WorldWideScience

Sample records for plume model results

  1. Field studies of submerged-diffuser thermal plumes with comparisons to predictive model results

    International Nuclear Information System (INIS)

    Frigo, A.A.; Paddock, R.A.; Ditmars, J.D.

    1976-01-01

    Thermal plumes from submerged discharges of cooling water from two power plants on Lake Michigan were studied. The system for the acquisition of water temperatures and ambient conditions permitted the three-dimensional structure of the plumes to be determined. The Zion Nuclear Power Station has two submerged discharge structures separated by only 94 m. Under conditions of flow from both structures, interaction between the two plumes resulted in larger thermal fields than would be predicted by the superposition of single non-interacting plumes. Maximum temperatures in the near-field region of the plume compared favorably with mathematical model predictions. A comparison of physical-model predictions for the plume at the D. C. Cook Nuclear Plant with prototype measurements indicated good agreement in the near-field region, but differences in the far-field occurred as similitude was not preserved there

  2. Field studies of the thermal plume from the D. C. Cook submerged discharge with comparisons to hydraulic-model results

    International Nuclear Information System (INIS)

    Frigo, A.A.; Paddock, R.A.; McCown, D.L.

    1975-06-01

    The Donald C. Cook Nuclear Plant at Bridgman, Michigan, uses submerged-diffuser discharges as a means of disposing waste heat into Lake Michigan. Preliminary results of temperature surveys of the thermal plume at the D. C. Cook Plant are presented. Indications are that the spatial extent of the plume at the surface is much smaller than previous results for surface shoreline discharges, particularly in the near and intermediate portions of the plume. Comparisons of limited prototype data with hydraulic (tank)-model predictions indicate that the model predictions for centerline temperature decay at the surface are too high for the initial 200 m from the discharge, but are generally correct beyond this point to the limits of the model. In addition, the hydraulic-model results underestimate the areal extent of the near and intermediate portions of the plume at the surface. Because this is the first report of a new field program, several inadequacies in the field-measurement techniques are noted and discussed. New techniques that have been developed to remedy these deficiencies, and which will be implemented for future field work, are also described. (auth)

  3. The impact from emitted NO{sub x} and VOC in an aircraft plume. Model results for the free troposphere

    Energy Technology Data Exchange (ETDEWEB)

    Pleijel, K.

    1998-04-01

    The chemical fate of gaseous species in a specific aircraft plume is investigated using an expanding box model. The model treats the gas phase chemical reactions in detail, while other parameters are subject to a high degree of simplification. Model simulations were carried out in a plume up to an age of three days. The role of emitted VOC, NO{sub x} and CO as well as of background concentrations of VOC, NO{sub x} and ozone on aircraft plume chemistry was investigated. Background concentrations were varied in a span of measured values in the free troposphere. High background concentrations of VOC were found to double the average plume production of ozone and organic nitrates. In a high NO{sub x} environment the plume production of ozone and organic nitrates decreased by around 50%. The production of nitric acid was found to be less sensitive to background concentrations of VOC, and increased by up to 50% in a high NO{sub x} environment. Mainly, emitted NO{sub x} caused the plume production of ozone, nitric acid and organic nitrates. The ozone production during the first hours is determined by the relative amount of NO{sub 2} in the NO{sub x} emissions. The impact from emitted VOC was in relative values up to 20% of the ozone production and 65% of the production of organic nitrates. The strongest relative influence from VOC was found in an environment characterized by low VOC and high NO{sub x} background concentrations, where the absolute peak production was lower than in the other scenarios. The effect from emitting VOC and NO{sub x} at the same time added around 5% for ozone, 15% for nitric acid and 10% for organic nitrates to the plume production caused by NO{sub x} and VOC when emitted separately 47 refs, 15 figs, 4 tabs

  4. Corrective Measures Study Modeling Results for the Southwest Plume - Burial Ground Complex/Mixed Waste Management Facility

    International Nuclear Information System (INIS)

    Harris, M.K.

    1999-01-01

    Groundwater modeling scenarios were performed to support the Corrective Measures Study and Interim Action Plan for the southwest plume of the Burial Ground Complex/Mixed Waste Management Facility. The modeling scenarios were designed to provide data for an economic analysis of alternatives, and subsequently evaluate the effectiveness of the selected remedial technologies for tritium reduction to Fourmile Branch. Modeling scenarios assessed include no action, vertical barriers, pump, treat, and reinject; and vertical recirculation wells

  5. Models of Hawaiian volcano growth and plume structure: Implications of results from the Hawaii Scientific Drilling Project

    OpenAIRE

    DePaolo, D. J.; Stolper, E. M.

    1996-01-01

    The shapes of typical Hawaiian volcanoes are simply parameterized, and a relationship is derived for the dependence of lava accumulation rates on volcano volume and volumetric growth rate. The dependence of lava accumulation rate on time is derived by estimating the eruption rate of a volcano as it traverses the Hawaiian plume, with the eruption rate determined from a specified radial dependence of magma generation in the plume and assuming that a volcano captures melt from a circular area ce...

  6. Cooling tower plume - model and experiment

    Science.gov (United States)

    Cizek, Jan; Gemperle, Jiri; Strob, Miroslav; Nozicka, Jiri

    The paper discusses the description of the simple model of the, so-called, steam plume, which in many cases forms during the operation of the evaporative cooling systems of the power plants, or large technological units. The model is based on semi-empirical equations that describe the behaviour of a mixture of two gases in case of the free jet stream. In the conclusion of the paper, a simple experiment is presented through which the results of the designed model shall be validated in the subsequent period.

  7. Cooling tower plume - model and experiment

    Directory of Open Access Journals (Sweden)

    Cizek Jan

    2017-01-01

    Full Text Available The paper discusses the description of the simple model of the, so-called, steam plume, which in many cases forms during the operation of the evaporative cooling systems of the power plants, or large technological units. The model is based on semi-empirical equations that describe the behaviour of a mixture of two gases in case of the free jet stream. In the conclusion of the paper, a simple experiment is presented through which the results of the designed model shall be validated in the subsequent period.

  8. Modeling contaminant plumes in fractured limestone aquifers

    DEFF Research Database (Denmark)

    Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika Sidelmann

    Determining the fate and transport of contaminant plumes from contaminated sites in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules, resulting in a complex transport...... model. The paper concludes with recommendations on how to identify and employ suitable models to advance the conceptual understanding and as decision support tools for risk assessment and the planning of remedial actions....... behavior. Improved conceptual models are needed for this type of site. Here conceptual models are developed by combining numerical models with field data. Several types of fracture flow and transport models are available for the modeling of contaminant transport in fractured media. These include...... the established approaches of the equivalent porous medium, discrete fracture and dual continuum models. However, these modeling concepts are not well tested for contaminant plume migration in limestone geologies. Our goal was to develop and evaluate approaches for modeling the transport of dissolved contaminant...

  9. Kinetic electron model for plasma thruster plumes

    Science.gov (United States)

    Merino, Mario; Mauriño, Javier; Ahedo, Eduardo

    2018-03-01

    A paraxial model of an unmagnetized, collisionless plasma plume expanding into vacuum is presented. Electrons are treated kinetically, relying on the adiabatic invariance of their radial action integral for the integration of Vlasov's equation, whereas ions are treated as a cold species. The quasi-2D plasma density, self-consistent electric potential, and electron pressure, temperature, and heat fluxes are analyzed. In particular, the model yields the collisionless cooling of electrons, which differs from the Boltzmann relation and the simple polytropic laws usually employed in fluid and hybrid PIC/fluid plume codes.

  10. Integrating wildfire plume rises within atmospheric transport models

    Science.gov (United States)

    Mallia, D. V.; Kochanski, A.; Wu, D.; Urbanski, S. P.; Krueger, S. K.; Lin, J. C.

    2016-12-01

    Wildfires can generate significant pyro-convection that is responsible for releasing pollutants, greenhouse gases, and trace species into the free troposphere, which are then transported a significant distance downwind from the fire. Oftentimes, atmospheric transport and chemistry models have a difficult time resolving the transport of smoke from these wildfires, primarily due to deficiencies in estimating the plume injection height, which has been highlighted in previous work as the most important aspect of simulating wildfire plume transport. As a result of the uncertainties associated with modeled wildfire plume rise, researchers face difficulties modeling the impacts of wildfire smoke on air quality and constraining fire emissions using inverse modeling techniques. Currently, several plume rise parameterizations exist that are able to determine the injection height of fire emissions; however, the success of these parameterizations has been mixed. With the advent of WRF-SFIRE, the wildfire plume rise and injection height can now be explicitly calculated using a fire spread model (SFIRE) that is dynamically linked with the atmosphere simulated by WRF. However, this model has only been tested on a limited basis due to computational costs. Here, we will test the performance of WRF-SFIRE in addition to several commonly adopted plume parameterizations (Freitas, Sofiev, and Briggs) for the 2013 Patch Springs (Utah) and 2012 Baker Canyon (Washington) fires, for both of which observations of plume rise heights are available. These plume rise techniques will then be incorporated within a Lagrangian atmospheric transport model (STILT) in order to simulate CO and CO2 concentrations during NASA's CARVE Earth Science Airborne Program over Alaska during the summer of 2012. Initial model results showed that STILT model simulations were unable to reproduce enhanced CO concentrations produced by Alaskan fires observed during 2012. Near-surface concentrations were drastically

  11. Numerical model simulation of atmospheric coolant plumes

    International Nuclear Information System (INIS)

    Gaillard, P.

    1980-01-01

    The effect of humid atmospheric coolants on the atmosphere is simulated by means of a three-dimensional numerical model. The atmosphere is defined by its natural vertical profiles of horizontal velocity, temperature, pressure and relative humidity. Effluent discharge is characterised by its vertical velocity and the temperature of air satured with water vapour. The subject of investigation is the area in the vicinity of the point of discharge, with due allowance for the wake effect of the tower and buildings and, where application, wind veer with altitude. The model equations express the conservation relationships for mometum, energy, total mass and water mass, for an incompressible fluid behaving in accordance with the Boussinesq assumptions. Condensation is represented by a simple thermodynamic model, and turbulent fluxes are simulated by introduction of turbulent viscosity and diffusivity data based on in-situ and experimental water model measurements. The three-dimensional problem expressed in terms of the primitive variables (u, v, w, p) is governed by an elliptic equation system which is solved numerically by application of an explicit time-marching algorithm in order to predict the steady-flow velocity distribution, temperature, water vapour concentration and the liquid-water concentration defining the visible plume. Windstill conditions are simulated by a program processing the elliptic equations in an axisymmetrical revolution coordinate system. The calculated visible plumes are compared with plumes observed on site with a view to validate the models [fr

  12. PLUME-MoM 1.0: A new integral model of volcanic plumes based on the method of moments

    Science.gov (United States)

    de'Michieli Vitturi, M.; Neri, A.; Barsotti, S.

    2015-08-01

    In this paper a new integral mathematical model for volcanic plumes, named PLUME-MoM, is presented. The model describes the steady-state dynamics of a plume in a 3-D coordinate system, accounting for continuous variability in particle size distribution of the pyroclastic mixture ejected at the vent. Volcanic plumes are composed of pyroclastic particles of many different sizes ranging from a few microns up to several centimeters and more. A proper description of such a multi-particle nature is crucial when quantifying changes in grain-size distribution along the plume and, therefore, for better characterization of source conditions of ash dispersal models. The new model is based on the method of moments, which allows for a description of the pyroclastic mixture dynamics not only in the spatial domain but also in the space of parameters of the continuous size distribution of the particles. This is achieved by formulation of fundamental transport equations for the multi-particle mixture with respect to the different moments of the grain-size distribution. Different formulations, in terms of the distribution of the particle number, as well as of the mass distribution expressed in terms of the Krumbein log scale, are also derived. Comparison between the new moments-based formulation and the classical approach, based on the discretization of the mixture in N discrete phases, shows that the new model allows for the same results to be obtained with a significantly lower computational cost (particularly when a large number of discrete phases is adopted). Application of the new model, coupled with uncertainty quantification and global sensitivity analyses, enables the investigation of the response of four key output variables (mean and standard deviation of the grain-size distribution at the top of the plume, plume height and amount of mass lost by the plume during the ascent) to changes in the main input parameters (mean and standard deviation) characterizing the

  13. Ship plume modeling in EOSTAR

    NARCIS (Netherlands)

    Iersel, M. van; Mack, A.; Degach, M.A.C.; Eijk, A.M.J. van

    2014-01-01

    The EOSTAR model aims at assessing the performance of electro-optical (EO) sensors deployed in a maritime surface scenario, by providing operational performance measures (such as detection ranges) and synthetic images. The target library of EOSTAR includes larger surface vessels, for which the

  14. Modeling of the near field plume of a Hall thruster

    International Nuclear Information System (INIS)

    Boyd, Iain D.; Yim, John T.

    2004-01-01

    In this study, a detailed numerical model is developed to simulate the xenon plasma near-field plume from a Hall thruster. The model uses a detailed fluid model to describe the electrons and a particle-based kinetic approach is used to model the heavy xenon ions and atoms. The detailed model is applied to compute the near field plume of a small, 200 W Hall thruster. Results from the detailed model are compared with the standard modeling approach that employs the Boltzmann model. The usefulness of the model detailed is assessed through direct comparisons with a number of different measured data sets. The comparisons illustrate that the detailed model accurately predicts a number of features of the measured data not captured by the simpler Boltzmann approach

  15. Liquid Booster Module (LBM) plume flowfield model

    Science.gov (United States)

    Smith, S. D.

    1981-01-01

    A complete definition of the LBM plume is important for many Shuttle design criteria. The exhaust plume shape has a significant effect on the vehicle base pressure. The LBM definition is also important to the Shuttle base heating, aerodynamics and the influence of the exhaust plume on the launch stand and environment. For these reasons a knowledge of the LBM plume characteristics is necessary. A definition of the sea level LBM plume as well as at several points along the Shuttle trajectory to LBM, burnout is presented.

  16. Plume Characterization of a Laboratory Model 22 N GPIM Thruster via High-Frequency Raman Spectroscopy

    Science.gov (United States)

    Williams, George J.; Kojima, Jun J.; Arrington, Lynn A.; Deans, Matthew C.; Reed, Brian D.; Kinzbach, McKenzie I.; McLean, Christopher H.

    2015-01-01

    The Green Propellant Infusion Mission (GPIM) will demonstrate the capability of a green propulsion system, specifically, one using the monopropellant, AF-M315E. One of the risks identified for GPIM is potential contamination of sensitive areas of the spacecraft from the effluents in the plumes of AF-M315E thrusters. Plume characterization of a laboratory-model 22 N thruster via optical diagnostics was conducted at NASA GRC in a space-simulated environment. A high-frequency pulsed laser was coupled with an electron-multiplied ICCD camera to perform Raman spectroscopy in the near-field, low-pressure plume. The Raman data yielded plume constituents and temperatures over a range of thruster chamber pressures and as a function of thruster (catalyst) operating time. Schlieren images of the near-field plume enabled calculation of plume velocities and revealed general plume structure of the otherwise invisible plume. The measured velocities are compared to those predicted by a two-dimensional, kinetic model. Trends in data and numerical results are presented from catalyst mid-life to end-of-life. The results of this investigation were coupled with the Raman and Schlieren data to provide an anchor for plume impingement analysis presented in a companion paper. The results of both analyses will be used to improve understanding of the nature of AF-M315E plumes and their impacts to GPIM and other future missions.

  17. Modelling the fate of the Tijuana River discharge plume

    Science.gov (United States)

    van Ormondt, M.; Terrill, E.; Hibler, L. F.; van Dongeren, A. R.

    2010-12-01

    After rainfall events, the Tijuana River discharges excess runoff into the ocean in a highly turbid plume. The runoff waters contain large suspended solids concentrations, as well as high levels of toxic contaminants, bacteria, and hepatitis and enteroviruses. Public health hazards posed by the effluent often result in beach closures for several kilometers northward along the U.S. shoreline. A Delft3D model has been set up to predict the fate of the Tijuana River plume. The model takes into account the effects of tides, wind, waves, salinity, and temperature stratification. Heat exchange with the atmosphere is also included. The model consists of a relatively coarse outer domain and a high-resolution surf zone domain that are coupled with Domain Decomposition. The offshore boundary conditions are obtained from the larger NCOM SoCal model (operated by the US Navy) that spans the entire Southern California Bight. A number of discharge events are investigated, in which model results are validated against a wide range of field measurements in the San Diego Bight. These include HF Radar surface currents, REMUS tracks, drifter deployments, satellite imagery, as well as current and temperature profile measurements at a number of locations. The model is able to reproduce the observed current and temperature patterns reasonably well. Under calm conditions, the model results suggest that the hydrodynamics in the San Diego Bight are largely governed by internal waves. During rainfall events, which are typically accompanied by strong winds and high waves, wind and wave driven currents become dominant. An analysis will be made of what conditions determine the trapping and mixing of the plume inside the surfzone and/or the propagation of the plume through the breakers and onto the coastal shelf. The model is now also running in operational mode. Three day forecasts are made every 24 hours. This study was funded by the Office of Naval Research.

  18. Towards LES Models of Jets and Plumes

    Science.gov (United States)

    Webb, A. T.; Mansour, N. N.

    2000-01-01

    As pointed out by Rodi standard integral solutions for jets and plumes developed for discharge into infinite, quiescent ambient are difficult to extend to complex situations, particularly in the presence of boundaries such as the sea floor or ocean surface. In such cases the assumption of similarity breaks down and it is impossible to find a suitable entrainment coefficient. The models are also incapable of describing any but the most slowly varying unsteady motions. There is therefore a need for full time-dependent modeling of the flow field for which there are three main approaches: (1) Reynolds averaged numerical simulation (RANS), (2) large eddy simulation (LES), and (3) direct numerical simulation (DNS). Rodi applied RANS modeling to both jets and plumes with considerable success, the test being a match with experimental data for time-averaged velocity and temperature profiles as well as turbulent kinetic energy and rms axial turbulent velocity fluctuations. This model still relies on empirical constants, some eleven in the case of the buoyant jet, and so would not be applicable to a partly laminar plume, may have limited use in the presence of boundaries, and would also be unsuitable if one is after details of the unsteady component of the flow (the turbulent eddies). At the other end of the scale DNS modeling includes all motions down to the viscous scales. Boersma et al. have built such a model for the non-buoyant case which also compares well with measured data for mean and turbulent velocity components. The model demonstrates its versatility by application to a laminar flow case. As its name implies, DNS directly models the Navier-Stokes equations without recourse to subgrid modeling so for flows with a broad spectrum of motions (high Re) the cost can be prohibitive - the number of required grid points scaling with Re(exp 9/4) and the number of time steps with Re(exp 3/4). The middle road is provided by LES whereby the Navier-Stokes equations are formally

  19. An integral model of plume rise from high explosive detonations

    International Nuclear Information System (INIS)

    Boughton, B.A.; De Laurentis, J.M.

    1987-01-01

    A numerical model has been developed which provides a complete description of the time evolution of both the physical and thermodynamic properties of the cloud formed when a high explosive is detonated. This simulation employs the integral technique. The model equations are derived by integrating the three-dimensional conservation equations of mass, momentum and energy over the plume cross section. Assumptions are made regarding (a) plume symmetry; (b) the shape of profiles of velocity, temperature, etc. across the plume; and (c) the methodology for simulating entrainment and the effects of the crossflow induced pressure drag force on the plume. With these assumptions, the integral equations can be reduced to a set of ordinary differential equations on the plume centerline variables. Only the macroscopic plume characteristics, e.g., plume radius, centerline height, temperature and density, are predicted; details of the plume intrastructure are ignored. The model explicitly takes into account existing meteorology and has been expanded to consider the alterations in plume behavior which occur when aqueous foam is used as a dispersal mitigating material. The simulation was tested by comparison with field measurements of cloud top height and diameter. Predictions were within 25% of field observations over a wide range of explosive yield and atmospheric stability

  20. Model Intercomparison Study to Investigate a Dense Contaminant Plume in a Complex Hydrogeologic System

    International Nuclear Information System (INIS)

    Williams, Mark D.; Cole, Charles R.; Foley, Michael G.; Zinina, Galina A.; Zinin, Alexander I.; Vasil'Kova, Nelly A.; Samsonova, Lilia M.

    2001-01-01

    A joint Russian and U.S. model intercomparison study was undertaken for developing more realistic contaminant transport models of the Mayak Site, Southern Urals. The test problems were developed by the Russian Team based on their experience modeling contaminant migration near Lake Karachai. The intercomparison problems were designed to address lake and contaminant plume interactions, as well as river interactions and plume density effects. Different numerical codes were used. Overall there is good agreement between the results of both models. Features shown by both models include (1) the sinking of the plume below the lake, (2) the raising of the water table in the fresh water adjacent to the lake in response to the increased pressure from the dense plume, and (3) the formation of a second sinking plume in an area where evapotranspiration exceeded infiltration, thus increasing the solute concentrations above the source (i.e., lake) values

  1. A mantle plume model for the Equatorial Highlands of Venus

    Science.gov (United States)

    Kiefer, Walter S.; Hager, Bradford H.

    1991-01-01

    The possibility that the Equatorial Highlands are the surface expressions of hot upwelling mantle plumes is considered via a series of mantle plume models developed using a cylindrical axisymmetric finite element code and depth-dependent Newtonian rheology. The results are scaled by assuming whole mantle convection and that Venus and the earth have similar mantle heat flows. The best model fits are for Beta and Atla. The common feature of the allowed viscosity models is that they lack a pronounced low-viscosity zone in the upper mantle. The shape of Venus's long-wavelength admittance spectrum and the slope of its geoid spectrum are also consistent with the lack of a low-viscosity zone. It is argued that the lack of an asthenosphere on Venus is due to the mantle of Venus being drier than the earth's mantle. Mantle plumes may also have contributed to the formation of some smaller highland swells, such as the Bell and Eistla regions and the Hathor/Innini/Ushas region.

