for simulating PM separation by hydrodynamic unit operations.

    Science.gov (United States)

    Dickenson, Joshua A; Sansalone, John J

    2009-11-01

    Modeling the separation of dilute particulate matter (PM) has been a topic of interest since the introduction of unit operations for clarification of rainfall-runoff. One consistent yet controversial issue is the representation of PM and PM separation mechanisms for treatment. While Newton's Law and surface overflow rate were utilized, many historical models represented PM as a lumped gravimetric index largely out of economy and lack of particle analysis methods. As a result such models did not provide information about particle fate in or through a unit operation. In this study, PM discrete phase modeling (DPM) and computational fluid dynamics (CFD) are applied to model PM fate as a function of particle size and flow rate in two common types of hydrodynamic separator (HS) units. The study examines the discretization requirements (as a discretization number, DN) and errors for particle size distributions (PSDs) that range from the common heterodisperse to a monodisperse PSD. PSDs are categorized based on granulometric indices. Results focus on ensuring modeling accuracy while examining the role of size dispersivity and overall PM fineness on DN requirements. The fate of common heterodisperse PSDs is accurately predicted for a DN of 16, whereas a single particle size index, commonly the d(50m), is limited to monodisperse PSDs in order to achieve similar accuracy.

  15. Radiation Belt Electron Dynamics: Modeling Atmospheric Losses

    Science.gov (United States)

    Selesnick, R. S.

    2003-01-01

    The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

  16. Hydrodynamical simulations of coupled and uncoupled quintessence models - I. Halo properties and the cosmic web

    Science.gov (United States)

    Carlesi, Edoardo; Knebe, Alexander; Lewis, Geraint F.; Wales, Scott; Yepes, Gustavo

    2014-04-01

    We present the results of a series of adiabatic hydrodynamical simulations of several quintessence models (both with a free and an interacting scalar field) in comparison to a standard Λ cold dark matter cosmology. For each we use 2 × 10243 particles in a 250 h-1 Mpc periodic box assuming 7-year Wilkinson Microwave Anisotropy Probe cosmology. In this work we focus on the properties of haloes in the cosmic web at z = 0. The web is classified into voids, sheets, filaments and knots depending on the eigenvalues of the velocity shear tensor, which are an excellent proxy for the underlying overdensity distribution. We find that the properties of objects classified according to their surrounding environment show a substantial dependence on the underlying cosmology; for example, while Vmax shows average deviations of ≈5 per cent across the different models when considering the full halo sample, comparing objects classified according to their environment, the size of the deviation can be as large as 20 per cent. We also find that halo spin parameters are positively correlated to the coupling, whereas halo concentrations show the opposite behaviour. Furthermore, when studying the concentration-mass relation in different environments, we find that in all cosmologies underdense regions have a larger normalization and a shallower slope. While this behaviour is found to characterize all the models, differences in the best-fitting relations are enhanced in (coupled) dark energy models, thus providing a clearer prediction for this class of models.

  17. Numerical modeling of hydrodynamics and sediment transport—an integrated approach

    Science.gov (United States)

    Gic-Grusza, Gabriela; Dudkowska, Aleksandra

    2017-10-01

    Point measurement-based estimation of bedload transport in the coastal zone is very difficult. The only way to assess the magnitude and direction of bedload transport in larger areas, particularly those characterized by complex bottom topography and hydrodynamics, is to use a holistic approach. This requires modeling of waves, currents, and the critical bed shear stress and bedload transport magnitude, with a due consideration to the realistic bathymetry and distribution of surface sediment types. Such a holistic approach is presented in this paper which describes modeling of bedload transport in the Gulf of Gdańsk. Extreme storm conditions defined based on 138-year NOAA data were assumed. The SWAN model (Booij et al. 1999) was used to define wind-wave fields, whereas wave-induced currents were calculated using the Kołodko and Gic-Grusza (2015) model, and the magnitude of bedload transport was estimated using the modified Meyer-Peter and Müller (1948) formula. The calculations were performed using a GIS model. The results obtained are innovative. The approach presented appears to be a valuable source of information on bedload transport in the coastal zone.

  18. Radiation Hydrodynamical Models for Type I Superluminous Supernovae: Constraints on Progenitors and Explosion Mechanisms

    Science.gov (United States)

    Nomoto, Ken&'Ichi; Tolstov, Alexey; Sorokina, Elena; Blinnikov, Sergei; Bersten, Melina; Suzuki, Tomoharu

    2017-11-01

    The physical origin of Type-I (hydrogen-less) superluminous supernovae (SLSNe-I), whose luminosities are 10 to 500 times higher than normal core-collapse supernovae, remains still unknown. Thanks to their brightness, SLSNe-I would be useful probes of distant Universe. For the power source of the light curves of SLSNe-I, radioactive-decays, magnetars, and circumstellar interactions have been proposed, although no definitive conclusions have been reached yet. Since most of light curve studies have been based on simplified semi-analytic models, we have constructed multi-color light curve models by means of detailed radiation hydrodynamical calculations for various mass of stars including very massive ones and large amount of mass loss. We compare the rising time, peak luminosity, width, and decline rate of the model light curves with observations of SLSNe-I and obtain constraints on their progenitors and explosion mechanisms. We particularly pay attention to the recently reported double peaks of the light curves. We discuss how to discriminate three models, relevant models parameters, their evolutionary origins, and implications for the early evolution of the Universe.

  19. Hydrodynamical-model analysis of high-energy interactions due to mesons, antiprotons and α-particles

    Science.gov (United States)

    Shivpuri, R. K.; Mian, Ajay; Gupt, Chandra

    1984-06-01

    The pseudorapidity distributions of secondary particles in 50 200 GeV meson and anti-proton interactions with various target nuclei and in α-emulsion interactions are compared with the predictions of the hydrodynamical model. The agreement between the experimental and the predicted distributions is excellent.

  20. One-dimensional and two-dimensional hydrodynamic modelling derived flow properties: Impacts on aquatic habitat quality predictions

    Science.gov (United States)

    Rohan Benjankar; Daniele Tonina; James McKean

    2014-01-01

    Studies of the effects of hydrodynamic model dimensionality on simulated flow properties and derived quantities such as aquatic habitat quality are limited. It is important to close this knowledge gap especially now that entire river networks can be mapped at the microhabitat scale due to the advent of point-cloud techniques. This study compares flow properties, such...

  1. Geometric and Hydrodynamic Characteristics of Three-dimensional Saturated Prefractal Porous Media Determined with Lattice Boltzmann Modeling

    Science.gov (United States)

    Fractal and prefractal geometric models have substantial potential of contributing to the analysis of flow and transport in porous media such as soils and reservoir rocks. In this study, geometric and hydrodynamic parameters of saturated 3D mass and pore-solid prefractal porous media were characteri...

  2. Experimental validation of an analytical model for predicting the thermal and hydrodynamic capabilities of flat micro heat pipes

    OpenAIRE

    Revellin, Rémi; Rullière, Romuald; Lefèvre, Frédéric; Bonjour, Jocelyn

    2009-01-01

    Experimental validation of an analytical model for predicting the thermal and hydrodynamic capabilities of flat micro heat pipes correspondance: Corresponding author. Tel.: +33 4 7243 82 51; fax: +33 4 7243 8811. (Lefevre, Frederic) (Lefevre, Frederic) Centre de Thermique de Lyon (CETHIL) UMR 5008 CNRS-INSA-Univ. Lyon 1 Bat. Sadi Carnot--> , INSA-Lyon--> , F-69621 Villeurbanne Cedex--> -...

  3. Integrating hydrodynamic models and COSMO-SkyMed derived products for flood damage assessment

    Science.gov (United States)

    Giuffra, Flavio; Boni, Giorgio; Pulvirenti, Luca; Pierdicca, Nazzareno; Rudari, Roberto; Fiorini, Mattia

    2015-04-01

    observe the temporal evolution of the event (e.g. the water receding). In this paper, the first outcomes of a study aiming at combining COSMO-SkyMed derived flood maps with hydrodynamic models are presented. The study is carried out within the framework of the EO-based CHange detection for Operational Flood Management (ECHO-FM) project, funded by the Italian Space Agency (ASI) as part of the research activities agreed in the cooperation between ASI and the Japan Aerospace Exploration Agency (JAXA). The flood that hit the region of Shkodër, in Albania, on January 2010, is considered as test case. The work focuses on the utility of a dense temporal series of SAR data, such as that available through CSK for this case study, used in combination with a hydrodynamic model to monitor over a long time (in the order of 3 weeks) the natural drainage of the Shkodër floodplain. It is shown that by matching the outputs of the model to SAR observations, the hydrodynamic inconsistencies in CSK estimates can be corrected.

  4. Submarine hydrodynamics

    CERN Document Server

    Renilson, Martin

    2015-01-01

    This book adopts a practical approach and presents recent research together with applications in real submarine design and operation. Topics covered include hydrostatics, manoeuvring, resistance and propulsion of submarines. The author briefly reviews basic concepts in ship hydrodynamics and goes on to show how they are applied to submarines, including a look at the use of physical model experiments. The issues associated with manoeuvring in both the horizontal and vertical planes are explained, and readers will discover suggested criteria for stability, along with rudder and hydroplane effectiveness. The book includes a section on appendage design which includes information on sail design, different arrangements of bow planes and alternative stern configurations. Other themes explored in this book include hydro-acoustic performance, the components of resistance and the effect of hull shape. Readers will value the author’s applied experience as well as the empirical expressions that are presented for use a...

  5. Radiation hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Pomraning, G.C.

    1982-12-31

    This course was intended to provide the participant with an introduction to the theory of radiative transfer, and an understanding of the coupling of radiative processes to the equations describing compressible flow. At moderate temperatures (thousands of degrees), the role of the radiation is primarily one of transporting energy by radiative processes. At higher temperatures (millions of degrees), the energy and momentum densities of the radiation field may become comparable to or even dominate the corresponding fluid quantities. In this case, the radiation field significantly affects the dynamics of the fluid, and it is the description of this regime which is generally the charter of radiation hydrodynamics. The course provided a discussion of the relevant physics and a derivation of the corresponding equations, as well as an examination of several simplified models. Practical applications include astrophysics and nuclear weapons effects phenomena.

  6. Flood Hazard Mapping Combining Hydrodynamic Modeling and Multi Annual Remote Sensing data

    Directory of Open Access Journals (Sweden)

    Laura Giustarini

    2015-10-01

    Full Text Available This paper explores a method to combine the time and space continuity of a large-scale inundation model with discontinuous satellite microwave observations, for high-resolution flood hazard mapping. The assumption behind this approach is that hydraulic variables computed from continuous spatially-distributed hydrodynamic modeling and observed as discrete satellite-derived flood extents are correlated in time, so that probabilities can be transferred from the model series to the observations. A prerequisite is, therefore, the existence of a significant correlation between a modeled variable (i.e., flood extent or volume and the synchronously-observed flood extent. If this is the case, the availability of model simulations over a long time period allows for a robust estimate of non-exceedance probabilities that can be attributed to corresponding synchronously-available satellite observations. The generated flood hazard map has a spatial resolution equal to that of the satellite images, which is higher than that of currently available large scale inundation models. The method was applied on the Severn River (UK, using the outputs of a global inundation model provided by the European Centre for Medium-range Weather Forecasts and a large collection of ENVISAT ASAR imagery. A comparison between the hazard map obtained with the proposed method and with a more traditional numerical modeling approach supports the hypothesis that combining model results and satellite observations could provide advantages for high-resolution flood hazard mapping, provided that a sufficient number of remote sensing images is available and that a time correlation is present between variables derived from a global model and obtained from satellite observations.

  7. Examining the utility of satellite-based wind sheltering estimates for lake hydrodynamic modeling

    Science.gov (United States)

    Van Den Hoek, Jamon; Read, Jordan S.; Winslow, Luke A.; Montesano, Paul; Markfort, Corey D.

    2015-01-01

    Satellite-based measurements of vegetation canopy structure have been in common use for the last decade but have never been used to estimate canopy's impact on wind sheltering of individual lakes. Wind sheltering is caused by slower winds in the wake of topography and shoreline obstacles (e.g. forest canopy) and influences heat loss and the flux of wind-driven mixing energy into lakes, which control lake temperatures and indirectly structure lake ecosystem processes, including carbon cycling and thermal habitat partitioning. Lakeshore wind sheltering has often been parameterized by lake surface area but such empirical relationships are only based on forested lakeshores and overlook the contributions of local land cover and terrain to wind sheltering. This study is the first to examine the utility of satellite imagery-derived broad-scale estimates of wind sheltering across a diversity of land covers. Using 30 m spatial resolution ASTER GDEM2 elevation data, the mean sheltering height, hs, being the combination of local topographic rise and canopy height above the lake surface, is calculated within 100 m-wide buffers surrounding 76,000 lakes in the U.S. state of Wisconsin. Uncertainty of GDEM2-derived hs was compared to SRTM-, high-resolution G-LiHT lidar-, and ICESat-derived estimates of hs, respective influences of land cover type and buffer width on hsare examined; and the effect of including satellite-based hs on the accuracy of a statewide lake hydrodynamic model was discussed. Though GDEM2 hs uncertainty was comparable to or better than other satellite-based measures of hs, its higher spatial resolution and broader spatial coverage allowed more lakes to be included in modeling efforts. GDEM2 was shown to offer superior utility for estimating hs compared to other satellite-derived data, but was limited by its consistent underestimation of hs, inability to detect within-buffer hs variability, and differing accuracy across land cover types. Nonetheless

  8. Hydrodynamic Models of Line-Driven Accretion Disk Winds III: Local Ionization Equilibrium

    Science.gov (United States)

    Pereyra, Nicolas Antonio; Kallman, Timothy R.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present time-dependent numerical hydrodynamic models of line-driven accretion disk winds in cataclysmic variable systems and calculate wind mass-loss rates and terminal velocities. The models are 2.5-dimensional, include an energy balance condition with radiative heating and cooling processes, and includes local ionization equilibrium introducing time dependence and spatial dependence on the line radiation force parameters. The radiation field is assumed to originate in an optically thick accretion disk. Wind ion populations are calculated under the assumption that local ionization equilibrium is determined by photoionization and radiative recombination, similar to a photoionized nebula. We find a steady wind flowing from the accretion disk. Radiative heating tends to maintain the temperature in the higher density wind regions near the disk surface, rather than cooling adiabatically. For a disk luminosity L (sub disk) = solar luminosity, white dwarf mass M(sub wd) = 0.6 solar mass, and white dwarf radii R(sub wd) = 0.01 solar radius, we obtain a wind mass-loss rate of M(sub wind) = 4 x 10(exp -12) solar mass yr(exp -1) and a terminal velocity of approximately 3000 km per second. These results confirm the general velocity and density structures found in our earlier constant ionization equilibrium adiabatic CV wind models. Further we establish here 2.5D numerical models that can be extended to QSO/AGN winds where the local ionization equilibrium will play a crucial role in the overall dynamics.

  9. Mathematical modeling of CSF pulsatile hydrodynamics based on fluid-solid interaction.

    Science.gov (United States)

    Masoumi, Nafiseh; Bastani, Dariush; Najarian, Siamak; Ganji, Fariba; Farmanzad, Farhad; Seddighi, Amir Saeed

    2010-06-01

    Intracranial pressure (ICP) is derived from cerebral blood pressure and cerebrospinal fluid (CSF) circulatory dynamics and can be affected in the course of many diseases. Computer analysis of the ICP time pattern plays a crucial role in the diagnosis and treatment of those diseases. This study proposes the application of Linninger et al.'s [IEEE Trans. Biomed. Eng., vol. 52, no. 4, pp. 557-565, Apr. 2005] fluid-solid interaction model of CSF hydrodynamic in ventricular system based on our clinical data from a group of patients with brain parenchyma tumor. The clinical experiments include the arterial blood pressure (ABP), venous blood pressure, and ICP in the subarachnoid space (SAS). These data were used as inputs to the model that predicts the intracranial dynamic phenomena. In addition, the model has been modified by considering CSF pulsatile production rate as the major factor of CSF motion. The approximations of ventricle enlargement, CSF pressure distribution in the ventricular system and CSF velocity magnitude in the aqueduct and foramina were obtained in this study. The observation of reversal flow in the CSF flow pattern due to brain tissue compression is another finding in our investigation. Based on the experimental results, no existence of large transmural pressure differences were found in the brain system. The measured pressure drop in the ventricular system was less than 5 Pa. Moreover, the CSF flow pattern, ICP distribution, and velocity magnitude were in good agreement with the published models and CINE (phase-contrast magnetic resonance imaging) experiments, respectively.

  10. Application of a 2D Hydrodynamic Model for Assessing Flood Risk from Extreme Storm Events

    Directory of Open Access Journals (Sweden)

    Sohan Ghimire

    2013-11-01

    Full Text Available In the wake of increasing flood disasters, there is an increasing use of flood inundation models to assess risks and impacts at different temporal and spatial scales. Assessing the impacts of extreme climatic rainfall events will require developing design rainfall profiles to represent rainfall under different conditions. Rainfall profiles of different return periods were developed using the Flood Estimation Handbook (FEH methodology for a small rural catchment of Scotland, to assess flood risks at a catchment scale. Rainfall induced runoff flows were estimated based on a set of catchment characteristics. The channel and floodplain flows were modelled using a two-dimensional hydrodynamic model-TUFLOW. The main channel was represented by a one-dimensional linear channel based on surveyed data and the floodplain topography, was represented by a digital terrain model based on Light Detection and Ranging (LiDAR. A range of hydrological events with different return periods are simulated. Results show that many residential houses and an extensive area of agricultural land are at risk of flooding from extreme events such as a 1 in 100 year flood.

  11. Hydrodynamic model of screen channel liquid acquisition devices for in-space cryogenic propellant management

    Science.gov (United States)

    Darr, S. R.; Camarotti, C. F.; Hartwig, J. W.; Chung, J. N.

    2017-01-01

    Technologies that enable the storage and transfer of cryogenic propellants in space will be needed for the next generation vehicles that will carry humans to Mars. One of the candidate technologies is the screen channel liquid acquisition device (LAD), which uses a metal woven wire mesh to separate the liquid and vapor phases so that single-phase liquid propellant can be transferred in microgravity. In this work, an experiment is carried out that provides measurements of the velocity and pressure fields in a screen channel LAD. These data are used to validate a new analytical solution of the liquid flow through a screen channel LAD. This hydrodynamic model, which accounts for non-uniform injection through the screen, is compared with the traditional pressure term summation model which assumes a constant, uniform injection velocity. Results show that the new model performs best against the new data and historical data. The velocity measurements inside the screen channel LAD are used to provide a more accurate velocity profile which further improves the new model. The result of this work is a predictive tool that will instill confidence in the design of screen channel LADs for future in-space propulsion systems.

  12. Establishment of drug-resistant HBV small-animal models by hydrodynamic injection

    Directory of Open Access Journals (Sweden)

    Junjun Cheng

    2014-08-01

    Full Text Available In antiviral therapy of hepatitis B virus (HBV infection, drug resistance remains a huge obstacle to the long-term effectiveness of nucleoside/tide analogs (NAs. Primary resistance mutation (rtM204V contributes to lamivudine (LAM-resistance, and compensatory mutations (rtL180M and rtV173L restore viral fitness and increase replication efficiency. The evaluation of new anti-viral agents against drug-resistant HBV is limited by the lack of available small-animal models. We established LAM-resistance HBV replication mice models based on clinical LAM-resistant HBV mutants. Double (rtM204V+rtL180M or triple (rtM204V+rtL180M+rtV173L lamivudine-resistant mutations were introduced into HBV expression vector, followed by hydrodynamic injection into tail vein of NOD/SCID mice. Viremia was detected on days 5, 9, 13 and 17 and liver HBV DNA was detected on day 17 after injection. The serum and liver HBV DNA levels in LAM-resistant model carrying triple mutations are the highest among the models. Two NAs, LAM and entecavir (ETV, were used to test the availability of the models. LAM and ETV inhibited viral replication on wild-type model. LAM was no longer effective on LAM-resistant models, but ETV retains a strong activity. Therefore, these models can be used to evaluate anti-viral agents against lamivudine-resistance, affording new opportunities to establish other drug-resistant HBV small-animal models.

  13. Understanding leachate flow in municipal solid waste landfills by combining time-lapse ERT and subsurface flow modelling - Part II: Constraint methodology of hydrodynamic models.

    Science.gov (United States)

    Audebert, M; Oxarango, L; Duquennoi, C; Touze-Foltz, N; Forquet, N; Clément, R

    2016-09-01

    Leachate recirculation is a key process in the operation of municipal solid waste landfills as bioreactors. To ensure optimal water content distribution, bioreactor operators need tools to design leachate injection systems. Prediction of leachate flow by subsurface flow modelling could provide useful information for the design of such systems. However, hydrodynamic models require additional data to constrain them and to assess hydrodynamic parameters. Electrical resistivity tomography (ERT) is a suitable method to study leachate infiltration at the landfill scale. It can provide spatially distributed information which is useful for constraining hydrodynamic models. However, this geophysical method does not allow ERT users to directly measure water content in waste. The MICS (multiple inversions and clustering strategy) methodology was proposed to delineate the infiltration area precisely during time-lapse ERT survey in order to avoid the use of empirical petrophysical relationships, which are not adapted to a heterogeneous medium such as waste. The infiltration shapes and hydrodynamic information extracted with MICS were used to constrain hydrodynamic models in assessing parameters. The constraint methodology developed in this paper was tested on two hydrodynamic models: an equilibrium model where, flow within the waste medium is estimated using a single continuum approach and a non-equilibrium model where flow is estimated using a dual continuum approach. The latter represents leachate flows into fractures. Finally, this methodology provides insight to identify the advantages and limitations of hydrodynamic models. Furthermore, we suggest an explanation for the large volume detected by MICS when a small volume of leachate is injected. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. A 30m resolution hydrodynamic model of the entire conterminous United States.

    Science.gov (United States)

    Bates, P. D.; Neal, J. C.; Smith, A.; Sampson, C.; Johnson, K.; Wing, O.

    2016-12-01

    In this paper we describe the development and validation of a 30m resolution hydrodynamic model covering the entire conterminous United States. The model can be used to simulate inundation and water depths resulting from either return period flows (so equivalent to FEMA Flood Insurance Rate Maps), hindcasts of historic events or forecasts of future river flow from a rainfall-runoff or land surface model. As topographic data the model uses the U.S. Geological Survey National Elevation Dataset or NED, and return period flows are generated using a regional flood frequency analysis methodology (Smith et al., 2015. Worldwide flood frequency estimation. Water Resources Research, 51, 539-553). Flood defences nationwide are represented using data from the US Army Corps of Engineers. Using these data flows are simulated using an explicit and highly efficient finite difference solution of the local inertial form of the Shallow Water equations identical to that implemented in the LISFLOOD-FP model. Even with this efficient numerical solution a simulation at this resolution over a whole continent is a huge undertaking, and a variety of High Performance Computing technologies therefore need to be employed to make these simulations possible. The size of the output datasets is also challenging, and to solve this we use the GIS and graphical display functions of Google Earth Engine to facilitate easy visualisation and interrogation of the results. The model is validated against the return period flood extents contained in FEMA Flood Insurance Rate Maps and real flood event data from the Texas 2015 flood event which was hindcast using the model. Finally, we present an application of the model to the Upper Mississippi river basin where simulations both with and without flood defences are used to determine floodplain areas benefitting from protection in order to quantify the benefits of flood defence spending.

  15. Global SWOT Data Assimilation of River Hydrodynamic Model; the Twin Simulation Test of CaMa-Flood

    Science.gov (United States)

    Ikeshima, D.; Yamazaki, D.; Kanae, S.

    2016-12-01

    CaMa-Flood is a global scale model for simulating hydrodynamics in large scale rivers. It can simulate river hydrodynamics such as river discharge, flooded area, water depth and so on by inputting water runoff derived from land surface model. Recently many improvements at parameters or terrestrial data are under process to enhance the reproducibility of true natural phenomena. However, there are still some errors between nature and simulated result due to uncertainties in each model. SWOT (Surface water and Ocean Topography) is a satellite, which is going to be launched in 2021, can measure open water surface elevation. SWOT observed data can be used to calibrate hydrodynamics model at river flow forecasting and is expected to improve model's accuracy. Combining observation data into model to calibrate is called data assimilation. In this research, we developed data-assimilated river flow simulation system in global scale, using CaMa-Flood as river hydrodynamics model and simulated SWOT as observation data. Generally at data assimilation, calibrating "model value" with "observation value" makes "assimilated value". However, the observed data of SWOT satellite will not be available until its launch in 2021. Instead, we simulated the SWOT observed data using CaMa-Flood. Putting "pure input" into CaMa-Flood produce "true water storage". Extracting actual daily swath of SWOT from "true water storage" made simulated observation. For "model value", we made "disturbed water storage" by putting "noise disturbed input" to CaMa-Flood. Since both "model value" and "observation value" are made by same model, we named this twin simulation. At twin simulation, simulated observation of "true water storage" is combined with "disturbed water storage" to make "assimilated value". As the data assimilation method, we used ensemble Kalman filter. If "assimilated value" is closer to "true water storage" than "disturbed water storage", the data assimilation can be marked effective. Also

  16. 3-D hydrodynamic modelling of flood impacts on a building and indoor flooding processes

    Science.gov (United States)

    Gems, Bernhard; Mazzorana, Bruno; Hofer, Thomas; Sturm, Michael; Gabl, Roman; Aufleger, Markus

    2016-06-01

    Given the current challenges in flood risk management and vulnerability assessment of buildings exposed to flood hazards, this study presents three-dimensional numerical modelling of torrential floods and its interaction with buildings. By means of a case study application, the FLOW-3D software is applied to the lower reach of the Rio Vallarsa torrent in the village of Laives (Italy). A single-family house on the flood plain is therefore considered in detail. It is exposed to a 300-year flood hydrograph. Different building representation scenarios, including an entire impervious building envelope and the assumption of fully permeable doors, light shafts and windows, are analysed. The modelling results give insight into the flooding process of the building's interior, the impacting hydrodynamic forces on the exterior and interior walls, and further, they quantify the impact of the flooding of a building on the flow field on the surrounding flood plain. The presented study contributes to the development of a comprehensive physics-based vulnerability assessment framework. For pure water floods, this study presents the possibilities and limits of advanced numerical modelling techniques within flood risk management and, thereby, the planning of local structural protection measures.

  17. Comparing galaxy formation in semi-analytic models and hydrodynamical simulations

    Science.gov (United States)

    Mitchell, Peter D.; Lacey, Cedric G.; Lagos, Claudia D. P.; Frenk, Carlos S.; Bower, Richard G.; Cole, Shaun; Helly, John C.; Schaller, Matthieu; Gonzalez-Perez, Violeta; Theuns, Tom

    2018-02-01

    It is now possible for hydrodynamical simulations to reproduce a representative galaxy population. Accordingly, it is timely to assess critically some of the assumptions of traditional semi-analytic galaxy formation models. We use the Eagle simulations to assess assumptions built into the Galform semi-analytic model, focussing on those relating to baryon cycling, angular momentum and feedback. We show that the assumption in Galform that newly formed stars have the same specific angular momentum as the total disc leads to a significant overestimate of the total stellar specific angular momentum of disc galaxies. In Eagle, stars form preferentially out of low specific angular momentum gas in the interstellar medium (ISM) due to the assumed gas density threshold for stars to form, leading to more realistic galaxy sizes. We find that stellar mass assembly is similar between Galform and Eagle but that the evolution of gas properties is different, with various indications that the rate of baryon cycling in Eagle is slower than is assumed in Galform. Finally, by matching individual galaxies between Eagle and Galform, we find that an artificial dependence of AGN feedback and gas infall rates on halo mass doubling events in Galform drives most of the scatter in stellar mass between individual objects. Put together our results suggest that the Galform semi-analytic model can be significantly improved in light of recent advances.

  18. Floodplain simulation for Musi River using integrated 1D/2D hydrodynamic model

    Directory of Open Access Journals (Sweden)

    Al Amin Muhammad B.