  2. Numerical Speadsheet Modeling of Natural Attenuation for Groundwater Contaminant Plumes

    National Research Council Canada - National Science Library

    Twesme, Troy

    1999-01-01

    .... The model was used to evaluate natural attenuation for removal of a trichloroethylene (TCE) plume from a surficial aquifer containing three regions with distinctly different processes for degradation of TCE...

  3. Laser-generated plasma plume expansion: Combined continuous-microscopic modeling

    Science.gov (United States)

    Itina, Tatiana E.; Hermann, Jörg; Delaporte, Philippe; Sentis, Marc

    2002-12-01

    The physical phenomena involved in the interaction of a laser-generated plasma plume with a background gas are studied numerically. A three-dimensional combined model is developed to describe the plasma plume formation and its expansion in vacuum or into a background gas. The proposed approach takes advantages of both continuous and microscopic descriptions. The simulation technique is suitable for the simulation of high-rate laser ablation for a wide range of background pressure. The model takes into account the mass diffusion and the energy exchange between the ablated and background species, as well as the collective motion of the ablated species and the background-gas particles. The developed approach is used to investigate the influence of the background gas on the expansion dynamics of the plume obtained during the laser ablation of aluminum. At moderate pressures, both plume and gas compressions are weak and the process is mainly governed by the diffusive mixing. At higher pressures, the interaction is determined by the plume-gas pressure interplay, the plume front is strongly compressed, and its center exhibits oscillations. In this case, the snowplough effect takes place, leading to the formation of a compressed gas layer in front of the plume. The background pressure needed for the beginning of the snowplough effect is determined from the plume and gas density profiles obtained at various pressures. Simulation results are compared with experimentally measured density distributions. It is shown that the calculations suggest localized formation of molecules during reactive laser ablation.

  4. Laser-generated plasma plume expansion: Combined continuous-microscopic modeling

    International Nuclear Information System (INIS)

    Itina, Tatiana E.; Hermann, Joerg; Delaporte, Philippe; Sentis, Marc

    2002-01-01

    The physical phenomena involved in the interaction of a laser-generated plasma plume with a background gas are studied numerically. A three-dimensional combined model is developed to describe the plasma plume formation and its expansion in vacuum or into a background gas. The proposed approach takes advantages of both continuous and microscopic descriptions. The simulation technique is suitable for the simulation of high-rate laser ablation for a wide range of background pressure. The model takes into account the mass diffusion and the energy exchange between the ablated and background species, as well as the collective motion of the ablated species and the background-gas particles. The developed approach is used to investigate the influence of the background gas on the expansion dynamics of the plume obtained during the laser ablation of aluminum. At moderate pressures, both plume and gas compressions are weak and the process is mainly governed by the diffusive mixing. At higher pressures, the interaction is determined by the plume-gas pressure interplay, the plume front is strongly compressed, and its center exhibits oscillations. In this case, the snowplough effect takes place, leading to the formation of a compressed gas layer in front of the plume. The background pressure needed for the beginning of the snowplough effect is determined from the plume and gas density profiles obtained at various pressures. Simulation results are compared with experimentally measured density distributions. It is shown that the calculations suggest localized formation of molecules during reactive laser ablation

  5. EM Modelling of RF Propagation Through Plasma Plumes

    Science.gov (United States)

    Pandolfo, L.; Bandinelli, M.; Araque Quijano, J. L.; Vecchi, G.; Pawlak, H.; Marliani, F.

    2012-05-01

    Electric propulsion is a commercially attractive solution for attitude and position control of geostationary satellites. Hall-effect ion thrusters generate a localized plasma flow in the surrounding of the satellite, whose impact on the communication system needs to be qualitatively and quantitatively assessed. An electromagnetic modelling tool has been developed and integrated into the Antenna Design Framework- ElectroMagnetic Satellite (ADF-EMS). The system is able to guide the user from the plume definition phases through plume installation and simulation. A validation activity has been carried out and the system has been applied to the plume modulation analysis of SGEO/Hispasat mission.

  6. Modeling Smoke Plume-Rise and Dispersion from Southern United States Prescribed Burns with Daysmoke

    Science.gov (United States)

    G L Achtemeier; S L Goodrick; Y Liu; F Garcia-Menendez; Y Hu; M. Odman

    2011-01-01

    We present Daysmoke, an empirical-statistical plume rise and dispersion model for simulating smoke from prescribed burns. Prescribed fires are characterized by complex plume structure including multiple-core updrafts which makes modeling with simple plume models difficult. Daysmoke accounts for plume structure in a three-dimensional veering/sheering atmospheric...

  7. Results of a jet plume effects test on Rockwell International integrated space shuttle vehicle using a vehicle 5 configuration 0.02-scale model (88-OTS) in the 11 by 11 foot leg of the NASA/Ames Research Center unitary plan wind tunnel (IA19), volume 1

    Science.gov (United States)

    Nichols, M. E.

    1975-01-01

    Results are presented of jet plume effects test IA19 using a vehicle 5 configuration integrated space shuttle vehicle 0.02-scale model in the NASA/Ames Research Center 11 x 11-foot leg of the unitary plan wind tunnel. The jet plume power effects on the integrated vehicle static pressure distribution were determined along with elevon, main propulsion system nozzle, and solid rocket booster nozzle effectiveness and elevon hinge moments.

  8. A hybrid plume model for local-scale dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Nikmo, J.; Tuovinen, J.P.; Kukkonen, J.; Valkama, I.

    1997-12-31

    The report describes the contribution of the Finnish Meteorological Institute to the project `Dispersion from Strongly Buoyant Sources`, under the `Environment` programme of the European Union. The project addresses the atmospheric dispersion of gases and particles emitted from typical fires in warehouses and chemical stores. In the study only the `passive plume` regime, in which the influence of plume buoyancy is no longer important, is addressed. The mathematical model developed and its numerical testing is discussed. The model is based on atmospheric boundary-layer scaling theory. In the vicinity of the source, Gaussian equations are used in both the horizontal and vertical directions. After a specified transition distance, gradient transfer theory is applied in the vertical direction, while the horizontal dispersion is still assumed to be Gaussian. The dispersion parameters and eddy diffusivity are modelled in a form which facilitates the use of a meteorological pre-processor. Also a new model for the vertical eddy diffusivity (K{sub z}), which is a continuous function of height in the various atmospheric scaling regions is presented. The model includes a treatment of the dry deposition of gases and particulate matter, but wet deposition has been neglected. A numerical solver for the atmospheric diffusion equation (ADE) has been developed. The accuracy of the numerical model was analysed by comparing the model predictions with two analytical solutions of ADE. The numerical deviations of the model predictions from these analytic solutions were less than two per cent for the computational regime. The report gives numerical results for the vertical profiles of the eddy diffusivity and the dispersion parameters, and shows spatial concentration distributions in various atmospheric conditions 39 refs.

  9. Merits of a Scenario Approach in Dredge Plume Modelling

    DEFF Research Database (Denmark)

    Pedersen, Claus; Chu, Amy Ling Chu; Hjelmager Jensen, Jacob

    2011-01-01

    Dredge plume modelling is a key tool for quantification of potential impacts to inform the EIA process. There are, however, significant uncertainties associated with the modelling at the EIA stage when both dredging methodology and schedule are likely to be a guess at best as the dredging...... contractor would rarely have been appointed. Simulation of a few variations of an assumed full dredge period programme will generally not provide a good representation of the overall environmental risks associated with the programme. An alternative dredge plume modelling strategy that attempts to encapsulate...... uncertainties associated with preliminary dredging programmes by using a scenario-based modelling approach is presented. The approach establishes a set of representative and conservative scenarios for key factors controlling the spill and plume dispersion and simulates all combinations of e.g. dredge, climatic...

  10. PLUME-MoM 1.0: a new 1-D model of volcanic plumes based on the method of moments

    Science.gov (United States)

    de'Michieli Vitturi, M.; Neri, A.; Barsotti, S.

    2015-05-01

    In this paper a new mathematical model for volcanic plumes, named PlumeMoM, is presented. The model describes the steady-state 1-D dynamics of the plume in a 3-D coordinate system, accounting for continuous variability in particle distribution of the pyroclastic mixture ejected at the vent. Volcanic plumes are composed of pyroclastic particles of many different sizes ranging from a few microns up to several centimeters and more. Proper description of such a multiparticle nature is crucial when quantifying changes in grain-size distribution along the plume and, therefore, for better characterization of source conditions of ash dispersal models. The new model is based on the method of moments, which allows description of the pyroclastic mixture dynamics not only in the spatial domain but also in the space of properties of the continuous size-distribution of the particles. This is achieved by formulation of fundamental transport equations for the multiparticle mixture with respect to the different moments of the grain-size distribution. Different formulations, in terms of the distribution of the particle number, as well as of the mass distribution expressed in terms of the Krumbein log scale, are also derived. Comparison between the new moments-based formulation and the classical approach, based on the discretization of the mixture in N discrete phases, shows that the new model allows the same results to be obtained with a significantly lower computational cost (particularly when a large number of discrete phases is adopted). Application of the new model, coupled with uncertainty quantification and global sensitivity analyses, enables investigation of the response of four key output variables (mean and standard deviation (SD) of the grain-size distribution at the top of the plume, plume height and amount of mass lost by the plume during the ascent) to changes in the main input parameters (mean and SD) characterizing the pyroclastic mixture at the base of the plume

  11. DeepBlow - a Lagrangian plume model for deep water blowouts

    International Nuclear Information System (INIS)

    Johansen, Oeistein

    2000-01-01

    This paper presents a sub-sea blowout model designed with special emphasis on deep-water conditions. The model is an integral plume model based on a Lagrangian concept. This concept is applied to multiphase discharges in the formation of water, oil and gas in a stratified water column with variable currents. The gas may be converted to hydrate in combination with seawater, dissolved into the plume water, or leaking out of the plume due to the slip between rising gas bubbles and the plume trajectory. Non-ideal behaviour of the gas is accounted for by the introduction of pressure- and temperature-dependent compressibility z-factor in the equation of state. A number of case studies are presented in the paper. One of the cases (blowout from 100 m depth) is compared with observations from a field experiment conducted in Norwegian waters in June 1996. The model results are found to compare favourably with the field observations when dissolution of gas into seawater is accounted in the model. For discharges at intermediate to shallow depths (100-250 m), the two major processes limiting plume rise will be: (a) dissolution of gas into ambient water, or (b) bubbles rising out of the inclined plume. These processes tend to be self-enforcing, i.e., when a gas is lost by either of these processes, plume rise tends to slow down and more time will be available for dissolution. For discharges in deep waters (700-1500 m depth), hydrate formation is found to be a dominating process in limiting plume rise. (Author)

  12. Modelling thermal plume impacts - Kalpakkam approach

    International Nuclear Information System (INIS)

    Rao, T.S.; Anup Kumar, B.; Narasimhan, S.V.

    2002-01-01

    A good understanding of temperature patterns in the receiving waters is essential to know the heat dissipation from thermal plumes originating from coastal power plants. The seasonal temperature profiles of the Kalpakkam coast near Madras Atomic Power Station (MAPS) thermal out fall site are determined and analysed. It is observed that the seasonal current reversal in the near shore zone is one of the major mechanisms for the transport of effluents away from the point of mixing. To further refine our understanding of the mixing and dilution processes, it is necessary to numerically simulate the coastal ocean processes by parameterising the key factors concerned. In this paper, we outline the experimental approach to achieve this objective. (author)

  13. A modified Gaussian model for the thermal plume from a ground-based heat source in a cross-wind

    International Nuclear Information System (INIS)

    Selander, W.N.; Barry, P.J.; Robertson, E.

    1990-06-01

    An array of propane burners operating at ground level in a cross-wind was used as a heat source to establish a blown-over thermal plume. A three-dimensional array of thermocouples was used to continuously measure the plume temperature downwind from the source. The resulting data were used to correlate the parameters of a modified Gaussian model for plume rise and dispersion with source strength, wind speed, and atmospheric dispersion parameters

  14. Modeling Macro- and Micro-Scale Turbulent Mixing and Chemistry in Engine Exhaust Plumes

    Science.gov (United States)

    Menon, Suresh

    1998-01-01

    Simulation of turbulent mixing and chemical processes in the near-field plume and plume-vortex regimes has been successfully carried out recently using a reduced gas phase kinetics mechanism which substantially decreased the computational cost. A detailed mechanism including gas phase HOx, NOx, and SOx chemistry between the aircraft exhaust and the ambient air in near-field aircraft plumes is compiled. A reduced mechanism capturing the major chemical pathways is developed. Predictions by the reduced mechanism are found to be in good agreement with those by the detailed mechanism. With the reduced chemistry, the computer CPU time is saved by a factor of more than 3.5 for the near-field plume modeling. Distributions of major chemical species are obtained and analyzed. The computed sensitivities of major species with respect to reaction step are deduced for identification of the dominant gas phase kinetic reaction pathways in the jet plume. Both the near field plume and the plume-vortex regimes were investigated using advanced mixing models. In the near field, a stand-alone mixing model was used to investigate the impact of turbulent mixing on the micro- and macro-scale mixing processes using a reduced reaction kinetics model. The plume-vortex regime was simulated using a large-eddy simulation model. Vortex plume behind Boeing 737 and 747 aircraft was simulated along with relevant kinetics. Many features of the computed flow field show reasonable agreement with data. The entrainment of the engine plumes into the wing tip vortices and also the partial detrainment of the plume were numerically captured. The impact of fluid mechanics on the chemical processes was also studied. Results show that there are significant differences between spatial and temporal simulations especially in the predicted SO3 concentrations. This has important implications for the prediction of sulfuric acid aerosols in the wake and may partly explain the discrepancy between past numerical studies

  15. Complex plume dynamics in the transition zone underneath the Hawaii hotspot: seismic imaging results

    Science.gov (United States)

    Cao, Q.; van der Hilst, R. D.; de Hoop, M. V.; Shim, S.

    2010-12-01

    In recent years, progress has been made in seismology to constrain the depth variations of the transition zone discontinuities, e.g. 410 km and 660 km discontinuities, which can be used to constrain the local temperature and chemistry profiles, and hence to infer the existences and morphology of mantle plumes. Taking advantage of the abundance of natural earthquake sources in western Pacific subduction zones and the many seismograph stations in the Americas, we used a generalized Radon transform (GRT), a high resolution inverse-scattering technique, of SS precursors to form 3-D images of the transition zone structures of a 30 degree by 40 degree area underneath Hawaii and the Hawaii-Emperor seamount chain. Rather than a simple mushroom-shape plume, our seismic images suggest complex plume dynamics interacting with the transition zone phase transitions, especially at the 660’ discontinuity. A conspicuous uplift of the 660 discontinuity in a region of 800km in diameter is observed to the west of Hawaii. No correspondent localized depression of the 410 discontinuity is found. This lack of correlation between and differences in lateral length scale of the topographies of the 410 and 660 km discontinuities are consistent with many geodynamical modeling results, in which a deep-mantle plume impinging on the transition zone, creating a pond of hot material underneath endothermic phase change at 660 km depth, and with secondary plumes connecting to the present-day hotspot at Earth’s surface. This more complex plume dynamics suggests that the complicated mass transport process across the transition zone should be taken into account when we try to link the geochemical observations of Hawaiian basalt geochemistry at the Earth’s surface to deep mantle domains. In addition to clear signals at 410km, 520km and 660km depth, the data also reveals rich structures near 350km depth and between 800 - 1000km depth, which may be regional, laterally intermittent scatter interfaces

  16. Subsurface oil release field experiment - observations and modelling of subsurface plume behaviour

    International Nuclear Information System (INIS)

    Rye, H.; Brandvik, P.J.; Reed, M.

    1996-01-01

    An experiment was conducted at sea, in which oil was released from 107 metres depth, in order to study plume behaviour. The objective of the underwater release was to simulate a pipeline leakage without gas and high pressure and to study the behaviour of the rising plume. A numerical model for the underwater plume behaviour was used for comparison with field data. The expected path of the plume, the time expected for the plume to reach the sea surface and the width of the plume was modelled. Field data and the numerical model were in good agreement. 10 refs., 2 tabs., 9 figs

  17. Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT)

    Science.gov (United States)

    Choi, Maria

    2016-01-01

    An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HPHall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.

  18. A numerical model for buoyant oil jets and smoke plumes

    International Nuclear Information System (INIS)

    Zheng, L.; Yapa, P. D.

    1997-01-01

    Development of a 3-D numerical model to simulate the behaviour of buoyant oil jets from underwater accidents and smoke plumes from oil burning was described. These jets/plumes can be oil-in-water, oil/gas mixture in water, gas in water, or gas in air. The ambient can have a 3-D flow structure, and spatially/temporally varying flow conditions. The model is based on the Lagrangian integral technique. The model formulation of oil jet includes the diffusion and dissolution of oil from the jet to the ambient environment. It is suitable to simulate well blowout accidents that can occur in deep waters, including that of the North Sea. The model has been thoroughly tested against a variety of data, including data from both laboratory and field experiments. In all cases the simulation data compared very well with experimental data. 26 refs., 10 figs

  19. Modeling of plasma plume induced during laser welding

    International Nuclear Information System (INIS)

    Moscicki, T.; Hoffman, J.; Szymanski, Z.

    2005-01-01

    During laser welding, the interaction of intense laser radiation with a work-piece leads to the formation of a long, thin, cylindrical cavity in a metal, called a keyhole. Generation of a keyhole enables the laser beam to penetrate into the work-piece and is essential for deep welding. The keyhole contains ionized metal vapour and is surrounded by molten material called the weld pool. The metal vapour, which flows from the keyhole mixes with the shielding gas flowing from the opposite direction and forms a plasma plume over the keyhole mouth. The plasma plume has considerable influence on the processing conditions. Plasma strongly absorbs laser radiation and significantly changes energy transfer from the laser beam to a material. In this paper the results of theoretical modelling of plasma plume induced during welding with CO 2 laser are presented. The set of equations consists of equation of conservation of mass, energy, momentum and the diffusion equation: ∂ρ/∂t + ∇·(ρ ρ ν =0; ∂(ρE)/∂t + ∇·( ρ ν (ρE + p)) = ∇ (k eff ∇T - Σ j h j ρ J j + (τ eff · ρ ν )) + Σ i κ i I i - R; ∂/∂t(ρ ρ ν ) + ∇· (ρ ρ ν ρ ν ) = - ∇p + ∇(τ) + ρ ρ g + ρ F, where τ is viscous tensor τ = μ[(∇ ρ ν + ∇ ρT ν )-2/3∇· ρ ν I]; ∂/∂t(ρY i ) + ∇·(ρ ρ ν Y i ) = ∇·ρD i,m ∇T i ; where μ ν denotes velocity vector, E - energy, ρ mass density; k - thermal conductivity, T- temperature, κ - absorption coefficient, I i local laser intensity, R - radiation loss function, p - pressure, h j enthalpy, J j - diffusion flux of j component, ν g - gravity, μ F - external force, μ - dynamic viscosity, I - unit tensor, Y i - mass fraction of iron vapor in the gas mixture, D i,m - mass diffusion coefficient. The terms k eff and τ eff contain the turbulent component of the thermal conductivity and the viscosity, respectively. All the material functions are functions of the temperature and mass fraction only. The equations

  20. Infrared signature modelling of a rocket jet plume - comparison with flight measurements

    International Nuclear Information System (INIS)

    Rialland, V; Perez, P; Roblin, A; Guy, A; Gueyffier, D; Smithson, T

    2016-01-01

    The infrared signature modelling of rocket plumes is a challenging problem involving rocket geometry, propellant composition, combustion modelling, trajectory calculations, fluid mechanics, atmosphere modelling, calculation of gas and particles radiative properties and of radiative transfer through the atmosphere. This paper presents ONERA simulation tools chained together to achieve infrared signature prediction, and the comparison of the estimated and measured signatures of an in-flight rocket plume. We consider the case of a solid rocket motor with aluminized propellant, the Black Brant sounding rocket. The calculation case reproduces the conditions of an experimental rocket launch, performed at White Sands in 1997, for which we obtained high quality infrared signature data sets from DRDC Valcartier. The jet plume is calculated using an in-house CFD software called CEDRE. The plume infrared signature is then computed on the spectral interval 1900-5000 cm -1 with a step of 5 cm -1 . The models and their hypotheses are presented and discussed. Then the resulting plume properties, radiance and spectra are detailed. Finally, the estimated infrared signature is compared with the spectral imaging measurements. The discrepancies are analyzed and discussed. (paper)

  1. Radiative modeling and characterization of aerosol plumes hyper-spectral imagery

    International Nuclear Information System (INIS)

    Alakian, A.

    2008-03-01

    This thesis aims at characterizing aerosols from plumes (biomass burning, industrial discharges, etc.) with hyper-spectral imagery. We want to estimate the optical properties of emitted particles and also their micro-physical properties such as number, size distribution and composition. To reach our goal, we have built a forward semi-analytical model, named APOM (Aerosol Plume Optical Model), which allows to simulate the radiative effects of aerosol plumes in the spectral range [0,4-2,5 μm] for nadir viewing sensors. Mathematical formulation and model coefficients are obtained from simulations performed with the radiative transfer code COMANCHE. APOM is assessed on simulated data and proves to be accurate with modeling errors between 1% and 3%. Three retrieval methods using APOM have been developed: L-APOM, M-APOM and A-APOM. These methods take advantage of spectral and spatial dimensions in hyper-spectral images. L-APOM and M-APOM assume a priori knowledge on particles but can estimate their optical and micro-physical properties. Their performances on simulated data are quite promising. A-APOM method does not require any a priori knowledge on particles but only estimates their optical properties. However, it still needs improvements before being usable. On real images, inversion provides satisfactory results for plumes above water but meets some difficulties for plumes above vegetation, which underlines some possibilities of improvement for the retrieval algorithm. (author)

  2. Performance of monitoring networks estimated from a Gaussian plume model

    International Nuclear Information System (INIS)

    Seebregts, A.J.; Hienen, J.F.A.