    2017-01-01

    Full Text Available This paper presents the simulation of floodplain at Musi River using integrated 1D and 2D hydrodynamic model. The 1D flow simulation was applied for the river channel with flow hydrograph as upstream boundary condition. The result of 1D flow simulation was integrated into 2D flow simulation in order to know the area and characteristics of flood inundation. The input data of digital terrain model which was used in this research had grid resolution of 10m×10m, but for 2D simulation the resolution was with grid resolution 50 m × 50 m so as to limit simulation time since the model size was big enough. The result of the simulation showed that the inundated area surrounding Musi River is about 107.44 km2 with maximum flood depth is 3.24 m, water surface velocity ranges from 0.00 to 0.83 m/s. Most of floodplain areas varied from middle to high flood hazard level, and only few areas had very high level of flood hazard especially on river side. The structural flood control measurement to be recommended to Palembang is to construct flood dike and flood gate. The non structural measurement one is to improve watershed management and socialization of flood awareness.

  19. The Importance of Spatially Heterogeneous Roughness Grids on Hydrodynamic Modeling of Coral Reefs

    Science.gov (United States)

    Hoeke, R. K.; Strolazzi, C.; Aucan, J.

    2007-05-01

    Hydrodynamics of two embayments in the Hawaiian archipelago, Hanalei Bay on the island of Kauai, and Kailua Bay, on the Island of Oahu, are estimated using a shallow-water finite-difference wave and circulation model. Both of the bay bottoms contain a mix of unconsolidated (mostly carbonate) sediment and fringing coral reefs. Model results of shoreline wave heights, shore-parallel and shore-perpendicular currents are found to vary by several orders of magnitude depending on what parameterization of bottom roughness is used. Several bottom roughness schemes are compared, including "standard" homogenous values for sediments, higher homogenous values for reefs, and spatially varying values derived from measurements of rugosity. Results from model runs using these different schemes are compared with in situ observations and indicate the importance of spatially heterogeneous roughness grids. Methods of: 1) deriving rugosity measurements from bathymetric data and 2) creating grids of hydraulic roughness lengths based on published values from the rugosity grids are presented. These methods have implications for providing near-real time bulletins and forecasts of water safety and water quality along Hawaii's coastlines.

  20. A hydrodynamic model of plasma initiation off irradiated metallic aerosols in vacuum - The diffusive regime

    Science.gov (United States)

    Chitanvis, Shirish M.

    1989-03-01

    The analogy between chemical reactions and cascade ionization is exploited to study the spatial and temporal dynamics of plasma formation in the vapor that is formed on a metallic aerosol that is being irradiated by a high-energy laser beam, in vacuum. The present hydrodynamic model is valid for relatively low laser fluences and pulses of the order of nanoseconds or less, when the diffusive approximation may be safely invoked. The main result of the paper is to show that the laser-induced plasma layer around aerosols shows a crossover, from being transparent to being opaque, as the fluence incident upon the aerosol is increased. The model of cascade ionization is used to show that for the laser fluxes for which the model is valid, the plasma in the vapor layer surrounding an aluminuim metallic sphere is not dense enough to obscure the laser beam. For flux levels of 10 to the 11th W/sq cm or higher and pulse lengths of 10 ns or longer, the plasma around individual aluminum aerosols becomes very absorbing.

  1. Hydrodynamic modelling of free water-surface constructed storm water wetlands using a finite volume technique.

    Science.gov (United States)

    Zounemat-Kermani, Mohammad; Scholz, Miklas; Tondar, Mohammad-Mahdi

    2015-01-01

    One of the key factors in designing free water-surface constructed wetlands (FWS CW) is the hydraulic efficiency (λ), which depends primarily on the retention time of the polluted storm water. Increasing the hydraulic retention time (HRT) at various flow levels will increase λ of the overall constructed wetland (CW). The effects of characteristic geometric features that increase HRT were explored through the use of a two-dimensional depth-average hydrodynamic model. This numerical model was developed to solve the equations of continuity and motions on an unstructured triangular mesh using the Galerkin finite volume formulation and equations of the k-ε turbulence model. Eighty-nine diverse forms of artificial FWS CW with 11 different aspect ratios were numerically simulated and subsequently analysed for four scenarios: rectangular CW, modified rectangular CW with rounded edges, different inlet/outlet configurations of CW, and surface and submerged obstructions in front of the inlet part of the CW. Results from the simulations showed that increasing the aspect ratio has a direct influence on the enhancement of λ in all cases. However, the aspect ratio should be at least 9 in order to achieve an appropriate rate for λ in rectangular CW. Modified rounded rectangular CW improved λ by up to 23%, which allowed for the selection of a reduced aspect ratio. Simulation results showed that CW with low aspect ratios benefited from obstructions and optimized inlet/outlet configurations in terms of improved HRT.

  2. A high resolution hydrodynamic model system suitable for novel harmful algal bloom modelling in areas of complex coastline and topography.

    Science.gov (United States)

    Aleynik, Dmitry; Dale, Andrew C; Porter, Marie; Davidson, Keith

    2016-03-01

    Fjordic coastlines provide sheltered locations for finfish and shellfish aquaculture, and are often subject to harmful algal blooms (HABs) some of which develop offshore and are then advected to impact nearshore aquaculture. Numerical models are a potentially important tool for providing early warning of such HAB events. However, the complex topography of fjordic shelf regions is a significant challenge to modelling. This is frequently compounded by complex bathymetry and local weather patterns. Existing structured grid models do not provide the resolution needed to represent these coastlines in their wider shelf context. In a number of locations advectively transported blooms of the ichthyotoxic dinoflagellate Karenia mikimotoi are of particular concern for the finfish industry. Here were present a novel hydrodynamic model of the coastal waters to the west of Scotland that is based on unstructured finite volume methodology, providing a sufficiently high resolution hydrodynamical structure to realistically simulate the transport of particles (such as K. mikimotoi cells) within nearshore waters where aquaculture sites are sited. Model-observation comparisons reveal close correspondence of tidal elevations for major semidiurnal and diurnal tidal constituents. The thermohaline structure of the model and its current fields are also in good agreement with a number of existing observational datasets. Simulations of the transport of Lagrangian drifting buoys, along with the incorporation of an individual-based biological model, based on a bloom of K. mikimotoi, demonstrate that unstructured grid models have considerable potential for HAB prediction in Scotland and in complex topographical regions elsewhere. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Sensitivity of a Floodplain Hydrodynamic Model to Satellite-Based DEM Scale and Accuracy: Case Study—The Atchafalaya Basin

    Directory of Open Access Journals (Sweden)

    Hahn Chul Jung

    2015-06-01

    Full Text Available The hydrodynamics of low-lying riverine floodplains and wetlands play a critical role in hydrology and ecosystem processes. Because small topographic features affect floodplain storage and flow velocity, a hydrodynamic model setup of these regions imposes more stringent requirements on the input Digital Elevation Model (DEM compared to upland regions with comparatively high slopes. This current study provides a systematic approach to evaluate the required relative vertical accuracy and spatial resolution of current and future satellite-based altimeters within the context of DEM requirements for 2-D floodplain hydrodynamic models. A case study is presented for the Atchafalaya Basin with a model domain of 1190 km2. The approach analyzes the sensitivity of modeled floodplain water elevation and velocity to typical satellite-based DEM grid-box scale and vertical error, using a previously calibrated version of the physically-based flood inundation model (LISFLOOD-ACC. Results indicate a trade-off relationship between DEM relative vertical error and grid-box size. Higher resolution models are the most sensitive to vertical accuracy, but the impact diminishes at coarser resolutions because of spatial averaging. The results provide guidance to engineers and scientists when defining the observation scales of future altimetry missions such as the   Surface Water and Ocean Topography (SWOT mission from the perspective of numerical modeling requirements for large floodplains of O[103] km2 and greater.

  4. Evaluation of the hydrodynamic behaviour of turbulence promoters in parallel plate electrochemical reactors by means of the dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Colli, A.N. [Programa de Electroquimica Aplicada e Ingenieria Electroquimica (PRELINE), Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina); Bisang, J.M., E-mail: jbisang@fiq.unl.edu.ar [Programa de Electroquimica Aplicada e Ingenieria Electroquimica (PRELINE), Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina)

    2011-08-30

    Highlights: {center_dot} The type of turbulence promoters has a strong influence on the hydrodynamics. {center_dot} The dispersion model is appropriate for expanded plastic turbulence promoters. {center_dot} The dispersion model is appropriate for glass beads turbulence promoters. - Abstract: The hydrodynamic behaviour of electrochemical reactors with parallel plate electrodes is experimentally studied using the stimulus-response method either with an empty reactor or with different turbulence promoters. Theoretical results which are in accordance with the analytical and numerical resolution of the dispersion model for a closed system are compared with the classical relationships of the normalized outlet concentration for open systems and the validity range of the equations is discussed. The experimental results were well correlated with the dispersion model using glass beads or expanded plastic meshes as turbulence promoters, which have shown the most advantageous performance. The Peclet number was higher than 63. The dispersion coefficient was found to increase linearly with flow velocity in these cases.

  5. The kinematics of σ-drop bulges from spectral synthesis modelling of a hydrodynamical simulation

    Science.gov (United States)

    Portaluri, Elisa; Debattista, Victor P.; Fabricius, Maximillian; Cole, David R.; Corsini, Enrico M.; Drory, Niv; Rowe, Andrew; Morelli, Lorenzo; Pizzella, Alessandro; Dalla Bontà, Elena

    2017-05-01

    A minimum in stellar velocity dispersion is often observed in the central regions of disc galaxies. To investigate the origin of this feature, known as a σ-drop, we analyse the stellar kinematics of a high-resolution N-body + smooth particle hydrodynamical simulation, which models the secular evolution of an unbarred disc galaxy. We compared the intrinsic mass-weighted kinematics to the recovered luminosity-weighted ones. The latter were obtained by analysing synthetic spectra produced by a new code, syntra, that generates synthetic spectra by assigning a stellar population synthesis model to each star particle based on its age and metallicity. The kinematics were derived from the synthetic spectra as in real spectra to mimic the kinematic analysis of real galaxies. We found that the recovered luminosity-weighted kinematics in the centre of the simulated galaxy are biased to higher rotation velocities and lower velocity dispersions due to the presence of young stars in a thin and kinematically cool disc, and are ultimately responsible for the σ-drop. Our procedure for building mock observations and thus recovering the luminosity-weighted kinematics of the stars in a galaxy simulation is a powerful tool that can be applied to a variety of scientific questions, such as multiple stellar populations in kinematically decoupled cores and counter-rotating components, and galaxies with both thick and thin disc components.

  6. Characterizing urban hydrodynamic models in densely settled river-corridors: Lessons from Jakarta

    Science.gov (United States)

    Shaad, K.; Ninsalam, Y.; Padawangi, R.; Burlando, P.

    2016-12-01

    The nature and pace of urbanization in South and South-east Asia has created unique circumstances for the inter-action between social and ecological systems linked to water resources - with the growing density of population; frequent and extensive modification on the flood plain alongside governance challenges creating large segment of the settled regions exposed to water security issues and flooding risks. The densely-settled river corridor in Jakarta, with nearly 590 km of waterfront exposed to frequent flooding, captures the scale and complexity typical of these systems. Developing models that can help improve our insights into these urban areas remain a challenge. Here, we present our attempts to apply high-resolution aerial and ground based mapping methods, alongside shallow groundwater monitoring and household surveys, to characterize hydrodynamic models of varying complexity, for a 7 km stretch on the Ciliwung River in the center of Jakarta. We explore the uncertainty associated with obtaining "hydraulically representative" ground description and influence of representation of structures in flood propagation over the short-term, while linking it to the diffusive forcings from settlement acting on the floodplain-river interaction over the long-term. Connecting, thus, flooding with water availability and contamination, we speculate on the ability to scale these approaches and technologies beyond the limits of the test site.

  7. Hydrodynamic model of the collective electron resonances in C60 fullerene

    Science.gov (United States)

    Gildenburtg, V. B.; Pavlichenko, I. A.

    2017-08-01

    The polarization-response spectrum of the fullerene C60 modeled as a homogeneous spherical plasma shell is calculated in the framework of the hydrodynamic approach, allowing for the spatial dispersion caused by the Fermi-distributed valence electrons. The dipole eigenoscillation spectrum of the shell is found to contain a series of plasmons distinguished by the frequency and the radial structure. The first two of them (whose structures for C60 are the subject of discussion up to now) pass to the lower and higher surface plasmons of the plasma shell if its thickness is much larger than the Tomas-Fermi length. However, under parameter values corresponding to the C60 molecule, when these lengths are of the same order, both these plasmons (providing the main contribution to the fullerene absorption spectrum) are found to be actually volume ones in their spatial structure, and the frequency of the higher of them becomes larger than the plasma frequency (as with all the higher volume plasmons). The resonance curve of the fullerene absorption cross-section calculated on the basis of the developed model with allowance for the surface losses caused by the reflection of electrons at the shell boundaries agrees well with the experimental data.

  8. Hydrodynamic Modeling Analysis for Leque Island and zis a ba Restoration Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Whiting, Jonathan M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Khangaonkar, Tarang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-31

    Ducks Unlimited, Inc. in collaboration with Washington State Department of Fish and Wildlife (WDFW), and Stillaguamish Tribe of Indians have proposed the restoration of Leque Island and zis a ba (formerly Matterand) sites near the mouth of Old Stillaguamish River Channel in Port Susan Bay, Washington. The Leque Island site, which is owned by WDFW, consists of nearly 253 acres of land south of Highway 532 that is currently behind a perimeter dike. The 90-acres zis a ba site, also shielded by dikes along the shoreline, is located just upstream of Leque Island and is owned by Stillaguamish Tribes. The proposed actions consider the removal or modification of perimeter dikes at both locations to allow estuarine functions to be restored. The overall objective of the proposed projects is to remove the dike barriers to 1) provide connectivity and access between the tidal river channel and the restoration site for use by juvenile migrating salmon and 2) create a self-sustaining tidal marsh habitat. Ducks Unlimited engaged Pacific Northwest National Laboratory (PNNL) to develop a three-dimensional hydrodynamic model of the Port Susan Bay, Skagit Bay, and the interconnecting Leque Island region for use in support of the feasibility assessment for the Leque Island and zis a ba restoration projects. The objective of this modeling-based feasibility assessment is to evaluate the performance of proposed restoration actions in terms of achieving habitat goals while assessing the potential hydraulic and sediment transport impacts to the site and surrounding parcels of land.

  9. 3D Realistic Radiative Hydrodynamic Modeling of a Moderate-Mass Star: Effects of Rotation

    Science.gov (United States)

    Kitiashvili, Irina; Kosovichev, Alexander G.; Mansour, Nagi N.; Wray, Alan A.

    2018-01-01

    Recent progress in stellar observations opens new perspectives in understanding stellar evolution and structure. However, complex interactions in the turbulent radiating plasma together with effects of magnetic fields and rotation make inferences of stellar properties uncertain. The standard 1D mixing-length-based evolutionary models are not able to capture many physical processes of stellar interior dynamics, but they provide an initial approximation of the stellar structure that can be used to initialize 3D time-dependent radiative hydrodynamics simulations, based on first physical principles, that take into account the effects of turbulence, radiation, and others. In this presentation we will show simulation results from a 3D realistic modeling of an F-type main-sequence star with mass 1.47 Msun, in which the computational domain includes the upper layers of the radiation zone, the entire convection zone, and the photosphere. The simulation results provide new insight into the formation and properties of the convective overshoot region, the dynamics of the near-surface, highly turbulent layer, the structure and dynamics of granulation, and the excitation of acoustic and gravity oscillations. We will discuss the thermodynamic structure, oscillations, and effects of rotation on the dynamics of the star across these layers.

  10. Hydrodynamic Modeling of Air Blast Propagation from the Humble Redwood Chemical High Explosive Detonations Using GEODYN

    Energy Technology Data Exchange (ETDEWEB)

    Chipman, V D

    2011-09-20

    Two-dimensional axisymmetric hydrodynamic models were developed using GEODYN to simulate the propagation of air blasts resulting from a series of high explosive detonations conducted at Kirtland Air Force Base in August and September of 2007. Dubbed Humble Redwood I (HR-1), these near-surface chemical high explosive detonations consisted of seven shots of varying height or depth of burst. Each shot was simulated numerically using GEODYN. An adaptive mesh refinement scheme based on air pressure gradients was employed such that the mesh refinement tracked the advancing shock front where sharp discontinuities existed in the state variables, but allowed the mesh to sufficiently relax behind the shock front for runtime efficiency. Comparisons of overpressure, sound speed, and positive phase impulse from the GEODYN simulations were made to the recorded data taken from each HR-1 shot. Where the detonations occurred above ground or were shallowly buried (no deeper than 1 m), the GEODYN model was able to simulate the sound speeds, peak overpressures, and positive phase impulses to within approximately 1%, 23%, and 6%, respectively, of the actual recorded data, supporting the use of numerical simulation of the air blast as a forensic tool in determining the yield of an otherwise unknown explosion.

  11. Hydrodynamics and sediment transport in a meandering channel with a model axial-flow hydrokinetic turbine

    Science.gov (United States)

    Hill, Craig; Kozarek, Jessica; Sotiropoulos, Fotis; Guala, Michele

    2016-02-01

    An investigation into the interactions between a model axial-flow hydrokinetic turbine (rotor diameter, dT = 0.15 m) and the complex hydrodynamics and sediment transport processes within a meandering channel was carried out in the Outdoor StreamLab research facility at the University of Minnesota St. Anthony Falls Laboratory. This field-scale meandering stream with bulk flow and sediment discharge control provided a location for high spatiotemporally resolved measurements of bed and water surface elevations around the model turbine. The device was installed within an asymmetric, erodible channel cross section under migrating bed form and fixed outer bank conditions. A comparative analysis between velocity and topographic measurements, with and without the turbine installed, highlights the local and nonlocal features of the turbine-induced scour and deposition patterns. In particular, it shows how the cross-section geometry changes, how the bed form characteristics are altered, and how the mean flow field is distorted both upstream and downstream of the turbine. We further compare and discuss how current energy conversion deployments in meander regions would result in different interactions between the turbine operation and the local and nonlocal bathymetry compared to straight channels.

  12. Experimental Investigation on the Characteristics of Hydrodynamic Stabilities in Francis Hydroturbine Models

    Directory of Open Access Journals (Sweden)

    Wen-Tao Su

    2014-03-01

    Full Text Available This paper presents an experimental investigation of flow phenomena related to the characteristic frequencies of pressure fluctuation in Francis hydroturbine models. The experiments were carried out on two test rigs with two model runners having hydraulic similarities. Flow field around the guide vanes was measured with a particle image velocimetry (PIV on the first PIV test rig. Flow structures at the inlet region of runner and in draft tube at different operating conditions were visualized on another hydrodynamic test rig. Analyses of dominant frequency of unsteady hydraulic behaviors in the tested hydroturbines were performed. It was observed that the main frequency of flow over the guide vanes and the dominant frequency of channel vortex equal the blade passing frequency; the dominant frequency of flow separation at the suction side of blade inlet equals the vane passing frequency; the vortex rope in the draft tube displays a low-frequency nature. The flow instabilities and fluctuations directly influence the running of hydroturbine, thus these experimental results could provide important evidence for the stability study of a real hydroturbine.

  13. Classifying initial conditions of long GRBs modeled with relativistic radiation hydrodynamics

    Science.gov (United States)

    Rivera-Paleo, F. J.; López Núñez, C. E.; Guzmán, F. S.; González, J. A.

    2017-06-01

    We present a method to classify initial conditions of a long gamma ray bursts model sourced by a single relativistic shock. It is based on the use of artificial neural networks (ANNs) that are trained with light curves (LC) generated with radiation relativistic hydrodynamics simulations. The model we use consists in a single shock with a highly relativistic injected beam into a stratified surrounding medium with profile 1 /r2. In the process we only consider the bremsstrahlung radiation and Thomson scattering process. The initial conditions we use to train the ANN are three: the rest mass density, Lorentz factor and radiation energy density of the beam that produces the relativistic shock, together with the LC generated during the process. The classification selects the location of a box in the 3d parameter space that better fits a given LC, and in order to decrease the uncertainty of the parameters this box is refined and the classification selects a new box of smaller size.

  14. Fe-Modeling Of Starved Hydrodynamic Lubrication With Free Surface Effects

    DEFF Research Database (Denmark)

    Poulios, Konstantinos; Vølund, Anders; Klit, Peder

    2017-01-01

    This work concerns a new finite-element formulation for solving hydrody-namic lubrication problems that include partially flooded regions, where the lubricant film behavior is governed by free surface flow.......This work concerns a new finite-element formulation for solving hydrody-namic lubrication problems that include partially flooded regions, where the lubricant film behavior is governed by free surface flow....

  15. A New Two-fluid Radiation-hydrodynamical Model for X-Ray Pulsar Accretion Columns

    Science.gov (United States)

    West, Brent F.; Wolfram, Kenneth D.; Becker, Peter A.

    2017-02-01

    Previous research centered on the hydrodynamics in X-ray pulsar accretion columns has largely focused on the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface. This type of model has been relatively successful in describing the overall properties of the accretion flows, but it does not account for the possible dynamical effect of the gas pressure. On the other hand, the most successful radiative transport models for pulsars generally do not include a rigorous treatment of the dynamical structure of the column, instead assuming an ad hoc velocity profile. In this paper, we explore the structure of X-ray pulsar accretion columns using a new, self-consistent, “two-fluid” model, which incorporates the dynamical effect of the gas and radiation pressures, the dipole variation of the magnetic field, the thermodynamic effect of all of the relevant coupling and cooling processes, and a rigorous set of physical boundary conditions. The model has six free parameters, which we vary in order to approximately fit the phase-averaged spectra in Her X-1, Cen X-3, and LMC X-4. In this paper, we focus on the dynamical results, which shed new light on the surface magnetic field strength, the inclination of the magnetic field axis relative to the rotation axis, the relative importance of gas and radiation pressures, and the radial variation of the ion, electron, and inverse-Compton temperatures. The results obtained for the X-ray spectra are presented in a separate paper.

  16. Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model)

    Science.gov (United States)

    2017-09-01

    ARL-TR-8155 ● SEP 2017 US Army Research Laboratory Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model... Energy Research, Volume 5 (Solar Radiation Flux Model) by Clayton Walker and Gail Vaucher Computational and Information Sciences Directorate, ARL...2017 June 28 4. TITLE AND SUBTITLE Atmospheric Renewable Energy Research, Volume 5 (Solar Radiation Flux Model) 5a. CONTRACT NUMBER ROTC Internship

  17. GLOFRIM v1.0 – A globally applicable computational framework for integrated hydrological–hydrodynamic modelling

    Directory of Open Access Journals (Sweden)

    J. M. Hoch

    2017-10-01

    Full Text Available We here present GLOFRIM, a globally applicable computational framework for integrated hydrological–hydrodynamic modelling. GLOFRIM facilitates spatially explicit coupling of hydrodynamic and hydrologic models and caters for an ensemble of models to be coupled. It currently encompasses the global hydrological model PCR-GLOBWB as well as the hydrodynamic models Delft3D Flexible Mesh (DFM; solving the full shallow-water equations and allowing for spatially flexible meshing and LISFLOOD-FP (LFP; solving the local inertia equations and running on regular grids. The main advantages of the framework are its open and free access, its global applicability, its versatility, and its extensibility with other hydrological or hydrodynamic models. Before applying GLOFRIM to an actual test case, we benchmarked both DFM and LFP for a synthetic test case. Results show that for sub-critical flow conditions, discharge response to the same input signal is near-identical for both models, which agrees with previous studies. We subsequently applied the framework to the Amazon River basin to not only test the framework thoroughly, but also to perform a first-ever benchmark of flexible and regular grids on a large-scale. Both DFM and LFP produce comparable results in terms of simulated discharge with LFP exhibiting slightly higher accuracy as expressed by a Kling–Gupta efficiency of 0.82 compared to 0.76 for DFM. However, benchmarking inundation extent between DFM and LFP over the entire study area, a critical success index of 0.46 was obtained, indicating that the models disagree as often as they agree. Differences between models in both simulated discharge and inundation extent are to a large extent attributable to the gridding techniques employed. In fact, the results show that both the numerical scheme of the inundation model and the gridding technique can contribute to deviations in simulated inundation extent as we control for model forcing and boundary

  18. Integrable hydrodynamic equations for initial chiral currents and infinite hydrodynamic chains from WZNW model and string model of WZNW type with SU(2), SO(3), SP(2), SU(∞), SO(∞), SP(∞) constant torsions

    Science.gov (United States)

    Cirilo-Lombardo, D. J.; Gershun, V. D.

    2014-09-01

    The WZNW and string models are considered in terms of the initial and invariant chiral currents assuming that the internal and external torsions coincide (anticoincide) and they are the structure constants of the SU(n), SO(n), SP(n) Lie algebras. These models are the auxiliary problems in order to construct integrable equations of hydrodynamic type. It was shown that the WZNW and string models in terms of invariant chiral currents are integrable for the constant torsion associated with the structure constants of the SU(2), SO(3), SP(2) and SU(3) algebras only. The equation of motion for the density of the first Casimir operator was obtained in the form of the inviscid Burgers equation. The solution of this equation is presented through the Lambert function. Also, a new equation of motion for the initial chiral current was found. The integrable infinite hydrodynamic chains obtained from the WZNW and string models are given in terms of invariant chiral currents with the SU(2), SO(3), SP(2) and with SU(∞), SO(∞), SP(∞) constant torsions. Also, the equations of motion for the density of any Casimir operator and new infinite-dimensional equations of hydrodynamic type for the initial chiral currents through the symmetric structure constant of SU(∞), SO(∞), SP(∞) algebras are obtained.

  19. EFDC1D - A ONE DIMENSIONAL HYDRODYNAMIC AND SEDIMENT TRANSPORT MODEL FOR RIVER AND STREAM NETWORKS: MODEL THEORY AND USERS GUIDE

    Science.gov (United States)

    This technical report describes the new one-dimensional (1D) hydrodynamic and sediment transport model EFDC1D. This model that can be applied to stream networks. The model code and two sample data sets are included on the distribution CD. EFDC1D can simulate bi-directional unstea...

  20. A hybrid molecular dynamics/fluctuating hydrodynamics method for modelling liquids at multiple scales in space and time

    Energy Technology Data Exchange (ETDEWEB)

    Korotkin, Ivan, E-mail: i.korotkin@qmul.ac.uk; Karabasov, Sergey; Markesteijn, Anton [The School of Engineering and Material Science, Queen Mary University of London, Mile End Road, E1 4NS London (United Kingdom); Nerukh, Dmitry; Scukins, Arturs [Institute of Systems Analytics, Aston University, Birmingham B4 7ET (United Kingdom); Farafonov, Vladimir [Department of Physical Chemistry, V. N. Karazin Kharkiv National University, Svobody Square 4, 61022 Kharkiv (Ukraine); Pavlov, Evgen [Institute of Systems Analytics, Aston University, Birmingham B4 7ET (United Kingdom); Faculty of Physics, Kiev National Taras Shevchenko University, Prospect Acad. Glushkova 4, Kiev 03127 (Ukraine)

    2015-07-07

    A new 3D implementation of a hybrid model based on the analogy with two-phase hydrodynamics has been developed for the simulation of liquids at microscale. The idea of the method is to smoothly combine the atomistic description in the molecular dynamics zone with the Landau-Lifshitz fluctuating hydrodynamics representation in the rest of the system in the framework of macroscopic conservation laws through the use of a single “zoom-in” user-defined function s that has the meaning of a partial concentration in the two-phase analogy model. In comparison with our previous works, the implementation has been extended to full 3D simulations for a range of atomistic models in GROMACS from argon to water in equilibrium conditions with a constant or a spatially variable function s. Preliminary results of simulating the diffusion of a small peptide in water are also reported.

  1. Modeling and simulations for molecular scale hydrodynamics of the moving contact line in immiscible two-phase flows

    KAUST Repository

    Qian, Tiezheng

    2009-10-29

    This paper starts with an introduction to the Onsager principle of minimum energy dissipation which governs the optimal paths of deviation and restoration to equilibrium. Then there is a review of the variational approach to moving contact line hydrodynamics. To demonstrate the validity of our continuum hydrodynamic model, numerical results from model calculations and molecular dynamics simulations are presented for immiscible Couette and Poiseuille flows past homogeneous solid surfaces, with remarkable overall agreement. Our continuum model is also used to study the contact line motion on surfaces patterned with stripes of different contact angles (i.e. surfaces of varying wettability). Continuum calculations predict the stick-slip motion for contact lines moving along these patterned surfaces, in quantitative agreement with molecular dynamics simulation results. This periodic motion is tunable through pattern period (geometry) and contrast in wetting property (chemistry). The consequence of stick-slip contact line motion on energy dissipation is discussed. © 2009 IOP Publishing Ltd.

  2. Application of a three-dimensional hydrodynamic model to the Himmerfjärden, Baltic Sea

    Science.gov (United States)

    Sokolov, Alexander

    2014-05-01

    Himmerfjärden is a coastal fjord-like bay situated in the north-western part of the Baltic Sea. The fjord has a mean depth of 17 m and a maximum depth of 52 m. The water is brackish (6 psu) with small salinity fluctuation (±2 psu). A sewage treatment plant, which serves about 300 000 people, discharges into the inner part of Himmerfjärden. This area is the subject of a long-term monitoring program. We are planning to develop a publicly available modelling system for this area, which will perform short-term forecast predictions of pertinent parameters (e.g., water-levels, currents, salinity, temperature) and disseminate them to users. A key component of the system is a three-dimensional hydrodynamic model. The open source Delft3D Flow system (http://www.deltaressystems.com/hydro) has been applied to model the Himmerfjärden area. Two different curvilinear grids were used to approximate the modelling domain (25 km × 50 km × 60 m). One grid has low horizontal resolution (cell size varies from 250 to 450 m) to perform long-term numerical experiments (modelling period of several months), while another grid has higher resolution (cell size varies from 120 to 250 m) to model short-term situations. In vertical direction both z-level (50 layers) and sigma coordinate (20 layers) were used. Modelling results obtained with different horizontal resolution and vertical discretisation will be presented. This model will be a part of the operational system which provides automated integration of data streams from several information sources: meteorological forecast based on the HIRLAM model from the Finnish Meteorological Institute (https://en.ilmatieteenlaitos.fi/open-data), oceanographic forecast based on the HIROMB-BOOS Model developed within the Baltic community and provided by the MyOcean Project (http://www.myocean.eu), riverine discharge from the HYPE model provided by the Swedish Meteorological Hydrological Institute (http://vattenwebb.smhi.se/modelarea/).

  3. Hydrodynamic Model of Inundation Event at Confluence of Ohio and Mississippi Rivers

    Science.gov (United States)

    Kaplan, B. A.; Luke, A.; Alsdorf, D. E.

    2013-12-01

    The goal of this project is to produce an accurate 2-D hydrodynamic model of an inundation event that occurred at the confluence of the Ohio and Mississippi River. The inundation occurred in the months of April and May 2011, with the city of interest being Cairo, Illinois. In order to relieve flooding within Cairo, a Bird's Point Levee was detonated by the Army Corps of Engineers. Cairo is a small city of 2,800 people, and is prone to flooding due to its proximity to the confluence of the Ohio and Mississippi River. Cairo is also the only city in the U.S. completely surrounded by levees. The advantage of a 2-D modeling approach compared to a 1-D approach is that the floodplain geomorphological processes are more accurately represented. Understanding non-channelized flow that occurs during inundation events is a subject of growing interest, and is being addressed in other projects such as the NASA-SWOT mission scheduled for launch in 2019. The 2-D model utilized in this study is LISFLOOD-FP. LISFLOOD-FP is a 2-D finite-difference flood inundation model that has been proven to accurately simulate flood inundation for urban, coastal, and fluvial environments. LISFLOOD-FP operates using known hydraulic principles along with continuity and momentum equations to describe the flow of water through channels and floodplains. The digital elevation model used to represent the area's topography was obtained from the USGS National Elevation Data set, and our model uses input data from USGS stream gauges located upstream of the confluence of the Ohio and Mississippi River. The gauging station located in Cairo will be used for model validation. Currently, many flood simulations are being modeled with varying conditions and input files. In situ cross sectional data is being used to represent the channel. We have found that using averages of the cross sectional data do not accurately represent the river channels, so future model runs will incorporate interpolation between

  4. Modelling of the impact of biofouling on hydrodynamics downstream of a tidal turbine

    Science.gov (United States)

    Bennis, A. C.; Rivier, A.; Dauvin, J. C.

    2016-02-01

    Biological organisms, like barnacles, mussels or bryozoans, colonize rapidly an immersed surface and could form a thickness until several centimeters on it. This biofouling could modify hydrodynamics around tidal turbine by increasing drag and hence resistance and could be detrimental to the performance of turbine (e.g. Orme et al., 2001; Khor and Xiao, 2011). Our work focuses on modifications of vortices downstream of a tidal turbine due to biofouling using CFD. Fixed biological organisms are solved explicitly by the model and are considered by modifying the blade profile. Firstly an airfoil colonized by barnacles is modelled for various fouling height and spacing and results are compared to experimental and simulated data (Orme et al., 2001; Khor and Xiao, 2011) in order to assess the capacity of the model to reproduce the flow around a blade with biofouling. Then a Darrieus vertical axis tidal turbine is modelled using a dynamic mesh. Configuration with smooth clean blades is assessed by comparison with experiments and simulations made by Roa (2011) and Bossard (2012). Biological organisms with various heights, spacing and shapes are fixed on blades and wakes downstream of clean and colonized tidal turbine are compared. Vorticity fields around the tidal turbine are clearly modified when blades are colonized. Samples will be taken from location where farms are planned to be built (Alderney Race/Raz Blanchard) to characterize more precisely the characteristics of species which are liable to fix on tidal turbine.Reference:Bossard (2012). Doctoral dissertation, Université de Grenoble.Khor & Xiao. (2011). Ocean Eng, 38(10), 1065-1079. Orme et al. (2001). Marine Renewable Energy Conference, Newcastle.Roa (2011).Doctoral dissertation, Université de Grenoble.

  5. Two-link hydrodynamic model development and motion planning for underwater manipulation

    Science.gov (United States)

    Leabourne, Kortney Noell

    Underwater robots with manipulators are a key resource for marine exploration, particularly for tasks involving intervention with the environment. For missions where small vehicles equipped with manipulators are required, there can be significant dynamic coupling between the arm and the vehicle, causing the vehicle to "swim" whenever the manipulator is actuated. This interaction affects the robot's ability to achieve precise end-point placement for intervention tasks, as well as the control performance of the system as a whole. Two issues that are affected by this complex interaction have been addressed in this research. First, a new model for the drag forces on a two-link underwater swinging manipulator has been developed. This model adds three newly-defined drag coefficients that are functions of the arm configuration. Joint torque predictions calculated using the new model show significant improvement over existing models in the literature for multiple-link manipulators, which assume that the links translate only. These improvements have been demonstrated for torque predictions on a fixed-base manipulator, as well as for a control scheme for hovering the OTTER experimental vehicle during manipulation maneuvers. Second, a new analytic tool called a Dynamic Disturbance Map has been developed. This tool is a graphical representation of the coupling characteristics of an underwater arm-vehicle system and can be used for arm-joint path analysis and planning. This work captures the benefits of a similar tool developed for space-based systems, where there is only inertial coupling, allowing the extension of planning techniques for underwater systems to include hydrodynamics terms and unconstrained end-effector paths. Arm motions planned to minimize vehicle motion were demonstrated experimentally on the OTTER arm-vehicle system with significant improvements.

  6. Characterization and Modelling of LeBlanc Hydrodynamic Stabilizer: A Novel Approach for Steady and Transient State Models

    Directory of Open Access Journals (Sweden)

    Marlon Wesley Machado Cunico

    2015-01-01

    Full Text Available As result of increase of customers’ demands, products become more complexes and dynamics control increased its role into product development. As example, clothing washing machines use LeBlanc balancers in order to reduce vibration issues. Nevertheless, the behaviour of such apparatus is still hard to describe and the numerical simulation of this sort of vibration control is based on ball rings. The main goal of this work is to define and characterize a numerical model that describes the hydrodynamics balance ring in the transient state in addition to steady state models. As consequence, the behaviour of balance ring was identified in a computational fluid dynamics tool and an equation that describes restoration forces, unbalance, force phase, and eccentricity was found.

  7. Characterization of the Treg Response in the Hepatitis B Virus Hydrodynamic Injection Mouse Model.

    Directory of Open Access Journals (Sweden)

    Kirsten K Dietze

    Full Text Available Regulatory T cells (Tregs play an important role in counter-regulating effector T cell responses in many infectious diseases. However, they can also contribute to the development of T cell dysfunction and pathogen persistence in chronic infections. Tregs have been reported to suppress virus-specific T cell responses in hepatitis B virus (HBV infection of human patients as well as in HBV animal models. However, the phenotype and expansion of Tregs has so far only been investigated in other infections, but not in HBV. We therefore performed hydrodynamic injections of HBV plasmids into mice and analyzed the Treg response in the spleen and liver. Absolute Treg numbers significantly increased in the liver but not the spleen after HBV injection. The cells were natural Tregs that surprisingly did not show any activation or proliferation in response to the infection. However, they were able to suppress effector T cell responses, as selective depletion of Tregs significantly increased HBV-specific CD8+ T cell responses and accelerated viral antigen clearance. The data implies that natural Tregs infiltrate the liver in HBV infection without further activation or expansion but are still able to interfere with T cell mediated viral clearance.

  8. A Mathematical Model for the Flow Resistance and the Related Hydrodynamic Dispersion Induced by River Dunes

    Directory of Open Access Journals (Sweden)

    Marilena Pannone

    2013-01-01

    Full Text Available Present work is aimed at the derivation of a simply usable equation for the total flow resistance associated with river bedforms, by a unifying approach allowing for bypassing some of the limiting restrictions usually adopted in similar types of studies. Specifically, we focused on the effect induced by the out-of-phase free surface undulations appearing in presence of sand dunes. The proposed expression, obtained by combining the balance of momentum referred to the control volume whose longitudinal dimension coincides with the dune wavelength and the energy balance integrated between its extreme sections, was tested by comparison with some laboratory experimental measurements available in the literature and referred to steady flow past fixed, variably rough bedforms. In terms of shear stress or friction factor, the proposed theory provides estimates in good agreement with the real data, especially if evaluated against the performances provided by other classical similar approaches. Moreover, when analyzed in terms of hydrodynamic dispersive properties as a function of the skin roughness on the basis of a previously derived analytical solution, the dune-covered beds seem to behave like meandering channels, responsible for a globally enhanced fluid particles longitudinal spreading, with a relatively reduced effect in the presence of less pronounced riverbed modelling.

  9. Gas Removal in the Ursa Minor Galaxy: Linking Hydrodynamics and Chemical Evolution Models

    Energy Technology Data Exchange (ETDEWEB)

    Caproni, Anderson; Lanfranchi, Gustavo Amaral; Baio, Gabriel Henrique Campos; Kowal, Grzegorz [Núcleo de Astrofísica Teórica, Universidade Cruzeiro do Sul, R. Galvão Bueno 868, Liberdade, 01506-000, São Paulo, SP (Brazil); Falceta-Gonçalves, Diego, E-mail: anderson.caproni@cruzeirodosul.edu.br [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Rua Arlindo Bettio 1000, CEP 03828-000 São Paulo (Brazil)

    2017-04-01

    We present results from a non-cosmological, three-dimensional hydrodynamical simulation of the gas in the dwarf spheroidal galaxy Ursa Minor. Assuming an initial baryonic-to-dark-matter ratio derived from the cosmic microwave background radiation, we evolved the galactic gas distribution over 3 Gyr, taking into account the effects of the types Ia and II supernovae. For the first time, we used in our simulation the instantaneous supernovae rates derived from a chemical evolution model applied to spectroscopic observational data of Ursa Minor. We show that the amount of gas that is lost in this process is variable with time and radius, being the highest rates observed during the initial 600 Myr in our simulation. Our results indicate that types Ia and II supernovae must be essential drivers of the gas loss in Ursa Minor galaxy (and probably in other similar dwarf galaxies), but it is ultimately the combination of galactic winds powered by these supernovae and environmental effects (e.g., ram-pressure stripping) that results in the complete removal of the gas content.

  10. Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

    Science.gov (United States)

    Travnikov, Oleg; Angot, Hélène; Artaxo, Paulo; Bencardino, Mariantonia; Bieser, Johannes; D'Amore, Francesco; Dastoor, Ashu; De Simone, Francesco; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Magand, Olivier; Martin, Lynwill; Matthias, Volker; Mashyanov, Nikolay; Pirrone, Nicola; Ramachandran, Ramesh; Read, Katie Alana; Ryjkov, Andrei; Selin, Noelle E.; Sena, Fabrizio; Song, Shaojie; Sprovieri, Francesca; Wip, Dennis; Wängberg, Ingvar; Yang, Xin

    2017-04-01

    Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM / GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM / GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg

  11. Variational data assimilation schemes for transport and transformation models of atmospheric chemistry

    Science.gov (United States)

    Penenko, Alexey; Penenko, Vladimir; Tsvetova, Elena; Antokhin, Pavel

    2016-04-01

    work has been partially supported by RFBR grant 14-01-00125 and RAS Presidium II.4P. References: [1] Penenko V.V., Tsvetova E.A., Penenko A.V. Development of variational approach for direct and inverse problems of atmospheric hydrodynamics and chemistry // IZVESTIYA ATMOSPHERIC AND OCEANIC PHYSICS, 2015, v 51 , p. 311 - 319 [2] A.V. Penenko and V.V. Penenko. Direct data assimilation method for convection-diffusion models based on splitting scheme. Computational technologies, 19(4):69-83, 2014. [3] A. Penenko; V. Penenko; R. Nuterman; A. Baklanov and A. Mahura Direct variational data assimilation algorithm for atmospheric chemistry data with transport and transformation model, Proc. SPIE 9680, 21st International Symposium Atmospheric and Ocean Optics: Atmospheric Physics, 968076 (November 19, 2015); doi:10.1117/12.2206008;http://dx.doi.org/10.1117/12.2206008

  12. Modelling the high-energy emission from gamma-ray binaries using numerical relativistic hydrodynamics

    Science.gov (United States)

    Dubus, G.; Lamberts, A.; Fromang, S.

    2015-09-01

    Context. Detailed modelling of the high-energy emission from gamma-ray binaries has been propounded as a path to pulsar wind physics. Aims: Fulfilling this ambition requires a coherent model of the flow and its emission in the region where the pulsar wind interacts with the stellar wind of its companion. Methods: We have developed a code that follows the evolution and emission of electrons in the shocked pulsar wind based on inputs from a relativistic hydrodynamical simulation. The code is used to model the well-documented spectral energy distribution and orbital modulations from LS 5039. Results: The pulsar wind is fully confined by a bow shock and a back shock. The particles are distributed into a narrow Maxwellian, emitting mostly GeV photons, and a power law radiating very efficiently over a broad energy range from X-rays to TeV gamma rays. Most of the emission arises from the apex of the bow shock. Doppler boosting shapes the X-ray and very high energy (VHE) lightcurves, constraining the system inclination to i ≈ 35°. There is tension between the hard VHE spectrum and the level of X-ray to MeV emission, which requires differing magnetic field intensities that are hard to achieve with constant magnetisation σ and Lorentz factor Γp of the pulsar wind. Our best compromise implies σ ≈ 1 and Γp ≈ 5 × 103, so respectively higher and lower than the typical values in pulsar wind nebulae. Conclusions: The high value of σ derived here, where the wind is confined close to the pulsar, supports the classical picture that has pulsar winds highly magnetised at launch. However, such magnetisations will require that further investigations are based on relativistic MHD simulations. Movies associated to Figs. A.1-A.4 are available in electronic form at http://www.aanda.org

  13. Atomic hydrogen distribution. [in Titan atmospheric model

    Science.gov (United States)

    Tabarie, N.

    1974-01-01

    Several possible H2 vertical distributions in Titan's atmosphere are considered with the constraint of 5 km-A a total quantity. Approximative calculations show that hydrogen distribution is quite sensitive to two other parameters of Titan's atmosphere: the temperature and the presence of other constituents. The escape fluxes of H and H2 are also estimated as well as the consequent distributions trapped in the Saturnian system.

  14. Hydrodynamics of a shallow coastal lagoon with submarine groundwater discharge: a numerical modeling exercise

    Science.gov (United States)

    Casares, R.; Marino-Tapia, I.

    2013-05-01

    Coastal lagoons are subjected to physical forces that make them vulnerable to climate change and human intervention. The karstic geology along the coastal zone of Yucatan Peninsula, Mexico, forces groundwater to discharge in the sea and coastal lagoons through underground conduits that can form small but numerous and scattered underwater springs. These freshwater inputs, along with other physical forces like ocean tides and meteorological events, can have a significant effect on the circulation and residence times in coastal lagoons. Climate change consequences such as sea level rise and changing rain patterns, as well as the increasing human impact, can cause or aggravate certain environmental effects. Since coastal lagoons provide important environmental services there is a need to understand and have predictive capability to simulate the transport processes and the forces acting on them. The present study was carried out in the coastal lagoon of Celestun, located at NW Yucatan Peninsula, a region of karstic geology. The aim of this research is to understand the barotropic hydrodynamic functioning of this shallow system, taking into account the oceanographical, meteorological and hydrological forcing. Emphasis is made on the residence times in different parts of the lagoon, and the effects of freshwater inputs. For the detailed understanding of the processes the hydrodynamic numerical model DELFT3D was implemented. The model was validated with data gathered on the field during two intensive oceanographic campaigns, which included installation of CTDs and acoustic current meters at strategic sites distributed in the system, and detailed bathymetric measurements using an echosounder coupled with a differential GPS on board of a motorboat. In order to improve model performance a sensitivity analysis to the main variables involved in the model was carried out, among them: the size of the grid cells, grid depth, time step, friction coefficients, boundary conditions

  15. Modeling of the transport and deposition of polydispersed particles: Effects of hydrodynamics and spatiotemporal evolution of the deposition rate.

    Science.gov (United States)

    Ma, Enze; Ouahbi, Tariq; Wang, Huaqing; Ahfir, Nasre-Dine; Alem, Abdellah; Hammadi, Ahmed

    2017-11-11

    A time-distance-dependent deposition model is built to investigate the effects of hydrodynamic forces on the transport and deposition of polydispersed particles and the evolution of deposition rates with time and distance. Straining and the heterogeneity of the particle population are considered to play important roles in the decreasing distribution of deposition rates. Numerical simulations were applied in a series of sand column experiments at different fluid velocities for three different porous media. The effects of hydrodynamics forces are elaborated with the systematic variations of deposition dynamic parameters of the proposed model. With retention distributions with particle size as well as temporal and spatial evolutions of deposition rates, the transport and deposition mechanisms of polydispersed particles will be elucidated through the interplay of the variation of the particle size distribution of mobile particle populations and the geometrical change of the porous medium due to retention (straining and blocking). Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Calibration of hydrodynamic behavior and biokinetics for TOC removal modeling in biofilm reactors under different hydraulic conditions.

    Science.gov (United States)

    Zeng, Ming; Soric, Audrey; Roche, Nicolas

    2013-09-01

    In this study, total organic carbon (TOC) biodegradation was simulated by GPS-X software in biofilm reactors with carriers of plastic rings and glass beads under different hydraulic conditions. Hydrodynamic model by retention time distribution and biokinetic measurement by in-situ batch test served as two significant parts of model calibration. Experimental results showed that TOC removal efficiency was stable in both media due to the enough height of column, although the actual hydraulic volume changed during the variation of hydraulic condition. Simulated TOC removal efficiencies were close to experimental ones with low theil inequality coefficient values (below 0.15). Compared with glass beads, more TOC was removed in the filter with plastic rings due to the larger actual hydraulic volume and lower half saturation coefficient in spite of its lower maximum specific growth rate of biofilm, which highlighted the importance of calibrating hydrodynamic behavior and biokinetics. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Models for the dynamics of dust-like matter in the self-gravity field: The method of hydrodynamic substitutions

    Science.gov (United States)

    Zhuravlev, V. M.

    2017-09-01

    Models for the dynamics of a dust-like medium in the self-gravity field are investigated. Solutions of the corresponding problems are constructed by the method of hydrodynamic substitutions generalizing the Cole-Hopf substitutions. The method is extended to multidimensional ideal and viscous fluid flows with cylindrical and spherical symmetries for which exact solutions are constructed. Solutions for the dynamics of self-gravitating dust with arbitrary initial distributions of both fluid density and velocity are constructed using special coordinate transformations. In particular, the problem of cosmological expansion is considered in terms of Newton's gravity theory. Models of a one-dimensional viscous dust fluid flow and some problems of gas hydrodynamics are considered. Examples of exact solutions and their brief analysis are provided.

  18. Atmospheric Modeling Using Accelerometer Data During Mars Atmosphere and Volatile Evolution (MAVEN) Flight Operations

    Science.gov (United States)

    Tolson, Robert H.; Lugo, Rafael A.; Baird, Darren T.; Cianciolo, Alicia D.; Bougher, Stephen W.; Zurek, Richard M.

    2017-01-01

    The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is a NASA orbiter designed to explore the Mars upper atmosphere, typically from 140 to 160 km altitude. In addition to the nominal science mission, MAVEN has performed several Deep Dip campaigns in which the orbit's closest point of approach, also called periapsis, was lowered to an altitude range of 115 to 135 km. MAVEN accelerometer data were used during mission operations to estimate atmospheric parameters such as density, scale height, along-track gradients, and wave structures. Density and scale height estimates were compared against those obtained from the Mars Global Reference Atmospheric Model and used to aid the MAVEN navigation team in planning maneuvers to raise and lower periapsis during Deep Dip operations. This paper describes the processes used to reconstruct atmosphere parameters from accelerometers data and presents the results of their comparison to model and navigation-derived values.

  19. Hydrodynamic modelling of extreme flood events in the Kashmir valley in India

    Science.gov (United States)

    Jain, Manoj; Parvaze, Sabah

    2017-04-01

    extreme flood events showed good agreement (within ±15%) with corresponding observed peak discharge. The model could simulated the most severe flood event of 2014 reasonably well with simulated peak discharge of 2055 m3/s which is just 3% more than the observed discharge. The developed hydrodynamic model may be useful in simulating extreme flood events in the Kashmir Valley with reasonably good reproduction of extreme flood events.

  20. Modelling hydrodynamics of horizontal flow steel slag filters designed to upgrade phosphorus removal in small wastewater treatment plants.

    Science.gov (United States)

    Barca, Cristian; Roche, Nicolas; Troesch, Stéphane; Andrès, Yves; Chazarenc, Florent

    2018-01-15

    Steel slag filters, if well designed and operated, may upgrade phosphorus removal in small wastewater treatment plants such as stabilization ponds and constructed wetlands. The main objective of this study was to develop a systemic modelling approach to describe changes in the hydraulic performances and internal hydrodynamics of steel slag filters under real dynamic operating conditions. The experimental retention time distribution curves (RTD curves) determined from tracer experiments performed at different times during the first year of operation of two field-scale steel slag filters were analyzed through a three stage process. First, a statistical analysis of the RTD curves was performed to determine statistical parameters of the retention time distribution. Second, classical tanks in series (TIS) and plug flow with dispersion (PFD) models were used to obtain a first evaluation of the dispersion and mixing regime. Finally, a multi-flow path TIS model, based on the assumption of several flow paths with different hydraulic properties, is proposed to accurately describe the internal hydrodynamics. Overall, the results of this study indicate that higher CaO content, round shape, and larger grain size distribution of steel slag may promote plug-like flow rather than dispersion. The results of the multi-flow path TIS model suggest that the internal hydrodynamics of steel slag filters can be primarily described by two main flow paths: (i) a faster main flow path showing higher plug flow, followed by (ii) a slower secondary flow path showing higher dispersion. The results also showed that internal hydrodynamics may change over time as a consequence of physical-chemical phenomena occurring in the filter, including accumulation of precipitates, slag hydration and carbonation, and particle segregation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Development of the Hydrodynamic Model for Long-Term Simulation of Water Quality Processes of the Tidal James River, Virginia

    Directory of Open Access Journals (Sweden)

    Jian Shen

    2016-11-01

    Full Text Available Harmful algal blooms (HABs have frequently occurred in the James River. The State has convened a Scientific Advisory Panel (SAP to review the James River chlorophyll-a standards. The SAP will conduct a scientific study to review the basis for setting the chlorophyll-a standards. To support the SAP study of chlorophyll-a standards, the State of Virginia has decided to develop a numerical modeling system that is capable of simulating phytoplankton and HABs. The modeling system includes a watershed model, a three-dimensional hydrodynamic model and water quality models. The focus of this study will be on the development and verification of the hydrodynamic model. In order to simulate the complex geometry of the James River, a high-resolution model has been implemented. The model has been calibrated for a long-term period of 23 years. A series of model experiments was conducted to evaluate the impact of forcings on dynamic simulation and transport time. It was found that freshwater discharge is the most sensitive for an accurate simulation of salinity and transport time. The water age predicted by the model in the tidal freshwater region represents the fluctuation of transport processes, and it has a good correlation with the algal bloom, while at the downstream, the transport time simulation agrees with the delay of the HAB in the mesohaline of the James after the HAB occurred in the Elizabeth River due to the transport processes. The results indicate that the hydrodynamic model is capable of simulating the dynamic processes of the James and driving water quality models in the James River.

  2. Comparison and Validation of Hydrological E-Flow Methods through Hydrodynamic Modelling

    Science.gov (United States)

    Kuriqi, Alban; Rivaes, Rui; Sordo-Ward, Alvaro; Pinheiro, António N.; Garrote, Luis

    2017-04-01

    Flow regime determines physical habitat conditions and local biotic configuration. The development of environmental flow guidelines to support the river integrity is becoming a major concern in water resources management. In this study, we analysed two sites located in southern part of Portugal, respectively at Odelouca and Ocreza Rivers, characterised by the Mediterranean climate. Both rivers are almost in pristine condition, not regulated by dams or other diversion construction. This study presents an analysis of the effect on fish habitat suitability by the implementation of different hydrological e-flow methods. To conduct this study we employed certain hydrological e-flow methods recommended by the European Small Hydropower Association (ESHA). River hydrology assessment was based on approximately 30 years of mean daily flow data, provided by the Portuguese Water Information System (SNIRH). The biological data, bathymetry, physical and hydraulic features, and the Habitat Suitability Index for fish species were collected from extensive field works. We followed the Instream Flow Incremental Methodology (IFIM) to assess the flow-habitat relationship taking into account the habitat suitability of different instream flow releases. Initially, we analysed fish habitat suitability based on natural conditions, and we used it as reference condition for other scenarios considering the chosen hydrological e-flow methods. We accomplished the habitat modelling through hydrodynamic analysis by using River-2D model. The same methodology was applied to each scenario by considering as input the e-flows obtained from each of the hydrological method employed in this study. This contribution shows the significance of ecohydrological studies in establishing a foundation for water resources management actions. Keywords: ecohydrology, e-flow, Mediterranean rivers, river conservation, fish habitat, River-2D, Hydropower.

  3. Modelling Growth and Form of the Scleractinian Coral Pocillopora verrucosa and the Influence of Hydrodynamics

    Science.gov (United States)

    Chindapol, Nol; Kaandorp, Jaap A.; Cronemberger, Carolina; Mass, Tali; Genin, Amatzia

    2013-01-01

    The growth of scleractinian corals is strongly influenced by the effect of water motion. Corals are known to have a high level of phenotypic variation and exhibit a diverse range of growth forms, which often contain a high level of geometric complexity. Due to their complex shape, simulation models represent an important option to complement experimental studies of growth and flow. In this work, we analyzed the impact of flow on coral's morphology by an accretive growth model coupled with advection-diffusion equations. We performed simulations under no-flow and uni-directional flow setup with the Reynolds number constant. The relevant importance of diffusion to advection was investigated by varying the diffusion coefficient, rather than the flow speed in Péclet number. The flow and transport equations were coupled and solved using COMSOL Multiphysics. We then compared the simulated morphologies with a series of Computed Tomography (CT) scans of scleractinian corals Pocillopora verrucosa exposed to various flow conditions in the in situ controlled flume setup. As a result, we found a similar trend associated with the increasing Péclet for both simulated forms and in situ corals; that is uni-directional current tends to facilitate asymmetrical growth response resulting in colonies with branches predominantly developed in the upstream direction. A closer look at the morphological traits yielded an interesting property about colony symmetry and plasticity induced by uni-directional flow. Both simulated and in situ corals exhibit a tendency where the degree of symmetry decreases and compactification increases in conjunction with the augmented Péclet thus indicates the significant importance of hydrodynamics. PMID:23326222

  4. A comparison between Smoothed-Particle Hydrodynamics and RANS Volume of Fluid method in modelling slamming

    Directory of Open Access Journals (Sweden)

    Marcus Sasson

    2016-04-01

    Full Text Available The oil and gas industry requires complex subsea infrastructure in order to develop offshore oil and gas fields. Upon installation, these components may encounter high slamming loads, stemming from impact with the water surface. This paper utilises two different numerical methods, the mesh-free Smoothed Particle Hydrodynamics (SPH approach and Reynolds Averaged Navier–Stokes (RANS Volume of Fluid (VOF method to quantify these loads on a free-falling object. The investigation is also interested in conducting a parameter study and determining the effect of varying simulation parameters on the prediction of slamming event kinematics and forces. The surface impact of a freefalling wedge was introduced as a case study and has been simulated using SPH and RANS, with the results being compared to an experimental investigation. It was found from the SPH simulations that particle resolution and the size of the SPH particle kernel are very important, whilst the diffusion term does not play an important role. The latter is due to the very transient nature of slamming events, which do not allow sufficient time for diffusion in the fluid domain. For the RANS simulations, motion of the wedge was achieved using the overset grid technique, whereby varying the discretising time step was found to have a pronounced impact on the accuracy of the captured slamming event. Through analysing the numerical data, one can observe that the RANS results correlate slightly better with the experimental data as opposed to that obtained from the SPH modelling. However, considering the robustness and quick set up of the SPH simulations, both of these two numerical approaches are considered to be promising tools for modelling more complicated slamming problems, including those potentially involving more intricate structures.