    1990-10-01

    In support of the ECN study on monitoring strategies after nuclear accidents, the present report describes the analysis of the performance of a monitoring network in a square grid. This network is used to estimate the distribution of the deposition pattern after a release of radioactivity into the atmosphere. The analysis is based upon a single release, a constant wind direction and an atmospheric dispersion according to a simplified Gaussian plume model. A technique is introduced to estimate the parameters in this Gaussian model based upon measurements at specific monitoring locations and linear regression, although this model is intrinsically non-linear. With these estimated parameters and the Gaussian model the distribution of the contamination due to deposition can be estimated. To investigate the relation between the network and the accuracy of the estimates for the deposition, deposition data have been generated by the Gaussian model, including a measurement error by a Monte Carlo simulation and this procedure has been repeated for several grid sizes, dispersion conditions, number of measurements per location, and errors per single measurement. The present technique has also been applied for the mesh sizes of two networks in the Netherlands, viz. the Landelijk Meetnet Radioaciviteit (National Measurement Network on Radioactivity, mesh size approx. 35 km) and the proposed Landelijk Meetnet Nucleaire Incidenten (National Measurement Network on Nuclear Incidents, mesh size approx. 15 km). The results show accuracies of 11 and 7 percent, respectively, if monitoring locations are used more than 10 km away from the postulated accident site. These figures are based upon 3 measurements per location and a dispersion during neutral weather with a wind velocity of 4 m/s. For stable weather conditions and low wind velocities, i.e. a small plume, the calculated accuracies are at least a factor 1.5 worse.The present type of analysis makes a cost-benefit approach to the

  3. Formation of mantle "lone plumes" in the global downwelling zone - A multiscale modelling of subduction-controlled plume generation beneath the South China Sea

    Science.gov (United States)

    Zhang, Nan; Li, Zheng-Xiang

    2018-01-01

    It has been established that almost all known mantle plumes since the Mesozoic formed above the two lower mantle large low shear velocity provinces (LLSVPs). The Hainan plume is one of the rare exceptions in that instead of rising above the LLSVPs, it is located within the broad global mantle downwelling zone, therefore classified as a "lone plume". Here, we use the Hainan plume example to investigate the feasibility of such lone plumes being generated by subducting slabs in the mantle downwelling zone using 3D geodynamic modelling. Our geodynamic model has a high-resolution regional domain embedded in a relatively low resolution global domain, which is set up in an adaptive-mesh-refined, 3D mantle convection code ASPECT (Advanced Solver for Problems in Earth's ConvecTion). We use a recently published plate motion model to define the top mechanical boundary condition. Our modelling results suggest that cold slabs under the present-day Eurasia, formed from the Mesozoic subduction and closure of the Tethys oceans, have prevented deep mantle hot materials from moving to the South China Sea from regions north or west of the South China Sea. From the east side, the Western Pacific subduction systems started to promote the formation of a lower-mantle thermal-chemical pile in the vicinity of the future South China Sea region since 70 Ma ago. As the top of this lower-mantle thermal-chemical pile rises, it first moved to the west, and finally rested beneath the South China Sea. The presence of a thermochemical layer (possible the D″ layer) in the model helps stabilizing the plume root. Our modelling is the first implementation of multi-scale mesh in the regional model. It has been proved to be an effective way of modelling regional dynamics within a global plate motion and mantle dynamics background.

  4. Sensitivity analysis of alkaline plume modelling: influence of mineralogy

    International Nuclear Information System (INIS)

    Gaboreau, S.; Claret, F.; Marty, N.; Burnol, A.; Tournassat, C.; Gaucher, E.C.; Munier, I.; Michau, N.; Cochepin, B.

    2010-01-01

    Document available in extended abstract form only. In the context of a disposal facility for radioactive waste in clayey geological formation, an important modelling effort has been carried out in order to predict the time evolution of interacting cement based (concrete or cement) and clay (argillites and bentonite) materials. The high number of modelling input parameters associated with non negligible uncertainties makes often difficult the interpretation of modelling results. As a consequence, it is necessary to carry out sensitivity analysis on main modelling parameters. In a recent study, Marty et al. (2009) could demonstrate that numerical mesh refinement and consideration of dissolution/precipitation kinetics have a marked effect on (i) the time necessary to numerically clog the initial porosity and (ii) on the final mineral assemblage at the interface. On the contrary, these input parameters have little effect on the extension of the alkaline pH plume. In the present study, we propose to investigate the effects of the considered initial mineralogy on the principal simulation outputs: (1) the extension of the high pH plume, (2) the time to clog the porosity and (3) the alteration front in the clay barrier (extension and nature of mineralogy changes). This was done through sensitivity analysis on both concrete composition and clay mineralogical assemblies since in most published studies, authors considered either only one composition per materials or simplified mineralogy in order to facilitate or to reduce their calculation times. 1D Cartesian reactive transport models were run in order to point out the importance of (1) the crystallinity of concrete phases, (2) the type of clayey materials and (3) the choice of secondary phases that are allowed to precipitate during calculations. Two concrete materials with either nanocrystalline or crystalline phases were simulated in contact with two clayey materials (smectite MX80 or Callovo- Oxfordian argillites). Both

  5. Modeling of Interactions of Ablated Plumes

    National Research Council Canada - National Science Library

    Povitsky, Alex

    2008-01-01

    Heat transfer modulation between the gas flow and the Thermal Protection Shield (TPS) that occurs because of ejection of under-expanded pyrolysis gases through the cracks in the TPS is studied by numerical modeling...

  6. Volcanic Plume Elevation Model Derived From Landsat 8: examples on Holuhraun (Iceland) and Mount Etna (Italy)

    Science.gov (United States)

    de Michele, Marcello; Raucoules, Daniel; Arason, Þórður; Spinetti, Claudia; Corradini, Stefano; Merucci, Luca

    2016-04-01

    . Standard spaceborne along-track stereo imagers (e.g. SPOT 5, ASTER or Quickbird among the others) present a long temporal lag between the two stereo image acquisitions. It can reach tens of seconds for baseline-to-height ratios (B/H) between 0.2 and 0.5, during which time the surface texture of the plume may have changed due to the plume fast displacement (i.e. velocities larger than 10 m/s) biasing automatic cross correlation offset measurements. For the purpose of the plume surface elevation model extraction, the ideal is as small as possible time lag, with still a B/H ratio large enough to provide a stereoscopic view for restituting the height. In this study we present a method to restitute a detailed map of the surface height of a volcanic eruptive column from optical satellite imagery. We call it the volcanic Plume Elevation Model (PEM). As the volcanic plume is moving rapidly, conventional satellite based photogrammetric height restitution methods do not apply as the epipolar offset due to plume motion adds up to the one generated by the stereoscopic view. This is because there are time-lags of tens of seconds between conventional satellite stereoscopic acquisitions, depending on the stereo acquisition mode. Our method is based on a single satellite pass. We exploit the short time lag and resulting baseline that exist between the multispectral (MS) and the panchromatic (PAN) bands to jointly measure the epipolar offsets and the perpendicular to the epipolar (P2E) offsets. The former are proportional to plume height plus the offsets due to plume velocity in the epipolar direction. The latter, are proportional to plume velocity in the P2E direction only. The latter is used to compensate the effect of plume velocity in the stereoscopic offsets by projecting it on the epipolar direction assuming a known plume direction, thus improving the height measurement precision. We apply the method to Landsat 8 data taking into account the specificities of the focal plane modules

  7. Water Resources Research Program. Surface thermal plumes: evaluation of mathematical models for the near and complete field

    International Nuclear Information System (INIS)

    Dunn, W.E.; Policastro, A.J.; Paddock, R.A.

    1975-08-01

    This report evaluates mathematical models that may be used to predict the flow and temperature distributions resulting from heated surface discharges from power-plant outfalls. Part One discusses the basic physics of surface-plume dispersion and provides a critical review of 11 of the most popular and promising plume models developed to predict the near- and complete-field plume. Part Two compares predictions from the models to prototype data, laboratory data, or both. Part Two also provides a generic discussion of the issues surrounding near- and complete-field modeling. The principal conclusion of the report is that the available models, in their present stage of development, may be used to give only general estimates of plume characteristics; precise predictions are not currently possible. The Shirazi-Davis and Pritchard (No. 1) models appear superior to the others tested and are capable of correctly predicting general plume characteristics. (The predictions show roughly factor-of-two accuracy in centerline distance to a given isotherm, factor-of-two accuracy in plume width, and factor-of-five accuracy in isotherm areas.) The state of the art can best be improved by pursuing basic laboratory studies of plume dispersion along with further development of numerical-modeling techniques

  8. Plume Tracker: Interactive mapping of volcanic sulfur dioxide emissions with high-performance radiative transfer modeling

    Science.gov (United States)

    Realmuto, Vincent J.; Berk, Alexander

    2016-11-01

    We describe the development of Plume Tracker, an interactive toolkit for the analysis of multispectral thermal infrared observations of volcanic plumes and clouds. Plume Tracker is the successor to MAP_SO2, and together these flexible and comprehensive tools have enabled investigators to map sulfur dioxide (SO2) emissions from a number of volcanoes with TIR data from a variety of airborne and satellite instruments. Our objective for the development of Plume Tracker was to improve the computational performance of the retrieval procedures while retaining the accuracy of the retrievals. We have achieved a 300 × improvement in the benchmark performance of the retrieval procedures through the introduction of innovative data binning and signal reconstruction strategies, and improved the accuracy of the retrievals with a new method for evaluating the misfit between model and observed radiance spectra. We evaluated the accuracy of Plume Tracker retrievals with case studies based on MODIS and AIRS data acquired over Sarychev Peak Volcano, and ASTER data acquired over Kilauea and Turrialba Volcanoes. In the Sarychev Peak study, the AIRS-based estimate of total SO2 mass was 40% lower than the MODIS-based estimate. This result was consistent with a 45% reduction in the AIRS-based estimate of plume area relative to the corresponding MODIS-based estimate. In addition, we found that our AIRS-based estimate agreed with an independent estimate, based on a competing retrieval technique, within a margin of ± 20%. In the Kilauea study, the ASTER-based concentration estimates from 21 May 2012 were within ± 50% of concurrent ground-level concentration measurements. In the Turrialba study, the ASTER-based concentration estimates on 21 January 2012 were in exact agreement with SO2 concentrations measured at plume altitude on 1 February 2012.

  9. State of the art atmospheric dispersion modelling. Should the Gaussian plume model still be used?

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Cornelia [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Koeln (Germany)

    2016-11-15

    For regulatory purposes with respect to licensing and supervision of airborne releases of nuclear installations, the Gaussian plume model is still in use in Germany. However, for complex situations the Gaussian plume model is to be replaced by a Lagrangian particle model. Now the new EU basic safety standards for protection against the dangers arising from exposure to ionising radiation (EU BSS) [1] asks for a realistic assessment of doses to the members of the public from authorised practices. This call for a realistic assessment raises the question whether dispersion modelling with the Gaussian plume model is an adequate approach anymore or whether the use of more complex models is mandatory.

  10. Using satellite imagery for qualitative evaluation of plume transport in modeling the effects of the Kuwait oil fire smoke plumes

    International Nuclear Information System (INIS)

    Bass, A.; Janota, P.

    1992-01-01

    To forecast the behavior of the Kuwait oil fire smoke plumes and their possible acute or chronic health effects over the Arabian Gulf region, TASC created a comprehensive health and environmental impacts modeling system. A specially-adapted Lagrangian puff transport model was used to create (a) short-term (multiday) forecasts of plume transport and ground-level concentrations of soot and SO 2 ; and (b) long-term (seasonal and longer) estimates of average surface concentrations and depositions. EPA-approved algorithms were used to transform exposures to SO 2 and soot (as PAH/BaP) into morbidity, mortality and crop damage risks. Absent any ground truth, satellite imagery from the NOAA Polar Orbiter and the ESA Geostationary Meteosat offered the only opportunity for timely qualitative evaluation of the long-range plume transport and diffusion predictions. This paper shows the use of actual satellite images (including animated loops of hourly Meteosat images) to evaluate plume forecasts in near-real-time, and to sanity-check the meso- and long-range plume transport projections for the long-term estimates. Example modeled concentrations, depositions and health effects are shown

  11. IR sensor design insight from missile-plume prediction models

    Science.gov (United States)

    Rapanotti, John L.; Gilbert, Bruno; Richer, Guy; Stowe, Robert

    2002-08-01

    Modern anti-tank missiles and the requirement of rapid deployment have significantly reduced the use of passive armour in protecting land vehicles. Vehicle survivability is becoming more dependent on sensors, computers and countermeasures to detect and avoid threats. An analysis of missile propellants suggests that missile detection based on plume characteristics alone may be more difficult than anticipated. Currently, the passive detection of missiles depends on signatures with a significant ultraviolet component. This approach is effective in detecting anti-aircraft missiles that rely on powerful motors to pursue high-speed aircraft. The high temperature exhaust from these missiles contains significant levels of carbon dioxide, water and, often, metal oxides such as alumina. The plumes emits strongest in the infrared, 1 to 5micrometers , regions with a significant component of the signature extending into the ultraviolet domain. Many anti-tank missiles do not need the same level of propulsion and radiate significantly less. These low velocity missiles, relying on the destructive force of shaped-charge warhead, are more difficult to detect. There is virtually no ultraviolet component and detection based on UV sensors is impractical. The transition in missile detection from UV to IR is reasonable, based on trends in imaging technology, but from the analysis presented in this paper even IR imagers may have difficulty in detecting missile plumes. This suggests that the emphasis should be placed in the detection of the missile hard body in the longer wavelengths of 8 to 12micrometers . The analysis described in this paper is based on solution of the governing equations of plume physics and chemistry. These models will be used to develop better sensors and threat detection algorithms.

  12. Aquatic dispersion modelling of a tritium plume in Lake Ontario

    International Nuclear Information System (INIS)

    Klukas, M.H.; Moltyaner, G.L.

    1996-05-01

    Approximately 2900 kg of tritiated water, containing 2.3E+15 Bq of tritium, were released to Lake Ontario via the cooling water discharge when a leak developed in a moderator heat exchanger in Unit 1 at the Pickering Nuclear Generating Station (PNGS) on 1992 August 2. The release provided the opportunity to study the dispersion of a tritium plume in the coastal zone of Lake Ontario. Current direction over the two-week period following the release was predominantly parallel to the shore, and elevated tritium concentrations were observed up to 20 km east and 85 km west of the PNGS. Predictions of the tritium plume movement were made using current velocity measurements taken at 8-m depth, 2.5 km offshore from Darlington and using a empirical relationship where alongshore current speed is assumed to be proportional to the alongshore component of the wind speed. The tritium migration was best described using current velocity measurements. The tritium plume dispersion is modelled using the one-dimensional advection-dispersion equation. Transport parameters are the alongshore current speed and longitudinal dispersion coefficient. Longitudinal dispersion coefficients, estimated by fitting the solution of the advection-dispersion equation to measured concentration distance profiles ranged from 3.75 to 10.57 m 2 s -1 . Simulations using the fitted values of the dispersion coefficient were able to describe maximum tritium concentrations measured at water supply plants located within 25 km of Pickering to within a factor of 3. The dispersion coefficient is a function of spatial and temporal variability in current velocity and the fitted dispersion coefficients estimated here may not be suitable for predicting tritium plume dispersion under different current conditions. The sensitivity of the dispersion coefficient to variability in current conditions should be evaluated in further field experiments. (author). 13 refs., 7 tabs., 12 figs

  13. An Overview of Plume Tracker: Mapping Volcanic Emissions with Interactive Radiative Transfer Modeling

    Science.gov (United States)

    Realmuto, V. J.; Berk, A.; Guiang, C.

    2014-12-01

    Infrared remote sensing is a vital tool for the study of volcanic plumes, and radiative transfer (RT) modeling is required to derive quantitative estimation of the sulfur dioxide (SO2), sulfate aerosol (SO4), and silicate ash (pulverized rock) content of these plumes. In the thermal infrared, we must account for the temperature, emissivity, and elevation of the surface beneath the plume, plume altitude and thickness, and local atmospheric temperature and humidity. Our knowledge of these parameters is never perfect, and interactive mapping allows us to evaluate the impact of these uncertainties on our estimates of plume composition. To enable interactive mapping, the Jet Propulsion Laboratory is collaborating with Spectral Sciences, Inc., (SSI) to develop the Plume Tracker toolkit. This project is funded by a NASA AIST Program Grant (AIST-11-0053) to SSI. Plume Tracker integrates (1) retrieval procedures for surface temperature and emissivity, SO2, NH3, or CH4 column abundance, and scaling factors for H2O vapor and O3 profiles, (2) a RT modeling engine based on MODTRAN, and (3) interactive visualization and analysis utilities under a single graphics user interface. The principal obstacle to interactive mapping is the computational overhead of the RT modeling engine. Under AIST-11-0053 we have achieved a 300-fold increase in the performance of the retrieval procedures through the use of indexed caches of model spectra, optimization of the minimization procedures, and scaling of the effects of surface temperature and emissivity on model radiance spectra. In the final year of AIST-11-0053 we will implement parallel processing to exploit multi-core CPUs and cluster computing, and optimize the RT engine to eliminate redundant calculations when iterating over a range of gas concentrations. These enhancements will result in an additional 8 - 12X increase in performance. In addition to the improvements in performance, we have improved the accuracy of the Plume Tracker

  14. Modeling Laser and e-Beam Generated Plasma-Plume Experiments Using LASNEX

    CERN Document Server

    Ho, D

    1999-01-01

    The hydrodynamics code LASNEX is used to model the laser and e-beam generated plasma-plume experiments. The laser used has a wavelength of 1 (micro)m and the FWHM spot size is 1 mm. The total laser energy is 160 mJ. The simulation shows that the plume expands at a velocity of about 6 cm/(micro)s. The e-beam generated from the Experimental Test Accelerator (ETA) has 5.5 MeV and FWHM spot size ranges from 2 to 3.3 mm. From the simulations, the plasma plume expansion velocity ranges from about 3 to 6 mm/(micro)s and the velocity increases with decreasing spot size. All the simulation results reported here are in close agreement with experimental data.

  15. Water Resources Research Program. Surface thermal plumes: evaluation of mathematical models for the near and complete field

    International Nuclear Information System (INIS)

    Dunn, W.E.; Policastro, A.J.; Paddock, R.A.

    1975-05-01

    This report evaluates mathematical models that may be used to predict the flow and temperature distributions resulting from heated surface discharges from power-plant outfalls. Part One discusses the basic physics of surface-plume dispersion and provides a critical review of 11 of the most popular and promising plume models developed to predict the near- and complete-field plume. The principal conclusion of the report is that the available models, in their present stage of development, may be used to give only general estimates of plume characteristics; precise predictions are not currently possible. The Shirazi-Davis and Pritchard (No. 1) models appear superior to the others tested and are capable of correctly predicting general plume characteristics. (The predictions show roughly factor-of-two accuracy in centerline distance to a given isotherm, factor-of-two accuracy in plume width, and factor-of-five accuracy in isotherm areas.) The state of the art can best be improved by pursuing basic laboratory studies of plume dispersion along with further development of numerical-modeling techniques

  16. Numerical modeling of continental lithospheric weak zone over plume

    Science.gov (United States)

    Perepechko, Y. V.; Sorokin, K. E.

    2011-12-01

    The work is devoted to the development of magmatic systems in the continental lithosphere over diffluent mantle plumes. The areas of tension originating over them are accompanied by appearance of fault zones, and the formation of permeable channels, which are distributed magmatic melts. The numerical simulation of the dynamics of deformation fields in the lithosphere due to convection currents in the upper mantle, and the formation of weakened zones that extend up to the upper crust and create the necessary conditions for the formation of intermediate magma chambers has been carried out. Thermodynamically consistent non-isothermal model simulates the processes of heat and mass transfer of a wide class of magmatic systems, as well as the process of strain localization in the lithosphere and their influence on the formation of high permeability zones in the lower crust. The substance of the lithosphere is a rheologic heterophase medium, which is described by a two-velocity hydrodynamics. This makes it possible to take into account the process of penetration of the melt from the asthenosphere into the weakened zone. The energy dissipation occurs mainly due to interfacial friction and inelastic relaxation of shear stresses. The results of calculation reveal a nonlinear process of the formation of porous channels and demonstrate the diversity of emerging dissipative structures which are determined by properties of both heterogeneous lithosphere and overlying crust. Mutual effect of a permeable channel and the corresponding filtration process of the melt on the mantle convection and the dynamics of the asthenosphere have been studied. The formation of dissipative structures in heterogeneous lithosphere above mantle plumes occurs in accordance with the following scenario: initially, the elastic behavior of heterophase lithosphere leads to the formation of the narrow weakened zone, though sufficiently extensive, with higher porosity. Further, the increase in the width of

  17. Numerical modeling of plasma plume evolution against ambient background gas in laser blow off experiments

    International Nuclear Information System (INIS)

    Patel, Bhavesh G.; Das, Amita; Kaw, Predhiman; Singh, Rajesh; Kumar, Ajai

    2012-01-01

    Two dimensional numerical modelling based on simplified hydrodynamic evolution for an expanding plasma plume (created by laser blow off) against an ambient background gas has been carried out. A comparison with experimental observations shows that these simulations capture most features of the plasma plume expansion. The plume location and other gross features are reproduced as per the experimental observation in quantitative detail. The plume shape evolution and its dependence on the ambient background gas are in good qualitative agreement with the experiment. This suggests that a simplified hydrodynamic expansion model is adequate for the description of plasma plume expansion.