  5. COMPUTER MODELING OF HYDRODYNAMIC PARAMETERS AT BOUNDARIES OF WATER INTAKE AREA WITH FILTERING INTAKE

    Directory of Open Access Journals (Sweden)

    Boronina Lyudmila Vladimirovna

    2012-12-01

    Full Text Available Improvement of water intake technologies are of great importance. These technologies are required to provide high quality water intake and treatment; they must be sufficiently simple and reliable, and they must be easily adjustable to particular local conditions. A mathematical model of a water supply area near the filtering water intake is proposed. On its basis, a software package designated for the calculation of parameters of the supply area along with its graphical representation is developed. To improve the efficiency of water treatment plants, the authors propose a new method of their integration into the landscape by taking account of velocity distributions in the water supply area within the water reservoir where the plant installation is planned. In the proposed relationship, the filtration rate and the scattering rate at the outlet of the supply area are taken into account, and they assure more precise projections of the inlet velocity. In the present study, assessment of accuracy of the mathematical model involving the scattering of a turbulent flow has been done. The assessment procedure is based on verification of the mean values equality hypothesis and on comparison with the experimental data. The results and conclusions obtained by means of the method developed by the authors have been verified through comparison of deviations of specific values calculated through the employment of similar algorithms in MathCAD, Maple and PLUMBING. The method of the water supply area analysis, with the turbulent scattering area having been taken into account, and the software package enable to numerically estimate the efficiency of the pre-purification process by tailoring a number of parameters of the filtering component of the water intake to the river hydrodynamic properties. Therefore, the method and the software package provide a new tool for better design, installation and operation of water treatment plants with respect to filtration and

  6. Mesoscale, Sources and Models: Sources for Nitrogen in the Atmosphere

    DEFF Research Database (Denmark)

    Hertel, O.

    1994-01-01

    Projektet Mesoscales, Sources and Models: Sources for Nitrogen in the Atmosphere er opdelt i 3 delprojekter: Sources - farmland, Sources - sea og Sources - biogenic nitrogen.......Projektet Mesoscales, Sources and Models: Sources for Nitrogen in the Atmosphere er opdelt i 3 delprojekter: Sources - farmland, Sources - sea og Sources - biogenic nitrogen....

  7. Assessing Potential Algal Blooms in a Shallow Fluvial Lake by Combining Hydrodynamic Modelling and Remote-Sensed Images

    Directory of Open Access Journals (Sweden)

    Monica Pinardi

    2015-04-01

    Full Text Available Shallow fluvial lakes are dynamic ecosystems shaped by physical and biological factors and characterized by the coexistence of phytoplankton and macrophytes. Due to multiple interplaying factors, understanding the distribution of phytoplankton in fluvial lakes is a complex but fundamental issue, in the context of increasing eutrophication, climate change, and multiple water uses. We analyze the distribution of phytoplankton by combining remotely sensed maps of chlorophyll-a with a hydrodynamic model in a dammed fluvial lake (Mantua Superior Lake, Northern Italy. The numerical simulation of different conditions shows that the main hydrodynamic effects which influence algal distribution are related to the combined effect of advection due to wind forces and local currents, as well as to the presence of large gyres which induce recirculation and stagnation regions, favoring phytoplankton accumulation. Therefore, the general characters of the phytoplankton horizontal patchiness can be inferred from the results of the hydrodynamic model. Conversely, hyperspectral remote-sensing products can be used to validate this model, as they provide chlorophyll-a distribution maps. The integration of ecological, hydraulic, and remote-sensing techniques may therefore help the monitoring and protection of inland water quality, with important improvements in management actions by policy makers.

  8. A new lattice hydrodynamic model based on control method considering the flux change rate and delay feedback signal

    Science.gov (United States)

    Qin, Shunda; Ge, Hongxia; Cheng, Rongjun

    2018-02-01

    In this paper, a new lattice hydrodynamic model is proposed by taking delay feedback and flux change rate effect into account in a single lane. The linear stability condition of the new model is derived by control theory. By using the nonlinear analysis method, the mKDV equation near the critical point is deduced to describe the traffic congestion. Numerical simulations are carried out to demonstrate the advantage of the new model in suppressing traffic jam with the consideration of flux change rate effect in delay feedback model.

  9. Hydrodynamic Instability in an Extended Landau/Levich Model of Liquid-Propellant Combustion at Normal and Reduced Gravity

    Science.gov (United States)

    Margolis, Stephen B.

    1998-01-01

    The classical Landau/Levich models of liquid-propellant combustion, despite their relative simplicity, serve as seminal examples that correctly describe the onset of hydrodynamic instability in reactive systems. Recently, these two separate models have been combined and extended to account for a dynamic dependence, absent in the original formulations, of the local burning rate on the local pressure and temperature fields. The resulting model admits an extremely rich variety of both hydrodynamic and reactive/diffusive instabilities that can be analyzed either numerically or analytically in various limiting parameter regimes. In the present work, a formal asymptotic analysis, based on the realistic smallness of the gas-to-liquid density ratio, is developed to investigate the combined effects of gravity and other parameters on the hydrodynamic instability of the propagating liquid/gas interface. In particular, an analytical expression is derived for the neutral stability boundary A(sub p)(k), where A(sub p) is the pressure sensitivity of the burning rate and k is the wavenumber of the disturbance. The results demonstrate explicitly the stabilizing effect of gravity on long-wave disturbances, the stabilizing effect of viscosity (both liquid and gas) and surface tension on short-wave perturbations, and the instability associated with intermediate wavenumbers for critical negative values of A(sub p). In the limiting case of weak gravity, it is shown that hydrodynamic instability in liquid-propellant combustion is a long-wave instability phenomenon, whereas at normal gravity, this instability is first manifested through O(1) wavenumber disturbances. It is also demonstrated that, in general, surface tension and the viscosity of both the liquid and gas phases each produce comparable stabilizing effects in the large-wavenumber regime, thereby providing important modifications to previous analyses in which one or more of these effects were neglected.

  10. Proposed reference models for atomic oxygen in the terrestrial atmosphere

    Science.gov (United States)

    Llewellyn, E. J.; Mcdade, I. C.; Lockerbie, M. D.

    1989-01-01

    A provisional Atomic Oxygen Reference model was derived from average monthly ozone profiles and the MSIS-86 reference model atmosphere. The concentrations are presented in tabular form for the altitude range 40 to 130 km.

  11. Electrical Resistivity Imaging and Hydrodynamic Modeling of Convective Fingering in a Sabkha Aquifer

    Science.gov (United States)

    Van Dam, Remke; Eustice, Brian; Hyndman, David; Wood, Warren; Simmons, Craig

    2014-05-01

    Free convection, or fluid motion driven by density differences, is an important groundwater flow mechanism that can enhance transport and mixing of heat and solutes in the subsurface. Various issues of environmental and societal relevance are exacerbated convective mixing; it has been studied in the context of dense contaminant plumes, nuclear waste disposal, greenhouse gas sequestration, the impacts of sea level rise and saline intrusion on drinking water resources. The basic theory behind convective flow in porous media is well understood, but important questions regarding this process in natural systems remain unanswered. Most previous research on this topic has focused on theory and modeling, with only limited attention to experimental studies and field measurements. The few published studies present single snapshots, making it difficult to quantify transient changes in these systems. Non-invasive electrical methods have the potential to exploit the relation between solute concentrations and electrical conductance of a fluid, and thereby estimate fluid salinity differences in time and space. We present the results of a two-year experimental study at a shallow sabkha aquifer in the United Arab Emirates, about 50 km southwest of the city of Abu Dhabi along the coast of the Arabian Gulf, that was designed to explore the transient nature of free convection. Electrical resistivity tomography (ERT) data documented the presence of convective fingers following a significant rainfall event. One year later, the complex fingering pattern had completely disappeared. This observation is supported by analysis of the aquifer solute budget as well as hydrodynamic modeling of the system. The transient dynamics of the gravitational instabilities in the modeling results are in agreement with the timing observed in the time-lapse ERT data. Our experimental observations and modeling are consistent with the hypothesis that the instabilities arose from a dense brine that infiltrated

  12. Surface plasmon dispersion relation at an interface between thin metal film and dielectric using a quantum hydrodynamic model

    Science.gov (United States)

    Zhang, Y.; Gao, M. X.; Guo, B.

    2017-11-01

    The plasmon excited at the surface of a thin metal film covering on a semi-infinite dielectric substrate is investigated in detailed. The surface plasmon dispersion relation is derived and presented by using the quantum hydrodynamic theory with taking into the quantum statistical and quantum diffraction effects. The effects of the thin metal film character rs and the dielectric constant ε1 on the dispersion relations are shown and discussed, i.e., without and with quantum effects. The results show that increasing rs weakens the quantum effects while increasing ε1 can enhance the quantum effects. In addition, the plasmon dispersion relation with quantum effects is also compared to a classical model. This simple structure proposed in the paper with quantum hydrodynamic theory can be used for yielding meaningful results for studying more complex systems related to surface plasmons.

  13. Building a High-Precision 2D Hydrodynamic Flood Model Using UAV Photogrammetry and Sensor Network Monitoring

    Directory of Open Access Journals (Sweden)

    Jakub Langhammer

    2017-11-01

    Full Text Available This paper explores the potential of the joint application of unmanned aerial vehicle (UAV-based photogrammetry and an automated sensor network for building a hydrodynamic flood model of a montane stream. UAV-based imagery was used for three-dimensional (3D photogrammetric reconstruction of the stream channel, achieving a resolution of 1.5 cm/pixel. Automated ultrasonic water level gauges, operating with a 10 min interval, were used as a source of hydrological data for the model calibration, and the MIKE 21 hydrodynamic model was used for building the flood model. Three different horizontal schematizations of the channel—an orthogonal grid, curvilinear grid, and flexible mesh—were used to evaluate the effect of spatial discretization on the results. The research was performed on Javori Brook, a montane stream in the Sumava (Bohemian Forest Mountains, Czech Republic, Central Europe, featuring a fast runoff response to precipitation events and that is located in a core zone of frequent flooding. The studied catchments have been, since 2007, equipped with automated water level gauges and, since 2013, under repeated UAV monitoring. The study revealed the high potential of these data sources for applications in hydrodynamic modeling. In addition to the ultra-high levels of spatial and temporal resolution, the major contribution is in the method’s high operability, enabling the building of highly detailed flood models even in remote areas lacking conventional monitoring. The testing of the data sources and model setup indicated the limitations of the UAV reconstruction of the stream bathymetry, which was completed by the geodetic-grade global navigation satellite system (GNSS measurements. The testing of the different model domain schematizations did not indicate the substantial differences that are typical for conventional low-resolution data, proving the high reliability of the tested modeling workflow.

  14. Mathematical modelling of the performance of hydrodynamic couplings using hybrid models; Mathematische Modellierung des Betriebsverhaltens hydrodynamischer Kupplungen mit hybriden Modellansaetzen

    Energy Technology Data Exchange (ETDEWEB)

    Jaschke, P.

    2000-02-01

    Mathematical models of the dynamic performance of hydrodynamic couplings are developed using hybrid modelling, i.e. a combination of analytical physical modelling and black box identification. The models developed were verified by measurements on a model powertrain. [German] In dieser Arbeit werden mit Hilfe der hybriden Modellierung mathematische Modelle zur Beschreibung des dynamischen Betriebsverhaltens hydrodynamischer Kupplungen ermittelt. Die Hybride Modellierung stellt eine Kombination der analytisch physikalischen Modellierung und der Black-Box-Identifikation dar. Diese Modellierungsart ist ausgewaehlt worden, um die Vorteile der analytisch physikalischen Modellierung und der Black-Box-Identifikation hydrodynamischer Kupplungen zu verbinden und deren Nachteile gering zu halten. Auf dieser Basis ist eine Vorgehensweise vorgestellt worden, die die Ermittlung der Modelle mit wenig Aufwand ermoeglicht. Mit Hilfe der Modelltheorie wird gezeigt, wie die ermittelten mathematischen Modelle zur Simulation des dynamischen Betriebsverhaltens geometrisch aehnlicher Kupplungen unterschiedlicher Baugroessen verwendet werden koennen. Darueber hinaus wird dargelegt, wie die ermittelten Modelle mit Modellen anderer Antriebsstrangelemente gekoppelt werden koennen, um Antriebsstrangsimulationen zu ermoeglichen. Verifikationsmessungen an einem Modellantriebsstrang verdeutlichen die Guete und Verwendbarkeit der mathematischen Modelle. (orig.)

  15. Hydrodynamic modelling of transient cavities in fluids generated by high voltage spark discharges

    Energy Technology Data Exchange (ETDEWEB)

    Timoshkin, I V; Fouracre, R A; Given, M J; MacGregor, S J [HVT Research Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, Royal College Building, 204 George St, Glasgow, G1 1XW (United Kingdom)

    2006-11-21

    Application of a voltage pulse having a rise time of tens of nanoseconds to electrodes immersed in water results in streamer development and the formation of a highly conductive plasma channel between the electrodes. The electrical resistance of such channels decreases rapidly from a few ohms to a few tens of milliohms due to Joule heating resulting from the high current which flows through the plasma. The dynamics of the plasma resistance depend on the parameters of the discharge circuit and the medium in which the discharge takes place. The resistance of the channel reaches a minimum value approximately at the moment of the peak current for under-damped current oscillations. During the resistance collapse, the pressure inside the channel rises to several GPa, causing a rapid expansion of the channel which forms a cavity in the liquid resulting in a high power ultrasound pulse. The cavity expands to a maximum size which is dependent on the circuit driving the discharge and the properties of the plasma discharge channel. The cavity then collapses producing a second acoustic pulse. In this paper the dynamic resistance of the spark channel is described using a phenomenological model based on the plasma channel energy balance equation used by Braginskii. The model which links the hydrodynamic characteristics of the channel and the resulting cavity with the parameters of the electric driving circuit allows the development of the plasma channel and cavity to be predicted. The peak high-power ultrasound (HPU) pressures calculated using this approach are compared with the pressure values estimated by an analytical model which uses a constant value of the spark channel resistance derived from experimental data. Comparisons are also made with direct measurements of HPU output made using a Pinducer sensor. Although the model is based on a phenomenological description of the plasma channel dynamics and its resistance and requires the value of the spark constant, the results

  16. Hydrodynamic modelling of transient cavities in fluids generated by high voltage spark discharges

    Science.gov (United States)

    Timoshkin, I. V.; Fouracre, R. A.; Given, M. J.; MacGregor, S. J.

    2006-11-01

    Application of a voltage pulse having a rise time of tens of nanoseconds to electrodes immersed in water results in streamer development and the formation of a highly conductive plasma channel between the electrodes. The electrical resistance of such channels decreases rapidly from a few ohms to a few tens of milliohms due to Joule heating resulting from the high current which flows through the plasma. The dynamics of the plasma resistance depend on the parameters of the discharge circuit and the medium in which the discharge takes place. The resistance of the channel reaches a minimum value approximately at the moment of the peak current for under-damped current oscillations. During the resistance collapse, the pressure inside the channel rises to several GPa, causing a rapid expansion of the channel which forms a cavity in the liquid resulting in a high power ultrasound pulse. The cavity expands to a maximum size which is dependent on the circuit driving the discharge and the properties of the plasma discharge channel. The cavity then collapses producing a second acoustic pulse. In this paper the dynamic resistance of the spark channel is described using a phenomenological model based on the plasma channel energy balance equation used by Braginskii. The model which links the hydrodynamic characteristics of the channel and the resulting cavity with the parameters of the electric driving circuit allows the development of the plasma channel and cavity to be predicted. The peak high-power ultrasound (HPU) pressures calculated using this approach are compared with the pressure values estimated by an analytical model which uses a constant value of the spark channel resistance derived from experimental data. Comparisons are also made with direct measurements of HPU output made using a Pinducer sensor. Although the model is based on a phenomenological description of the plasma channel dynamics and its resistance and requires the value of the spark constant, the results

  17. Modeling the effects of atmospheric emissions on groundwater composition

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Theresa Jean [Univ. of Wisconsin, Madison, WI (United States)

    1994-01-01

    A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport.

  18. COSTA a problem solving environment for data assimilation applied for hydrodynamical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Velzen, N. van [Delft Univ. of Tech., Delft (Netherlands); Verlaan, M. [National Inst. for Coastal and Marine Management (RIKZ), The Hague (Netherlands)

    2007-12-15

    A problem solving environment for data assimilation called COSTA is developed at Delft University of Technology. The goal of COSTA is to offer a modular framework where simulation models can be combined with various data assimilation methods. COSTA defines a number of building blocks called components. Examples of components are model, method, stochastic observer and state-vector. New data assimilation systems can be created by combining these components. This paper describes the application of COSTA to the WAQUA/TRIWAQ shallow water simulation model. In the past a model specific RRSQRT Kalman filter has been implemented for WAQUA/TRIWAQ. However, this implementation cannot be used in combination with other models. The WAQUA/TRIWAQ model is changed into a COSTA model component and the original RRSQRT Kalman filter is changed into a generic filter that can be used for other models as well. The new filter is now a part of the COSTA environment. The original filter contained a number of WAQUA/TRIWAQ specific aspects e.g. the drying and flooding of areas in the model. These model specific issues are identified, isolated and moved into the model component. A COSTA based implementation of WAQUA/TRIWAQ with the RRSQRT Kalman filter is realized and compared to the original system in a number of experiments. The experiments show that the COSTA based system produces the correct results and the computational overhead for using COSTA is low. The new RRSQRT Kalman filter is also combined with other COSTA models including the LOTOS-EUROS model for atmospherical transport, chemistry (chemical reaction) and deposition of air pollution on the scale of Europe. (orig.)

  19. A Management Tool for Assessing Aquaculture Environmental Impacts in Chilean Patagonian Fjords: Integrating Hydrodynamic and Pellets Dispersion Models

    Science.gov (United States)

    Tironi, Antonio; Marin, Víctor H.; Campuzano, Francisco J.

    2010-05-01

    This article introduces a management tool for salmon farming, with a scope in the local sustainability of salmon aquaculture of the Aysen Fjord, Chilean Patagonia. Based on Integrated Coastal Zone Management (ICZM) principles, the tool combines a large 3-level nested hydrodynamic model, a particle tracking module and a GIS application into an assessment tool for particulate waste dispersal of salmon farming activities. The model offers an open source alternative to particulate waste modeling and evaluation, contributing with valuable information for local decision makers in the process of locating new facilities and monitoring stations.

  20. A management tool for assessing aquaculture environmental impacts in Chilean Patagonian Fjords: integrating hydrodynamic and pellets dispersion models.

    Science.gov (United States)

    Tironi, Antonio; Marin, Víctor H; Campuzano, Francisco J

    2010-05-01

    This article introduces a management tool for salmon farming, with a scope in the local sustainability of salmon aquaculture of the Aysen Fjord, Chilean Patagonia. Based on Integrated Coastal Zone Management (ICZM) principles, the tool combines a large 3-level nested hydrodynamic model, a particle tracking module and a GIS application into an assessment tool for particulate waste dispersal of salmon farming activities. The model offers an open source alternative to particulate waste modeling and evaluation, contributing with valuable information for local decision makers in the process of locating new facilities and monitoring stations.

  1. Modelling Hermetic Compressors Using Different Constraint Equations to Accommodate Multibody Dynamics and Hydrodynamic Lubrication

    DEFF Research Database (Denmark)

    Estupinan, Edgar Alberto; Santos, Ilmar

    2009-01-01

    elements are supported by fluid film bearings, where the hydrodynamic interaction forces are described by the Reynolds equation. The system of nonlinear equations is numerically solved for three different restrictive conditions of the motion of the crank, where the third case takes into account lateral...

  2. Comparison between physical variables acquired by a new multiparametric platform, ELFO, and data calculated by a three-dimensional hydrodynamic model in different weather conditions at Tiber River mouth (Latium coast, Italy)

    Science.gov (United States)

    Bonamano, Simone; Piermattei, Viviana; Marcelli, Marco; Peviani, Maximo

    2010-05-01

    The coastal ecosystem is characterized by high variability physical processes, which are strongly influenced by sudden changes in weather conditions. For this reason instruments able to collect data in a short time or mathematical models able to simulate the same phenomena from experimental data are basic. In this study in situ data are compared with data calculated by three-dimensional hydrodynamic model. The multiparametric platform was developed ad hoc by Laboratory of Experimental Oceanology and Marine Ecology (DECOS, Tuscia University) for coastal monitoring by small vessels (ELFO), and integrates temperature, conductivity, dissolved oxygen and suspended solids measures with bio-optical measures like fluorescence, photosynthetic efficiency and PAR. The hydrodynamic model is the three-dimensional coastal hydrodynamic DELFT3D-FLOW simulating processes of temperature and salinity diffusion and the transport of suspended sediment (cohesive and non cohesive) in the water column. This study analyses the area at mouth of Tiber river investigated by two surveys wiht different weather conditions. Data collected during the first survey were used to calibrate the DELFT3D-FLOW model which computational domain extends from the Argentario headland to Capo Anzio. A microscale wind field (resolution of about 7 km), provided by the atmospheric model COSMO-ME (developed by CNMCA of Aeronautica Militare, Italy), was used to reproduce the hydrodynamic field and the distribution of the physical variables of the whole period. In this way the data calculated by the model can be compared with those collected in situ during the second survey. Moreover dynamic phenomena existed between the two monitoring periods can be investigated.

  3. Hydrodynamic model of a dielectric-barrier discharge in pure chlorine

    Science.gov (United States)

    Avtaeva, S. V.

    2017-08-01

    A one-dimensional hydrodynamic model of a dielectric-barrier discharge (DBD) in pure chlorine is developed, and the properties of the discharge are modeled. The discharge is excited in an 8-mm-long discharge gap between 2-mm-thick dielectric quartz layers covering metal electrodes. The DBD spatiotemporal characteristics at gas pressures of 15-100 Torr are modeled for the case in which a 100-kHz harmonic voltage with an amplitude of 8 kV is applied to the electrodes. The average power density deposited in the discharge over one voltage period is 2.5-5.8 W/cm3. It is shown that ions and electrons absorb about 95 and 5% of the discharge power, respectively. In this case, from 67 to 97% of the power absorbed by electrons is spent on the dissociation and ionization of Cl2 molecules. Two phases can be distinguished in the discharge dynamics: the active (multispike) phase, which follows the breakdown of the discharge gap, and the passive phase. The active phase is characterized by the presence of multiple current spikes, a relatively high current, small surface charge density on the dielectrics, and large voltage drop across the discharge gap. The passive phase (with no current spikes) is characterized by a low current, large surface charge density on the dielectrics, and small voltage drop across the discharge gap. The peak current density in the spikes at all pressures is about 4 mA/cm2. In the multispike phase, there are distinct space charge sheaths with thicknesses of 1.5-1.8 mm and a mean electron energy of 4.3-7 eV and the central region of quasineutral plasma with a weak electric field and a mean electron energy of 0.8-3 eV. The degree of ionization of chlorine molecules in the discharge is 0.02% at a pressure of 15 Torr and 0.01% at 100 Torr. The DBD plasma is electronegative due to the fast attachment of electrons to chlorine atoms: e + Cl2 → Cl + Cl-. The most abundant charged particles are Cl 2 + and Cl- ions, and the degree of ionization during current

  4. Modeling Exoplanetary Atmospheres using BART, TEA, and Drift-RHD; Theoretical studies and Observational Implications

    Science.gov (United States)

    Dobbs-Dixon, Ian

    The explosion in the number of exoplanets detected to date has revealed a surprising diversity. When attempting to model this diversity, it is crucial to account for the uncertainties resulting from our limited knowledge of chemical, dynamical, and cloud formation processes in their atmospheres. Combining a retrieval technique with theorydriven models is a particularly promising way to address these processes and constrain a physically plausible atmospheric structure. In particular, a detailed micro-physical treatment of clouds and the longitudinal and latitudinal assessments of temperature and chemical profiles, have yet to be addressed in the field. Our team members are experts in radiative-hydrodynamic modeling (Dr. Ian DobbsDixon), cloud kinetics (Dr. Christiana Helling), retrievals and thermo-equilibrium chemistry (Dr. Jasmina Blecic), and observational diagnostics and predictions (Dr. Thomas Greene). The key goals of this proposal are to extend our understanding of the 3D atmospheric structure of gas-giant exoplanets by coupling state-of-the-art selfconsistent models together with a retrieval framework to 1) address cloud kinetics in retrievals, 2) assess 3D temperature and chemical structures in retrievals, 3) model a suite of well-observed planets within the framework of our models, and 4) make observational predictions for current and future NASA missions. To address these goals we have developed a number of tools: Drift-RHD, TEA, BART, and OBS. Drift-RHD solves both the 3D radiative-hydrodynamic equations and a time dependent kinetic cloud model. TEA, Thermochemical Equilibrium Abundances, calculates abundances of chemical species present in the atmosphere. BART, a Bayesian Atmospheric Radiative Transfer code, is a statistical retrieval framework to explore the parameter space of atmospheric chemical abundances and thermal profiles. OBS is a suite of tools developed to simulate observations. Though these tools exist and have been utilized independently in

  5. Pulsating Hydrodynamic Instability in a Dynamic Model of Liquid-Propellant Combustion

    Science.gov (United States)

    Margolis, Stephen B.; Sacksteder, Kurt (Technical Monitor)

    1999-01-01

    Hydrodynamic (Landau) instability in combustion is typically associated with the onset of wrinkling of a flame surface, corresponding to the formation of steady cellular structures as the stability threshold is crossed. In the context of liquid-propellant combustion, such instability has recently been shown to occur for critical values of the pressure sensitivity of the burning rate and the disturbance wavenumber, significantly generalizing previous classical results for this problem that assumed a constant normal burning rate. Additionally, however, a pulsating form of hydrodynamic instability has been shown to occur as well, corresponding to the onset of temporal oscillations in the location of the liquid/gas interface. In the present work, we consider the realistic influence of a nonzero temperature sensitivity in the local burning rate on both types of stability thresholds. It is found that for sufficiently small values of this parameter, there exists a stable range of pressure sensitivities for steady, planar burning such that the classical cellular form of hydrodynamic instability and the more recent pulsating form of hydrodynamic instability can each occur as the corresponding stability threshold is crossed. For larger thermal sensitivities, however, the pulsating stability boundary evolves into a C-shaped curve in the disturbance-wavenumber/ pressure-sensitivity plane, indicating loss of stability to pulsating perturbations for all sufficiently large disturbance wavelengths. It is thus concluded, based on characteristic parameter values, that an equally likely form of hydrodynamic instability in liquid-propellant combustion is of a nonsteady, long-wave nature, distinct from the steady, cellular form originally predicted by Landau.