  18. Simulation of Mexico City plumes during the MIRAGE-Mex field campaign using the WRF-Chem model

    Directory of Open Access Journals (Sweden)

    X. Tie

    2009-07-01

    Full Text Available The quantification of tropospheric O3 production in the downwind of the Mexico City plume is a major objective of the MIRAGE-Mex field campaign. We used a regional chemistry-transport model (WRF-Chem to predict the distribution of O3 and its precursors in Mexico City and the surrounding region during March 2006, and compared the model with in-situ aircraft measurements of O3, CO, VOCs, NOx, and NOy concentrations. The comparison shows that the model is capable of capturing the timing and location of the measured city plumes, and the calculated variability along the flights is generally consistent with the measured results, showing a rapid increase in O3 and its precursors when city plumes are detected. However, there are some notable differences between the calculated and measured values, suggesting that, during transport from the surface of the city to the outflow plume, ozone mixing ratios are underestimated by about 0–25% during different flights. The calculated O3-NOx, O3-CO, and O3-NOz correlations generally agree with the measured values, and the analyses of these correlations suggest that photochemical O3 production continues in the plume downwind of the city (aged plume, adding to the O3 already produced in the city and exported with the plume. The model is also used to quantify the contributions to OH reactivity from various compounds in the aged plume. This analysis suggests that oxygenated organics (OVOCs have the highest OH reactivity and play important roles for the O3 production in the aging plume. Furthermore, O3 production per NOx molecule consumed (O3 production efficiency is more efficient in the aged plume than in the young plume near the city. The major contributor to the high O3 production efficiency in the aged plume is the

  19. Numerical Modeling of Water Thermal Plumes Emitted by Thermal Power Plants

    Directory of Open Access Journals (Sweden)

    Azucena Durán-Colmenares

    2016-10-01

    Full Text Available This work focuses on the study of thermal dispersion of plumes emitted by power plants into the sea. Wastewater discharge from power stations causes impacts that require investigation or monitoring. A study to characterize the physical effects of thermal plumes into the sea is carried out here by numerical modeling and field measurements. The case study is the thermal discharges of the Presidente Adolfo López Mateos Power Plant, located in Veracruz, on the coast of the Gulf of Mexico. This plant is managed by the Federal Electricity Commission of Mexico. The physical effects of such plumes are related to the increase of seawater temperature caused by the hot water discharge of the plant. We focus on the implementation, calibration, and validation of the Delft3D-FLOW model, which solves the shallow-water equations. The numerical simulations consider a critical scenario where meteorological and oceanographic parameters are taken into account to reproduce the proper physical conditions of the environment. The results show a local physical effect of the thermal plumes within the study zone, given the predominant strong winds conditions of the scenario under study.

  20. Modeling and Mechanisms of Intercontinental Transport of Biomass-Burning Plumes

    Science.gov (United States)

    Reid, J. S.; Westphal, D. L.; Christopher, S. A.; Prins, E. M.; Justice, C. O.; Richardson, K. A.; Reid, E. A.; Eck, T. F.

    2003-12-01

    With the aid of fire products from GOES and MODIS, the NRL Aerosol Analysis and Prediction System (NAAPS) successfully monitors and predicts the formation and transport of massive smoke plumes between the continents in near real time. The goal of this system, formed under the joint Navy, NASA, and NOAA sponsored Fire Locating and Modeling of Burning Emissions (FLAMBE) project, is to provide 5 day forecasts of large biomass burning plumes and evaluate impacts on air quality, visibility, and regional radiative balance. In this paper we discuss and compare the mechanisms of intercontinental transport from the three most important sources in the world prone to long range advection: Africa, South/Central America, and Siberia. We demonstrate how these regions impact neighboring continents. As the meteorology of these three regions are distinct, differences in transport phenomenon subsequently result, particularly with respect to vertical distribution. Specific examples will be given on prediction and the impact of Siberian and Central American smoke plumes on the United States as well as transport phenomena from Africa to Australia. We present rules of thumb for radiation and air quality impacts. We also model clear sky bias (both positive and negative) with respect to MODIS data, and show the frequency to which frontal advection of smoke plumes masks remote sensing retrievals of smoke optical depth.

  1. Flowfield and Radiation Analysis of Missile Exhaust Plumes Using a Turbulent-Chemistry Interaction Model

    National Research Council Canada - National Science Library

    Calhoon, W. H; Kenzakowski, D. C

    2000-01-01

    ... components and missile defense systems. Current engineering level models neglect turbulent-chemistry interactions and typically underpredict the intensity of plume afterburning and afterburning burnout...

  2. Investigation of Balcony Plume Entrainment

    OpenAIRE

    Liu, F.; Nielsen, Peter V.; Heiselberg, Per; Brohus, Henrik; Li, B. Z.

    2009-01-01

    An investigation on the scenarios of the spill plume and its equation was presented in this paper. The study includes two aspects, i.e., the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the FDS (Fire Dynamic Simulation) and small scale model experiment results. Besides validating the spill model by experiments, the effect of different fire location on balcony plume is also discussed.The results show that the balcony equatio...

  3. The influence of model resolution on ozone in industrial volatile organic compound plumes.

    Science.gov (United States)

    Henderson, Barron H; Jeffries, Harvey E; Kim, Byeong-Uk; Vizuete, William G

    2010-09-01

    Regions with concentrated petrochemical industrial activity (e.g., Houston or Baton Rouge) frequently experience large, localized releases of volatile organic compounds (VOCs). Aircraft measurements suggest these released VOCs create plumes with ozone (O3) production rates 2-5 times higher than typical urban conditions. Modeling studies found that simulating high O3 productions requires superfine (1-km) horizontal grid cell size. Compared with fine modeling (4-kmin), the superfine resolution increases the peak O3 concentration by as much as 46%. To understand this drastic O3 change, this study quantifies model processes for O3 and "odd oxygen" (Ox) in both resolutions. For the entire plume, the superfine resolution increases the maximum O3 concentration 3% but only decreases the maximum Ox concentration 0.2%. The two grid sizes produce approximately equal Ox mass but by different reaction pathways. Derived sensitivity to oxides of nitrogen (NOx) and VOC emissions suggests resolution-specific sensitivity to NOx and VOC emissions. Different sensitivity to emissions will result in different O3 responses to subsequently encountered emissions (within the city or downwind). Sensitivity of O3 to emission changes also results in different simulated O3 responses to the same control strategies. Sensitivity of O3 to NOx and VOC emission changes is attributed to finer resolved Eulerian grid and finer resolved NOx emissions. Urban NOx concentration gradients are often caused by roadway mobile sources that would not typically be addressed with Plume-in-Grid models. This study shows that grid cell size (an artifact of modeling) influences simulated control strategies and could bias regulatory decisions. Understanding the dynamics of VOC plume dependence on grid size is the first step toward providing more detailed guidance for resolution. These results underscore VOC and NOx resolution interdependencies best addressed by finer resolution. On the basis of these results, the

  4. A regional scale model for ozone in the United States with subgrid representation of urban and power plant plumes

    International Nuclear Information System (INIS)

    Sillman, S.; Logan, J.A.; Wofsy, S.C.

    1990-01-01

    A new approach to modeling regional air chemistry is presented for application to industrialized regions such as the continental US. Rural chemistry and transport are simulated using a coarse grid, while chemistry and transport in urban and power plant plumes are represented by detailed subgrid models. Emissions from urban and power plant sources are processed in generalized plumes where chemistry and dilution proceed for 8-12 hours before mixing with air in a large resolution element. A realistic fraction of pollutants reacts under high-NO x conditions, and NO x is removed significantly before dispersal. Results from this model are compared with results from grid odels that do not distinguish plumes and with observational data defining regional ozone distributions. Grid models with coarse resolution are found to artificially disperse NO x over rural areas, therefore overestimating rural levels of both NO x and O 3 . Regional net ozone production is too high in coarse grid models, because production of O 3 is more efficient per molecule of NO x in the low-concentration regime of rural areas than in heavily polluted plumes from major emission sources. Ozone levels simulated by this model are shown to agree with observations in urban plumes and in rural regions. The model reproduces accurately average regional and peak ozone concentrations observed during a 4-day ozone episode. Computational costs for the model are reduced 25-to 100-fold as compared to fine-mesh models

  5. Entrainment by turbulent plumes

    Science.gov (United States)

    Parker, David; Burridge, Henry; Partridge, Jamie; Linden, Paul

    2017-11-01

    Plumes are of relevance to nature and real consequence to industry. While the Morton, Taylor & Turner (1956) plume model is able to estimate the mean physical flux parameters, the process of entrainment is only parametrised in a time-averaged sense and a deeper understanding is key to understanding how they evolve. Various flow configurations, resulting in different entrainment values, are considered; we perform simultaneous PIV and plume-edge detection on saline plumes in water resulting from a point source, a line source and a line source where a vertical wall is placed immediately adjacent. Of particular interest is the effect the large scale eddies, forming at the edge of the plume and engulfing ambient fluid, have on the entrainment process. By using velocity statistics in a coordinate system based on the instantaneous scalar edge of the plume the significance of this large scale engulfment is quantified. It is found that significant mass is transported outside the plumes, in particular in regions where large scale structures are absent creating regions of relatively high-momentum ambient fluid. This suggests that the large scale processes, whereby ambient fluid is engulfed into the plume, contribute significantly to the entrainment.

  6. The mantle-plume model, its feasibility and consequences

    NARCIS (Netherlands)

    Calsteren, van P.W.C.

    1981-01-01

    High beat-flow foci on the Earth have been named ‘hot-spots’ and are commonly correlated with ‘mantle-plumes’ in the deep. A mantle plume may be described as a portion of mantle material with a higher heat content than its surroundings. The intrusion of a mantle-plume is inferred to be similar to

  7. Multiphase CFD modeling of nearfield fate of sediment plumes

    DEFF Research Database (Denmark)

    Saremi, Sina; Hjelmager Jensen, Jacob

    2014-01-01

    Disposal of dredged material and the overflow discharge during the dredging activities is a matter of concern due to the potential risks imposed by the plumes on surrounding marine environment. This gives rise to accurately prediction of the fate of the sediment plumes released in ambient waters...

  8. Modeling of Heat Transfer and Ablation of Refractory Material Due to Rocket Plume Impingement

    Science.gov (United States)

    Harris, Michael F.; Vu, Bruce T.

    2012-01-01

    CR Tech's Thermal Desktop-SINDA/FLUINT software was used in the thermal analysis of a flame deflector design for Launch Complex 39B at Kennedy Space Center, Florida. The analysis of the flame deflector takes into account heat transfer due to plume impingement from expected vehicles to be launched at KSC. The heat flux from the plume was computed using computational fluid dynamics provided by Ames Research Center in Moffet Field, California. The results from the CFD solutions were mapped onto a 3-D Thermal Desktop model of the flame deflector using the boundary condition mapping capabilities in Thermal Desktop. The ablation subroutine in SINDA/FLUINT was then used to model the ablation of the refractory material.

  9. Mathematical modelling of thermal-plume interaction at Waterford Nuclear Power Station

    International Nuclear Information System (INIS)

    Tsai, S.Y.H.

    1981-01-01

    The Waldrop plume model was used to analyze the mixing and interaction of thermal effluents in the Mississippi River resulting from heated-water discharges from the Waterford Nuclear Power Station Unit 3 and from two nearby fossil-fueled power stations. The computer program of the model was modified and expanded to accommodate the multiple intake and discharge boundary conditions at the Waterford site. Numerical results of thermal-plume temperatures for individual and combined operation of the three power stations were obtained for typical low river flow (200,000 cfs) and maximum station operating conditions. The predicted temperature distributions indicated that the surface jet discharge from Waterford Unit 3 would interact with the thermal plumes produced by the two fossil-fueled stations. The results also showed that heat recirculation between the discharge of an upstream fossil-fueled plant and the intake of Waterford Unit 3 is to be expected. However, the resulting combined temperature distributions were found to be well within the thermal standards established by the state of Louisiana

  10. Martian methane plume models for defining Mars rover methane source search strategies

    Science.gov (United States)

    Nicol, Christopher; Ellery, Alex; Lynch, Brian; Cloutis, Ed

    2018-07-01

    The detection of atmospheric methane on Mars implies an active methane source. This introduces the possibility of a biotic source with the implied need to determine whether the methane is indeed biotic in nature or geologically generated. There is a clear need for robotic algorithms which are capable of manoeuvring a rover through a methane plume on Mars to locate its source. We explore aspects of Mars methane plume modelling to reveal complex dynamics characterized by advection and diffusion. A statistical analysis of the plume model has been performed and compared to analyses of terrestrial plume models. Finally, we consider a robotic search strategy to find a methane plume source. We find that gradient-based techniques are ineffective, but that more sophisticated model-based search strategies are unlikely to be available in near-term rover missions.

  11. Numerical analysis and modeling of plume meandering in passive scalar dispersion downstream of a wall-mounted cube

    International Nuclear Information System (INIS)

    Rossi, R.; Iaccarino, G.

    2013-01-01

    Highlights: • Scalar dispersion downstream of a wall-mounted cube is examined by DNS and RANS models. • Vortex-shedding and plume meandering are established in the wake of the cube. • Low-frequency modulation is observed in the vortex-shedding and plume meandering. • Counter-gradient transport takes place in the streamwise component of the scalar flux. • Concentration decay and plume spread improved by the unsteady RANS model. -- Abstract: A DNS database is employed to examine the onset of plume meandering downstream of a wall-mounted cube and to address the impact of large-scale unsteadiness in modeling dispersion using the RANS equations. The cube is immersed in a uniform stream where the thin boundary-layer developing over the flat plate is responsible for the onset of vortex-shedding in the wake of the bluff-body. Spectra of velocity and concentration fluctuations exhibit a prominent peak in the energy content at the same frequency, showing that the plume meandering is established by the action of the vortex-shedding. The vortex-shedding and plume meandering display a low-frequency modulation where coherent fluctuations are suppressed at times with a quasi-regular period. The onset of the low-frequency modulation is indicated by a secondary peak in the energy spectrum and confirmed by the autocorrelation of velocity and scalar fluctuations. Unsteady RANS simulations performed with the v 2 − f model are able to detect the onset of the plume meandering and show remarkable improvement of the predicted decay rate and rate of spread of the scalar plume when compared to steady RANS solutions. By computing explicitly the periodic component of velocity and scalar fluctuations, the unsteady v 2 − f model is able to provide a representation of scalar flux components consistent with DNS statistics, where the counter-gradient transport mechanism that takes place in the streamwise component is also captured by URANS results. Nonetheless, the agreement with DNS

  12. Initialization of the Euler model MODIS with field data from the 'EPRI plume model validation project'

    International Nuclear Information System (INIS)

    Petersen, G.; Eppel, D.; Lautenschlager, M.; Mueller, A.

    1985-01-01

    The program deck MODIS (''MOment DIStribution'') is designed to be used as operational tool for modelling the dispersion of a point source under general atmospheric conditions. The concentration distribution is determined by calculating its cross-wind moments on a vertical grid oriented in the main wind direction. The model contains a parametrization for horizontal and vertical coefficients based on a second order closure model. The Eulerian time scales, preliminary determined by fitting measured plume cross sections, are confirmed by comparison with data from the EPRI plume model validation project. (orig.) [de

  13. ALOFT-PC a smoke plume trajectory model for personal computers

    International Nuclear Information System (INIS)

    Walton, W.D.; McGrattan, K.B.; Mullin, J.V.

    1996-01-01

    A computer model, named ALOFT-PC, was developed for use during in-situ burning of oil spills to predict smoke plume trajectory. The downwind distribution of smoke particulate is a complex function of fire parameters, meteorological conditions, and topographic features. Experimental burns have shown that the downwind distribution of smoke is not Gaussian and simple smoke plume models do not capture the observed plume features. ALOFT-PC consists of the Navier-Stokes equations using an eddy viscosity over a uniform grid that spans the smoke plume and its surroundings. The model inputs are wind speed and variability, atmospheric temperature profile, and fire parameters and the output is the average of the plume. 7 refs., 3 tabs

  14. A New GPU-Enabled MODTRAN Thermal Model for the PLUME TRACKER Volcanic Emission Analysis Toolkit

    Science.gov (United States)

    Acharya, P. K.; Berk, A.; Guiang, C.; Kennett, R.; Perkins, T.; Realmuto, V. J.

    2013-12-01

    Real-time quantification of volcanic gaseous and particulate releases is important for (1) recognizing rapid increases in SO2 gaseous emissions which may signal an impending eruption; (2) characterizing ash clouds to enable safe and efficient commercial aviation; and (3) quantifying the impact of volcanic aerosols on climate forcing. The Jet Propulsion Laboratory (JPL) has developed state-of-the-art algorithms, embedded in their analyst-driven Plume Tracker toolkit, for performing SO2, NH3, and CH4 retrievals from remotely sensed multi-spectral Thermal InfraRed spectral imagery. While Plume Tracker provides accurate results, it typically requires extensive analyst time. A major bottleneck in this processing is the relatively slow but accurate FORTRAN-based MODTRAN atmospheric and plume radiance model, developed by Spectral Sciences, Inc. (SSI). To overcome this bottleneck, SSI in collaboration with JPL, is porting these slow thermal radiance algorithms onto massively parallel, relatively inexpensive and commercially-available GPUs. This paper discusses SSI's efforts to accelerate the MODTRAN thermal emission algorithms used by Plume Tracker. Specifically, we are developing a GPU implementation of the Curtis-Godson averaging and the Voigt in-band transmittances from near line center molecular absorption, which comprise the major computational bottleneck. The transmittance calculations were decomposed into separate functions, individually implemented as GPU kernels, and tested for accuracy and performance relative to the original CPU code. Speedup factors of 14 to 30× were realized for individual processing components on an NVIDIA GeForce GTX 295 graphics card with no loss of accuracy. Due to the separate host (CPU) and device (GPU) memory spaces, a redesign of the MODTRAN architecture was required to ensure efficient data transfer between host and device, and to facilitate high parallel throughput. Currently, we are incorporating the separate GPU kernels into a

  15. Gaussian model for emission rate measurement of heated plumes using hyperspectral data

    Science.gov (United States)

    Grauer, Samuel J.; Conrad, Bradley M.; Miguel, Rodrigo B.; Daun, Kyle J.

    2018-02-01

    This paper presents a novel model for measuring the emission rate of a heated gas plume using hyperspectral data from an FTIR imaging spectrometer. The radiative transfer equation (RTE) is used to relate the spectral intensity of a pixel to presumed Gaussian distributions of volume fraction and temperature within the plume, along a line-of-sight that corresponds to the pixel, whereas previous techniques exclusively presume uniform distributions for these parameters. Estimates of volume fraction and temperature are converted to a column density by integrating the local molecular density along each path. Image correlation velocimetry is then employed on raw spectral intensity images to estimate the volume-weighted normal velocity at each pixel. Finally, integrating the product of velocity and column density along a control surface yields an estimate of the instantaneous emission rate. For validation, emission rate estimates were derived from synthetic hyperspectral images of a heated methane plume, generated using data from a large-eddy simulation. Calculating the RTE with Gaussian distributions of volume fraction and temperature, instead of uniform distributions, improved the accuracy of column density measurement by 14%. Moreover, the mean methane emission rate measured using our approach was within 4% of the ground truth. These results support the use of Gaussian distributions of thermodynamic properties in calculation of the RTE for optical gas diagnostics.

  16. The tropospheric processing of acidic gases and hydrogen sulphide in volcanic gas plumes as inferred from field and model investigations

    Directory of Open Access Journals (Sweden)

    A. Aiuppa

    2007-01-01

    variations in the modelled SO2/HCl ratios were predicted under cloudy conditions, due to heterogeneous chlorine cycling in the aerosol phase. The modelled evolution of the SO2/H2S ratios is found to be substantially dependent on whether or not the interactions of H2S with halogens are included in the model. In the former case, H2S is assumed to be oxidized in the atmosphere mainly by OH, which results in minor chemical loss for H2S during plume aging and produces a fair match between modelled and measured SO2/H2S ratios. In the latter case, fast oxidation of H2S by Cl leads to H2S chemical lifetimes in the early plume of a few seconds, and thus SO2 to H2S ratios that increase sharply during plume transport. This disagreement between modelled and observed plume compositions suggests that more in-detail kinetic investigations are required for a proper evaluation of H2S chemical processing in volcanic plumes.

  17. Contaminant plume configuration and movement: an experimental model

    Science.gov (United States)

    Alencoao, A.; Reis, A.; Pereira, M. G.; Liberato, M. L. R.; Caramelo, L.; Amraoui, M.; Amorim, V.

    2009-04-01

    The relevance of Science and Technology in our daily routines makes it compulsory to educate citizens who have both scientific literacy and scientific knowledge. These will allow them to be intervening citizens in a constantly changing society. Thus, physical and natural sciences are included in school curricula, both in primary and secondary education, with the fundamental aim of developing in the students the skills, attitudes and knowledge needed for the understanding of the planet Earth and its real problems. On the other hand, teaching in Geosciences is more and more based on practical methodologies which use didactic material, sustaining teachers' pedagogical practices and facilitating students' learning tasks suggested on the syllabus defined for each school level. Themes related to exploring the different components of the Hydrological Cycle and themes related to natural environment protection and preservation, namely water resources and soil contamination by industrial and urban sewage are examples of subject matters included on the Portuguese syllabus. These topics motivated the conception and construction of experimental models for the study of the propagation of pollutants on a porous medium. The experimental models allow inducing a horizontal flux of water though different kinds of permeable substances (e.g. sand, silt), with contamination spots on its surface. These experimental activities facilitate the student to understand the flow path of contaminating substances on the saturated zone and to observe the contaminant plume configuration and movement. The activities are explored in a teaching and learning process perspective where the student builds its own knowledge through real question- problem based learning which relate Science, Technology and Society. These activities have been developed in the framework of project ‘Water in the Environment' (CV/PVI/0854) of the POCTI Program (Programa Operacional "Ciência, Tecnologia, Inovação") financed

  18. Descent and mixing of the overflow plume from Storfjord in Svalbard: an idealized numerical model study

    Directory of Open Access Journals (Sweden)

    I. Fer

    2008-05-01

    Full Text Available Storfjorden in the Svalbard Archipelago is a sill-fjord that produces significant volumes of dense, brine-enriched shelf water through ice formation. The dense water produced in the fjord overflows the sill and can reach deep into the Fram Strait. For conditions corresponding to a moderate ice production year, the pathway of the overflow, its descent and evolving water mass properties due to mixing are investigated for the first time using a high resolution 3-D numerical model. An idealized modeling approach forced by a typical annual cycle of buoyancy forcing due to ice production is chosen in a terrain-following vertical co-ordinate. Comparison with observational data, including hydrography, fine resolution current measurements and direct turbulence measurements using a microstructure profiler, gives confidence on the model performance. The model eddy diffusivity profiles contrasted to those inferred from the turbulence measurements give confidence on the skill of the Mellor Yamada scheme in representing sub-grid scale mixing for the Storfjorden overflow, and probably for gravity current modeling, in general. The Storfjorden overflow is characterized by low Froude number dynamics except at the shelf break where the plume narrows, accelerates with speed reaching 0.6 m s−1, yielding local Froude number in excess of unity. The volume flux of the plume increases by five-fold from the sill to downstream of the shelf-break. Rotational hydraulic control is not applicable for transport estimates at the sill using upstream basin information. To the leading order, geostrophy establishes the lateral slope of the plume interface at the sill. This allows for a transport estimate that is consistent with the model results by evaluating a weir relation at the sill.