  6. Modeling the Atmosphere of Solar and Other Stars: Radiative Transfer with PHOENIX/3D

    Science.gov (United States)

    Baron, Edward

    The chemical composition of stars is an important ingredient in our understanding of the formation, structure, and evolution of both the Galaxy and the Solar System. The composition of the sun itself is an essential reference standard against which the elemental contents of other astronomical objects are compared. Recently, redetermination of the elemental abundances using three-dimensional, time-dependent hydrodynamical models of the solar atmosphere has led to a reduction in the inferred metal abundances, particularly C, N, O, and Ne. However, this reduction in metals reduces the opacity such that models of the Sun no longer agree with the observed results obtained using helioseismology. Three dimensional (3-D) radiative transfer is an important problem in physics, astrophysics, and meteorology. Radiative transfer is extremely computationally complex and it is a natural problem that requires computation on the exascale. We intend to calculate the detailed compositional structure of the Sun and other stars at high resolution with full NLTE, treating the turbulent velocity flows in full detail in order to compare results from hydrodynamics and helioseismology, and understand the nature of the discrepancies found between the two approaches. We propose to perform 3-D high-resolution radiative transfer calculations with the PHOENIX/3D suite of solar and other stars using 3-D hydrodynamic models from different groups. While NLTE radiative transfer has been treated by the groups doing hydrodynamics, they are necessarily limited in their resolution to the consideration of only a few (4-20) frequency bins, whereas we can calculate full NLTE including thousands of wavelength points, resolving the line profiles, and solving the scattering problem with extremely high angular resolution. The code has been used for the analysis of supernova spectra, stellar and planetary spectra, and for time-dependent modeling of transient objects. PHOENIX/3D runs and scales very well on Cray

  7. Mesoscale atmospheric modelling technology as a tool for creating a long-term meteorological dataset

    Science.gov (United States)

    Platonov, Vladimir; Kislov, Alexander; Rivin, Gdaly; Varentsov, Mikhail; Rozinkina, Inna; Nikitin, Mikhail; Chumakov, Mikhail

    2017-11-01

    A detailed hydrodynamic simulation of major meteorological parameters for the last 30 years (1985 – 2014) has been performed for the Sea of Okhotsk and the Sakhalin Island. The regional non-hydrostatic atmospheric model COSMO-CLM was used for this long-term simulation with horizontal resolutions of ~13.2, ~6.6 and ~2.2 km. This dataset was created to help in the investigation of statistical characteristics and physical mechanisms of formation of extreme weather events (primarily wind speed extremes) on small spatio-temporal scales. The detailed meteorological information thus obtained could be used to take into account the coast configuration, mountain systems, and other important mesoscale features of the terrain. This paper describes a proposed downscaling technology for long-term simulations with three “nested domains”. The results of verification of the dataset and estimation of extreme wind velocities are presented.

  8. Atmospheric muon simulation using the FLUKA MC Model

    CERN Document Server

    Battistoni, G; Muraro, S; Sala, P R

    2007-01-01

    The FLUKA code has been used to reproduce experimental data concerning muon fluxes in atmosphere in a wide energy range with the aim of testing the performance of this Monte Carlo model in predicting secondary cosmic ray spectra in atmosphere. Here new results are presented, concerning in particular the cases of BESS and L3+C experiments.

  9. Atmospheric muon simulation using the FLUKA MC Model

    Energy Technology Data Exchange (ETDEWEB)

    Battistoni, G. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy)], E-mail: battistoni@mi.infn.it; Ferrari, A. [CERN, CH-1211 Geneva (Switzerland); Muraro, S.; Sala, P.R. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy)

    2007-06-15

    The FLUKA code has been used to reproduce experimental data concerning muon fluxes in atmosphere in a wide energy range with the aim of testing the performance of this Monte Carlo model in predicting secondary cosmic ray spectra in atmosphere. Here new results are presented, concerning in particular the cases of BESS and L3+C experiments.

  10. Ozone transmittance in a model atmosphere at Ikeja, Lagos state ...

    African Journals Online (AJOL)

    Variation of ozone transmittance with height in the atmosphere for radiation in the 9.6m absorption band was studied using Goody's model atmosphere, with cubic spline interpolation technique to improve the quality of the curve. The data comprising of pressure and temperature at different altitudes (0-22 km) for the month of ...

  11. UV- Radiation Absorption by Ozone in a Model Atmosphere using ...

    African Journals Online (AJOL)

    UV- radiation absorption is studied through variation of ozone transmittance with altitude in the atmosphere for radiation in the 9.6μm absorption band using Goody's model atmosphere with cubic spline interpolation technique to improve the quality of the curve. The data comprising of pressure and temperature at different ...

  12. Meteorological Uncertainty of atmospheric Dispersion model results (MUD)

    DEFF Research Database (Denmark)

    Havskov Sørensen, Jens; Amstrup, Bjarne; Feddersen, Henrik

    The MUD project addresses assessment of uncertainties of atmospheric dispersion model predictions, as well as optimum presentation to decision makers. Previously, it has not been possible to estimate such uncertainties quantitatively, but merely to calculate the 'most likely' dispersion scenario....... In MUD, corresponding ensembles of atmospheric dispersion are computed from which uncertainties of predicted radionuclide concentration and deposition patterns are derived....

  13. Persistent draining crossover in DNA and other semi-flexible polymers: Evidence from hydrodynamic models and extensive measurements on DNA solutions.

    Science.gov (United States)

    Mansfield, Marc L; Tsortos, Achilleas; Douglas, Jack F

    2015-09-28

    Although the scaling theory of polymer solutions has had many successes, this type of argument is deficient when applied to hydrodynamic solution properties. Since the foundation of polymer science, it has been appreciated that measurements of polymer size from diffusivity, sedimentation, and solution viscosity reflect a convolution of effects relating to polymer geometry and the strength of the hydrodynamic interactions within the polymer coil, i.e., "draining." Specifically, when polymers are expanded either by self-excluded volume interactions or inherent chain stiffness, the hydrodynamic interactions within the coil become weaker. This means there is no general relationship between static and hydrodynamic size measurements, e.g., the radius of gyration and the hydrodynamic radius. We study this problem by examining the hydrodynamic properties of duplex DNA in solution over a wide range of molecular masses both by hydrodynamic modeling using a numerical path-integration method and by comparing with extensive experimental observations. We also considered how excluded volume interactions influence the solution properties of DNA and confirm that excluded volume interactions are rather weak in duplex DNA in solution so that the simple worm-like chain model without excluded volume gives a good leading-order description of DNA for molar masses up to 10(7) or 10(8) g/mol or contour lengths between 5 μm and 50 μm. Since draining must also depend on the detailed chain monomer structure, future work aiming to characterize polymers in solution through hydrodynamic measurements will have to more carefully consider the relation between chain molecular structure and hydrodynamic solution properties. In particular, scaling theory is inadequate for quantitative polymer characterization.

  14. Developing an integrated 3D-hydrodynamic and emerging contaminant model for assessing water quality in a Yangtze Estuary Reservoir.

    Science.gov (United States)

    Xu, Cong; Zhang, Jingjie; Bi, Xiaowei; Xu, Zheng; He, Yiliang; Gin, Karina Yew-Hoong

    2017-12-01

    An integrated 3D-hydrodynamic and emerging contaminant model was developed for better understanding of the fate and transport of emerging contaminants in Qingcaosha Reservoir. The reservoir, which supplies drinking water for nearly half of Shanghai's population, is located in Yangtze Delta. The integrated model was built by Delft3D suite, a fully integrated multidimensional modeling software. Atrazine and Bisphenol A (BPA) were selected as two representative emerging contaminants for the study in this reservoir. The hydrodynamic model was calibrated and validated against observations from 2011 to 2015 while the integrated model was calibrated against observations from 2014 to 2015 and then applied to explore the potential risk of high atrazine concentrations in the reservoir driven by agriculture activities. Our results show that the model is capable of describing the spatial and temporal patterns of water temperature, salinity and the dynamic distributions of two representative emerging contaminants (i.e. atrazine and BPA) in the reservoir. The physical and biodegradation processes in this study were found to play a crucial role in determining the fate and transport of atrazine and BPA in the reservoir. The model also provides an insight into the potential risk of emerging contaminants and possible mitigation thresholds. The integrated approach can be a very useful tool to support policy-makers in the future management of Qingcaosha Reservoir. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Theoretical hydrodynamics

    CERN Document Server

    Milne-Thomson, L M

    2011-01-01

    This classic exposition of the mathematical theory of fluid motion is applicable to both hydrodynamics and aerodynamics. Based on vector methods and notation with their natural consequence in two dimensions - the complex variable - it offers more than 600 exercises and nearly 400 diagrams. Prerequisites include a knowledge of elementary calculus. 1968 edition.

  16. Hydrodynamic Lubrication

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 9. Hydrodynamic Lubrication Experiment with 'Floating' Drops. Jaywant H Arakeri K R Sreenivas. General Article Volume 1 Issue 9 September 1996 pp 51-58. Fulltext. Click here to view fulltext PDF. Permanent link:

  17. Identifying eastern Baltic cod nursery grounds using hydrodynamic modelling: knowledge for the design of Marine Protected Areas

    DEFF Research Database (Denmark)

    Hinrichsen, Hans-Harald; Kraus, Gerd; Böttcher, Uwe

    2009-01-01

    Knowledge of the spatial and temporal distribution of juvenile cod is essential to closing the life cycle in population dynamic models, and it is a prerequisite for the design of Marine Protected Areas (MPAs) aiming at the protection of juveniles. In this study, we use a hydrodynamic model...... evidence that the final destinations of juvenile cod drift routes are affected by decadal climate variability. Application of the methodology to MPA design is discussed, e.g. identifying the overlap of areas with a high probability of successful juvenile cod settlement and regions of high fishing effort...

  18. Understanding pollen tube growth: the hydrodynamic model versus the cell wall model

    NARCIS (Netherlands)

    Zonia, L.; Munnik, T.

    2011-01-01

    Scientific progress stimulates the evolution of models used to understand and conceptualize biological behaviors. The widely accepted cell wall model of pollen tube growth explains stochastic growth of the apical pectin wall, but fails to explain the mechanism driving oscillations in growth and cell

  19. Ensemble data assimilation in the Whole Atmosphere Community Climate Model

    Science.gov (United States)

    Pedatella, N. M.; Raeder, K.; Anderson, J. L.; Liu, H.-L.

    2014-08-01

    We present results pertaining to the assimilation of real lower, middle, and upper atmosphere observations in the Whole Atmosphere Community Climate Model (WACCM) using the Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter. The ability to assimilate lower atmosphere observations of aircraft and radiosonde temperature and winds, satellite drift winds, and Constellation Observing System for Meteorology, Ionosphere, and Climate refractivity along with middle/upper atmosphere temperature observations from SABER and Aura MLS is demonstrated. The WACCM+DART data assimilation system is shown to be able to reproduce the salient features, and variability, of the troposphere present in the National Centers for Environmental Prediction/National Center for Atmospheric Research Re-Analysis. In the mesosphere, the fit of WACCM+DART to observations is found to be slightly worse when only lower atmosphere observations are assimilated compared to a control experiment that is reflective of the model climatological variability. This differs from previous results which found that assimilation of lower atmosphere observations improves the fit to mesospheric observations. This discrepancy is attributed to the fact that due to the gravity wave drag parameterizations, the model climatology differs significantly from the observations in the mesosphere, and this is not corrected by the assimilation of lower atmosphere observations. The fit of WACCM+DART to mesospheric observations is, however, significantly improved compared to the control experiment when middle/upper atmosphere observations are assimilated. We find that assimilating SABER observations reduces the root-mean-square error and bias of WACCM+DART relative to the independent Aura MLS observations by ˜50%, demonstrating that assimilation of middle/upper atmosphere observations is essential for accurate specification of the mesosphere and lower thermosphere region in WACCM+DART. Last, we demonstrate that

  20. A coupled wave-hydrodynamic model of a highly frictional atoll reef system: mechanisms for flow, connectivity, and ecological implications

    Science.gov (United States)

    Rogers, J.; Monismith, S. G.; Fringer, O. B.; Koweek, D.; Dunbar, R. B.

    2016-12-01

    We present a hydrodynamic analysis of an atoll system from modeling simulations using a coupled wave and three-dimensional hydrodynamic model (COAWST) applied to Palmyra Atoll in the Central Pacific. This is the first time the vortex force formalism has been applied in a highly frictional reef environment. The model results agree well with field observations considering the model complexity in terms of bathymetry, bottom roughness, and forcing (waves, wind, metrological, tides, regional boundary conditions), and open boundary conditions. At the atoll scale, strong regional flows create flow separation and a well-defined wake, similar to 2D flow past a cylinder. Circulation within the atoll is typically forced by waves and tides, with strong waves from the north driving flow from north to south across the atoll, and from east to west through the lagoon system. Bottom stress is significant for depths less than about 60 m, and in addition to the model bathymetry, is important for correct representation of flow in the model. Connectivity within the atoll system shows that the general trends follow the mean flow paths. However, some connectivity exists between all regions of the atoll system due to nonlinear processes such as eddies and tidal phasing. While high mean flow and travel time less than 20 hours appears to differentiate very productive coral regions, low temperature and moderate wave stress appear to be the most ideal conditions for high coral cover on Palmyra.

  1. UAV based hydromorphological mapping of a river reach to improve hydrodynamic numerical models

    Science.gov (United States)

    Lükő, Gabriella; Baranya, Sándor; Rüther, Nils

    2017-04-01

    Unmanned Aerial Vehicles (UAVs) are increasingly used in the field of engineering surveys. In river engineering, or in general, water resources engineering, UAV based measurements have a huge potential. For instance, indirect measurements of the flow discharge using e.g. large-scale particle image velocimetry (LSPIV), particle tracking velocimetry (PTV), space-time image velocimetry (STIV) or radars became a real alternative for direct flow measurements. Besides flow detection, topographic surveys are also essential for river flow studies as the channel and floodplain geometry is the primary steering feature of the flow. UAVs can play an important role in this field, too. The widely used laser based topographic survey method (LIDAR) can be deployed on UAVs, moreover, the application of the Structure from Motion (SfM) method, which is based on images taken by UAVs, might be an even more cost-efficient alternative to reveal the geometry of distinct objects in the river or on the floodplain. The goal of this study is to demonstrate the utilization of photogrammetry and videogrammetry from airborne footage to provide geometry and flow data for a hydrodynamic numerical simulation of a 2 km long river reach in Albania. First, the geometry of the river is revealed from photogrammetry using the SfM method. Second, a more detailed view of the channel bed at low water level is taken. Using the fine resolution images, a Matlab based code, BASEGrain, developed by the ETH in Zürich, will be applied to determine the grain size characteristics of the river bed. This information will be essential to define the hydraulic roughness in the numerical model. Third, flow mapping is performed using UAV measurements and LSPIV method to quantitatively asses the flow field at the free surface and to estimate the discharge in the river. All data collection and analysis will be carried out using a simple, low-cost UAV, moreover, for all the data processing, open source, freely available

  2. Galaxy formation in semi-analytic models and cosmological hydrodynamic zoom simulations

    Science.gov (United States)

    Hirschmann, Michaela; Naab, Thorsten; Somerville, Rachel S.; Burkert, Andreas; Oser, Ludwig

    2012-02-01

    We present a detailed comparison between numerical cosmological hydrodynamic zoom simulations and the semi-analytic model (SAM) of Somerville et al., run within merger trees extracted from the simulations. The high-resolution simulations represent 48 individual haloes with virial masses in the range ?. They include radiative H and He cooling, photoionization, star formation and thermal supernova (SN) feedback. We compare with different SAM versions including only this complement of physical processes, and also ones including SN-driven winds, metal cooling and feedback from active galactic nuclei (AGN). Our analysis is focused on the cosmic evolution of the baryon content in galaxies and its division into various components (stars, cold gas and hot gas), as well as how those galaxies acquired their gas and stellar mass. Both the SAMs and simulations are compared with observational relations between halo mass and stellar mass, and between stellar mass and star formation rate, at low and high redshifts. We find some points of agreement and some important disagreements. SAMs that include the same physical processes as the simulations reproduce the total baryon fraction in haloes and the fraction of cold gas plus stars in the central galaxy to better than 20 per cent. However, the simulations turn out to have much higher star formation efficiencies (by about a factor of 10) than the SAMs, despite nominally being both normalized to the same empirical Kennicutt relation at z= 0. Therefore the cold gas is consumed much more rapidly in the simulations, and stars form much earlier. Also, simulations show a transition from stellar mass growth that is dominated by in situ formation of stars to growth that is predominantly through accretion of stars formed in external galaxies. In SAMs, stellar growth is always dominated by in situ star formation, because they significantly underpredict the fraction of mass growth from accreted stars relative to the simulations. In addition

  3. Hydrodynamic modeling of 3He–Au collisions at sNN=200 GeV

    Directory of Open Access Journals (Sweden)

    Piotr Bożek

    2015-07-01

    Full Text Available Collective flow and femtoscopy in ultrarelativistic 3He–Au collisions are investigated within the 3+1-dimensional (3+1D viscous event-by-event hydrodynamics. We evaluate elliptic and triangular flow coefficients as functions of the transverse momentum. We find the typical long-range ridge structures in the two-particle correlations in the relative azimuth and pseudorapidity, in the pseudorapidity directions of both Au and 3He. We also make predictions for the pionic interferometric radii, which decrease with the transverse momentum of the pion pair. All features found hint on collectivity of the dynamics of the system formed in 3He–Au collisions, with hydrodynamics leading to quantitative agreement with the up-to-now released data.

  4. On the construction of a regional atmospheric climate model

    DEFF Research Database (Denmark)

    Christensen, J. H.; Van Meijgaard, E.

    1992-01-01

    A Regional Atmospheric Climate Model which combines the physical parameterization package of the General Circulation or Climate Model (ECHAM) used at the Max Planck Institute for Meteorology in Hamburg, and the dynamics package of the Nordic - Dutch - Irish Limited Area Model (HIRLAM), has been...... developed. The necessary changes applied to both model packages in order to obtain a working code are described. -from Authors...

  5. Hydrodynamics and water quality modelling in a regulated river segment: application on the instream flow definition

    OpenAIRE

    Lopes, Luis Filipe Gomes; Carmo, José S. Antunes Do; Cortes, Rui Manuel Vitor; de Oliveira, Daniel

    2004-01-01

    The aim of this paper is to present a global study on the hydrodynamics, water quality and their influence on aquatic fauna. The case study was conducted on a segment of the Lima river (North Portugal), downstream of the Touvedo dam, which was mainly constructed for hydroelectric power production. http://www.sciencedirect.com/science/article/B6VBS-4BHVGYD-7/1/7765917f49c0a6b3764cf34a8227cfc2

  6. Colloidal suspensions hydrodynamic retention mechanisms in model porous media; Mecanismes de retention hydrodynamique de suspensions colloidales en milieux poreux modeles

    Energy Technology Data Exchange (ETDEWEB)

    Salehi, N.

    1996-04-19

    This study deals with the retention mechanisms of colloidal particles in porous media flows, and the subsequent reduction in permeability in the case of stable and non adsorbing colloids. It combines experimental results and modelling. This study has been realised with stable dispersion of monodispersed carboxylate polystyrene latexes negatively charged injected through negatively charged polycarbonate membranes having mono-sized cylindrical pores. The mean particle diameter is smaller than the mean pore diameter. Both batch and flow experiments in Nuclepore membranes have been done. The results of batch experiments have proved no adsorption of the colloidal latex particles on the surface of the Nuclepore membranes without flow at low salinity. In flow experiments at low particle concentration, only deposition on the upstream side of the membrane have been induced by hydrodynamic forces even for non adsorbing particles without creating any permeability reduction. The retention levels are zero at low and high Peclet numbers with a maximum at intermediate values. Partial plugging was observed at higher colloid concentration even at low salinity without any upstream surface deposition. The modelling of plugging processes is achieved by considering the particle concentration, fluid rate and ratio between the mean pore diameter and the mean particle diameter. This study can be particularly useful in the fields of water treatment and of restoration of lands following radioactive contamination. (author). 96 refs., 99 figs., 29 tabs.

  7. AN ANALYTIC RADIATIVE-CONVECTIVE MODEL FOR PLANETARY ATMOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Tyler D. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Catling, David C., E-mail: robinson@astro.washington.edu [Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195-1310 (United States)

    2012-09-20

    We present an analytic one-dimensional radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power-law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric-pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries; (2) worlds with some attenuation of sunlight throughout the atmosphere, which we show can produce either shallow or deep radiative-convective boundaries, depending on the strength of sunlight attenuation; and (3) strongly irradiated giant planets (including hot Jupiters), where we explore the conditions under which these worlds acquire detached convective regions in their mid-tropospheres. Finally, we validate our model and demonstrate its utility through comparisons to the average observed thermal structure of Venus, Jupiter, and Titan, and by comparing computed flux profiles to more complex models.

  8. GrayStarServer: Stellar atmospheric modeling and spectrum synthesis

    Science.gov (United States)

    Short, C. Ian

    2017-01-01

    GrayStarServer is a stellar atmospheric modeling and spectrum synthesis code of pedagogical accuracy that is accessible in any web browser on commonplace computational devices and that runs on a timescale of a few seconds.

  9. Venus Global Reference Atmospheric Model Status and Planned Updates

    Science.gov (United States)

    Justh, H. L.; Dwyer Cianciolo, A. M.

    2017-05-01

    Details the current status of Venus Global Reference Atmospheric Model (Venus-GRAM). Provides new sources of data and upgrades that need to be incorporated to maintain credibility and identifies options and features that could increase capability.

  10. Weather Research and Forecasting (WRF) Regional Atmospheric Model: Guam

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Research and Forecasting (WRF) mesoscale numerical weather prediction model 7-day hourly forecast for the region surrounding the island of Guam at...

  11. Weather Research and Forecasting (WRF) Regional Atmospheric Model: Samoa

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Research and Forecasting (WRF) mesoscale numerical weather prediction model 7-day hourly forecast for the region surrounding the islands of Samoa at...

  12. Predicted macroinvertebrate response to water diversion from a montane stream using two-dimensional hydrodynamic models and zero flow approximation

    Science.gov (United States)

    Holmquist, Jeffrey G.; Waddle, Terry J.

    2013-01-01

    We used two-dimensional hydrodynamic models for the assessment of water diversion effects on benthic macroinvertebrates and associated habitat in a montane stream in Yosemite National Park, Sierra Nevada Mountains, CA, USA. We sampled the macroinvertebrate assemblage via Surber sampling, recorded detailed measurements of bed topography and flow, and coupled a two-dimensional hydrodynamic model with macroinvertebrate indicators to assess habitat across a range of low flows in 2010 and representative past years. We also made zero flow approximations to assess response of fauna to extreme conditions. The fauna of this montane reach had a higher percentage of Ephemeroptera, Plecoptera, and Trichoptera (%EPT) than might be expected given the relatively low faunal diversity of the study reach. The modeled responses of wetted area and area-weighted macroinvertebrate metrics to decreasing discharge indicated precipitous declines in metrics as flows approached zero. Changes in area-weighted metrics closely approximated patterns observed for wetted area, i.e., area-weighted invertebrate metrics contributed relatively little additional information above that yielded by wetted area alone. Loss of habitat area in this montane stream appears to be a greater threat than reductions in velocity and depth or changes in substrate, and the modeled patterns observed across years support this conclusion. Our models suggest that step function losses of wetted area may begin when discharge in the Merced falls to 0.02 m3/s; proportionally reducing diversions when this threshold is reached will likely reduce impacts in low flow years.

  13. Atmospheric correction for superconducting gravimeters based on operational weather models

    Science.gov (United States)

    Karbon, M.; Boehm, J.; Meurers, B.; Schuh, H.

    2012-04-01

    Atmospheric pressure fluctuations are a major source of noise in precise gravimetric measurements and must be corrected carefully. This is usually done by using the local air pressure, which reduces up to 90-95 % of the atmospheric signal. However, modern superconducting gravimeters require an even better atmospheric correction if small signals are to be identified. For this task the use of 3-dimensional modeling of atmospheric mass attraction based on operational numerical weather models has shown promising results. Similar strategies are realized and applied successfully for de -aliasing measurements of satellite gravity missions, such as GRACE and GOCE. For example, within the project GGOS Atmosphere at the Institute of Geodesy and Geophysics of TU Vienna a service was established providing atmospheric gravity corrections in form of global spherical harmonic coefficients (AGC). In this study we show that these products, originally dedicated to correct the gravity mission data, can also be used to correct the atmospheric effects on superconducting gravimeters (SG), i.e., the global contribution of the effect is obtained directly from the AGC. Furthermore, it will be examined if the additional effort of implementing high resolution regional models as well as analytical models in the near field is justified. The Conrad Observatory near Vienna is taken as example station for the SG corrections.

  14. Mars Global Reference Atmospheric Model 2010 Version: Users Guide

    Science.gov (United States)

    Justh, H. L.

    2014-01-01

    This Technical Memorandum (TM) presents the Mars Global Reference Atmospheric Model 2010 (Mars-GRAM 2010) and its new features. Mars-GRAM is an engineering-level atmospheric model widely used for diverse mission applications. Applications include systems design, performance analysis, and operations planning for aerobraking, entry, descent and landing, and aerocapture. Additionally, this TM includes instructions on obtaining the Mars-GRAM source code and data files as well as running Mars-GRAM. It also contains sample Mars-GRAM input and output files and an example of how to incorporate Mars-GRAM as an atmospheric subroutine in a trajectory code.

  15. Coastal erosion vulnerability estimations by coupling field data and hydrodynamic modeling

    Science.gov (United States)

    Finikianaki, Vasilia; Alexandrakis, George; Poulos, Serafim; Ghionis, George; Kampanis, Nikolaos

    2017-04-01

    Wind generated waves are a dominant factor of coastal zone evolution as they induce nearshore sediment movement. Significant sediment transport and the associated morphological changes of the coastal zone are related, mainly, to storm events. In this study, the effects of a severe storm event, associated with the Etesian winds, that took place from the 24th to 30th of July at Gouves beach (north coast of Crete) were monitored ([1], [2]) and subsequently simulated, with the use of the Delft3D model, in order to provide necessary data for estimating beach vulnerability. Beach vulnerability to erosion was estimated by the BVI method ([3]), which has the ability to refer to smaller sectors of an individual beach. The interaction between waves and currents, which is required for the computation of the BVI, was obtained by the coupling of two models included in Delft3D: the Delft3D - FLOW, for the hydrodynamic computations and the sediment transport processes; and the Delft3D - WAVE, for the computation of the wave field. Boundary conditions were derived from the field data, assuming a JONSWAP spectrum. Additionally, 3 observation points were used for the monitoring of the computed quantities as a function of time. Their positions coincide with those of the three Valeport Autonomous Benthic Recorders, which were deployed at water depths of 2.60m, 3.95m and 5.62m during the field measurements. The outputs of the simulation fit well with the measured data, leading to accurate forecasted results regarding the morphodynamic conditions of the study area. Bottom changes occur mainly during the first peak of the event. The model slightly overestimates the significant wave height, the current velocity in the nearshore area and the suspended sediment concentration near the bed at the observation points. Furthermore, the model predicts a shoreward increase of sediment concentration at the observation points, with the value of accumulation at the second observation point being

  16. Developing Tighter Constraints on Exoplanet Biosignatures by Modeling Atmospheric Haze

    Science.gov (United States)

    Felton, Ryan; Neveu, Marc; Domagal-Goldman, Shawn David; Desch, Steven; Arney, Giada

    2018-01-01

    As we increase our capacity to resolve the atmospheric composition of exoplanets, we must continue to refine our ability to distinguish true biosignatures from false positives in order to ultimately distinguish a life-bearing from a lifeless planet. Of the possible true and false biosignatures, methane (CH4) and carbon dioxide (CO2) are of interest, because on Earth geological and biological processes can produce them on large scales. To identify a biotic, Earth-like exoplanet, we must understand how these biosignatures shape their atmospheres. High atmospheric abundances of CH4 produce photochemical organic haze, which dramatically alters the photochemistry, climate, and spectrum of a planet. Arney et al. (2017) have suggested that haze-bearing atmospheres rich in CO2 may be a type of biosignature because the CH4 flux required to produce the haze is similar to the amount of biogenic CH4 on modern Earth. Atmospheric CH4 and CO2 both affect haze-formation photochemistry, and the potential for hazes to form in Earth-like atmospheres at abiotic concentrations of these gases has not been well studied. We will explore a wide range of parameter space of abiotic concentration levels of these gases to determine what spectral signatures are possible from abiotic environments and look for measurable differences between abiotic and biotic atmospheres. We use a 1D photochemical model with an upgraded haze production mechanism to compare Archean and modern Earth atmospheres to abiotic versions while varying atmospheric CH4 and CO2 levels and atmospheric pressure. We will vary CO2 from a trace gas to an amount such that it dominates atmospheric chemistry. For CH4, there is uncertainty regarding the amount of abiotic CH4 that comes from serpentinizing systems. To address this uncertainty, we will model three cases: 1) assume all CH4 comes from photochemistry; 2) use estimates of modern-day serpentinizing fluxes, assuming they are purely abiotic; and 3) assume serpentinizing

  17. Parameterizations of Chromospheric Condensations in dG and dMe Model Flare Atmospheres

    Science.gov (United States)

    Kowalski, Adam F.; Allred, Joel C.

    2018-01-01

    The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic (RHD) simulations in 1D have shown that high energy deposition rates from electron beams produce two flaring layers at T ∼ 104 K that develop in the chromosphere: a cooling condensation (downflowing compression) and heated non-moving (stationary) flare layers just below the condensation. These atmospheres reproduce several observed phenomena in flare spectra, such as the red-wing asymmetry of the emission lines in solar flares and a small Balmer jump ratio in M dwarf flares. The high beam flux simulations are computationally expensive in 1D, and the (human) timescales for completing NLTE models with adaptive grids in 3D will likely be unwieldy for some time to come. We have developed a prescription for predicting the approximate evolved states, continuum optical depth, and emergent continuum flux spectra of RHD model flare atmospheres. These approximate prescriptions are based on an important atmospheric parameter: the column mass ({m}{ref}) at which hydrogen becomes nearly completely ionized at the depths that are approximately in steady state with the electron beam heating. Using this new modeling approach, we find that high energy flux density (>F11) electron beams are needed to reproduce the brightest observed continuum intensity in IRIS data of the 2014 March 29 X1 solar flare, and that variation in {m}{ref} from 0.001 to 0.02 g cm‑2 reproduces most of the observed range of the optical continuum flux ratios at the peak of M dwarf flares.

  18. Evaluation protocol for the WIND system atmospheric models

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J.D.

    1991-12-31

    Atmospheric transport and diffusion models have been developed for real-time calculations of the location and concentration of toxic or radioactive materials during a accidental release at the Savannah River Site (SRS). These models are have been incorporated into an automated menu-driven computer based system called the WIND (Weather INformation and Display) system. In an effort to establish more formal quality assurance procedures for the WIND system atmospheric codes, a software evaluation protocol is being developed. An evaluation protocol is necessary to determine how well they may perform in emergency response (real-time) situations. The evaluation of high-impact software must be conducted in accordance with WSRC QA Manual, 1Q, QAP 20-1. This report will describe the method that will be used to evaluate the atmospheric models. The evaluation will determine the effectiveness of the atmospheric models in emergency response situations, which is not necessarily the same procedure used for research purposes. The format of the evaluation plan will provide guidance for the evaluation of atmospheric models that may be added to the WIND system in the future. The evaluation plan is designed to provide the user with information about the WIND system atmospheric models that is necessary for emergency response situations.

  19. Evaluation protocol for the WIND system atmospheric models

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J.D.

    1991-01-01

    Atmospheric transport and diffusion models have been developed for real-time calculations of the location and concentration of toxic or radioactive materials during a accidental release at the Savannah River Site (SRS). These models are have been incorporated into an automated menu-driven computer based system called the WIND (Weather INformation and Display) system. In an effort to establish more formal quality assurance procedures for the WIND system atmospheric codes, a software evaluation protocol is being developed. An evaluation protocol is necessary to determine how well they may perform in emergency response (real-time) situations. The evaluation of high-impact software must be conducted in accordance with WSRC QA Manual, 1Q, QAP 20-1. This report will describe the method that will be used to evaluate the atmospheric models. The evaluation will determine the effectiveness of the atmospheric models in emergency response situations, which is not necessarily the same procedure used for research purposes. The format of the evaluation plan will provide guidance for the evaluation of atmospheric models that may be added to the WIND system in the future. The evaluation plan is designed to provide the user with information about the WIND system atmospheric models that is necessary for emergency response situations.

  20. Studying urban land-atmospheric interactions by coupling an urban canopy model with a single column atmospheric models

    Science.gov (United States)

    Song, J.; Wang, Z.

    2013-12-01

    Studying urban land-atmospheric interactions by coupling an urban canopy model with a single column atmospheric models Jiyun Song and Zhi-Hua Wang School of Sustainable Engineering and the Built Environment, Arizona State University, PO Box 875306, Tempe, AZ 85287-5306 Landuse landcover changes in urban area will modify surface energy budgets, turbulent fluxes as well as dynamic and thermodynamic structures of the overlying atmospheric boundary layer (ABL). In order to study urban land-atmospheric interactions, we coupled a single column atmospheric model (SCM) to a cutting-edge single layer urban canopy model (SLUCM). Modification of surface parameters such as the fraction of vegetation and engineered pavements, thermal properties of building and pavement materials, and geometrical features of street canyon, etc. in SLUCM dictates the evolution of surface balance of energy, water and momentum. The land surface states then provide lower boundary conditions to the overlying atmosphere, which in turn modulates the modification of ABL structure as well as vertical profiles of temperature, humidity, wind speed and tracer gases. The coupled SLUCM-SCM model is tested against field measurements of surface layer fluxes as well as profiles of temperature and humidity in the mixed layer under convective conditions. After model test, SLUCM-SCM is used to simulate the effect of changing urban land surface conditions on the evolution of ABL structure and dynamics. Simulation results show that despite the prescribed atmospheric forcing, land surface states impose significant impact on the physics of the overlying vertical atmospheric layer. Overall, this numerical framework provides a useful standalone modeling tool to assess the impacts of urban land surface conditions on the local hydrometeorology through land-atmospheric interactions. It also has potentially far-reaching implications to urban ecohydrological services for cities under future expansion and climate challenges.

  1. 3D MODEL ATMOSPHERES FOR EXTREMELY LOW-MASS WHITE DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Tremblay, P.-E. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218 (United States); Gianninas, A.; Kilic, M. [Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK, 73019 (United States); Ludwig, H.-G. [Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, D-69117 Heidelberg (Germany); Steffen, M. [Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Freytag, B. [Department of Physics and Astronomy at Uppsala University, Regementsvägen 1, Box 516, SE-75120 Uppsala (Sweden); Hermes, J. J., E-mail: tremblay@stsci.edu [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-08-20

    We present an extended grid of mean three-dimensional (3D) spectra for low-mass, pure-hydrogen atmosphere DA white dwarfs (WDs). We use CO5BOLD radiation-hydrodynamics 3D simulations covering T{sub eff} = 6000–11,500 K and log g = 5–6.5 (g in cm s{sup −2}) to derive analytical functions to convert spectroscopically determined 1D temperatures and surface gravities to 3D atmospheric parameters. Along with the previously published 3D models, the 1D to 3D corrections are now available for essentially all known convective DA WDs (i.e., log g = 5–9). For low-mass WDs, the correction in temperature is relatively small (a few percent at the most), but the surface gravities measured from the 3D models are lower by as much as 0.35 dex. We revisit the spectroscopic analysis of the extremely low-mass (ELM) WDs, and demonstrate that the 3D models largely resolve the discrepancies seen in the radius and mass measurements for relatively cool ELM WDs in eclipsing double WD and WD + millisecond pulsar binary systems. We also use the 3D corrections to revise the boundaries of the ZZ Ceti instability strip, including the recently found ELM pulsators.

  2. PCBs in the Arctic atmosphere: determining important driving forces using a global atmospheric transport model

    Directory of Open Access Journals (Sweden)

    C. L. Friedman

    2016-03-01

    Full Text Available We present a spatially and temporally resolved global atmospheric polychlorinated biphenyl (PCB model, driven by meteorological data, that is skilled at simulating mean atmospheric PCB concentrations and seasonal cycles in the Northern Hemisphere midlatitudes and mean Arctic concentrations. However, the model does not capture the observed Arctic summer maximum in atmospheric PCBs. We use the model to estimate global budgets for seven PCB congeners, and we demonstrate that congeners that deposit more readily show lower potential for long-range transport, consistent with a recently described "differential removal hypothesis" regarding the hemispheric transport of PCBs. Using sensitivity simulations to assess processes within, outside, or transport to the Arctic, we examine the influence of climate- and emissions-driven processes on Arctic concentrations and their effect on improving the simulated Arctic seasonal cycle. We find evidence that processes occurring outside the Arctic have a greater influence on Arctic atmospheric PCB levels than processes that occur within the Arctic. Our simulations suggest that re-emissions from sea ice melting or from the Arctic Ocean during summer would have to be unrealistically high in order to capture observed temporal trends of PCBs in the Arctic atmosphere. We conclude that midlatitude processes are likely to have a greater effect on the Arctic under global change scenarios than re-emissions within the Arctic.

  3. Quantum hydrodynamic model for the enhanced moments of inertia of molecules in helium nanodroplets: Application to SF6

    Science.gov (United States)

    Lehmann, Kevin K.; Callegari, Carlo

    2002-07-01

    The increase in moment of inertia, DeltaI, of SF6 in helium nanodroplets is calculated using the quantum hydrodynamic approach [Callegari [et al.], Phys. Rev. Lett. 83, 5058 (1999); 84, 1848 (2000)], which we extend here to an explicit three-dimensional treatment. Three plausible helium densities are reconstructed by interpolation of previously published "density cuts" in terms of an expansion into cubic harmonics (several interpolation strategies are presented). This allows us to predict a value of DeltaI that ranges from as low as 30 u[middle dot]A2 to as high as 318 u[middle dot]A2. The lower limit reproduces the prediction of Kwon [et al.] [J. Chem. Phys. 113, 6469 (2000)], who use the same hydrodynamic model and an unpublished density based upon a Path Integral Monte Carlo calculation. These values can be compared with the experimentally measured DeltaI (310plus-or-minus10 u[middle dot]A2) for large (N[greater-than-or-equal, slanted]103 He atoms), and with Fixed Node, Diffusion Monte Carlo calculations by Lee, Farrelly, and Whaley [Phys. Rev. Lett. 83, 3812 (1999)], which found DeltaI=290-305 u[middle dot]A2 for N=8-20 helium atoms. The present results show that the value of DeltaI obtained from the hydrodynamic model is quite sensitive to physically reasonable variations in the helium density; therefore one has to be careful as to which density to use. Because the model is based upon the assumption that the helium is in the ground "quasienergy" state of the helium-molecule time-dependent potential, we propose that calculations should be done using densities calculated at 0 K rather than at finite temperature. We have extended our original algorithm to also handle irregular boundaries. We find that in the present case the calculated value of DeltaI only changes by a few percent.

  4. A global atmospheric model of meteoric iron

    National Research Council Canada - National Science Library

    Feng, Wuhu; Marsh, Daniel R; Chipperfield, Martyn P; Janches, Diego; Höffner, Josef; Yi, Fan; Plane, John M. C

    2013-01-01

    .... The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD...

  5. Modeling Plant-Atmosphere Interactions and Ramifications on the Surface Energy Balance in Arctic Ecosystems

    Science.gov (United States)

    Linn, R.; Cunningham, P.; Wilson, C. J.

    2011-12-01

    There is broad recognition that the melting of the permafrost in arctic landscapes could have pronounced global climatological impacts. The evolution of the permafrost and its impacts on the carbon and water balances is directly related to balances in the surface energy budget. There are a number of factors that are expected to impact the net heat flux at the surface of the soil including regional atmospheric conditions. However, ultimately this surface energy balance is controlled by local processes including evaporation from the surface, transpiration from vegetation as well as radiative and convective heat transfer. These four processes are directly impacted by coupling between the vegetation and atmosphere, and thus depend heavily upon the horizontal and vertical vegetation structure. If shrubs replace grasses in the arctic ecosystem there will be net shifts in the heat transfer to the ground. For example, the solar radiation that is absorbed by shrubs is separated from the soil by a stem space through which winds blow. In order for the energy to reach the soil it must warm the air and then warm the soil, however some of the warm air is mixed into the atmosphere and diffused. This structural feature can act in a fashion similar to a closed canopy forest, which frequently have cooler temperatures below the canopy than nearby grasslands An atmospheric hydrodynamics model, HIGRAD, has been enhanced to simulate complex, three-dimensional plant-atmosphere interactions at extremely high resolution (~0.1 m in all three directions). The model represents the transport of momentum, heat, moisture, and CO2 and their exchange between the vegetation and surrounding air. HIGRAD was used to simulate coupled atmosphere/vegetation systems representative of heterogeneous shrub and tussock grass surrounding a thermokarst. In these simulations shrubs, uneven grasses, and a thermokarst depression are explicitly resolved, and atmospheric conditions are similar to those of summer

  6. Air-Sea Exchange of Legacy POPs in the North Sea Based on Results of Fate and Transport, and Shelf-Sea Hydrodynamic Ocean Models

    Directory of Open Access Journals (Sweden)

    Kieran O'Driscoll

    2014-04-01

    Full Text Available The air-sea exchange of two legacy persistent organic pollutants (POPs, γ-HCH and PCB 153, in the North Sea, is presented and discussed using results of regional fate and transport and shelf-sea hydrodynamic ocean models for the period 1996–2005. Air-sea exchange occurs through gas exchange (deposition and volatilization, wet deposition and dry deposition. Atmospheric concentrations are interpolated into the model domain from results of the EMEP MSC-East multi-compartmental model (Gusev et al, 2009. The North Sea is net depositional for γ-HCH, and is dominated by gas deposition with notable seasonal variability and a downward trend over the 10 year period. Volatilization rates of γ-HCH are generally a factor of 2–3 less than gas deposition in winter, spring and summer but greater in autumn when the North Sea is net volatilizational. A downward trend in fugacity ratios is found, since gas deposition is decreasing faster than volatilization. The North Sea is net volatilizational for PCB 153, with highest rates of volatilization to deposition found in the areas surrounding polluted British and continental river sources. Large quantities of PCB 153 entering through rivers lead to very high local rates of volatilization.

  7. Prediction of hydrodynamic and other solution properties of rigid proteins from atomic- and residue-level models.

    Science.gov (United States)

    Ortega, A; Amorós, D; García de la Torre, J

    2011-08-17

    Here we extend the ability to predict hydrodynamic coefficients and other solution properties of rigid macromolecular structures from atomic-level structures, implemented in the computer program HYDROPRO, to models with lower, residue-level resolution. Whereas in the former case there is one bead per nonhydrogen atom, the latter contains one bead per amino acid (or nucleotide) residue, thus allowing calculations when atomic resolution is not available or coarse-grained models are preferred. We parameterized the effective hydrodynamic radius of the elements in the atomic- and residue-level models using a very large set of experimental data for translational and rotational coefficients (intrinsic viscosity and radius of gyration) for >50 proteins. We also extended the calculations to very large proteins and macromolecular complexes, such as the whole 70S ribosome. We show that with proper parameterization, the two levels of resolution yield similar and rather good agreement with experimental data. The new version of HYDROPRO, in addition to considering various computational and modeling schemes, is far more efficient computationally and can be handled with the use of a graphical interface. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. Modeling of Hydrodynamic Processes at a Large Leak of Water into Sodium in the Fast Reactor Coolant Circuit

    OpenAIRE

    Perevoznikov, Sergey; Shvetsov, Yuriy; Kamayev, Aleksey; Pakhomov, Ilia; Borisov, Viacheslav; Pazin, Gennadiy; Mirzeabasov, Oleg; Korzun, Olga

    2016-01-01

    In this paper, we describe a physicomathematical model of the processes that occur in a sodium circuit with a variable flow cross-section in the case of a water leak into sodium. The application area for this technique includes the possibility of analyzing consequences of this leak as applied to sodium–water steam generators in fast neutron reactors. Hydrodynamic processes that occur in sodium circuits in the event of a water leak are described within the framework of a one-dimensional therma...

  9. Hydrodynamic, Atomic Kinetic, and Monte Carlo Radiation Transfer Models of the X-ray Spectra of Compact Binaries

    Energy Technology Data Exchange (ETDEWEB)

    Mauche, C W; Liedahl, D A; Akiyama, S; Plewa, T

    2008-02-08

    We describe the results of an effort, funded by the Lawrence Livermore National Laboratory Directed Research and Development Program, to model, using FLASH time-dependent adaptive-mesh hydrodynamic simulations, XSTAR photoionization calculations, HULLAC atomic data, and Monte Carlo radiation transport, the radiatively-driven photoionized wind and accretion flow of high-mass X-ray binaries (HMXBs). In this final report, we describe the purpose, approach, and technical accomplishments of this effort, including maps of the density, temperature, velocity, ionization parameter, and emissivity distributions of the X-ray emission lines of the well-studied HMXB Vela X-1.

  10. Smart Voyage Planning Model Sensitivity Analysis Using Ocean and Atmospheric Models Including Ensemble Methods

    Science.gov (United States)

    2012-09-01

    exceeding wind and sea limits specified by competent authority. STARS utilizes a Dijkstra exhaustive search algorithm for minimum cost as follows... Navigation Toolkit CONOPS Concept of Operations COTS Commercial Off-the-Shelf DBDB-V Digital Bathymetric Data Base Variable Resolution DCAP...platform hydrodynamic models and environmental forecasts combined with improved algorithms enable fuel savings in addition to aiding in heavy weather

  11. Nanoflow hydrodynamics

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Dyre, Jeppe C.; Daivis, Peter J.

    2011-01-01

    We show by nonequilibrium molecular dynamics simulations that the Navier-Stokes equation does not correctly describe water flow in a nanoscale geometry. It is argued that this failure reflects the fact that the coupling between the intrinsic rotational and translational degrees of freedom becomes...... important for nanoflows. The coupling is correctly accounted for by the extended Navier-Stokes equations that include the intrinsic angular momentum as an independent hydrodynamic degree of freedom. © 2011 American Physical Society....

  12. Atmospheric Dispersion Model Validation in Low Wind Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patrick

    2007-11-01

    Atmospheric plume dispersion models are used for a variety of purposes including emergency planning and response to hazardous material releases, determining force protection actions in the event of a Weapons of Mass Destruction (WMD) attack and for locating sources of pollution. This study provides a review of previous studies that examine the accuracy of atmospheric plume dispersion models for chemical releases. It considers the principles used to derive air dispersion plume models and looks at three specific models currently in use: Aerial Location of Hazardous Atmospheres (ALOHA), Emergency Prediction Information Code (EPIcode) and Second Order Closure Integrated Puff (SCIPUFF). Results from this study indicate over-prediction bias by the EPIcode and SCIPUFF models and under-prediction bias by the ALOHA model. The experiment parameters were for near field dispersion (less than 100 meters) in low wind speed conditions (less than 2 meters per second).

  13. Southeast Atmosphere Studies: learning from model-observation syntheses

    Directory of Open Access Journals (Sweden)

    J. Mao

    2018-02-01

    Full Text Available Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and

  14. Measuring the basic parameters of neutron stars using model atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Suleimanov, V.F. [Universitaet Tuebingen, Institut fuer Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Kazan Federal University, Kazan (Russian Federation); Poutanen, J. [University of Turku, Tuorla Observatory, Department of Physics and Astronomy, Piikkioe (Finland); KTH Royal Institute of Technology and Stockholm University, Nordita, Stockholm (Sweden); Klochkov, D.; Werner, K. [Universitaet Tuebingen, Institut fuer Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany)

    2016-02-15

    Model spectra of neutron star atmospheres are nowadays widely used to fit the observed thermal X-ray spectra of neutron stars. This fitting is the key element in the method of the neutron star radius determination. Here, we present the basic assumptions used for the neutron star atmosphere modeling as well as the main qualitative features of the stellar atmospheres leading to the deviations of the emergent model spectrum from blackbody. We describe the properties of two of our model atmosphere grids: i) pure carbon atmospheres for relatively cool neutron stars (1-4MK) and ii) hot atmospheres with Compton scattering taken into account. The results obtained by applying these grids to model the X-ray spectra of the central compact object in supernova remnant HESS 1731-347, and two X-ray bursting neutron stars in low-mass X-ray binaries, 4U 1724-307 and 4U 1608-52, are presented. Possible systematic uncertainties associated with the obtained neutron star radii are discussed. (orig.)

  15. Uncertainty quantification in hydrodynamics bidimensional models : the case of Gironde estuary forecast model

    Science.gov (United States)

    Laborie, Vanessya; Goutal, Nicole; Ricci, Sophie; Sergent, Philippe

    2017-04-01

    In the context of the development and the implementation of data assimilation techniques in Gironde estuary for flood forecasting, a Telemac 2D model is used to calculate water depths and velocity fields at each node of an unstructured mesh. Upstream, the model boundaries are respectively La Réole and Pessac on the Garonne and Dordogne river. The maritime boundary is 32 km off the mouth of Gironde estuary, located in Verdon. This model, which contains 7351 nodes and 12838 finite elements, does not take into account overflows. It has been calibrated on 4 non-overflowing events and then validated on 6 overflowing events. In a first step, a mesh convergence study was carried out in order to evaluate the error related to the spatial discretization and to determine the mesh allowing to obtain results "independent" of it. Three additional meshes obtained by dividing the number of finite elements at each refinement by 4 were realized and used to simulate the event of 2003. It appears that a mesh of intermediate size (approximately 27000 nodes) seems required. In a second step, propagation and quantification of uncertainties by an unidirectional analysis method (creation of a set of 2000 members perturbed for each parameter and input forcings and analysis of output water depths) was carried out on the numerical parameters (wind influence coefficient, Strickler friction coefficients for 4 zones) and forcings of the model (rivers discharges and maritime boundary conditions, meteorological forcings). The objective is to determine the variation coefficient (if possible standardized by the input variation coefficient) of water depths for 13 major events between 1981 and 2016. The exploitation of 1981 event results shows a predominance of the influence of the maritime boundary conditions and the Strickler coefficient corresponding to the zone studied for the estuarine part and the confluence, to which must be added the Garonne discharge as a predominant parameter for the latter

  16. Information Flow in an Atmospheric Model and Data Assimilation

    Science.gov (United States)

    Yoon, Young-noh

    2011-01-01

    Weather forecasting consists of two processes, model integration and analysis (data assimilation). During the model integration, the state estimate produced by the analysis evolves to the next cycle time according to the atmospheric model to become the background estimate. The analysis then produces a new state estimate by combining the background…

  17. Applying a mesoscale atmospheric model to Svalbard glaciers

    NARCIS (Netherlands)

    Claremar, B.; Obleitner, F.; Reijmer, C.H.|info:eu-repo/dai/nl/229345956; Pohjola, V.; Waxegard, A.; Karner, F.; Rutgersson, A.

    2012-01-01

    The mesoscale atmospheric model WRF is used over three Svalbard glaciers. The simulations are done with a setup of the model corresponding to the state-of-the-art model for polar conditions, Polar WRF, and it was validated using surface observations. The ERA-Interim reanalysis was used for boundary

  18. Some results regarding the comparison of the Earth's atmospheric models

    Directory of Open Access Journals (Sweden)

    Šegan S.

    2005-01-01

    Full Text Available In this paper we examine air densities derived from our realization of aeronomic atmosphere models based on accelerometer measurements from satellites in a low Earth's orbit (LEO. Using the adapted algorithms we derive comparison parameters. The first results concerning the adjustment of the aeronomic models to the total-density model are given.

  19. IInvestigations of space-time variability of the sea level in the Barents Sea and the White Sea by satellite altimetry data and results of hydrodynamic modelling

    Science.gov (United States)

    Lebedev, S. A.; Zilberstein, O. I.; Popov, S. K.; Tikhonova, O. V.

    2003-04-01

    The problem of retrieving of the sea level anomalies in the Barents and White Seas from satellite can be considered as two different problems. The first one is to calculate the anomalies of sea level along the trek taking into account all amendments including tidal heights. The second one is to obtain of fields of the sea level anomalies on the grid over one cycle of the exact repeat altimetry mission. Experience results show that there is preferable to use the regional tidal model for calculating tidal heights. To construct of the anomalies fields of the sea level during the exact repeat mission (cycle 35 days for ERS-1 and ERS-2), when a density of the coverage of the area of water of the Barents and White Seas by satellite measurements achieves maximum. It is necessary to solve the problem of the error minimum. This error is based by the temporal difference of the measurements over one cycle and by the specific of the hydrodynamic regime of the both seas (tidal, storm surge variations, tidal currents). To solve this problem it is assumed to use the results of the hydrodynamic modeling. The error minimum is preformed by the regression of the model results and satellite measurements. As a version it is considered the possibility of the utilizing of the neuronet obtained by the model results to construct maps of the sea level anomalies. The comparison of the model results and the calculation of the satellite altimetry variability of the sea level of Barents and White Seas shows a good coincidence between them. The satellite altimetry data of ERS-1/2 and TOPEX/POSEIDON of Ocean Altimeter Pathfinder Project (NASA/GSFC) has been used in this study. Results of the regional tidal model computations and three dimensional baroclinic model created in the Hydrometeocenter have been used as well. This study also exploited the atmosphere date of the Project REANALYSIS. The research was undertaken with partial support from the Russian Basic Research Foundation (Project No. 01-07-90106).

  20. Impact of hydrodynamic injection and phiC31 integrase on tumor latency in a mouse model of MYC-induced hepatocellular carcinoma.

    Directory of Open Access Journals (Sweden)

    Lauren E Woodard

    2010-06-01

    Full Text Available Hydrodynamic injection is an effective method for DNA delivery in mouse liver and is being translated to larger animals for possible clinical use. Similarly, phiC31 integrase has proven effective in mediating long-term gene therapy in mice when delivered by hydrodynamic injection and is being considered for clinical gene therapy applications. However, chromosomal aberrations have been associated with phiC31 integrase expression in tissue culture, leading to questions about safety.To study whether hydrodynamic delivery alone, or in conjunction with delivery of phiC31 integrase for long-term transgene expression, could facilitate tumor formation, we used a transgenic mouse model in which sustained induction of the human C-MYC oncogene in the liver was followed by hydrodynamic injection. Without injection, mice had a median tumor latency of 154 days. With hydrodynamic injection of saline alone, the median tumor latency was significantly reduced, to 105 days. The median tumor latency was similar, 106 days, when a luciferase donor plasmid and backbone plasmid without integrase were administered. In contrast, when active or inactive phiC31 integrase and donor plasmid were supplied to the mouse liver, the median tumor latency was 153 days, similar to mice receiving no injection.Our data suggest that phiC31 integrase does not facilitate tumor formation in this C-MYC transgenic mouse model. However, in groups lacking phiC31 integrase, hydrodynamic injection appeared to contribute to C-MYC-induced hepatocellular carcinoma in adult mice. Although it remains to be seen to what extent these findings may be extrapolated to catheter-mediated hydrodynamic delivery in larger species, they suggest that caution should be used during translation of hydrodynamic injection to clinical applications.

  1. AirSWOT observations versus hydrodynamic model outputs of water surface elevation and slope in a multichannel river

    Science.gov (United States)

    Altenau, Elizabeth H.; Pavelsky, Tamlin M.; Moller, Delwyn; Lion, Christine; Pitcher, Lincoln H.; Allen, George H.; Bates, Paul D.; Calmant, Stéphane; Durand, Michael; Neal, Jeffrey C.; Smith, Laurence C.

    2017-04-01

    Anabranching rivers make up a large proportion of the world's major rivers, but quantifying their flow dynamics is challenging due to their complex morphologies. Traditional in situ measurements of water levels collected at gauge stations cannot capture out of bank flows and are limited to defined cross sections, which presents an incomplete picture of water fluctuations in multichannel systems. Similarly, current remotely sensed measurements of water surface elevations (WSEs) and slopes are constrained by resolutions and accuracies that limit the visibility of surface waters at global scales. Here, we present new measurements of river WSE and slope along the Tanana River, AK, acquired from AirSWOT, an airborne analogue to the Surface Water and Ocean Topography (SWOT) mission. Additionally, we compare the AirSWOT observations to hydrodynamic model outputs of WSE and slope simulated across the same study area. Results indicate AirSWOT errors are significantly lower than model outputs. When compared to field measurements, RMSE for AirSWOT measurements of WSEs is 9.0 cm when averaged over 1 km squared areas and 1.0 cm/km for slopes along 10 km reaches. Also, AirSWOT can accurately reproduce the spatial variations in slope critical for characterizing reach-scale hydraulics, while model outputs of spatial variations in slope are very poor. Combining AirSWOT and future SWOT measurements with hydrodynamic models can result in major improvements in model simulations at local to global scales. Scientists can use AirSWOT measurements to constrain model parameters over long reach distances, improve understanding of the physical processes controlling the spatial distribution of model parameters, and validate models' abilities to reproduce spatial variations in slope. Additionally, AirSWOT and SWOT measurements can be assimilated into lower-complexity models to try and approach the accuracies achieved by higher-complexity models.