  19. FOOTPRINT: A Screening Model for Estimating the Area of a Plume Produced From Gasoline Containing Ethanol

    Science.gov (United States)

    FOOTPRINT is a screening model used to estimate the length and surface area of benzene, toluene, ethylbenzene, and xylene (BTEX) plumes in groundwater, produced from a gasoline spill that contains ethanol.

  20. Coupled petrological-geodynamical modeling of a compositionally heterogeneous mantle plume

    Science.gov (United States)

    Rummel, Lisa; Kaus, Boris J. P.; White, Richard W.; Mertz, Dieter F.; Yang, Jianfeng; Baumann, Tobias S.

    2018-01-01

    Self-consistent geodynamic modeling that includes melting is challenging as the chemistry of the source rocks continuously changes as a result of melt extraction. Here, we describe a new method to study the interaction between physical and chemical processes in an uprising heterogeneous mantle plume by combining a geodynamic code with a thermodynamic modeling approach for magma generation and evolution. We pre-computed hundreds of phase diagrams, each of them for a different chemical system. After melt is extracted, the phase diagram with the closest bulk rock chemistry to the depleted source rock is updated locally. The petrological evolution of rocks is tracked via evolving chemical compositions of source rocks and extracted melts using twelve oxide compositional parameters. As a result, a wide variety of newly generated magmatic rocks can in principle be produced from mantle rocks with different degrees of depletion. The results show that a variable geothermal gradient, the amount of extracted melt and plume excess temperature affect the magma production and chemistry by influencing decompression melting and the depletion of rocks. Decompression melting is facilitated by a shallower lithosphere-asthenosphere boundary and an increase in the amount of extracted magma is induced by a lower critical melt fraction for melt extraction and/or higher plume temperatures. Increasing critical melt fractions activates the extraction of melts triggered by decompression at a later stage and slows down the depletion process from the metasomatized mantle. Melt compositional trends are used to determine melting related processes by focusing on K2O/Na2O ratio as indicator for the rock type that has been molten. Thus, a step-like-profile in K2O/Na2O might be explained by a transition between melting metasomatized and pyrolitic mantle components reproducible through numerical modeling of a heterogeneous asthenospheric mantle source. A potential application of the developed method

  1. A Plume Scale Model of Chlorinated Ethene Degradation

    DEFF Research Database (Denmark)

    Murray, Alexandra Marie; Broholm, Mette Martina; Badin, Alice

    leaked from a dry cleaning facility, and a 2 km plume extends from the source in an unconfined aquifer of homogenous fluvio-glacial sand. The area has significant iron deposits, most notably pyrite, which can abiotically degrade chlorinated ethenes. The source zone underwent thermal (steam) remediation...

  2. Observation of thermal plumes from submerged discharges in the Great Lakes and their implications for modeling and monitoring

    International Nuclear Information System (INIS)

    Ditmars, J.D.; Paddock, R.A.; Frigo, A.A.

    1977-01-01

    Measurements of thermal plumes from submerged discharges of power plant cooling waters into the Great Lakes provide the opportunity to view the mixing processes at prototype scales and to observe the effects of the ambient environment on those processes. Examples of thermal plume behavior in Great Lakes' ambient environments are presented to demonstrate the importance of measurements of the detailed structure of the ambient environment, as well as of the plumes, for interpretation of prototype data for modeling and monitoring purposes. The examples are drawn from studies by Argonne National Laboratory (ANL) at the Zion Nuclear PowerStation and the D. C. Cook Nuclear Plant on Lake Michigan and at the J. A. FitzPatrick Nuclear Power Plant on Lake Ontario. These studies included measurements of water temperatures from a moving boat which provide a quasi-synoptic view of the three-dimensional temperature structure of the thermal plume and ambient water environment. Additional measurements of water velocities, which are made with continuously recording, moored, and profiling current meters, and of wind provide data on the detailed structure of the ambient environment. The detailed structure of the ambient environment, in terms of current, current shear, variable winds, and temperature stratification, often influence greatly thermal plume behavior. Although predictive model techniques and monitoring objectives often ignore the detailed aspects of the ambient environment, useful interpretation of prototype data for model evaluation or calibration and monitoring purposes requires detailed measurement of the ambient environment. Examination of prototype thermal plume data indicates that, in several instances, attention to only the gross characteristics of the ambient environment can be misleading and could result in significant errors in model calibration and extrapolation of data bases gathered in monitoring observations

  3. The importance of vertical resolution in the free troposphere for modeling intercontinental plumes

    Science.gov (United States)

    Zhuang, Jiawei; Jacob, Daniel J.; Eastham, Sebastian D.

    2018-05-01

    Chemical plumes in the free troposphere can preserve their identity for more than a week as they are transported on intercontinental scales. Current global models cannot reproduce this transport. The plumes dilute far too rapidly due to numerical diffusion in sheared flow. We show how model accuracy can be limited by either horizontal resolution (Δx) or vertical resolution (Δz). Balancing horizontal and vertical numerical diffusion, and weighing computational cost, implies an optimal grid resolution ratio (Δx / Δz)opt ˜ 1000 for simulating the plumes. This is considerably higher than current global models (Δx / Δz ˜ 20) and explains the rapid plume dilution in the models as caused by insufficient vertical resolution. Plume simulations with the Geophysical Fluid Dynamics Laboratory Finite-Volume Cubed-Sphere Dynamical Core (GFDL-FV3) over a range of horizontal and vertical grid resolutions confirm this limiting behavior. Our highest-resolution simulation (Δx ≈ 25 km, Δz ≈ 80 m) preserves the maximum mixing ratio in the plume to within 35 % after 8 days in strongly sheared flow, a drastic improvement over current models. Adding free tropospheric vertical levels in global models is computationally inexpensive and would also improve the simulation of water vapor.

  4. The importance of vertical resolution in the free troposphere for modeling intercontinental plumes

    Directory of Open Access Journals (Sweden)

    J. Zhuang

    2018-05-01

    Full Text Available Chemical plumes in the free troposphere can preserve their identity for more than a week as they are transported on intercontinental scales. Current global models cannot reproduce this transport. The plumes dilute far too rapidly due to numerical diffusion in sheared flow. We show how model accuracy can be limited by either horizontal resolution (Δx or vertical resolution (Δz. Balancing horizontal and vertical numerical diffusion, and weighing computational cost, implies an optimal grid resolution ratio (Δx ∕ Δzopt ∼ 1000 for simulating the plumes. This is considerably higher than current global models (Δx ∕ Δz ∼ 20 and explains the rapid plume dilution in the models as caused by insufficient vertical resolution. Plume simulations with the Geophysical Fluid Dynamics Laboratory Finite-Volume Cubed-Sphere Dynamical Core (GFDL-FV3 over a range of horizontal and vertical grid resolutions confirm this limiting behavior. Our highest-resolution simulation (Δx ≈ 25 km, Δz  ≈  80 m preserves the maximum mixing ratio in the plume to within 35 % after 8 days in strongly sheared flow, a drastic improvement over current models. Adding free tropospheric vertical levels in global models is computationally inexpensive and would also improve the simulation of water vapor.

  5. Modeling ozone plumes observed downwind of New York City over the North Atlantic Ocean during the ICARTT field campaign

    Directory of Open Access Journals (Sweden)

    S.-H. Lee

    2011-07-01

    Full Text Available Transport and chemical transformation of well-defined New York City (NYC urban plumes over the North Atlantic Ocean were studied using aircraft measurements collected on 20–21 July 2004 during the ICARTT (International Consortium for Atmospheric Research on Transport and Transformation field campaign and WRF-Chem (Weather Research and Forecasting-Chemistry model simulations. The strong NYC urban plumes were characterized by carbon monoxide (CO mixing ratios of 350–400 parts per billion by volume (ppbv and ozone (O3 levels of about 100 ppbv near New York City on 20 July in the WP-3D in-situ and DC-3 lidar aircraft measurements. On 21 July, the two aircraft captured strong urban plumes with about 350 ppbv CO and over 150 ppbv O3 (~160 ppbv maximum about 600 km downwind of NYC over the North Atlantic Ocean. The measured urban plumes extended vertically up to about 2 km near New York City, but shrank to 1–1.5 km over the stable marine boundary layer (MBL over the North Atlantic Ocean. The WRF-Chem model reproduced ozone formation processes, chemical characteristics, and meteorology of the measured urban plumes near New York City (20 July and in the far downwind region over the North Atlantic Ocean (21 July. The quasi-Lagrangian analysis of transport and chemical transformation of the simulated NYC urban plumes using WRF-Chem results showed that the pollutants can be efficiently transported in (isentropic layers in the lower atmosphere (<2–3 km over the North Atlantic Ocean while maintaining a dynamic vertical decoupling by cessation of turbulence in the stable MBL. The O3 mixing ratio in the NYC urban plumes remained at 80–90 ppbv during nocturnal transport over the stable MBL, then grew to over 100 ppbv by daytime oxidation of nitrogen oxides (NOx = NO + NO2 with mixing ratios on the order of 1 ppbv. Efficient transport of reactive nitrogen species (NOy, specifically nitric

  6. 3D Numerical Model of Continental Breakup via Plume Lithosphere Interaction Near Cratonic Blocks: Implications for the Tanzanian Craton

    Science.gov (United States)

    Koptev, A.; Calais, E.; Burov, E. B.; Leroy, S. D.; Gerya, T.

    2014-12-01

    Although many continental rift basins and their successfully rifted counterparts at passive continental margins are magmatic, some are not. This dichotomy prompted end-member views of the mechanism driving continental rifting, deep-seated and mantle plume-driven for some, owing to shallow lithospheric stretching for others. In that regard, the East African Rift (EAR), the 3000 km-long divergent boundary between the Nubian and Somalian plates, provides a unique setting with the juxtaposition of the eastern, magma-rich, and western, magma-poor, branches on either sides of the 250-km thick Tanzanian craton. Here we implement high-resolution rheologically realistic 3D numerical model of plume-lithosphere interactions in extensional far-field settings to explain this contrasted behaviour in a unified framework starting from simple, symmetrical initial conditions with an isolated mantle plume rising beneath a craton in an east-west tensional far field stress. The upwelling mantle plume is deflected by the cratonic keel and preferentially channelled along one of its sides. This leads to the coeval development of a magma-rich branch above the plume head and a magma-poor one along the opposite side of the craton, the formation of a rotating microplate between the two rift branches, and the feeding of melt to both branches form a single mantle source. The model bears strong similarities with the evolution of the eastern and western branches of the central EAR and the geodetically observed rotation of the Victoria microplate. This result reconciles the passive (plume-activated) versus active (far-field tectonic stresses) rift models as our experiments shows both processes in action and demonstrate the possibility of developing both magmatic and amagmatic rifts in identical geotectonic environments.

  7. Modelling the possible interaction between edge-driven convection and the Canary Islands mantle plume

    Science.gov (United States)

    Negredo, A. M.; Rodríguez-González, J.; Fullea, J.; Van Hunen, J.

    2017-12-01

    The close location between many hotspots and the edges of cratonic lithosphere has led to the hypothesis that these hotspots could be explained by small-scale mantle convection at the edge of cratons (Edge Driven Convection, EDC). The Canary Volcanic Province hotspot represents a paradigmatic example of this situation due to its close location to the NW edge of the African Craton. Geochemical evidence, prominent low seismic velocity anomalies in the upper and lower mantle, and the rough NE-SW age-progression of volcanic centers consistently point out to a deep-seated mantle plume as the origin of the Canary Volcanic Province. It has been hypothesized that the plume material could be affected by upper mantle convection caused by the thermal contrast between thin oceanic lithosphere and thick (cold) African craton. Deflection of upwelling blobs due to convection currents would be responsible for the broader and more irregular pattern of volcanism in the Canary Province compared to the Madeira Province. In this study we design a model setup inspired on this scenario to investigate the consequences of possible interaction between ascending mantle plumes and EDC. The Finite Element code ASPECT is used to solve convection in a 2D box. The compositional field and melt fraction distribution are also computed. Free slip along all boundaries and constant temperature at top and bottom boundaries are assumed. The initial temperature distribution assumes a small long-wavelength perturbation. The viscosity structure is based on a thick cratonic lithosphere progressively varying to a thin, or initially inexistent, oceanic lithosphere. The effects of assuming different rheologies, as well as steep or gradual changes in lithospheric thickness are tested. Modelling results show that a very thin oceanic lithosphere (models assuming temperature-dependent viscosity and large viscosity variations evolve to large-scale (upper mantle) convection cells, with upwelling of hot material being

  8. Expansion dynamics and equilibrium conditions in a laser ablation plume of lithium: Modeling and experiment

    International Nuclear Information System (INIS)

    Stapleton, M.W.; McKiernan, A.P.; Mosnier, J.-P.

    2005-01-01

    The gas dynamics and atomic kinetics of a laser ablation plume of lithium, expanding adiabatically in vacuum, are included in a numerical model, using isothermal and isentropic self-similar analytical solutions and steady-state collisional radiative equations, respectively. Measurements of plume expansion dynamics using ultrafast imaging for various laser wavelengths (266-1064 nm), fluences (2-6.5 J cm -2 ), and spot sizes (50-1000 μm) are performed to provide input parameters for the model and, thereby, study the influence of laser spot size, wavelength, and fluence, respectively, on both the plume expansion dynamics and atomic kinetics. Target recoil pressure, which clearly affects plume dynamics, is included in the model. The effects of laser wavelength and spot size on plume dynamics are discussed in terms of plasma absorption of laser light. A transition from isothermal to isentropic behavior for spot sizes greater than 50 μm is clearly evidenced. Equilibrium conditions are found to exist only up to 300 ns after the plume creation, while complete local thermodynamic equilibrium is found to be confined to the very early parts of the expansion

  9. Results of the eruptive column model inter-comparison study

    Science.gov (United States)

    Costa, Antonio; Suzuki, Yujiro; Cerminara, M.; Devenish, Ben J.; Esposti Ongaro, T.; Herzog, Michael; Van Eaton, Alexa; Denby, L.C.; Bursik, Marcus; de' Michieli Vitturi, Mattia; Engwell, S.; Neri, Augusto; Barsotti, Sara; Folch, Arnau; Macedonio, Giovanni; Girault, F.; Carazzo, G.; Tait, S.; Kaminski, E.; Mastin, Larry G.; Woodhouse, Mark J.; Phillips, Jeremy C.; Hogg, Andrew J.; Degruyter, Wim; Bonadonna, Costanza

    2016-01-01

    This study compares and evaluates one-dimensional (1D) and three-dimensional (3D) numerical models of volcanic eruption columns in a set of different inter-comparison exercises. The exercises were designed as a blind test in which a set of common input parameters was given for two reference eruptions, representing a strong and a weak eruption column under different meteorological conditions. Comparing the results of the different models allows us to evaluate their capabilities and target areas for future improvement. Despite their different formulations, the 1D and 3D models provide reasonably consistent predictions of some of the key global descriptors of the volcanic plumes. Variability in plume height, estimated from the standard deviation of model predictions, is within ~ 20% for the weak plume and ~ 10% for the strong plume. Predictions of neutral buoyancy level are also in reasonably good agreement among the different models, with a standard deviation ranging from 9 to 19% (the latter for the weak plume in a windy atmosphere). Overall, these discrepancies are in the range of observational uncertainty of column height. However, there are important differences amongst models in terms of local properties along the plume axis, particularly for the strong plume. Our analysis suggests that the simplified treatment of entrainment in 1D models is adequate to resolve the general behaviour of the weak plume. However, it is inadequate to capture complex features of the strong plume, such as large vortices, partial column collapse, or gravitational fountaining that strongly enhance entrainment in the lower atmosphere. We conclude that there is a need to more accurately quantify entrainment rates, improve the representation of plume radius, and incorporate the effects of column instability in future versions of 1D volcanic plume models.

  10. Comparing the performance of geostatistical models with additional information from covariates for sewage plume characterization.

    Science.gov (United States)

    Del Monego, Maurici; Ribeiro, Paulo Justiniano; Ramos, Patrícia

    2015-04-01

    In this work, kriging with covariates is used to model and map the spatial distribution of salinity measurements gathered by an autonomous underwater vehicle in a sea outfall monitoring campaign aiming to distinguish the effluent plume from the receiving waters and characterize its spatial variability in the vicinity of the discharge. Four different geostatistical linear models for salinity were assumed, where the distance to diffuser, the west-east positioning, and the south-north positioning were used as covariates. Sample variograms were fitted by the Matèrn models using weighted least squares and maximum likelihood estimation methods as a way to detect eventual discrepancies. Typically, the maximum likelihood method estimated very low ranges which have limited the kriging process. So, at least for these data sets, weighted least squares showed to be the most appropriate estimation method for variogram fitting. The kriged maps show clearly the spatial variation of salinity, and it is possible to identify the effluent plume in the area studied. The results obtained show some guidelines for sewage monitoring if a geostatistical analysis of the data is in mind. It is important to treat properly the existence of anomalous values and to adopt a sampling strategy that includes transects parallel and perpendicular to the effluent dispersion.

  11. Modeling investigation of the nutrient and phytoplankton variability in the Chesapeake Bay outflow plume

    Science.gov (United States)

    Jiang, Long; Xia, Meng

    2018-03-01

    The Chesapeake Bay outflow plume (CBOP) is the mixing zone between Chesapeake Bay and less eutrophic continental shelf waters. Variations in phytoplankton distribution in the CBOP are critical to the fish nursery habitat quality and ecosystem health; thus, an existing hydrodynamic-biogeochemical model for the bay and the adjacent coastal ocean was applied to understand the nutrient and phytoplankton variability in the plume and the dominant environmental drivers. The simulated nutrient and chlorophyll a distribution agreed well with field data and real-time satellite imagery. Based on the model calculation, the net dissolved inorganic nitrogen (DIN) and phosphorus (DIP) flux at the bay mouth was seaward and landward during 2003-2012, respectively. The CBOP was mostly nitrogen-limited because of the relatively low estuarine DIN export. The highest simulated phytoplankton biomass generally occurred in spring in the near field of the plume. Streamflow variations could regulate the estuarine residence time, and thus modulate nutrient export and phytoplankton biomass in the plume area; in comparison, changing nutrient loading with fixed streamflow had a less extensive impact, especially in the offshore and far-field regions. Correlation analyses and numerical experiments revealed that southerly winds on the shelf were effective in promoting the offshore plume expansion and phytoplankton accumulation. Climate change including precipitation and wind pattern shifts is likely to complicate the driving mechanisms of phytoplankton variability in the plume region.

  12. Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

    Science.gov (United States)

    Mena, Francisco; Bond, Tami C.; Riemer, Nicole

    2017-08-01

    Residential biofuel combustion is an important source of aerosols and gases in the atmosphere. The change in cloud characteristics due to biofuel burning aerosols is uncertain, in part, due to the uncertainty in the added number of cloud condensation nuclei (CCN) from biofuel burning. We provide estimates of the CCN activity of biofuel burning aerosols by explicitly modeling plume dynamics (coagulation, condensation, chemical reactions, and dilution) in a young biofuel burning plume from emission until plume exit, defined here as the condition when the plume reaches ambient temperature and specific humidity through entrainment. We found that aerosol-scale dynamics affect CCN activity only during the first few seconds of evolution, after which the CCN efficiency reaches a constant value. Homogenizing factors in a plume are co-emission of semi-volatile organic compounds (SVOCs) or emission at small particle sizes; SVOC co-emission can be the main factor determining plume-exit CCN for hydrophobic or small particles. Coagulation limits emission of CCN to about 1016 per kilogram of fuel. Depending on emission factor, particle size, and composition, some of these particles may not activate at low supersaturation (ssat). Hygroscopic Aitken-mode particles can contribute to CCN through self-coagulation but have a small effect on the CCN activity of accumulation-mode particles, regardless of composition differences. Simple models (monodisperse coagulation and average hygroscopicity) can be used to estimate plume-exit CCN within about 20 % if particles are unimodal and have homogeneous composition, or when particles are emitted in the Aitken mode even if they are not homogeneous. On the other hand, if externally mixed particles are emitted in the accumulation mode without SVOCs, an average hygroscopicity overestimates emitted CCN by up to a factor of 2. This work has identified conditions under which particle populations become more homogeneous during plume processes. This

  13. Using MOPITT data and a Chemistry and Transport Model to Investigate Injection Height of Plumes from Boreal Forest Fires

    Science.gov (United States)

    Hyer, E. J.; Allen, D. J.; Kasischke, E. S.; Warner, J. X.

    2003-12-01

    Trace gas emissions from boreal forest fires are a significant factor in atmospheric composition and its interannual variability. A number of recent observations of emissions plumes above individual fire events (Fromm and Servranckx, 2003; COBRA 2003; Lamarque et al., 2003; Wotawa and Trainer, 2000) suggest that vertical properties of forest fire emission plumes can be very different from fossil fuel emission plumes. Understanding and constraining the vertical properties of forest fire emission plumes and their injection into the atmosphere during fire events is critical for accurate modeling of atmospheric transport and chemistry. While excellent data have been collected in a handful of experiments on individual fire events, a systematic examination of the range of behavior observed in fire events has been hampered by the scarcity of vertical profiles of atmospheric composition. In this study, we used a high-resolution model of boreal forest fire emissions (Kasischke et al, in review) as input to the Goddard/UM CTM driven by the GEOS-3 DAS, operating at 2 by 2.5 degrees with 35 vertical levels. We modeled atmospheric injection and transport of CO emissions during the fire season of 2000 (May-September). We altered the parameters of the model to simulate a range of scenarios of plume injection, and compared the resulting output to the CO profiles from the MOPITT instrument. The results presented here pertain to the boreal forest, but our methods should be useful for atmospheric modelers hoping to more realistically model transport of emission plumes from biomass burning. References: COBRA2003: see http://www.fas.harvard.edu/~cobra/smoke_canada_030530.pdf Fromm, M. and R. Servranckx, 2003. "Stratospheric Injection of Forest Fire Emissions on August 4, 1998: A Satellite Image Analysis of the Causal Supercell Convection." Geophysical Research Abstracts 5:13118. Kasischke, E.S.; E.J. Hyer, N.H.F. French, A.I. Sukhinin, J.H. Hewson, B.J. Stocks, in review. "Carbon

  14. Automated Generation of 3D Volcanic Gas Plume Models for Geobrowsers

    Science.gov (United States)

    Wright, T. E.; Burton, M.; Pyle, D. M.

    2007-12-01

    A network of five UV spectrometers on Etna automatically gathers column amounts of SO2 during daylight hours. Near-simultaneous scans from adjacent spectrometers, comprising 210 column amounts in total, are then converted to 2D slices showing the spatial distribution of the gas by tomographic reconstruction. The trajectory of the plume is computed using an automatically-submitted query to NOAA's HYSPLIT Trajectory Model. This also provides local estimates of air temperature, which are used to determine the atmospheric stability and therefore the degree to which the plume is dispersed by turbulence. This information is sufficient to construct an animated sequence of models which show how the plume is advected and diffused over time. These models are automatically generated in the Collada Digital Asset Exchange format and combined into a single file which displays the evolution of the plume in Google Earth. These models are useful for visualising and predicting the shape and distribution of the plume for civil defence, to assist field campaigns and as a means of communicating some of the work of volcano observatories to the public. The Simultaneous Algebraic Reconstruction Technique is used to create the 2D slices. This is a well-known method, based on iteratively updating a forward model (from 2D distribution to column amounts). Because it is based on a forward model, it also provides a simple way to quantify errors.

  15. Airborne Detection and Dynamic Modeling of Carbon Dioxide and Methane Plumes

    Science.gov (United States)

    Jacob, Jamey; Mitchell, Taylor; Whyte, Seabrook

    2015-11-01

    To facilitate safe storage of greenhouse gases such as CO2 and CH4, airborne monitoring is investigated. Conventional soil gas monitoring has difficulty in distinguishing gas flux signals from leakage with those associated with meteorologically driven changes. A low-cost, lightweight sensor system has been developed and implemented onboard a small unmanned aircraft that measures gas concentration and is combined with other atmospheric diagnostics, including thermodynamic data and velocity from hot-wire and multi-hole probes. To characterize the system behavior and verify its effectiveness, field tests have been conducted over controlled rangeland burns and over simulated leaks. In the former case, since fire produces carbon dioxide over a large area, this was an opportunity to test in an environment that while only vaguely similar to a carbon sequestration leak source, also exhibits interesting plume behavior. In the simulated field tests, compressed gas tanks are used to mimic leaks and generate gaseous plumes. Since the sensor response time is a function of vehicle airspeed, dynamic calibration models are required to determine accurate location of gas concentration in (x , y , z , t) . Results are compared with simulations using combined flight and atmospheric dynamic models. Supported by Department of Energy Award DE-FE0012173.

  16. First results of the Piton de la Fournaise STRAP 2015 experiment: multidisciplinary tracking of a volcanic gas and aerosol plume

    Science.gov (United States)

    Tulet, Pierre; Di Muro, Andréa; Colomb, Aurélie; Denjean, Cyrielle; Duflot, Valentin; Arellano, Santiago; Foucart, Brice; Brioude, Jérome; Sellegri, Karine; Peltier, Aline; Aiuppa, Alessandro; Barthe, Christelle; Bhugwant, Chatrapatty; Bielli, Soline; Boissier, Patrice; Boudoire, Guillaume; Bourrianne, Thierry; Brunet, Christophe; Burnet, Fréderic; Cammas, Jean-Pierre; Gabarrot, Franck; Galle, Bo; Giudice, Gaetano; Guadagno, Christian; Jeamblu, Fréderic; Kowalski, Philippe; Leclair de Bellevue, Jimmy; Marquestaut, Nicolas; Mékies, Dominique; Metzger, Jean-Marc; Pianezze, Joris; Portafaix, Thierry; Sciare, Jean; Tournigand, Arnaud; Villeneuve, Nicolas

    2017-04-01

    The STRAP (Synergie Transdisciplinaire pour Répondre aux Aléas liés aux Panaches volcaniques) campaign was conducted over the entire year of 2015 to investigate the volcanic plumes of Piton de La Fournaise (La Réunion, France). For the first time, measurements at the local (near the vent) and at the regional scales were conducted around the island. The STRAP 2015 campaign has become possible thanks to strong cross-disciplinary collaboration between volcanologists and meteorologists. The main observations during four eruptive periods (85 days) are summarised. They include the estimates of SO2, CO2 and H2O emissions, the altitude of the plume at the vent and over different areas of La Réunion Island, the evolution of the SO2 concentration, the aerosol size distribution and the aerosol extinction profile. A climatology of the volcanic plume dispersion is also reported. Simulations and measurements show that the plumes formed by weak eruptions have a stronger interaction with the surface of the island. Strong SO2 mixing ratio and particle concentrations above 1000 ppb and 50 000 cm-3 respectively are frequently measured over a distance of 20 km from Piton de la Fournaise. The measured aerosol size distribution shows the predominance of small particles in the volcanic plume. Several cases of strong nucleation of sulfuric acid have been observed within the plume and at the distal site of the Maïdo observatory. The STRAP 2015 campaign provides a unique set of multi-disciplinary data that can now be used by modellers to improve the numerical parameterisations of the physical and chemical evolution of the volcanic plumes.

  17. Modelling the transport of suspended particulate matter by the Rhone River plume (France). Implications for pollutant dispersion

    International Nuclear Information System (INIS)

    Perianez, R.

    2005-01-01

    A model to simulate the transport of suspended particulate matter by the Rhone River plume has been developed. The model solves the 3D hydrodynamic equations, including baroclinic terms and a 1-equation turbulence model, and the suspended matter equations including advection/diffusion of particles, settling and deposition. Four particle classes are considered simultaneously according to observations in the Rhone. Computed currents, salinity and particle distributions are, in general, in good agreement with observations or previous calculations. The model also provides sedimentation rates and the distribution of different particle classes over the sea bed. It has been found that high sedimentation rates close to the river mouth are due to coarse particles that sink rapidly. Computed sedimentation rates are also similar to those derived from observations. The model has been applied to simulate the transport of radionuclides by the plume, since suspended matter is the main vector for them. The radionuclide transport model, previously described and validated, includes exchanges of radionuclides between water, suspended matter and bottom sediment described in terms of kinetic rates. A new feature is the explicit inclusion of the dependence of kinetic rates upon salinity. The model has been applied to 137 Cs and 239,240 Pu. Results are, in general, in good agreement with observations. - A model has been developed to simulate transport of suspended particulate matter in the Rhone River plume

  18. Visual plumes coastal dispersion modeling in southwest Sabah ...

    African Journals Online (AJOL)

    In theory, the dilution capacity of open waters, particularly coastal areas, straits and oceans are enormous. This means that for surface and sub-merged ... Prior to the modeling exercise, field data pertaining to ambient water quality, hydraulic characteristics and tide patterns were collected. The modeling results indicated that ...

  19. Late Cenozoic Samtskhe-Javakheti Volcanic Highland, Georgia:The Result of Mantle Plumes Activity

    Science.gov (United States)

    Okrostsvaridze, Avtandil

    2017-04-01

    intraplate volcanic ridge. Based on our studies, we assume that the Samtskhe-Javakheti volcanic highland is a result of full cycle mantle plume activity and not of by adiabatic decompression melting of the asthenosphere, as it is considered at present (Keskin, 2007). Therefore, we assume that this volcanic highland is a Northern marginal manifestation of the Eastern Africa-Red Sea -Anatolia mantle plume flow. If we accept this idea, then the Pliocene-Pleistocene Samtskhe-Javakheti volcanic highland is the youngest continental mantle plume formation of the Earth. REFERENCES Keskin M., 2007. Eastern Anatolia: a hotspot in a collision zone without a mantle plume. Geological Society of America, Special Paper 430, pp. 693 - 722. Okrostsavridze A., Popkhadze A., Kirkitadze G., 2016. Megavolcano in the Late Cenozoic Samtckhe-Javakheti Volcanic Province? In procceding of 6th workshop on Collapse Caldera, Hokkaido, Japan. p. 42-43.

  20. Export of reactive nitrogen from coal-fired power plants in the U.S.: Estimates from a plume-in-grid modeling study - article no. D04308

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaraghavan, K.; Zhang, Y.; Seigneur, C.; Karamchandani, P.; Snell, H.E.

    2009-02-15

    The export of reactive nitrogen (nitrogen oxides and their oxidation products, collectively referred to as NOy) from coal-fired power plants in the U.S. to the rest of the world could have a significant global contribution to ozone. Traditional Eulerian gridded air quality models cannot characterize accurately the chemistry and transport of plumes from elevated point sources such as power plant stacks. A state-of-the-science plume-in-grid (PinG) air quality model, a reactive plume model embedded in an Eulerian gridded model, is used to estimate the export of NOy from 25 large coal-fired power plants in the U. S. (in terms of NOx and SO{sub 2} emissions) in July 2001 to the global atmosphere. The PinG model used is the Community Multiscale Air Quality Model with Advanced Plume Treatment (CMAQ-APT). A benchmark simulation with only the gridded model, CMAQ, is also conducted for comparison purposes. The simulations with and without advanced plume treatment show differences in the calculated export of NOy from the 25 plants considered reflecting the effect of using a detailed and explicit treatment of plume transport and chemistry. The advanced plume treatment results in 31% greater simulated export of NOy compared to the purely grid-based modeling approach. The export efficiency of NOy (the fraction of NOy emitted that is exported) is predicted to be 21% without APT and 27% with APT. When considering only export through the eastern boundary across the Atlantic, CMAQ-APT predicts that the export efficiency is 24% and that 2% of NOy is exported as NOx, 49% as inorganic nitrate, and 25% as PAN. These results are in reasonably good agreement with an analysis reported in the literature of aircraft measurements over the North Atlantic.

  1. Observation and modeling of the evolution of Texas power plant plumes

    Directory of Open Access Journals (Sweden)

    W. Zhou

    2012-01-01

    Full Text Available During the second Texas Air Quality Study 2006 (TexAQS II, a full range of pollutants was measured by aircraft in eastern Texas during successive transects of power plant plumes (PPPs. A regional photochemical model is applied to simulate the physical and chemical evolution of the plumes. The observations reveal that SO2 and NOy were rapidly removed from PPPs on a cloudy day but not on the cloud-free days, indicating efficient aqueous processing of these compounds in clouds. The model reasonably represents observed NOx oxidation and PAN formation in the plumes, but fails to capture the rapid loss of SO2 (0.37 h−1 and NOy (0.24 h−1 in some plumes on the cloudy day. Adjustments to the cloud liquid water content (QC and the default metal concentrations in the cloud module could explain some of the SO2 loss. However, NOy in the model was insensitive to QC. These findings highlight cloud processing as a major challenge to atmospheric models. Model-based estimates of ozone production efficiency (OPE in PPPs are 20–50 % lower than observation-based estimates for the cloudy day.

  2. Modelling of plume chemistry of high flying aircraft with H2 combustion engines

    International Nuclear Information System (INIS)

    Weibring, G.; Zellner, R.

    1993-01-01

    Emissions from hydrogen fueled aircraft engines include large concentrations of radicals such as NO, OH, O and H. We describe the result of modelling studies in which the evolution of the radical chemistry in an expanding and cooling plume for three different mixing velocities is evaluated. The simulations were made for hydrogen combustion engines at an altitude of 26 km. For the fastest mixing conditions, the radical concentrations decrease only because of dilution with the ambient air, since the time for chemical reaction is too short. With lower mixing velocities, however, larger chemical conversions were determined. For the slowest mixing conditions the unburned hydrogen is converted into water. As a consequence the radicals O and OH increase considerably around 1400 K. The only exception being NO, for which no chemical change during the expansion is found. The concentrations of the reservoir molecules like H 2 O 2 , N 2 O 5 or HNO 3 have been calculated to remain relatively small. (orig.)

  3. Footprint (A Screening Model for Estimating the Area of a Plume Produced from Gasoline Containing Ethanol

    Science.gov (United States)

    FOOTPRINT is a simple and user-friendly screening model to estimate the length and surface area of BTEX plumes in ground water produced from a spill of gasoline that contains ethanol. Ethanol has a potential negative impact on the natural biodegradation of BTEX compounds in groun...

  4. Modeling Emissions and Vertical Plume Transport of Crop Residue Burning Experiments in the Pacific Northwest

    Science.gov (United States)

    Zhou, L.; Baker, K. R.; Napelenok, S. L.; Pouliot, G.; Elleman, R. A.; ONeill, S. M.; Urbanski, S. P.; Wong, D. C.

    2017-12-01

    Crop residue burning has long been a common practice in agriculture with the smoke emissions from the burning linked to negative health impacts. A field study in eastern Washington and northern Idaho in August 2013 consisted of multiple burns of well characterized fuels with nearby surface and aerial measurements including trace species concentrations, plume rise height and boundary layer structure. The chemical transport model CMAQ (Community Multiscale Air Quality Model) was used to assess the fire emissions and subsequent vertical plume transport. The study first compared assumptions made by the 2014 National Emission Inventory approach for crop residue burning with the fuel and emissions information obtained from the field study and then investigated the sensitivity of modeled carbon monoxide (CO) and PM2.5 concentrations to these different emission estimates and plume rise treatment with CMAQ. The study suggests that improvements to the current parameterizations are needed in order for CMAQ to reliably reproduce smoke plumes from burning. In addition, there is enough variability in the smoke emissions, stemming from variable field-specific information such as field size, that attempts to model crop residue burning should use field-specific information whenever possible.

  5. Reactive transport modelling of biogeochemical processes and carbon isotope geochemistry inside a landfill leachate plume.

    NARCIS (Netherlands)

    van Breukelen, B.M.; Griffioen, J.; Roling, W.F.M.; van Verseveld, H.W.

    2004-01-01

    The biogeochemical processes governing leachate attenuation inside a landfill leachate plume (Banisveld, the Netherlands) were revealed and quantified using the 1D reactive transport model PHREEQC-2. Biodegradation of dissolved organic carbon (DOC) was simulated assuming first-order oxidation of two

  6. Small rocket exhaust plume data

    Science.gov (United States)

    Chirivella, J. E.; Moynihan, P. I.; Simon, W.

    1972-01-01

    During recent cryodeposit tests with an 0.18-N thruster, the mass flux in the plume back field was measured for the first time for nitrogen, carbon dioxide, and a mixture of nitrogen, hydrogen, and ammonia at various inlet pressures. This mixture simulated gases that would be generated by a hydrazine plenum attitude propulsion system. The measurements furnish a base upon which to build a mathematical model of plume back flow that will be used in predicting the mass distribution in the boundary region of other plumes. The results are analyzed and compared with existing analytical predictions.

  7. A comparison of the Gaussian Plume models of Pasquill and Smith

    International Nuclear Information System (INIS)

    Barker, C.D.

    1978-03-01

    The Gaussian Plume models of Pasquill and Smith are compared over the full range of atmospheric stability for both short and continuous releases of material. For low level releases the two models compare well (to within a factor of approximately 2) except for very unstable conditions. The agreement between the two models for high level sources is not so good. It is concluded that the two Gaussian models are cheap and simple to use, but may require experimental verification in specific applications. (author)

  8. User's manual for DWNWND: an interactive Gaussian plume atmospheric transport model with eight dispersion parameter options

    International Nuclear Information System (INIS)

    Fields, D.E.; Miller, C.W.

    1980-05-01

    The most commonly used approach for estimating the atmospheric concentration and deposition of material downwind from its point of release is the Gaussian plume atmospheric dispersion model. Two of the critical parameters in this model are sigma/sub y/ and sigma/sub z/, the horizontal and vertical dispersion parameters, respectively. A number of different sets of values for sigma/sub y/ and sigma/sub z/ have been determined empirically for different release heights and meteorological and terrain conditions. The computer code DWNWND, described in this report, is an interactive implementation of the Gaussian plume model. This code allows the user to specify any one of eight different sets of the empirically determined dispersion paramters. Using the selected dispersion paramters, ground-level normalized exposure estimates are made at any specified downwind distance. Computed values may be corrected for plume depletion due to deposition and for plume settling due to gravitational fall. With this interactive code, the user chooses values for ten parameters which define the source, the dispersion and deposition process, and the sampling point. DWNWND is written in FORTRAN for execution on a PDP-10 computer, requiring less than one second of central processor unit time for each simulation

  9. Mathematical model of drift deposition from a bifurcated cooling tower plume

    International Nuclear Information System (INIS)

    Chen, N.C.J.; Jung, L.

    1978-01-01

    Cooling tower drift deposition modeling has been extended by including centrifugal force induced through plume bifurcation in a crosswind as a mechanism for drift droplet removal from the plume. The model, in its current state of development, is capable of predicting the trajectory of a single droplet from the stage of strong interaction with the vortex field soon after droplet emission at the tower top through the stage of droplet evaporation in an unsaturated atmosphere after droplet breakaway from the plume. The computer program developed from the mathematical formulation has been used to explore the dependency of the droplet trajectory on droplet size, vortex strength, point of droplet emission, drag coefficient, droplet efflux speed, and ambient conditions. A specific application to drift from a mechanical-draft cooling tower (for a wind speed twice the efflux speed, a relative humidity of 70 per cent, and an initial droplet radius of 100 μm) showed the droplet to follow a helical trajectory within the plume, with breakaway occurring at 2.5 tower diameters downwind and ground impact of the droplet (reduced through evaporation to 55 μm radius) at 11 tower diameters

  10. Modelling of transport and biogeochemical processes in pollution plumes: Vejen landfill, Denmark

    DEFF Research Database (Denmark)

    Brun, A.; Engesgaard, Peter Knudegaard; Christensen, Thomas Højlund

    2002-01-01

    A biogeochemical transport code is used to simulate leachate attenuation. biogeochemical processes. and development of redox zones in a pollution plume downstream of the Vejen landfill in Denmark. Calibration of the degradation parameters resulted in a good agreement with the observed distribution...

  11. Particle-Resolved Modeling of Aerosol Mixing State in an Evolving Ship Plume

    Science.gov (United States)

    Riemer, N. S.; Tian, J.; Pfaffenberger, L.; Schlager, H.; Petzold, A.

    2011-12-01

    The aerosol mixing state is important since it impacts the particles' optical and CCN properties and thereby their climate impact. It evolves continuously during the particles' residence time in the atmosphere as a result of coagulation with other particles and condensation of secondary aerosol species. This evolution is challenging to represent in traditional aerosol models since they require the representation of a multi-dimensional particle distribution. While modal or sectional aerosol representations cannot practically resolve the aerosol mixing state for more than a few species, particle-resolved models store the composition of many individual aerosol particles directly. They thus sample the high-dimensional composition state space very efficiently and so can deal with tens of species, fully resolving the mixing state. Here we use the capabilities of the particle-resolved model PartMC-MOSAIC to simulate the evolution of particulate matter emitted from marine diesel engines and compare the results to aircraft measurements made in the English Channel in 2007 as part of the European campaign QUANTIFY. The model was initialized with values of gas concentrations and particle size distributions and compositions representing fresh ship emissions. These values were obtained from a test rig study in the European project HERCULES in 2006 using a serial four-stroke marine diesel engine operating on high-sulfur heavy fuel oil. The freshly emitted particles consisted of sulfate, black carbon, organic carbon and ash. We then tracked the particle population for several hours as it evolved undergoing coagulation, dilution with the background air, and chemical transformations in the aerosol and gas phase. This simulation was used to compute the evolution of CCN properties and optical properties of the plume on a per-particle basis. We compared our results to size-resolved data of aged ship plumes from the QUANTIFY Study in 2007 and showed that the model was able to reproduce

  12. 3D Thermo-Mechanical Models of Plume-Lithosphere Interactions: Implications for the Kenya rift

    Science.gov (United States)

    Scheck-Wenderoth, M.; Koptev, A.; Sippel, J.