  2. South African seasonal rainfall prediction performance by a coupled ocean-atmosphere model

    CSIR Research Space (South Africa)

    Landman, WA

    2010-12-01

    Full Text Available Evidence is presented that coupled ocean-atmosphere models can already outscore computationally less expensive atmospheric models. However, if the atmospheric models are forced with highly skillful SST predictions, they may still be a very strong...

  3. AMORE: Atmospheric Modeling Of Radiation Experiment

    Science.gov (United States)

    Slusser, J.; Harrison, L.; Gao, W.

    2001-12-01

    The purpose of this talk is to present a comparison of modeled and measured clear-sky erythemal UV irradiances. Are the various models in reasonable agreement with the various measurements? Measurements were made with the USDA Reference Spectroradiometer, New Zealand's NIWA Spectroradiometer, a USEPA Brewer, and a Yankee UV-RSS. Modeling groups were given a list of clear days between June 5 and August 5, 2001. The average measured morning and afternoon aerosol optical depths at 368 nm and 332 nm were measured with a UV-MFRSR. The estimated wavelength independent aerosol asymmetry parameter and single scattering albedo, surface pressure and albedo, total column ozone, extraterrestrial solar spectrum, erythemal weighting function were supplied. Modeling groups submitted erythemally weight irradiances for every half hour. Comparisons of measurements to models showed good ageement to within 10% for SZAs out to 60 degrees. Reasons for discrepancies will be discussed.

  4. Modeling the nanoscale viscoelasticity of fluids by bridging non-Markovian fluctuating hydrodynamics and molecular dynamics simulations.

    Science.gov (United States)

    Voulgarakis, Nikolaos K; Satish, Siddarth; Chu, Jhih-Wei

    2009-12-21

    A multiscale computational method is developed to model the nanoscale viscoelasticity of fluids by bridging non-Markovian fluctuating hydrodynamics (FHD) and molecular dynamics (MD) simulations. To capture the elastic responses that emerge at small length scales, we attach an additional rheological model parallel to the macroscopic constitutive equation of a fluid. The widely used linear Maxwell model is employed as a working choice; other models can be used as well. For a fluid that is Newtonian in the macroscopic limit, this approach results in a parallel Newtonian-Maxwell model. For water, argon, and an ionic liquid, the power spectrum of momentum field autocorrelation functions of the parallel Newtonian-Maxwell model agrees very well with those calculated from all-atom MD simulations. To incorporate thermal fluctuations, we generalize the equations of FHD to work with non-Markovian rheological models and colored noise. The fluctuating stress tensor (white noise) is integrated in time in the same manner as its dissipative counterpart and numerical simulations indicate that this approach accurately preserves the set temperature in a FHD simulation. By mapping position and velocity vectors in the molecular representation onto field variables, we bridge the non-Markovian FHD with atomistic MD simulations. Through this mapping, we quantitatively determine the transport coefficients of the parallel Newtonian-Maxwell model for water and argon from all-atom MD simulations. For both fluids, a significant enhancement in elastic responses is observed as the wave number of hydrodynamic modes is reduced to a few nanometers. The mapping from particle to field representations and the perturbative strategy of developing constitutive equations provide a useful framework for modeling the nanoscale viscoelasticity of fluids.

  5. The physical theory and propagation model of THz atmospheric propagation

    Science.gov (United States)

    Wang, R.; Yao, J. Q.; Xu, D. G.; Wang, J. L.; Wang, P.

    2011-02-01

    Terahertz (THz) radiation is extensively applied in diverse fields, such as space communication, Earth environment observation, atmosphere science, remote sensing and so on. And the research on propagation features of THz wave in the atmosphere becomes more and more important. This paper firstly illuminates the advantages and outlook of THz in space technology. Then it introduces the theoretical framework of THz atmospheric propagation, including some fundamental physical concepts and processes. The attenuation effect (especially the absorption of water vapor), the scattering of aerosol particles and the effect of turbulent flow mainly influence THz atmosphere propagation. Fundamental physical laws are illuminated as well, such as Lamber-beer law, Mie scattering theory and radiative transfer equation. The last part comprises the demonstration and comparison of THz atmosphere propagation models like Moliere(V5), SARTre and AMATERASU. The essential problems are the deep analysis of physical mechanism of this process, the construction of atmospheric propagation model and databases of every kind of material in the atmosphere, and the standardization of measurement procedures.

  6. Modeling of Hydrodynamic Processes at a Large Leak of Water into Sodium in the Fast Reactor Coolant Circuit

    Directory of Open Access Journals (Sweden)

    Sergey Perevoznikov

    2016-10-01

    Full Text Available In this paper, we describe a physicomathematical model of the processes that occur in a sodium circuit with a variable flow cross-section in the case of a water leak into sodium. The application area for this technique includes the possibility of analyzing consequences of this leak as applied to sodium–water steam generators in fast neutron reactors. Hydrodynamic processes that occur in sodium circuits in the event of a water leak are described within the framework of a one-dimensional thermally nonequilibrium three-component gas–liquid flow model (sodium–hydrogen–sodium hydroxide. Consideration is given to the results of a mathematical modeling of experiments involving steam injection into the sodium loop of a circulation test facility. That was done by means of the computer code in which the proposed model had been implemented.

  7. An Analytic Radiative-Convective Model for Planetary Atmospheres

    Science.gov (United States)

    Robinson, T. D.; Catling, D. C.

    2012-12-01

    A fundamental aspect of planetary atmospheres is the vertical thermal structure. Simple one-dimensional (vertical) models can provide reasonable estimates of a planet's global-mean temperature profile while providing insights into the physics behind the thermal profile of an atmosphere. The best basic models are those that incorporate the minimum amount of complexity while still remaining general enough to provide intuitive understanding. Here, we present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres [1]. We assume that thermal radiative transfer is gray, and we include two shortwave channels for absorbed solar (or stellar) light so that the model can compute realistic stratospheric temperature inversions. A convective profile is placed at the base of the portion of the atmosphere that is in radiative equilibrium, and the model ensures that both the temperature profile and the upwelling flux profile are continuous across the radiation-convection boundary. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce analytic expressions that allow calculations of the atmospheric pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. The utility, validity, and generality of our model are demonstrated by applying it to a disparate range of worlds, including Jupiter, Venus, and Titan. Our model can be used to explain general observed phenomena in the Solar System [2], and we explore the behaviors of variants of our model, showing its ability to provide clear insights. Given the wealth of new problems posed by exoplanets, development of an analytic model with few parameters is likely to be useful for future application to such worlds, for which only limited data will be known. Our model can be used to help interpret

  8. Atmospheric Turbulence Modeling for Aero Vehicles: Fractional Order Fits

    Science.gov (United States)

    Kopasakis, George

    2015-01-01

    Atmospheric turbulence models are necessary for the design of both inlet/engine and flight controls, as well as for studying coupling between the propulsion and the vehicle structural dynamics for supersonic vehicles. Models based on the Kolmogorov spectrum have been previously utilized to model atmospheric turbulence. In this paper, a more accurate model is developed in its representative fractional order form, typical of atmospheric disturbances. This is accomplished by first scaling the Kolmogorov spectral to convert them into finite energy von Karman forms and then by deriving an explicit fractional circuit-filter type analog for this model. This circuit model is utilized to develop a generalized formulation in frequency domain to approximate the fractional order with the products of first order transfer functions, which enables accurate time domain simulations. The objective of this work is as follows. Given the parameters describing the conditions of atmospheric disturbances, and utilizing the derived formulations, directly compute the transfer function poles and zeros describing these disturbances for acoustic velocity, temperature, pressure, and density. Time domain simulations of representative atmospheric turbulence can then be developed by utilizing these computed transfer functions together with the disturbance frequencies of interest.

  9. Atmospheric Turbulence Modeling for Aerospace Vehicles: Fractional Order Fit

    Science.gov (United States)

    Kopasakis, George (Inventor)

    2015-01-01

    An improved model for simulating atmospheric disturbances is disclosed. A scale Kolmogorov spectral may be scaled to convert the Kolmogorov spectral into a finite energy von Karman spectral and a fractional order pole-zero transfer function (TF) may be derived from the von Karman spectral. Fractional order atmospheric turbulence may be approximated with an integer order pole-zero TF fit, and the approximation may be stored in memory.

  10. Modeling Hydrodynamics and Heat Transport in Upper Klamath Lake, Oregon, and Implications for Water Quality

    Science.gov (United States)

    Wood, Tamara M.; Cheng, Ralph T.; Gartner, Jeffrey W.; Hoilman, Gene R.; Lindenberg, Mary K.; Wellman, Roy E.

    2008-01-01

    The three-dimensional numerical model UnTRIM was used to model hydrodynamics and heat transport in Upper Klamath Lake, Oregon, between mid-June and mid-September in 2005 and between mid-May and mid-October in 2006. Data from as many as six meteorological stations were used to generate a spatially interpolated wind field to use as a forcing function. Solar radiation, air temperature, and relative humidity data all were available at one or more sites. In general, because the available data for all inflows and outflows did not adequately close the water budget as calculated from lake elevation and stage-capacity information, a residual inflow or outflow was used to assure closure of the water budget. Data used for calibration in 2005 included lake elevation at 3 water-level gages around the lake, water currents at 5 Acoustic Doppler Current Profiler (ADCP) sites, and temperature at 16 water-quality monitoring locations. The calibrated model accurately simulated the fluctuations of the surface of the lake caused by daily wind patterns. The use of a spatially variable surface wind interpolated from two sites on the lake and four sites on the shoreline generally resulted in more accurate simulation of the currents than the use of a spatially invariant surface wind as observed at only one site on the lake. The simulation of currents was most accurate at the deepest site (ADCP1, where the velocities were highest) using a spatially variable surface wind; the mean error (ME) and root mean square error (RMSE) for the depth-averaged speed over a 37-day simulation from July 26 to August 31, 2005, were 0.50 centimeter per second (cm/s) and 3.08 cm/s, respectively. Simulated currents at the remaining sites were less accurate and, in general, underestimated the measured currents. The maximum errors in simulated currents were at a site near the southern end of the trench at the mouth of Howard Bay (ADCP7), where the ME and RMSE in the depth-averaged speed were 3.02 and 4.38 cm

  11. A model derived from hydrodynamic simulations for extracting the size of spherical particles from the quartz crystal microbalance.

    Science.gov (United States)

    Gillissen, Jurriaan J J; Tabaei, Seyed R; Jackman, Joshua A; Cho, Nam-Joon

    2017-09-08

    One challenging aspect of quartz crystal microbalance (QCM) measurements is the characterization of adsorbed particles as the change in resonance frequency (Δf) is proportional not only to the inertia of the adsorbed layer but also to that of the hydrodynamically coupled fluid. Herein, by solving numerically the Navier-Stokes equations, we scrutinize Δf for sparsely deposited, rigid spherical particles that are firmly attached to an oscillating surface. The analysis is shown to be applicable to adsorbed, small unilamellar vesicles (SUVs) of controlled size under experimental conditions in which adhesion-induced vesicle deformation is negligible. The model supports a hydrodynamic explanation for the overtone dependence of Δf, and was fitted to experimental data concerning three monodisperse populations of SUVs with different average sizes ranging between 56 and 114 nm diameter. Using this procedure, we determined the average size of adsorbed vesicles to be within 16% of the size that was measured by dynamic light scattering experiments in bulk solution. In conclusion, this model offers a means to extract the particle size from QCM-D measurement data, with applications to biological and synthetic nanoparticles.

  12. Modelling the influence of spatially varying hydrodynamics on the cross-sectional stability of double inlet systems, doi: 10.1007/s10236-013-0657-6

    NARCIS (Netherlands)

    Brouwer, R.L.; Schuttelaars, H.M.; Roos, Pieter C.

    2013-01-01

    The cross-sectional stability of double inlet systems is investigated using an exploratory model that combines Escoffier’s stability concept for the evolution of the inlet’s cross-sectional area with a two-dimensional, depth-averaged (2DH) hydrodynamic model for tidal flow. The model geometry

  13. Internal atmospheric noise characteristics in twentieth century coupled atmosphere-ocean model simulations

    Science.gov (United States)

    Colfescu, Ioana; Schneider, Edwin K.

    2017-09-01

    The statistical characteristics of the atmospheric internal variability (hereafter internal atmospheric noise) for surface pressure (PS) in twentieth century simulations of a coupled general circulation model are documented. The atmospheric noise is determined from daily post-industrial (1871-1998) Community Climate System Model 3 simulations by removing the SST and externally forced responses from the total fields. The forced responses are found from atmosphere-only simulations forced by the SST and external forcing of the coupled runs. However, we do not address the influence of the SST variability on the synoptic scale high frequency weather noise.The spatial patterns of the main seasonal modes of atmospheric noise variability are found for boreal winter and summer from empirical orthogonal function analyses performed globally and for various regions, including the North Atlantic, the North Pacific, and the equatorial Pacific. The temporal characteristics of the modes are illustrated by power spectra and probability density functions (PDF) of the principal components (PC). Our findings show that, for two different realizations of noise, the variability is dominated by large scale spatial structures of the atmospheric noise that resemble observed patterns, and that their relative amplitudes in the CGCM and AGCM simulations are very similar. The regional expression of the dominant global mode, a seasonally dependent AO-like or AAO-like pattern is also found in the regional analyses, with similar time dependence. The PCs in the CGCM and the corresponding SST forced AGCM simulations are uncorrelated, but the spectra and PDFs of the CGCM and AGCM PCs are similar.The temporal structures of the noise PCs are white at timescales larger than few months, so that these modes can be thought of as stochastic forcings (in time) for the climate system. The PDFs of the noise PCs are not statistically distinguishable from Gaussian distributions with the same standard deviation

  14. Proposed ozone reference models for the middle atmosphere

    Science.gov (United States)

    Keating, G. M.; Young, D. F.

    1985-01-01

    Since the publication of the last COSPAR International Reference Atmosphere (CIRA 72), large amounts of ozone data acquired from satellites have become available in addition to increasing quantities of rocketsonde, balloonsonde, Dobson, M83, and Umkehr measurements. From the available archived satellite data, models are developed for the new CIRA using 5 satellite experiments (Nimbus 7 SBUV and LIMS, AEM-2 SAGE, and SME IR and UVS) of the monthly latitudinal and altitudinal variations in the ozone mixing ratio in the middle atmosphere. Standard deviations and interannual variations are also quantified. The satellite models are shown to agree well with a previous reference model based on rocket and balloon measurements.

  15. Uncertainty modelling of atmospheric dispersion by stochastic ...

    Indian Academy of Sciences (India)

    The parameters associated to a environmental dispersion model may include different kinds of variability, imprecision and uncertainty. More often, it is seen that available information is interpreted in probabilistic sense. Probability theory is a well-established theory to measure such kind of variability. However, not all ...

  16. A hydrodynamical model for the Fermi-LAT γ-ray light curve of blazar PKS 1510-089

    Directory of Open Access Journals (Sweden)

    Cabrera J.I.

    2013-12-01

    Full Text Available A physical description of the formation and propagation of working surfaces inside the relativistic jet of the blazar PKS 1510-089 are used to model its γ -ray variability light curve using Fermi-LAT data from 2008 to 2012. The physical model is based on conservation laws of mass and momentum at the working surface as explained by Mendoza et al. (2009. The hydrodynamical description of a working surface is parametrized by the initial velocity and mass injection rate at the base of the jet. We show that periodic variations on the injected velocity profiles are able to account for the observed luminosity, fixing model parameters such as mass ejection rates of the central engine injected at the base of the jet, oscillation frequencies of the flow and maximum Lorentz factors of the bulk flow during a particular burst.

  17. Coupled Atmospheric Chemistry Schemes for Modeling Regional and Global Atmospheric Chemistry

    Science.gov (United States)

    Saunders, E.; Stockwell, W. R.

    2016-12-01

    Atmospheric chemistry models require chemical reaction mechanisms to simulate the production of air pollution. GACM (Global Atmospheric Chemistry Mechanism) is intended for use in global scale atmospheric chemistry models to provide chemical boundary conditions for regional scale simulations by models such as CMAQ. GACM includes additional chemistry for marine environments while reducing its treatment of the chemistry needed for highly polluted urban regions. This keeps GACM's size small enough to allow it to be used efficiently in global models. GACM's chemistry of volatile organic compounds (VOC) is highly compatible with the VOC chemistry in RACM2 allowing a global model with GACM to provide VOC boundary conditions to a regional scale model with RACM2 with reduced error. The GACM-RACM2 system of mechanisms should yield more accurate forecasts by regional air quality models such as CMAQ. Chemical box models coupled with the regional and global atmospheric chemistry mechanisms (RACM2 & GACM) will be used to make simulations of tropospheric ozone, nitric oxides, and volatile organic compounds that are produced in regional and global domains. The simulations will focus on the Los Angeles' South Coast Air Basin (SoCAB) where the Pacific Ocean meets a highly polluted urban area. These two mechanisms will be compared on the basis of simulated ozone concentrations over this marine-urban region. Simulations made with the more established RACM2 will be compared with simulations made with the newer GACM. In addition WRF-Chem will be used to simulate how RACM2 will produce regional simulations of tropospheric ozone and NOx, which can be further, analyzed for air quality impacts. Both the regional and global model in WRF-Chem will be used to predict how the concentrations of ozone and nitrogen oxides change over land and ocean. The air quality model simulation results will be applied to EPA's BenMAP-CE (Environmental Benefits Mapping & Analysis Program-Community Edition

  18. Thermosphere Extension of the Whole Atmosphere Community Climate Model

    Science.gov (United States)

    2010-12-04

    for Atmospheric Research is sponsored by the National Science Foundation. [40] Robert Lysak thanks the reviewers for their assistance in evaluating...F. Muller, L. K. Emmons , and M. A. Carroll (1998), MOZART: A global chemical transport model for ozone and related chemical tracers: 2. Model results

  19. Atmospheric modelling for seasonal prediction at the CSIR

    CSIR Research Space (South Africa)

    Landman, WA

    2014-10-01

    Full Text Available by observed monthly sea-surface temperature (SST) and sea-ice fields. The AGCM is the conformal-cubic atmospheric model (CCAM) administered by the Council for Scientific and Industrial Research. Since the model is forced with observed rather than predicted...

  20. Challenges in Modeling of the Global Atmosphere

    Science.gov (United States)

    Janjic, Zavisa; Djurdjevic, Vladimir; Vasic, Ratko; Black, Tom

    2015-04-01

    The massively parallel computer architectures require that some widely adopted modeling paradigms be reconsidered in order to utilize more productively the power of parallel processing. For high computational efficiency with distributed memory, each core should work on a small subdomain of the full integration domain, and exchange only few rows of halo data with the neighbouring cores. However, the described scenario implies that the discretization used in the model is horizontally local. The spherical geometry further complicates the problem. Various grid topologies will be discussed and examples will be shown. The latitude-longitude grid with local in space and explicit in time differencing has been an early choice and remained in use ever since. The problem with this method is that the grid size in the longitudinal direction tends to zero as the poles are approached. So, in addition to having unnecessarily high resolution near the poles, polar filtering has to be applied in order to use a time step of decent size. However, the polar filtering requires transpositions involving extra communications. The spectral transform method and the semi-implicit semi-Lagrangian schemes opened the way for a wide application of the spectral representation. With some variations, these techniques are used in most major centers. However, the horizontal non-locality is inherent to the spectral representation and implicit time differencing, which inhibits scaling on a large number of cores. In this respect the lat-lon grid with a fast Fourier transform represents a significant step in the right direction, particularly at high resolutions where the Legendre transforms become increasingly expensive. Other grids with reduced variability of grid distances such as various versions of the cubed sphere and the hexagonal/pentagonal ("soccer ball") grids were proposed almost fifty years ago. However, on these grids, large-scale (wavenumber 4 and 5) fictitious solutions ("grid imprinting

  1. Tree level hydrodynamic approach for resolving aboveground water storage and stomatal conductance and modeling the effects of tree hydraulic strategy

    Science.gov (United States)

    Mirfenderesgi, Golnazalsadat; Bohrer, Gil; Matheny, Ashley M.; Fatichi, Simone; de Moraes Frasson, Renato Prata; Schäfer, Karina V. R.

    2016-07-01

    The finite difference ecosystem-scale tree crown hydrodynamics model version 2 (FETCH2) is a tree-scale hydrodynamic model of transpiration. The FETCH2 model employs a finite difference numerical methodology and a simplified single-beam conduit system to explicitly resolve xylem water potentials throughout the vertical extent of a tree. Empirical equations relate water potential within the stem to stomatal conductance of the leaves at each height throughout the crown. While highly simplified, this approach brings additional realism to the simulation of transpiration by linking stomatal responses to stem water potential rather than directly to soil moisture, as is currently the case in the majority of land surface models. FETCH2 accounts for plant hydraulic traits, such as the degree of anisohydric/isohydric response of stomata, maximal xylem conductivity, vertical distribution of leaf area, and maximal and minimal xylem water content. We used FETCH2 along with sap flow and eddy covariance data sets collected from a mixed plot of two genera (oak/pine) in Silas Little Experimental Forest, NJ, USA, to conduct an analysis of the intergeneric variation of hydraulic strategies and their effects on diurnal and seasonal transpiration dynamics. We define these strategies through the parameters that describe the genus level transpiration and xylem conductivity responses to changes in stem water potential. Our evaluation revealed that FETCH2 considerably improved the simulation of ecosystem transpiration and latent heat flux in comparison to more conventional models. A virtual experiment showed that the model was able to capture the effect of hydraulic strategies such as isohydric/anisohydric behavior on stomatal conductance under different soil-water availability conditions.

  2. Tree-Level Hydrodynamic Approach for Modeling Aboveground Water Storage and Stomatal Conductance Highlights the Effects of Tree Hydraulic Strategy

    Science.gov (United States)

    Mirfenderesgi, G.; Bohrer, G.; Matheny, A. M.; Fatichi, S.; Frasson, R. P. M.; Schafer, K. V.

    2016-12-01

    The Finite-difference Ecosystem-scale Tree-Crown Hydrodynamics model version 2 (FETCH2) is a novel tree-scale hydrodynamic model of transpiration. The FETCH2 model employs a finite difference numerical methodology and a simplified single-beam conduit system and simulates water flow through the tree as a continuum of porous media conduits. It explicitly resolves xylem water potential throughout the tree's vertical extent. Empirical equations relate water potential within the stem to stomatal conductance of the leaves at each height throughout the crown. While highly simplified, this approach brings additional realism to the simulation of transpiration by linking stomatal responses to stem water potential rather than directly to soil moisture, as is currently the case in the majority of land-surface models. FETCH2 accounts for plant hydraulic traits, such as the degree of anisohydric/isohydric response of stomata, maximal xylem conductivity, vertical distribution of leaf area, and maximal and minimal stemwater content. We used FETCH2 along with sap flow and eddy covariance data sets collected from a mixed plot of two genera (oak/pine) in Silas Little Experimental Forest, NJ, USA, to conduct an analysis of the inter-genera variation of hydraulic strategies and their effects on diurnal and seasonal transpiration dynamics. We define these strategies through the parameters that describe the genus-level transpiration and xylem conductivity responses to changes in stem water potential. A virtual experiment showed that the model was able to capture the effect of hydraulic strategies such as isohydric/anisohydric behavior on stomatal conductance under different soil-water availability conditions. Our evaluation revealed that FETCH2 considerably improved the simulation of ecosystem transpiration and latent heat flux than more conventional models.

  3. Dissecting the regulation of pollen tube growth by modelling the interplay of hydrodynamics, cell wall and ion dynamics

    Directory of Open Access Journals (Sweden)

    Junli eLiu

    2014-08-01

    Full Text Available Hydrodynamics, cell wall and ion dynamics are all important properties that regulate pollen tube growth. Currently, the two main pollen tube growth models, the cell wall model and the hydrodynamic model do not appear to be reconcilable. Here we develop an integrative model for pollen tube growth and show that our model reproduces key experimental observations: 1 that the hypertonic condition leads to a much longer oscillatory period and that the hypotonic condition halves the oscillatory period; 2 that oscillations in turgor are experimentally undetectable; 3 that increasing the extracellular calcium concentration or decreasing the pH decreases the growth oscillatory amplitude; 4 that knockout of Raba4d, a member of the Rab family of small GTPase proteins, decreases pollen tube length after germination for 24 hours. Using the model generated here, we reveal that 1 when cell wall extensibility is large, pollen tube may sustain growth at different volume changes and maintain relatively stable turgor; 2 turgor increases if cell wall extensibility decreases; 3 increasing turgor due to decrease in osmolarity in the media, although very small, increases volume change . However, increasing turgor due to decrease in cell wall extensibility decreases volume change. In this way regulation of pollen tube growth by turgor is context dependent. By changing the osmolarity in the media, the main regulatory points are extracellular osmolarity for water flow and turgor for the volume encompassed by the cell wall. However, if the viscosity of cell wall changes, the main regulatory points are turgor for water flow and wall extensibility for the volume encompassed by the cell wall. The novel methodology developed here reveals the underlying context-dependent regulatory principle of pollen tube growth.

  4. Upper Atmosphere Neutral and Plasma Density Modeling

    Science.gov (United States)

    1993-03-31

    Semidiurnal density amplitude vs. height and latitude at 429N. 15 Figure 2. Percent density variation vs. height and local time over the equator during...March. 16 Figure 3. Semidiurnal (top) and diurnal (bottom) density variations as a function of height near the equator , for the 1979 Kwajalein...M.W., Klobuchar , J.A. and Doherty, P.H. Evaluation of six iono- spheric models as predictors of total electron content, Radio Science, 26, p. 1007, 1991

  5. Box models for the evolution of atmospheric oxygen: an update

    Science.gov (United States)

    Kasting, J. F.

    1991-01-01

    A simple 3-box model of the atmosphere/ocean system is used to describe the various stages in the evolution of atmospheric oxygen. In Stage I, which probably lasted until redbeds began to form about 2.0 Ga ago, the Earth's surface environment was generally devoid of free O2, except possibly in localized regions of high productivity in the surface ocean. In Stage II, which may have lasted for less than 150 Ma, the atmosphere and surface ocean were oxidizing, while the deep ocean remained anoxic. In Stage III, which commenced with the disappearance of banded iron formations around 1.85 Ga ago and has lasted until the present, all three surface reservoirs contained appreciable amounts of free O2. Recent and not-so-recent controversies regarding the abundance of oxygen in the Archean atmosphere are identified and discussed. The rate of O2 increase during the Middle and Late Proterozoic is identified as another outstanding question.

  6. GEOS Atmospheric Model: Challenges at Exascale

    Science.gov (United States)

    Putman, William M.; Suarez, Max J.

    2017-01-01

    The Goddard Earth Observing System (GEOS) model at NASA's Global Modeling and Assimilation Office (GMAO) is used to simulate the multi-scale variability of the Earth's weather and climate, and is used primarily to assimilate conventional and satellite-based observations for weather forecasting and reanalysis. In addition, assimilations coupled to an ocean model are used for longer-term forecasting (e.g., El Nino) on seasonal to interannual times-scales. The GMAO's research activities, including system development, focus on numerous time and space scales, as detailed on the GMAO website, where they are tabbed under five major themes: Weather Analysis and Prediction; Seasonal-Decadal Analysis and Prediction; Reanalysis; Global Mesoscale Modeling, and Observing System Science. A brief description of the GEOS systems can also be found at the GMAO website. GEOS executes as a collection of earth system components connected through the Earth System Modeling Framework (ESMF). The ESMF layer is supplemented with the MAPL (Modeling, Analysis, and Prediction Layer) software toolkit developed at the GMAO, which facilitates the organization of the computational components into a hierarchical architecture. GEOS systems run in parallel using a horizontal decomposition of the Earth's sphere into processing elements (PEs). Communication between PEs is primarily through a message passing framework, using the message passing interface (MPI), and through explicit use of node-level shared memory access via the SHMEM (Symmetric Hierarchical Memory access) protocol. Production GEOS weather prediction systems currently run at 12.5-kilometer horizontal resolution with 72 vertical levels decomposed into PEs associated with 5,400 MPI processes. Research GEOS systems run at resolutions as fine as 1.5 kilometers globally using as many as 30,000 MPI processes. Looking forward, these systems can be expected to see a 2 times increase in horizontal resolution every two to three years, as well as

  7. Mars Entry Atmospheric Data System Modeling, Calibration, and Error Analysis

    Science.gov (United States)

    Karlgaard, Christopher D.; VanNorman, John; Siemers, Paul M.; Schoenenberger, Mark; Munk, Michelle M.