    2017-12-01

    We present three-dimensional (3D) thermo-mechanical models aiming to explore the interaction of an active mantle plume with heterogeneous pre-stressed lithosphere in the Kenya rift region. As shown by the recent data-driven 3D gravity and thermal modeling (Sippel et al., 2017), the integrated strength of the lithosphere for the region of Kenya and northern Tanzania appears to be strongly controlled by the complex inherited crustal structure, which may have been decisive for the onset, localization and propagation of rifting. In order to test this hypothesis, we have performed a series of ultra-high resolution 3D numerical experiments that include a coupled mantle/lithosphere system in a dynamically and rheologically consistent framework. In contrast to our previous studies assuming a simple and quasi-symmetrical initial condition (Koptev et al., 2015, 2016, 2017), the complex 3D distribution of rock physical properties inferred from geological and geophysical observations (Sippel et al., 2017) has been incorporated into the model setup that comprises a stratified three-layer continental lithosphere composed of an upper and lower crust and lithospheric mantle overlaying the upper mantle. Following the evidence of the presence of a broad low-velocity seismic anomaly under the central parts of the East African Rift system (e.g. Nyblade et al, 2000; Chang et al., 2015), a 200-km radius mantle plume has been seeded at the bottom of a 635 km-depth model box representing a thermal anomaly of 300°C temperature excess. In all model runs, results show that the spatial distribution of surface deformation is indeed strongly controlled by crustal structure: within the southern part of the model box, a localized narrow zone stretched in NS direction (i.e. perpendicularly to applied far-field extension) is aligned along a structural boundary within the lower crust, whereas in the northern part of the model domain, deformation is more diffused and its eastern limit coincides with

  13. Sediment plume model-a comparison between use of measured turbidity data and satellite images for model calibration.

    Science.gov (United States)

    Sadeghian, Amir; Hudson, Jeff; Wheater, Howard; Lindenschmidt, Karl-Erich

    2017-08-01

    In this study, we built a two-dimensional sediment transport model of Lake Diefenbaker, Saskatchewan, Canada. It was calibrated by using measured turbidity data from stations along the reservoir and satellite images based on a flood event in 2013. In June 2013, there was heavy rainfall for two consecutive days on the frozen and snow-covered ground in the higher elevations of western Alberta, Canada. The runoff from the rainfall and the melted snow caused one of the largest recorded inflows to the headwaters of the South Saskatchewan River and Lake Diefenbaker downstream. An estimated discharge peak of over 5200 m 3 /s arrived at the reservoir inlet with a thick sediment front within a few days. The sediment plume moved quickly through the entire reservoir and remained visible from satellite images for over 2 weeks along most of the reservoir, leading to concerns regarding water quality. The aims of this study are to compare, quantitatively and qualitatively, the efficacy of using turbidity data and satellite images for sediment transport model calibration and to determine how accurately a sediment transport model can simulate sediment transport based on each of them. Both turbidity data and satellite images were very useful for calibrating the sediment transport model quantitatively and qualitatively. Model predictions and turbidity measurements show that the flood water and suspended sediments entered upstream fairly well mixed and moved downstream as overflow with a sharp gradient at the plume front. The model results suggest that the settling and resuspension rates of sediment are directly proportional to flow characteristics and that the use of constant coefficients leads to model underestimation or overestimation unless more data on sediment formation become available. Hence, this study reiterates the significance of the availability of data on sediment distribution and characteristics for building a robust and reliable sediment transport model.

  14. Source-term development for a contaminant plume for use by multimedia risk assessment models

    International Nuclear Information System (INIS)

    Whelan, Gene; McDonald, John P.; Taira, Randal Y.; Gnanapragasam, Emmanuel K.; Yu, Charley; Lew, Christine S.; Mills, William B.

    1999-01-01

    Multimedia modelers from the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE) are collaborating to conduct a comprehensive and quantitative benchmarking analysis of four intermedia models: DOE's Multimedia Environmental Pollutant Assessment System (MEPAS), EPA's MMSOILS, EPA's PRESTO, and DOE's RESidual RADioactivity (RESRAD). These models represent typical analytically, semi-analytically, and empirically based tools that are utilized in human risk and endangerment assessments for use at installations containing radioactive and/or hazardous contaminants. Although the benchmarking exercise traditionally emphasizes the application and comparison of these models, the establishment of a Conceptual Site Model (CSM) should be viewed with equal importance. This paper reviews an approach for developing a CSM of an existing, real-world, Sr-90 plume at DOE's Hanford installation in Richland, Washington, for use in a multimedia-based benchmarking exercise bet ween MEPAS, MMSOILS, PRESTO, and RESRAD. In an unconventional move for analytically based modeling, the benchmarking exercise will begin with the plume as the source of contamination. The source and release mechanism are developed and described within the context of performing a preliminary risk assessment utilizing these analytical models. By beginning with the plume as the source term, this paper reviews a typical process and procedure an analyst would follow in developing a CSM for use in a preliminary assessment using this class of analytical tool

  15. Radiative modeling and characterization of aerosol plumes hyper-spectral imagery; Modelisation radiative et caracterisation des panaches d'aerosols en imagerie hyperspectrale

    Energy Technology Data Exchange (ETDEWEB)

    Alakian, A

    2008-03-15

    This thesis aims at characterizing aerosols from plumes (biomass burning, industrial discharges, etc.) with hyper-spectral imagery. We want to estimate the optical properties of emitted particles and also their micro-physical properties such as number, size distribution and composition. To reach our goal, we have built a forward semi-analytical model, named APOM (Aerosol Plume Optical Model), which allows to simulate the radiative effects of aerosol plumes in the spectral range [0,4-2,5 {mu}m] for nadir viewing sensors. Mathematical formulation and model coefficients are obtained from simulations performed with the radiative transfer code COMANCHE. APOM is assessed on simulated data and proves to be accurate with modeling errors between 1% and 3%. Three retrieval methods using APOM have been developed: L-APOM, M-APOM and A-APOM. These methods take advantage of spectral and spatial dimensions in hyper-spectral images. L-APOM and M-APOM assume a priori knowledge on particles but can estimate their optical and micro-physical properties. Their performances on simulated data are quite promising. A-APOM method does not require any a priori knowledge on particles but only estimates their optical properties. However, it still needs improvements before being usable. On real images, inversion provides satisfactory results for plumes above water but meets some difficulties for plumes above vegetation, which underlines some possibilities of improvement for the retrieval algorithm. (author)

  16. FIREPLUME model for plume dispersion from fires: Application to uranium hexafluoride cylinder fires

    International Nuclear Information System (INIS)

    Brown, D.F.; Dunn, W.E.

    1997-06-01

    This report provides basic documentation of the FIREPLUME model and discusses its application to the prediction of health impacts resulting from releases of uranium hexafluoride (UF 6 ) in fires. The model application outlined in this report was conducted for the Draft Programmatic Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of Depleted UF 6 . The FIREPLUME model is an advanced stochastic model for atmospheric plume dispersion that predicts the downwind consequences of a release of toxic materials from an explosion or a fire. The model is based on the nonbuoyant atmospheric dispersion model MCLDM (Monte Carlo Lagrangian Dispersion Model), which has been shown to be consistent with available laboratory and field data. The inclusion of buoyancy and the addition of a postprocessor to evaluate time-varying concentrations lead to the current model. The FIREPLUME model, as applied to fire-related UF 6 cylinder releases, accounts for three phases of release and dispersion. The first phase of release involves the hydraulic rupture of the cylinder due to heating of the UF 6 in the fire. The second phase involves the emission of material into the burning fire, and the third phase involves the emission of material after the fire has died during the cool-down period. The model predicts the downwind concentration of the material as a function of time at any point downwind at or above the ground. All together, five fire-related release scenarios are examined in this report. For each scenario, downwind concentrations of the UF 6 reaction products, uranyl fluoride and hydrogen fluoride, are provided for two meteorological conditions: (1) D stability with a 4-m/s wind speed, and (2) F stability with a 1-m/s wind speed

  17. Discontinuous Galerkin modeling of the Columbia River's coupled estuary-plume dynamics

    Science.gov (United States)

    Vallaeys, Valentin; Kärnä, Tuomas; Delandmeter, Philippe; Lambrechts, Jonathan; Baptista, António M.; Deleersnijder, Eric; Hanert, Emmanuel

    2018-04-01

    The Columbia River (CR) estuary is characterized by high river discharge and strong tides that generate high velocity flows and sharp density gradients. Its dynamics strongly affects the coastal ocean circulation. Tidal straining in turn modulates the stratification in the estuary. Simulating the hydrodynamics of the CR estuary and plume therefore requires a multi-scale model as both shelf and estuarine circulations are coupled. Such a model has to keep numerical dissipation as low as possible in order to correctly represent the plume propagation and the salinity intrusion in the estuary. Here, we show that the 3D baroclinic discontinuous Galerkin finite element model SLIM 3D is able to reproduce the main features of the CR estuary-to-ocean continuum. We introduce new vertical discretization and mode splitting that allow us to model a region characterized by complex bathymetry and sharp density and velocity gradients. Our model takes into account the major forcings, i.e. tides, surface wind stress and river discharge, on a single multi-scale grid. The simulation period covers the end of spring-early summer of 2006, a period of high river flow and strong changes in the wind regime. SLIM 3D is validated with in-situ data on the shelf and at multiple locations in the estuary and compared with an operational implementation of SELFE. The model skill in the estuary and on the shelf indicate that SLIM 3D is able to reproduce the key processes driving the river plume dynamics, such as the occurrence of bidirectional plumes or reversals of the inner shelf coastal currents.

  18. Sensitivity experiments with a one-dimensional coupled plume - iceflow model

    Science.gov (United States)

    Beckmann, Johanna; Perette, Mahé; Alexander, David; Calov, Reinhard; Ganopolski, Andrey

    2016-04-01

    Over the last few decades Greenland Ice sheet mass balance has become increasingly negative, caused by enhanced surface melting and speedup of the marine-terminating outlet glaciers at the ice sheet margins. Glaciers speedup has been related, among other factors, to enhanced submarine melting, which in turn is caused by warming of the surrounding ocean and less obviously, by increased subglacial discharge. While ice-ocean processes potentially play an important role in recent and future mass balance changes of the Greenland Ice Sheet, their physical understanding remains poorly understood. In this work we performed numerical experiments with a one-dimensional plume model coupled to a one-dimensional iceflow model. First we investigated the sensitivity of submarine melt rate to changes in ocean properties (ocean temperature and salinity), to the amount of subglacial discharge and to the glacier's tongue geometry itself. A second set of experiments investigates the response of the coupled model, i.e. the dynamical response of the outlet glacier to altered submarine melt, which results in new glacier geometry and updated melt rates.

  19. Propagation of uncertainty and sensitivity analysis in an integral oil-gas plume model

    KAUST Repository

    Wang, Shitao

    2016-05-27

    Polynomial Chaos expansions are used to analyze uncertainties in an integral oil-gas plume model simulating the Deepwater Horizon oil spill. The study focuses on six uncertain input parameters—two entrainment parameters, the gas to oil ratio, two parameters associated with the droplet-size distribution, and the flow rate—that impact the model\\'s estimates of the plume\\'s trap and peel heights, and of its various gas fluxes. The ranges of the uncertain inputs were determined by experimental data. Ensemble calculations were performed to construct polynomial chaos-based surrogates that describe the variations in the outputs due to variations in the uncertain inputs. The surrogates were then used to estimate reliably the statistics of the model outputs, and to perform an analysis of variance. Two experiments were performed to study the impacts of high and low flow rate uncertainties. The analysis shows that in the former case the flow rate is the largest contributor to output uncertainties, whereas in the latter case, with the uncertainty range constrained by aposteriori analyses, the flow rate\\'s contribution becomes negligible. The trap and peel heights uncertainties are then mainly due to uncertainties in the 95% percentile of the droplet size and in the entrainment parameters.

  20. Using ASCEM Modeling and Visualization to Inform Stakeholders of Contaminant Plume Evolution and Remediation Efficacy at F-Basin Savannah River, SC – 15156

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wainwright, H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Molins, S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Davis, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Arora, B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Faybishenko, B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Krishnan, H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hubbard, S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Denham, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Eddy-Dilek, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Moulton, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lipnikov, K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gable, C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Miller, T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Freshley, M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-28

    Communication with stakeholders, regulatory agencies, and the public is an essential part of implementing different remediation and monitoring activities, and developing site closure strategies at contaminated sites. Modeling of contaminant plume evolution plays a critical role in estimating the benefit, cost, and risk of particular options. At the same time, effective visualization of monitoring data and modeling results are particularly important for conveying the significance of the results and observations. In this paper, we present the results of the Advanced Simulation Capability for Environmental Management (ASCEM) project, including the discussion of the capabilities of newly developed ASCEM software package, along with its application to the F-Area Seepage Basins located in the U.S. Department of Energy Savannah River Site (SRS). ASCEM software includes state-of-the-art numerical methods for simulating complex flow and reactive transport, as well as various toolsets such as a graphical user interface (GUI), visualization, data management, uncertainty quantification, and parameter estimation. Using this software, we have developed an advanced visualization of tritium plume migration coupled with a data management system, and simulated a three-dimensional model of flow and plume evolution on a high-performance computing platform. We evaluated the effect of engineered flow barriers on a nonreactive tritium plume, through advanced plume visualization and modeling of tritium plume migration. In addition, we developed a geochemical reaction network to describe complex geochemical processes at the site, and evaluated the impact of coupled hydrological and geochemical heterogeneity. These results are expected to support SRS’s monitoring activities and operational decisions.

  1. Tridimensional statistic analysis of cooling tower plumes. Methods and results relating to power effect and disposal conditions

    International Nuclear Information System (INIS)

    Sabaton, M.; Viollet, P.L.; Darles, A.; Gland, H.

    1980-07-01

    The PANACH three dimensional calculation code developed from tests on a small scale model and validated from full scale measurement campaigns, was used to estimate a three dimensional statistic of plumes. As it is not possible with the calculation times to make a calculation for each radio sondage, a classification method was adopted. This method developed by the French National Meteorological Office is based on a double classification comprising basic classes in which the plumes are assumed to be dynamically similar and a sub-classification to take better account of the true moisture profiles. This statistical method was then applied to the case of 2 or 4 1300 MWe units fitted with natural draught cooling towers of the wet, dry or wet-dry types [fr

  2. Modeling the Response of Primary Production and Sedimentation to Variable Nitrate Loading in the Mississippi River Plume

    National Research Council Canada - National Science Library

    Green, Rebecca E; Breed, Greg A; Dagg, Michael J; Lohrenz, Steven E

    2008-01-01

    ...% reduction in annual nitrogen discharge into the Gulf of Mexico. We developed an ecosystem model for the Mississippi River plume to investigate the response of organic matter production and sedimentation to variable nitrate loading...

  3. Data and Model-Driven Decision Support for Environmental Management of a Chromium Plume at Los Alamos National Laboratory - 13264

    Energy Technology Data Exchange (ETDEWEB)

    Vesselinov, Velimir V.; Broxton, David; Birdsell, Kay; Reneau, Steven; Harp, Dylan; Mishra, Phoolendra [Computational Earth Science - EES-16, Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos NM 87545 (United States); Katzman, Danny; Goering, Tim [Environmental Programs (ADEP), Los Alamos National Laboratory, Los Alamos NM 87545 (United States); Vaniman, David; Longmire, Pat; Fabryka-Martin, June; Heikoop, Jeff; Ding, Mei; Hickmott, Don; Jacobs, Elaine [Earth Systems Observations - EES-14, Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos NM 87545 (United States)

    2013-07-01

    A series of site investigations and decision-support analyses have been performed related to a chromium plume in the regional aquifer beneath the Los Alamos National Laboratory (LANL). Based on the collected data and site information, alternative conceptual and numerical models representing governing subsurface processes with different complexity and resolution have been developed. The current conceptual model is supported by multiple lines of evidence based on comprehensive analyses of the available data and modeling results. The model is applied for decision-support analyses related to estimation of contaminant- arrival locations and chromium mass flux reaching the regional aquifer, and to optimization of a site monitoring-well network. Plume characterization is a challenging and non-unique problem because multiple models and contamination scenarios are consistent with the site data and conceptual knowledge. To solve this complex problem, an advanced methodology based on model calibration and uncertainty quantification has been developed within the computational framework MADS (http://mads.lanl.gov). This work implements high-performance computing and novel, efficient and robust model analysis techniques for optimization and uncertainty quantification (ABAGUS, Squads, multi-try (multi-start) techniques), which allow for solving problems with large degrees of freedom. (authors)

  4. Dispersion of a Passive Scalar Fluctuating Plume in a Turbulent Boundary Layer. Part III: Stochastic Modelling

    Science.gov (United States)

    Marro, Massimo; Salizzoni, Pietro; Soulhac, Lionel; Cassiani, Massimo

    2018-01-01

    We analyze the reliability of the Lagrangian stochastic micromixing method in predicting higher-order statistics of the passive scalar concentration induced by an elevated source (of varying diameter) placed in a turbulent boundary layer. To that purpose we analyze two different modelling approaches by testing their results against the wind-tunnel measurements discussed in Part I (Nironi et al., Boundary-Layer Meteorology, 2015, Vol. 156, 415-446). The first is a probability density function (PDF) micromixing model that simulates the effects of the molecular diffusivity on the concentration fluctuations by taking into account the background particles. The second is a new model, named VPΓ, conceived in order to minimize the computational costs. This is based on the volumetric particle approach providing estimates of the first two concentration moments with no need for the simulation of the background particles. In this second approach, higher-order moments are computed based on the estimates of these two moments and under the assumption that the concentration PDF is a Gamma distribution. The comparisons concern the spatial distribution of the first four moments of the concentration and the evolution of the PDF along the plume centreline. The novelty of this work is twofold: (i) we perform a systematic comparison of the results of micro-mixing Lagrangian models against experiments providing profiles of the first four moments of the concentration within an inhomogeneous and anisotropic turbulent flow, and (ii) we show the reliability of the VPΓ model as an operational tool for the prediction of the PDF of the concentration.

  5. Dispersion of a Passive Scalar Fluctuating Plume in a Turbulent Boundary Layer. Part III: Stochastic Modelling

    Science.gov (United States)

    Marro, Massimo; Salizzoni, Pietro; Soulhac, Lionel; Cassiani, Massimo

    2018-06-01

    We analyze the reliability of the Lagrangian stochastic micromixing method in predicting higher-order statistics of the passive scalar concentration induced by an elevated source (of varying diameter) placed in a turbulent boundary layer. To that purpose we analyze two different modelling approaches by testing their results against the wind-tunnel measurements discussed in Part I (Nironi et al., Boundary-Layer Meteorology, 2015, Vol. 156, 415-446). The first is a probability density function (PDF) micromixing model that simulates the effects of the molecular diffusivity on the concentration fluctuations by taking into account the background particles. The second is a new model, named VPΓ, conceived in order to minimize the computational costs. This is based on the volumetric particle approach providing estimates of the first two concentration moments with no need for the simulation of the background particles. In this second approach, higher-order moments are computed based on the estimates of these two moments and under the assumption that the concentration PDF is a Gamma distribution. The comparisons concern the spatial distribution of the first four moments of the concentration and the evolution of the PDF along the plume centreline. The novelty of this work is twofold: (i) we perform a systematic comparison of the results of micro-mixing Lagrangian models against experiments providing profiles of the first four moments of the concentration within an inhomogeneous and anisotropic turbulent flow, and (ii) we show the reliability of the VPΓ model as an operational tool for the prediction of the PDF of the concentration.

  6. The evolution of photochemical smog in a power plant plume

    Science.gov (United States)

    Luria, Menachem; Valente, Ralph J.; Tanner, Roger L.; Gillani, Noor V.; Imhoff, Robert E.; Mueller, Stephen F.; Olszyna, Kenneth J.; Meagher, James F. Present address: Aeronomy Laboratory, NOAA, 325 Broadway, Boulder CO 80303, USA.)

    The evolution of photochemical smog in a plant plume was investigated with the aid of an instrumented helicopter. Air samples were taken in the plume of the Cumberland Power Plant, located in central Tennessee, during the afternoon of 16 July 1995 as part of the Southern Oxidants Study - Nashville Middle Tennessee Ozone Study. Twelve cross-wind air sampling traverses were made at six distance groups from 35 to 116 km from the source. During the sampling period the winds were from the west-northwest and the plume drifted towards the city of Nashville TN. Ten of the traverses were made upwind of the city, where the power plant plume was isolated, and two traverses downwind of the city when the plumes were possibly mixed. The results revealed that even six hours after the release, excess ozone production was limited to the edges of the plume. Only when the plume was sufficiently dispersed, but still upwind of Nashville, was excess ozone (up to 109 ppbv, 50-60 ppbv above background levels) produced in the center of the plume. The concentrations image of the plume and a Lagrangian particle model suggests that portions of the power plant plume mixed with the urban plume. The mixed urban power plant plume began to regenerate O 3 that peaked at 120 ppbv at a short distance (15-25 km) downwind of Nashville. Ozone productivity (the ratio of excess O 3 to NO y and NO z) in the isolated plume was significantly lower compared with that found in the city plume. The production of nitrate, a chain termination product, was significantly higher in the power plant plume compared to the mixed plume, indicating shorter chain length of the photochemical smog chain reaction mechanism.

  7. The evolution of photochemical smog in a power plant plume

    International Nuclear Information System (INIS)

    Luria, M.; The Hebrew University, Jerusalem; Valente, R.J.; Tanner, R.L.; Imhoff, R.E.; Mueller, S.F.; Olszyna, K.J.; Meagher, J.F.; Gillani, N.V.; University of Alabama, Huntsville, AL

    1999-01-01

    The evolution of photochemical smog in a plant plume was investigated with the aid of an instrumented helicopter. Air samples were taken in the plume of the Cumberland Power Plant, located in central Tennessee, during the afternoon of 16 July 1995 as part of the Southern Oxidants Study - Nashville Middle Tennessee Ozone Study. Twelve cross-wind air sampling traverses were made at six distance groups from 35 to 116 km from the source. During the sampling period the winds were from the west-northwest and the plume drifted towards the city of Nashville TN. Ten of the traverses were made upwind of the city, where the power plant plume was isolated, and two traverses downwind of the city when the plumes were possibly mixed. The results revealed that even six hours after the release, excess ozone production was limited to the edges of the plume. Only when the plume was sufficiently dispersed, but still upwind of Nashville, was excess ozone (up to 109 ppbv, 50-60 ppbv above background levels) produced in the center of the plume. The concentrations image of the plume and a Lagrangian particle model suggests that portions of the power plant plume mixed with the urban plume. The mixed urban power plant plume began to regenerate O 3 that peaked at 120 ppbv at a short distance (15-25 km) downwind of Nashville. Ozone productivity (the ratio of excess O 3 to NO y and NO z ) in the isolated plume was significantly lower compared with that found in the city plume. The production of nitrate, a chain termination product, was significantly higher in the power plant plume compared to the mixed plume, indicating shorter chain length of the photochemical smog chain reaction mechanism. (author)

  8. Model analysis of the chemical conversion of exhaust species in the expanding plumes of subsonic aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Moellhoff, M.; Hendricks, J.; Lippert, E.; Petry, H. [Koeln Univ. (Germany). Inst. fuer Geophysik und Meteorologie; Sausen, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    A box model and two different one-dimensional models are used to investigate the chemical conversion of exhaust species in the dispersing plume of a subsonic aircraft flying at cruise altitude. The effect of varying daytime of release as well as the impact of changing dispersion time is studied with special respect to the aircraft induced O{sub 3} production. Effective emission amounts for consideration in mesoscale and global models are calculated. Simulations with modified photolysis rates are performed to show the sensitivity of the photochemistry to the occurrence of cirrus clouds. (author) 8 refs.