    2014-01-01

    The Mars Science Laboratory (MSL) Entry, Descent, and Landing Instrumentation (MEDLI)/Mars Entry Atmospheric Data System (MEADS) project installed seven pressure ports through the MSL Phenolic Impregnated Carbon Ablator (PICA) heatshield to measure heatshield surface pressures during entry. These measured surface pressures are used to generate estimates of atmospheric quantities based on modeled surface pressure distributions. In particular, the quantities to be estimated from the MEADS pressure measurements include the dynamic pressure, angle of attack, and angle of sideslip. This report describes the calibration of the pressure transducers utilized to reconstruct the atmospheric data and associated uncertainty models, pressure modeling and uncertainty analysis, and system performance results. The results indicate that the MEADS pressure measurement system hardware meets the project requirements.

  8. Hydrodynamic model of cells for designing systems of urban groundwater drainage

    Science.gov (United States)

    Zimmermann, Eric; Riccardi, Gerardo

    2000-08-01

    An improved mathematical hydrodynamic quasi-two-dimensional model of cells, CELSUB3, is presented for simulating drainage systems that consist of pumping well fields or subsurface drains. The CELSUB3 model is composed of an assemblage of algorithms that have been developed and tested previously and that simulate saturated flow in porous media, closed conduit flow, and flow through pumping stations. A new type of link between aquifer cells and drainage conduits is proposed. This link is verified in simple problems with well known analytical solutions. The correlation between results from analytical and mathematical solutions was considered satisfactory in all cases. To simulate more complex situations, the new proposed version, CELSUB3, was applied in a project designed to control the water-table level within a sewer system in Chañar Ladeado Town, Santa Fe Province, Argentina. Alternative drainage designs, which were evaluated under conditions of dynamic recharge caused by rainfall in a critical year (wettest year for the period of record) and a typical year, are briefly described. After analyzing ten alternative designs, the best technical-economic solution is a subsurface drainage system of closed conduits with pumping stations and evacuation channels. Résumé. Un modèle hydrodynamique perfectionné de cellules en quasi 2D, CELSUB3, est présenté dans le but de simuler des systèmes de drainage qui consistent en des champs de puits de pompage ou de drains souterrains. Le modèle CELSUB3 est composé d'un assemblage d'algorithmes développés et testés précédemment et qui simulent des écoulements en milieu poreux saturé, en conduites et dans des stations de pompage. Un nouveau type de lien entre des cellules d'aquifères et des drains est proposé. Ce lien est vérifié dans des problèmes simples dont les solutions analytiques sont bien connues. La corrélation entre les résultats des solutions analytiques et des solutions mathématiques a été consid

  9. Modeling and experimental validation of hydrodynamics in an ultrasonic batch reactor.

    Science.gov (United States)

    Ajmal, M; Rusli, S; Fieg, G

    2016-01-01

    Simulation of hydrodynamics in ultrasonic batch reactor containing immobilized enzymes as catalyst is done. A transducer with variable power and constant frequency (24 kHz) is taken as source of ultrasound (US). Simulation comprises two steps. In first step, acoustic pressure field is simulated and in second step effect of this field on particle trajectories is simulated. Simulation results are compared with experimentally determined particle trajectories using PIV Lab (particle image velocimetry). Effect of varying ultrasonic power, positioning and number of ultrasonic sources on particle trajectories is studied. It is observed that catalyst particles tend to orientate according to pattern of acoustic pressure field. An increase in ultrasonic power increases particle velocity and also brings more particles into motion. Simulation results are found to be in agreement with experimentally determined data. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. The Development of New Atmospheric Models for K and M DwarfStars with Exoplanets

    Science.gov (United States)

    Linsky, Jeffrey L.

    2018-01-01

    The ultraviolet and X-ray emissions of host stars play critical roles in the survival and chemical composition of the atmospheres of their exoplanets. The need to measure and understand this radiative output, in particular for K and M dwarfs, is the main rationale for computing a new generation of stellar models that includes magnetically heated chromospheres and coronae in addition to their photospheres. We describe our method for computing semi-empirical models that includes solutions of the statistical equilibrium equations for 52 atoms and ions and of the non-LTE radiative transfer equations for all important spectral lines. The code is an offspring of the Solar Radiation Physical Modelling system (SRPM) developed by Fontenla et al. (2007--2015) to compute one-dimensional models in hydrostatic equilibrium to fit high-resolution stellar X-ray to IR spectra. Also included are 20 diatomic molecules and their more than 2 million spectral lines. Our-proof-of-concept model is for the M1.5 V star GJ 832 (Fontenla et al. ApJ 830, 154 (2016)). We will fit the line fluxes and profiles of X-ray lines and continua observed by Chandra and XMM-Newton, UV lines observed by the COS and STIS instruments on HST (N V, C IV, Si IV, Si III, Mg II, C II, and O I), optical lines (including H$\\alpha$, Ca II, Na I), and continua. These models will allow us to compute extreme-UV spectra, which are unobservable but required to predict the hydrodynamic mass-loss rate from exoplanet atmospheres, and to predict panchromatic spectra of new exoplanet host stars discovered after the end of the HST mission.This work is supported by grant HST-GO-15038 from the Space Telescope Science Institute to the Univ. of Colorado

  11. Towards a Global Unified Model of Europa's Tenuous Atmosphere

    Science.gov (United States)

    Plainaki, Christina; Cassidy, Tim A.; Shematovich, Valery I.; Milillo, Anna; Wurz, Peter; Vorburger, Audrey; Roth, Lorenz; Galli, André; Rubin, Martin; Blöcker, Aljona; Brandt, Pontus C.; Crary, Frank; Dandouras, Iannis; Jia, Xianzhe; Grassi, Davide; Hartogh, Paul; Lucchetti, Alice; McGrath, Melissa; Mangano, Valeria; Mura, Alessandro; Orsini, Stefano; Paranicas, Chris; Radioti, Aikaterini; Retherford, Kurt D.; Saur, Joachim; Teolis, Ben

    2018-02-01

    Despite the numerous modeling efforts of the past, our knowledge on the radiation-induced physical and chemical processes in Europa's tenuous atmosphere and on the exchange of material between the moon's surface and Jupiter's magnetosphere remains limited. In lack of an adequate number of in situ observations, the existence of a wide variety of models based on different scenarios and considerations has resulted in a fragmentary understanding of the interactions of the magnetospheric ion population with both the moon's icy surface and neutral gas envelope. Models show large discrepancy in the source and loss rates of the different constituents as well as in the determination of the spatial distribution of the atmosphere and its variation with time. The existence of several models based on very different approaches highlights the need of a detailed comparison among them with the final goal of developing a unified model of Europa's tenuous atmosphere. The availability to the science community of such a model could be of particular interest in view of the planning of the future mission observations (e.g., ESA's JUpiter ICy moons Explorer (JUICE) mission, and NASA's Europa Clipper mission). We review the existing models of Europa's tenuous atmosphere and discuss each of their derived characteristics of the neutral environment. We also discuss discrepancies among different models and the assumptions of the plasma environment in the vicinity of Europa. A summary of the existing observations of both the neutral and the plasma environments at Europa is also presented. The characteristics of a global unified model of the tenuous atmosphere are, then, discussed. Finally, we identify needed future experimental work in laboratories and propose some suitable observation strategies for upcoming missions.

  12. Quasi 2D hydrodynamic modelling of the flooded hinterland due to dyke breaching on the Elbe River

    Directory of Open Access Journals (Sweden)

    S. Huang

    2007-01-01

    Full Text Available In flood modeling, many 1D and 2D combination and 2D models are used to simulate diversion of water from rivers through dyke breaches into the hinterland for extreme flood events. However, these models are too demanding in data requirements and computational resources which is an important consideration when uncertainty analysis using Monte Carlo techniques is used to complement the modeling exercise. The goal of this paper is to show the development of a quasi-2D modeling approach, which still calculates the dynamic wave in 1D but the discretisation of the computational units are in 2D, allowing a better spatial representation of the flow in the hinterland due to dyke breaching without a large additional expenditure on data pre-processing and computational time. A 2D representation of the flow and velocity fields is required to model sediment and micro-pollutant transport. The model DYNHYD (1D hydrodynamics from the WASP5 modeling package was used as a basis for the simulations. The model was extended to incorporate the quasi-2D approach and a Monte-Carlo Analysis was used to conduct a flood sensitivity analysis to determine the sensitivity of parameters and boundary conditions to the resulting water flow. An extreme flood event on the Elbe River, Germany, with a possible dyke breach area was used as a test case. The results show a good similarity with those obtained from another 1D/2D modeling study.

  13. Recent progress in the development of the general circulation and climate model of the martian atmosphere MART-ACC

    Science.gov (United States)

    Meister, C.-V.; Hartogh, P.; Sonnemann, G.; Berger, U.; Feofilov, A.; Kutepov, A.; Elbern, H.

    The seasonal dependence of the Martian general circulation and climate is studied within a fully non-linear, global and three-dimensional hydrodynamic Eulerian gridpoint model which extends from the surface of the planet to the lower thermosphere. Therefore the dust-free pure carbon dioxide model MART-ACC which was presented by Meister et al. on the EGS-AGU-EUG Assembly in Nice 2003 was essentially improved. Especially, the parametrizations for the solar and infrared radiation transport are further developed. The seasonal and diurnal dependences of the atmospheric LTE heating rates obtained by the general circulation and climate model are also compared with rates based on the nadir temperature profiles published in the Mars Global Surveyor Data Archives distributed by the NASA Planetary Data System (http://emma.la.asu.edu/data_archives). Besides, the influence of the surface albedo on the atmospheric heating is studied. Further non-LTE corrections of the heating rates at larger atmospheric altitudes are estimated and compared with results of other working groups. Basing on the calculations of the heating rates and taking into account influences of diffusion by gravity waves and molecular collisions, the temperature profiles and wind velocities of the atmosphere are obtained. Finally, first attempts to describe chemical processes are shown.

  14. Modeling Atmospheric Emission for CMB Ground-based Observations

    Science.gov (United States)

    Errard, J.; Ade, P. A. R.; Akiba, Y.; Arnold, K.; Atlas, M.; Baccigalupi, C.; Barron, D.; Boettger, D.; Borrill, J.; Chapman, S.; Chinone, Y.; Cukierman, A.; Delabrouille, J.; Dobbs, M.; Ducout, A.; Elleflot, T.; Fabbian, G.; Feng, C.; Feeney, S.; Gilbert, A.; Goeckner-Wald, N.; Halverson, N. W.; Hasegawa, M.; Hattori, K.; Hazumi, M.; Hill, C.; Holzapfel, W. L.; Hori, Y.; Inoue, Y.; Jaehnig, G. C.; Jaffe, A. H.; Jeong, O.; Katayama, N.; Kaufman, J.; Keating, B.; Kermish, Z.; Keskitalo, R.; Kisner, T.; Le Jeune, M.; Lee, A. T.; Leitch, E. M.; Leon, D.; Linder, E.; Matsuda, F.; Matsumura, T.; Miller, N. J.; Myers, M. J.; Navaroli, M.; Nishino, H.; Okamura, T.; Paar, H.; Peloton, J.; Poletti, D.; Puglisi, G.; Rebeiz, G.; Reichardt, C. L.; Richards, P. L.; Ross, C.; Rotermund, K. M.; Schenck, D. E.; Sherwin, B. D.; Siritanasak, P.; Smecher, G.; Stebor, N.; Steinbach, B.; Stompor, R.; Suzuki, A.; Tajima, O.; Takakura, S.; Tikhomirov, A.; Tomaru, T.; Whitehorn, N.; Wilson, B.; Yadav, A.; Zahn, O.

    2015-08-01

    Atmosphere is one of the most important noise sources for ground-based cosmic microwave background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3D-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive a new analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using an original numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the polarbear-i project first season data set. We derive a new 1.0% upper limit on the linear polarization fraction of atmospheric emission. We also compare our results to previous studies and weather station measurements. The proposed model can be used for realistic simulations of future ground-based CMB observations.

  15. Applying Atmospheric Measurements to Constrain Parameters of Terrestrial Source Models

    Science.gov (United States)

    Hyer, E. J.; Kasischke, E. S.; Allen, D. J.

    2004-12-01

    Quantitative inversions of atmospheric measurements have been widely applied to constrain atmospheric budgets of a range of trace gases. Experiments of this type have revealed persistent discrepancies between 'bottom-up' and 'top-down' estimates of source magnitudes. The most common atmospheric inversion uses the absolute magnitude as the sole parameter for each source, and returns the optimal value of that parameter. In order for atmospheric measurements to be useful for improving 'bottom-up' models of terrestrial sources, information about other properties of the sources must be extracted. As the density and quality of atmospheric trace gas measurements improve, examination of higher-order properties of trace gas sources should become possible. Our model of boreal forest fire emissions is parameterized to permit flexible examination of the key uncertainties in this source. Using output from this model together with the UM CTM, we examined the sensitivity of CO concentration measurements made by the MOPITT instrument to various uncertainties in the boreal source: geographic distribution of burned area, fire type (crown fires vs. surface fires), and fuel consumption in above-ground and ground-layer fuels. Our results indicate that carefully designed inversion experiments have the potential to help constrain not only the absolute magnitudes of terrestrial sources, but also the key uncertainties associated with 'bottom-up' estimates of those sources.

  16. Validation of coupled atmosphere-fire behavior models

    Energy Technology Data Exchange (ETDEWEB)

    Bossert, J.E.; Reisner, J.M.; Linn, R.R.; Winterkamp, J.L. [Los Alamos National Lab., NM (United States); Schaub, R. [Dynamac Corp., Kennedy Space Center, FL (United States); Riggan, P.J. [Forest Service, Riverside, CA (United States)

    1998-12-31

    Recent advances in numerical modeling and computer power have made it feasible to simulate the dynamical interaction and feedback between the heat and turbulence induced by wildfires and the local atmospheric wind and temperature fields. At Los Alamos National Laboratory, the authors have developed a modeling system that includes this interaction by coupling a high resolution atmospheric dynamics model, HIGRAD, with a fire behavior model, BEHAVE, to predict the spread of wildfires. The HIGRAD/BEHAVE model is run at very high resolution to properly resolve the fire/atmosphere interaction. At present, these coupled wildfire model simulations are computationally intensive. The additional complexity of these models require sophisticated methods for assuring their reliability in real world applications. With this in mind, a substantial part of the research effort is directed at model validation. Several instrumented prescribed fires have been conducted with multi-agency support and participation from chaparral, marsh, and scrub environments in coastal areas of Florida and inland California. In this paper, the authors first describe the data required to initialize the components of the wildfire modeling system. Then they present results from one of the Florida fires, and discuss a strategy for further testing and improvement of coupled weather/wildfire models.

  17. Model Atmospheres and Transit Spectra for Hot Rocky Planets

    Science.gov (United States)

    Lupu, Roxana

    We propose to build a versatile set of self-consistent atmospheric models for hot rocky exoplanets and use them to predict their transit and eclipse spectra. Hot rocky exoplanets will form the majority of small planets in close-in orbits to be discovered by the TESS and Kepler K2 missions, and offer the best opportunity for characterization with current and future instruments. We will use fully non-grey radiative-convective atmospheric structure codes with cloud formation and vertical mixing, combined with a self-consistent treatment of gas chemistry above the magma ocean. Being in equilibrium with the surface, the vaporized rock material can be a good tracer of the bulk composition of the planet. We will derive the atmospheric structure and escape rates considering both volatile-free and volatile bearing compositions, which reflect the diversity of hot rocky planet atmospheres. Our models will inform follow- up observations with JWST and ground-based instruments, aid the interpretation of transit and eclipse spectra, and provide a better understanding of volatile loss in these atmospheres. Such results will help refine our picture of rocky planet formation and evolution. Planets in ultra-short period (USP) orbits are a special class of hot rocky exoplanets. As shown by Kepler, these planets are generally smaller than 2 Earth radii, suggesting that they are likely to be rocky and could have lost their volatiles through photo-evaporation. Being close to their host stars, these planets are ultra-hot, with estimated temperatures of 1000-3000 K. A number of USP planets have been already discovered (e.g. Kepler-78 b, CoRoT-7 b, Kepler-10 b), and this number is expected to grow by confirming additional planet candidates. The characterization of planets on ultra-short orbits is advantageous due to the larger number of observable transits, and the larger transit signal in the case of an evaporating atmosphere. Much advance has been made in understanding and characterizing

  18. Fractional Order Modeling of Atmospheric Turbulence - A More Accurate Modeling Methodology for Aero Vehicles

    Science.gov (United States)

    Kopasakis, George

    2014-01-01

    The presentation covers a recently developed methodology to model atmospheric turbulence as disturbances for aero vehicle gust loads and for controls development like flutter and inlet shock position. The approach models atmospheric turbulence in their natural fractional order form, which provides for more accuracy compared to traditional methods like the Dryden model, especially for high speed vehicle. The presentation provides a historical background on atmospheric turbulence modeling and the approaches utilized for air vehicles. This is followed by the motivation and the methodology utilized to develop the atmospheric turbulence fractional order modeling approach. Some examples covering the application of this method are also provided, followed by concluding remarks.

  19. CFD approach to modelling, hydrodynamic analysis and motion characteristics of a laboratory underwater glider with experimental results

    Directory of Open Access Journals (Sweden)

    Yogang Singh

    2017-06-01

    Full Text Available Underwater gliders are buoyancy propelled vehicle which make use of buoyancy for vertical movement and wings to propel the glider in forward direction. Autonomous underwater gliders are a patented technology and are manufactured and marketed by corporations. In this study, we validate the experimental lift and drag characteristics of a glider from the literature using Computational fluid dynamics (CFD approach. This approach is then used for the assessment of the steady state characteristics of a laboratory glider designed at Indian Institute of Technology (IIT Madras. Flow behaviour and lift and drag force distribution at different angles of attack are studied for Reynolds numbers varying from 105 to 106 for NACA0012 wing configurations. The state variables of the glider are the velocity, gliding angle and angle of attack which are simulated by making use of the hydrodynamic drag and lift coefficients obtained from CFD. The effect of the variable buoyancy is examined in terms of the gliding angle, velocity and angle of attack. Laboratory model of glider is developed from the final design asserted by CFD. This model is used for determination of static and dynamic properties of an underwater glider which were validated against an equivalent CAD model and simulation results obtained from equations of motion of glider in vertical plane respectively. In the literature, only empirical approach has been adopted to estimate the hydrodynamic coefficients of the AUG that are required for its trajectory simulation. In this work, a CFD approach has been proposed to estimate the hydrodynamic coefficients and validated with experimental data. A two-mass variable buoyancy engine has been designed and implemented. The equations of motion for this two-mass engine have been obtained by modifying the single mass version of the equations described in the literature. The objectives of the present study are to understand the glider dynamics adopting a CFD approach

  20. Atmospheric dispersion modeling: Challenges of the Fukushima Daiichi response

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Gayle [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pobanz, Brenda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Foster, Kevin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vogt, Phil [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Aluzzi, Fernando [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homann, Steve [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-05-01

    In this research, the U.S. Department of Energy’s (DOE) National Atmospheric Release Advisory Center (NARAC) provided a wide range of predictions and analyses as part of the response to the Fukushima Daiichi Nuclear Power Plant accident including: daily Japanese weather forecasts and atmospheric transport predictions to inform planning for field monitoring operations and to provide U.S. government agencies with ongoing situational awareness of meteorological conditions; estimates of possible dose in Japan based on hypothetical U.S. Nuclear Regulatory Commission scenarios of potential radionuclide releases to support protective action planning for U.S. citizens; predictions of possible plume arrival times and dose levels at U.S. locations; and source estimation and plume model refinement based on atmospheric dispersion modeling and available monitoring data.

  1. A Coupled Atmosphere-Ocean-Wave Modeling System

    Science.gov (United States)

    Allard, R. A.; Smith, T.; Rogers, W. E.; Jensen, T. G.; Chu, P.; Campbell, T. J.

    2012-12-01

    A growing interest in the impacts that large and small scale ocean and atmospheric events (El Niño, hurricanes, etc.) have on weather forecasting has led to the coupling of atmospheric, ocean circulation and ocean wave models. The Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS™ ) consists of the Navy's atmospheric model coupled to the Navy Coastal Ocean Model (NCOM) and the wave models SWAN (Simulating WAves Nearshore) and WAVEWATCH III (WW3™). In a fully coupled mode, COAMPS, NCOM, and SWAN (or WW3) may be integrated concurrently so that currents and water levels, wave-induced stress, bottom drag, Stokes drift current, precipitation, and surface fluxes of heat, moisture, and momentum are exchanged across the air-wave-sea interface. This coupling is facilitated through the Earth System Modeling Framework (ESMF). The ESMF version of COAMPS is being transitioned to operational production centers at the Naval Oceanographic Office and the Fleet Numerical Meteorology and Oceanography Center. Highlights from validation studies for the Florida Straits, Hurricane Ivan and the Adriatic Sea will be presented. COAMPS® is a registered trademark of the Naval Research Laboratory.

  2. Systematic evaluation of atmospheric chemistry-transport model CHIMERE

    Science.gov (United States)

    Khvorostyanov, Dmitry; Menut, Laurent; Mailler, Sylvain; Siour, Guillaume; Couvidat, Florian; Bessagnet, Bertrand; Turquety, Solene

    2017-04-01

    Regional-scale atmospheric chemistry-transport models (CTM) are used to develop air quality regulatory measures, to support environmentally sensitive decisions in the industry, and to address variety of scientific questions involving the atmospheric composition. Model performance evaluation with measurement data is critical to understand their limits and the degree of confidence in model results. CHIMERE CTM (http://www.lmd.polytechnique.fr/chimere/) is a French national tool for operational forecast and decision support and is widely used in the international research community in various areas of atmospheric chemistry and physics, climate, and environment (http://www.lmd.polytechnique.fr/chimere/CW-articles.php). This work presents the model evaluation framework applied systematically to the new CHIMERE CTM versions in the course of the continuous model development. The framework uses three of the four CTM evaluation types identified by the Environmental Protection Agency (EPA) and the American Meteorological Society (AMS): operational, diagnostic, and dynamic. It allows to compare the overall model performance in subsequent model versions (operational evaluation), identify specific processes and/or model inputs that could be improved (diagnostic evaluation), and test the model sensitivity to the changes in air quality, such as emission reductions and meteorological events (dynamic evaluation). The observation datasets currently used for the evaluation are: EMEP (surface concentrations), AERONET (optical depths), and WOUDC (ozone sounding profiles). The framework is implemented as an automated processing chain and allows interactive exploration of the results via a web interface.

  3. Restoration of Haemoglobin Level Using Hydrodynamic Gene Therapy with Erythropoietin Does Not Alleviate the Disease Progression in an Anaemic Mouse Model for TGFβ1-Induced Chronic Kidney Disease

    DEFF Research Database (Denmark)

    Pedersen, Lea Hougaard; Wogensen, Lise; Marcussen, N.

    2015-01-01

    expressed in non-haematopoietic tissue and today, Epo is recognised as a cytokine with many pleiotropic effects. We hypothesize that hydrodynamic gene therapy with Epo can restore haemoglobin levels in anaemic transgenic mice and that this will attenuate the extracellular matrix accumulation in the kidneys....... The experiment is conducted by hydrodynamic gene transfer of a plasmid encoding murine Epo in a transgenic mouse model that overexpresses TGF-β1 locally in the kidneys. This model develops anaemia due to chronic kidney disease characterised by thickening of the glomerular basement membrane, deposition...... of mesangial matrix and mild interstitial fibrosis. A group of age matched wildtype littermates are treated accordingly. After a single hydrodynamic administration of plasmid DNA containing murine EPO gene, sustained high haemoglobin levels are observed in both transgenic and wildtype mice from 7.5 ± 0.6 mmol...

  4. Hydrodynamics, temperature/salinity variability and residence time in the Chilika lagoon during dry and wet period: Measurement and modeling

    Science.gov (United States)

    Mahanty, M. M.; Mohanty, P. K.; Pattnaik, A. K.; Panda, U. S.; Pradhan, S.; Samal, R. N.

    2016-08-01

    This paper investigated the hydrodynamics, spatio-temporal variability of temperature/salinity and the residence time of tracer concentrations in a largest brackish water coastal lagoon in Asia, namely the Chilika lagoon, India. An integrated approach combined the measurement and 2D hydrodynamic-advection/dispersion model is used to simulate circulation and temperature/salinity, and estimated the water residence time in lagoon under different forcing mechanisms, such as tide, wind and freshwater discharge during the dry and wet periods. Water circulation inside the lagoon is simulated when wind is included with the tide only forcing during dry period, and freshwater influx is included with the tide and wind forcing during wet period. Under the realistic forcing conditions, the computed temporal variability of water temperature and salinity are well correlated with the measurements in both the periods. The spatial variations of water temperature within the lagoon is influenced by the meteorological conditions, tide and freshwater influx as well as the shallowness of the lagoon, whereas the salinity is spatially controlled by the freshwater influx from the riverine system and seawater intrusion through the tidal inlets. The numerical model results show that in the Chilika lagoon tidal and river influx affect significantly the residence time spatially, and is site specific. The residence time varies from values of 4-5 days in the outer channel (OC) and 132 days at the northern sector (NS) in the main body of lagoon. The current study represents a first attempt to use a combined model approach, which is therefore, a useful tool to support the ecological implication of the lagoon ecosystem.

  5. A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation

    Directory of Open Access Journals (Sweden)

    Gabriel Kaless

    2013-09-01

    Full Text Available This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina. The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence closure. Sediment transport can be divided in different size classes (sand-gravel mixture and the equilibrium approach is used for Exner’s equation. The amour layer is also included in the structure of the model and the surface grain size distribution is also allowed to evolve. The model simulates bank slides that enable channel widening. Models predictions were tested against a flume experiment where a static armour layer was developed under conditions of sediment starvations and general good agreements were found: the model predicted adequately the sediment transport, grain size of transported material, final armour grain size distribution and bed elevation.

  6. A Coupled Model of the 1D River Network and 3D Estuary Based on Hydrodynamics and Suspended Sediment Simulation

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2014-01-01

    Full Text Available River networks and estuaries are very common in coastal areas. Runoff from the upper stream interacts with tidal current from open sea in these two systems, leading to a complex hydrodynamics process. Therefore, it is necessary to consider the two systems as a whole to study the flow and suspended sediment transport. Firstly, a 1D model is established in the Pearl River network and a 3D model is applied in its estuary. As sufficient mass exchanges between the river network and its estuary, a strict mathematical relationship of water level at the interfaces can be adopted to couple the 1D model with the 3D model. By doing so, the coupled model does not need to have common nested grids. The river network exchanges the suspended sediment with its estuary by adding the continuity conditions at the interfaces. The coupled model is, respectively, calibrated in the dry season and the wet season. The results demonstrate that the coupled model works excellently in simulating water level and discharge. Although there are more errors in simulating suspended sediment concentration due to some reasons, the coupled model is still good enough to evaluate the suspended sediment transport in river network and estuary systems.

  7. Physical hydrodynamics

    CERN Document Server

    Guyon, Etienne; Petit, Luc; Mitescu, Catalin D

    2015-01-01

    This new edition is an enriched version of the textbook of fluid dynamics published more than 10 years ago. It retains the same physically oriented pedagogical perspective. This book emphasizes, as in the first edition, experimental inductive approaches and relies on the study of the mechanisms at play and on dimensional analysis rather than more formal approaches found in many classical textbooks in the field. The need for a completely new version also originated from the increase, over the last few decades, of the cross-overs between the mechanical and physical approaches, as is visible in international meetings and joint projects.