  9. Model analysis of the chemical conversion of exhaust species in the expanding plumes of subsonic aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Moellhoff, M; Hendricks, J; Lippert, E; Petry, H [Koeln Univ. (Germany). Inst. fuer Geophysik und Meteorologie; Sausen, R [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

    1998-12-31

    A box model and two different one-dimensional models are used to investigate the chemical conversion of exhaust species in the dispersing plume of a subsonic aircraft flying at cruise altitude. The effect of varying daytime of release as well as the impact of changing dispersion time is studied with special respect to the aircraft induced O{sub 3} production. Effective emission amounts for consideration in mesoscale and global models are calculated. Simulations with modified photolysis rates are performed to show the sensitivity of the photochemistry to the occurrence of cirrus clouds. (author) 8 refs.

  10. Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands

    Science.gov (United States)

    Zaczek, Kirsten; Troll, Valentin R.; Cachao, Mario; Ferreira, Jorge; Deegan, Frances M.; Carracedo, Juan Carlos; Soler, Vicente; Meade, Fiona C.; Burchardt, Steffi

    2015-01-01

    The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

  11. Modelling present-day basal melt rates for Antarctic ice shelves using a parametrization of buoyant meltwater plumes

    Science.gov (United States)

    Lazeroms, Werner M. J.; Jenkins, Adrian; Hilmar Gudmundsson, G.; van de Wal, Roderik S. W.

    2018-01-01

    Basal melting below ice shelves is a major factor in mass loss from the Antarctic Ice Sheet, which can contribute significantly to possible future sea-level rise. Therefore, it is important to have an adequate description of the basal melt rates for use in ice-dynamical models. Most current ice models use rather simple parametrizations based on the local balance of heat between ice and ocean. In this work, however, we use a recently derived parametrization of the melt rates based on a buoyant meltwater plume travelling upward beneath an ice shelf. This plume parametrization combines a non-linear ocean temperature sensitivity with an inherent geometry dependence, which is mainly described by the grounding-line depth and the local slope of the ice-shelf base. For the first time, this type of parametrization is evaluated on a two-dimensional grid covering the entire Antarctic continent. In order to apply the essentially one-dimensional parametrization to realistic ice-shelf geometries, we present an algorithm that determines effective values for the grounding-line depth and basal slope in any point beneath an ice shelf. Furthermore, since detailed knowledge of temperatures and circulation patterns in the ice-shelf cavities is sparse or absent, we construct an effective ocean temperature field from observational data with the purpose of matching (area-averaged) melt rates from the model with observed present-day melt rates. Our results qualitatively replicate large-scale observed features in basal melt rates around Antarctica, not only in terms of average values, but also in terms of the spatial pattern, with high melt rates typically occurring near the grounding line. The plume parametrization and the effective temperature field presented here are therefore promising tools for future simulations of the Antarctic Ice Sheet requiring a more realistic oceanic forcing.

  12. A comparison of the Gaussian Plume Diffusion Model with experimental data from Tilbury and Northfleet

    International Nuclear Information System (INIS)

    Barker, C.D.

    1979-07-01

    The Gaussian Plume Diffusion Model, using Smith's scheme for σsub(z) and various models for σsub(y), is compared with measured values of the location and strength of maximum ground level concentration taken during the Tilbury and Northfleet experiments. The position of maximum ground level concentration (xsub(m)) is found to be relatively insensitive to σsub(y) and Smith's model for σsub(z) is found to predict xsub(m) on average to within 50% for plume heights less than 200 - 400m (dependent on atmosphere stability). Several models for σsub(y) are examined by comparing predicted and observed values for the normalised maximum ground level concentration (Xsub(m)) and a modified form of Moore's model for σsub(y) is found to give the best overall fit, on average to within 30%. Gifford's release duration dependent model for σsub(y) is found to consistently underestimate Xsub(m) by 35 - 45%. This comparison is only a partial validation of the models described above and suggestions are made as to where further work is required. (author)

  13. Experimentally Identify the Effective Plume Chimney over a Natural Draft Chimney Model

    Science.gov (United States)

    Rahman, M. M.; Chu, C. M.; Tahir, A. M.; Ismail, M. A. bin; Misran, M. S. bin; Ling, L. S.

    2017-07-01

    The demands of energy are in increasing order due to rapid industrialization and urbanization. The researchers and scientists are working hard to improve the performance of the industry so that the energy consumption can be reduced significantly. Industries like power plant, timber processing plant, oil refinery, etc. performance mainly depend on the cooling tower chimney’s performance, either natural draft or forced draft. Chimney is used to create sufficient draft, so that air can flow through it. Cold inflow or flow reversal at chimney exit is one of the main identified problems that may alter the overall plant performance. The presence Effective Plume Chimney (EPC) is an indication of cold inflow free operation of natural draft chimney. Different mathematical model equations are used to estimate the EPC height over the heat exchanger or hot surface. In this paper, it is aim to identify the EPC experimentally. In order to do that, horizontal temperature profiling is done at the exit of the chimneys of face area 0.56m2, 1.00m2 and 2.25m2. A wire mesh screen is installed at chimneys exit to ensure cold inflow chimney operation. It is found that EPC exists in all modified chimney models and the heights of EPC varied from 1 cm to 9 cm. The mathematical models indicate that the estimated heights of EPC varied from 1 cm to 2.3 cm. Smoke test is also conducted to ensure the existence of EPC and cold inflow free option of chimney. Smoke test results confirmed the presence of EPC and cold inflow free operation of chimney. The performance of the cold inflow free chimney is increased by 50% to 90% than normal chimney.

  14. Active space of pheromone plume and its relationship to effective attraction radius in applied models.

    Science.gov (United States)

    Byers, John A

    2008-09-01

    The release rate of a semiochemical lure that attracts flying insects has a specific effective attraction radius (EAR) that corresponds to the lure's orientation response strength. EAR is defined as the radius of a passive sphere that intercepts the same number of insects as a semiochemical-baited trap. It is estimated by calculating the ratio of trap catches in the field in baited and unbaited traps and the interception area of the unbaited trap. EAR serves as a standardized method for comparing the attractive strengths of lures that is independent of population density. In two-dimensional encounter rate models that are used to describe insect mass trapping and mating disruption, a circular EAR (EAR(c)) describes a key parameter that affects catch or influence by pheromone in the models. However, the spherical EAR, as measured in the field, should be transformed to an EAR(c) for appropriate predictions in such models. The EAR(c) is calculated as (pi/2EAR(2))/F (L), where F (L) is the effective thickness of the flight layer where the insect searches. F (L) was estimated from catches of insects (42 species in the orders Coleoptera, Lepidoptera, Diptera, Hemiptera, and Thysanoptera) on traps at various heights as reported in the literature. The EAR(c) was proposed further as a simple but equivalent alternative to simulations of highly complex active-space plumes with variable response surfaces that have proven exceedingly difficult to quantify in nature. This hypothesis was explored in simulations where flying insects, represented as coordinate points, moved about in a correlated random walk in an area that contained a pheromone plume, represented as a sector of active space composed of a capture probability surface of variable complexity. In this plume model, catch was monitored at a constant density of flying insects and then compared to simulations in which a circular EAR(c) was enlarged until an equivalent rate was caught. This demonstrated that there is a

  15. Effect of grid resolution and subgrid assumptions on the model prediction of a reactive buoyant plume under convective conditions

    International Nuclear Information System (INIS)

    Chock, D.P.; Winkler, S.L.; Pu Sun

    2002-01-01

    We have introduced a new and elaborate approach to understand the impact of grid resolution and subgrid chemistry assumption on the grid-model prediction of species concentrations for a system with highly non-homogeneous chemistry - a reactive buoyant plume immediately downwind of the stack in a convective boundary layer. The Parcel-Grid approach plume was used to describe both the air parcel turbulent transport and chemistry. This approach allows an identical transport process for all simulations. It also allows a description of subgrid chemistry. The ambient and plume parcel transport follows the description of Luhar and Britter (Atmos. Environ, 23 (1989) 1911, 26A (1992) 1283). The chemistry follows that of the Carbon-Bond mechanism. Three different grid sizes were considered: fine, medium and coarse, together with three different subgrid chemistry assumptions: micro-scale or individual parcel, tagged-parcel (plume and ambient parcels treated separately), and untagged-parcel (plume and ambient parcels treated indiscriminately). Reducing the subgrid information is not necessarily similar to increasing the model grid size. In our example, increasing the grid size leads to a reduction in the suppression of ozone in the presence of a high-NO x stack plume, and a reduction in the effectiveness of the NO x -inhibition effect. On the other hand, reducing the subgrid information (by using the untagged-parcel assumption) leads to an increase in ozone reduction and an enhancement of the NO x -inhibition effect insofar as the ozone extremum is concerned. (author)

  16. HGSYSTEM/UF6 model enhancements for plume rise and dispersion around buildings, lift-off of buoyant plumes, and robustness of numerical solver

    International Nuclear Information System (INIS)

    Hanna, S.R.; Chang, J.C.

    1997-01-01

    The HGSYSTEM/UF 6 model was developed for use in preparing Safety Analysis Reports (SARs) by estimating the consequences of possible accidental releases of UF 6 to the atmosphere at the gaseous diffusion plants (GDPs) located in Portsmouth, Ohio, and Paducah, Kentucky. Although the latter report carries a 1996 date, the work that is described was completed in late 1994. When that report was written, the primary release scenarios of interest were thought to be gas pipeline and liquid tank ruptures over open terrain away from the influence of buildings. However, upon further analysis of possible release scenarios, the developers of the SARs decided it was necessary to also consider accidental releases within buildings. Consequently, during the fall and winter of 1995-96, modules were added to HGSYSTEM/UF 6 to account for flow and dispersion around buildings. The original HGSYSTEM/UF 6 model also contained a preliminary method for accounting for the possible lift-off of ground-based buoyant plumes. An improved model and a new set of wind tunnel data for buoyant plumes trapped in building recirculation cavities have become available that appear to be useful for revising the lift-off algorithm and modifying it for use in recirculation cavities. This improved lift-off model has been incorporated in the updated modules for dispersion around buildings

  17. Hybrid 3D model for the interaction of plasma thruster plumes with nearby objects

    Science.gov (United States)

    Cichocki, Filippo; Domínguez-Vázquez, Adrián; Merino, Mario; Ahedo, Eduardo

    2017-12-01

    This paper presents a hybrid particle-in-cell (PIC) fluid approach to model the interaction of a plasma plume with a spacecraft and/or any nearby object. Ions and neutrals are modeled with a PIC approach, while electrons are treated as a fluid. After a first iteration of the code, the domain is split into quasineutral and non-neutral regions, based on non-neutrality criteria, such as the relative charge density and the Debye length-to-cell size ratio. At the material boundaries of the former quasineutral region, a dedicated algorithm ensures that the Bohm condition is met. In the latter non-neutral regions, the electron density and electric potential are obtained by solving the coupled electron momentum balance and Poisson equations. Boundary conditions for both the electric current and potential are finally obtained with a plasma sheath sub-code and an equivalent circuit model. The hybrid code is validated by applying it to a typical plasma plume-spacecraft interaction scenario, and the physics and capabilities of the model are finally discussed.

  18. Are splash plumes the origin of minor hotspots?

    Science.gov (United States)

    Davies, J. H.; Bunge, H.-P.

    2006-05-01

    It has been claimed that focused hot cylindrical upwelling plumes cause many of the surface volcanic hotspots on Earth. It has also been argued that they must originate from thermal boundary layers. In this paper, we present spherical simulations of mantle circulation at close to Earth-like vigor with significant internal heating. These show, in addition to thermal boundary layer plumes, a new class of plumes that are not rooted in thermal boundary layers. These plumes develop as instabilities from the edge of bowls of hot mantle, which are produced by cold downwelling material deforming hot sheets of mantle. The resulting bowl and plume structure can look a bit like the “splash” of a water droplet. These splash plumes might provide an explanation for some hotspots that are not underlain by thermal boundary layer sourced plumes and not initiated by large igneous provinces. We suggest that in Earth's mantle, lithospheric instabilities or small pieces of subducting slab could play the role of the model downwelling material in initiating splash plumes. Splash plumes would have implications for interpreting ocean-island basalt geochemistry, plume fixity, excess plume temperature, and estimating core heat flux. Improved seismic imaging will ultimately test this hypothesis.

  19. Propagation of uncertainty and sensitivity analysis in an integral oil-gas plume model

    KAUST Repository

    Wang, Shitao; Iskandarani, Mohamed; Srinivasan, Ashwanth; Thacker, W. Carlisle; Winokur, Justin; Knio, Omar

    2016-01-01

    Polynomial Chaos expansions are used to analyze uncertainties in an integral oil-gas plume model simulating the Deepwater Horizon oil spill. The study focuses on six uncertain input parameters—two entrainment parameters, the gas to oil ratio, two parameters associated with the droplet-size distribution, and the flow rate—that impact the model's estimates of the plume's trap and peel heights, and of its various gas fluxes. The ranges of the uncertain inputs were determined by experimental data. Ensemble calculations were performed to construct polynomial chaos-based surrogates that describe the variations in the outputs due to variations in the uncertain inputs. The surrogates were then used to estimate reliably the statistics of the model outputs, and to perform an analysis of variance. Two experiments were performed to study the impacts of high and low flow rate uncertainties. The analysis shows that in the former case the flow rate is the largest contributor to output uncertainties, whereas in the latter case, with the uncertainty range constrained by aposteriori analyses, the flow rate's contribution becomes negligible. The trap and peel heights uncertainties are then mainly due to uncertainties in the 95% percentile of the droplet size and in the entrainment parameters.

  20. On the significance of contaminant plume-scale and dose-response models in defining hydrogeological characterization needs

    Science.gov (United States)

    de Barros, F.; Rubin, Y.; Maxwell, R.; Bai, H.

    2007-12-01

    Defining rational and effective hydrogeological data acquisition strategies is of crucial importance since financial resources available for such efforts are always limited. Usually such strategies are developed with the goal of reducing uncertainty, but less often they are developed in the context of the impacts of uncertainty. This paper presents an approach for determining site characterization needs based on human health risk factors. The main challenge is in striking a balance between improved definition of hydrogeological, behavioral and physiological parameters. Striking this balance can provide clear guidance on setting priorities for data acquisition and for better estimating adverse health effects in humans. This paper addresses this challenge through theoretical developments and numerical testing. We will report on a wide range of factors that affect the site characterization needs including contaminant plume's dimensions, travel distances and other length scales that characterize the transport problem, as well as health risk models. We introduce a new graphical tool that allows one to investigate the relative impact of hydrogeological and physiological parameters in risk. Results show that the impact of uncertainty reduction in the risk-related parameters decreases with increasing distances from the contaminant source. Also, results indicate that human health risk becomes less sensitive to hydrogeological measurements when dealing with ergodic plumes. This indicates that under ergodic conditions, uncertainty reduction in human health risk may benefit from better understanding of the physiological component as opposed to a detailed hydrogeological characterization

  1. Smoke plume trajectory from in-situ burning of crude oil: complex terrain modeling

    International Nuclear Information System (INIS)

    McGrattan, K.

    1997-01-01

    Numerical models have been used to predict the concentration of particulate matter or other combustion products downwind from a proposed in- situ burning of an oil spill. One of the models used was the National Institute of Standards and Technology (NIST) model, ALOFT (A Large Outdoor Fire plume Trajectory), which is based on the conservation equations that govern the introduction of hot gases and particulate matter into the atmosphere. By using a model based on fundamental equations, it becomes a relatively simple matter to simulate smoke dispersal flow patterns, and to compute the solution to the equations of motion that govern the transport of pollutants in the lower atmosphere at a resolution that is comparable to that of the underlying terrain data. 9 refs., 2 tabs., 5 figs

  2. Characterization and modeling of turbidity density plume induced into stratified reservoir by flood runoffs.

    Science.gov (United States)

    Chung, S W; Lee, H S

    2009-01-01

    In monsoon climate area, turbidity flows typically induced by flood runoffs cause numerous environmental impacts such as impairment of fish habitat and river attraction, and degradation of water supply efficiency. This study was aimed to characterize the physical dynamics of turbidity plume induced into a stratified reservoir using field monitoring and numerical simulations, and to assess the effect of different withdrawal scenarios on the control of downstream water quality. Three different turbidity models (RUN1, RUN2, RUN3) were developed based on a two-dimensional laterally averaged hydrodynamic and transport model, and validated against field data. RUN1 assumed constant settling velocity of suspended sediment, while RUN2 estimated the settling velocity as a function of particle size, density, and water temperature to consider vertical stratification. RUN3 included a lumped first-order turbidity attenuation rate taking into account the effects of particles aggregation and degradable organic particles. RUN3 showed best performance in replicating the observed variations of in-reservoir and release turbidity. Numerical experiments implemented to assess the effectiveness of different withdrawal depths showed that the alterations of withdrawal depth can modify the pathway and flow regimes of the turbidity plume, but its effect on the control of release water quality could be trivial.

  3. Ion Formation Resulting from Freezing, Thawing, and Collisional Processes in Plumes Emitted from Planetary Bodies: Implications for Plume Chemistry and the Detection of Trace Organics Present in Enceladus Geysers

    Science.gov (United States)

    Beauchamp, J. L.; Wiley, J. S.; Thomas, D. A.

    2014-12-01

    Icy plumes emitted into space from Enceladus and other planetary bodies offer the intriguing possibility of sampling the composition of subsurface liquid reservoirs that may comprise habitable zones of particular astrobiological significance in our solar system. Mass spectrometric sampling of plume materials enables the detection of molecules that facilitate an assessment of the extent of chemical and biological evolution that may have occurred in a subsurface sea. In laboratory experiments we have investigated the physical and chemical processes that occur in the complex plume environment that lead to ionization of trace organic constituents, both as a result of the freezing of liquid droplets and the thawing of icy particles. We also demonstrate that collisions between icy particles lead to triboelectric charging. Subsequent discharges between oppositely charged particles result not only in the ionization of trace organics but to chemical reactions between molecular components present in the particles. For example, nitriles react with water to form amides and acids. In particular, icy particles doped with small amounts of aminoacetonitrile and water lead to the formation of the simplest amino acid glycine. The implications which these observations may have for sampling plume composition from orbit in a future mission to Enceladus will be discussed.

  4. Multi-scale Modeling of Power Plant Plume Emissions and Comparisons with Observations

    Science.gov (United States)

    Costigan, K. R.; Lee, S.; Reisner, J.; Dubey, M. K.; Love, S. P.; Henderson, B. G.; Chylek, P.

    2011-12-01

    The Remote Sensing Verification Project (RSVP) test-bed located in the Four Corners region of Arizona, Utah, Colorado, and New Mexico offers a unique opportunity to develop new approaches for estimating emissions of CO2. Two major power plants located in this area produce very large signals of co-emitted CO2 and NO2 in this rural region. In addition to the Environmental Protection Agency (EPA) maintaining Continuous Emissions Monitoring Systems (CEMS) on each of the power plant stacks, the RSVP program has deployed an array of in-situ and remote sensing instruments, which provide both point and integrated measurements. To aid in the synthesis and interpretation of the measurements, a multi-scale atmospheric modeling approach is implemented, using two atmospheric numerical models: the Weather Research and Forecasting Model with chemistry (WRF-Chem; Grell et al., 2005) and the HIGRAD model (Reisner et al., 2003). The high fidelity HIGRAD model incorporates a multi-phase Lagrangian particle based approach to track individual chemical species of stack plumes at ultra-high resolution, using an adaptive mesh. It is particularly suited to model buoyancy effects and entrainment processes at the edges of the power plant plumes. WRF-Chem is a community model that has been applied to a number of air quality problems and offers several physical and chemical schemes that can be used to model the transport and chemical transformation of the anthropogenic plumes out of the local region. Multiple nested grids employed in this study allow the model to incorporate atmospheric variability ranging from synoptic scales to micro-scales (~200 m), while including locally developed flows influenced by the nearby complex terrain of the San Juan Mountains. The simulated local atmospheric dynamics are provided to force the HIGRAD model, which links mesoscale atmospheric variability to the small-scale simulation of the power plant plumes. We will discuss how these two models are applied and

  5. A new conceptual model for whole mantle convection and the origin of hotspot plumes

    Science.gov (United States)

    Yoshida, Masaki

    2014-08-01

    A new conceptual model of mantle convection is constructed for consideration of the origin of hotspot plumes, using recent evidence from seismology, high-pressure experiments, geodynamic modeling, geoid inversion studies, and post-glacial rebound analyses. This conceptual model delivers several key points. Firstly, some of the small-scale mantle upwellings observed as hotspots on the Earth's surface originate at the base of the mantle transition zone (MTZ), in which the Archean granitic continental material crust (TTG; tonalite-trondhjemite-granodiorite) with abundant radiogenic elements is accumulated. Secondly, the TTG crust and the subducted oceanic crust that have accumulated at the base of MTZ could act as thermal or mechanical insulators, leading to the formation of a hot and less viscous layer just beneath the MTZ; which may enhance the instability of plume generation at the base of the MTZ. Thirdly, the origin of some hotspot plumes is isolated from the large low shear-wave velocity provinces (LLSVPs) under Africa and the South Pacific. I consider that the conceptual model explains why almost all the hotspots around Africa are located above the margins of the African LLSVP. Because a planetary-scale trench system surrounding a “Pangean cell” has been spatially stable throughout the Phanerozoic, a large amount of the oceanic crustal layer is likely to be trapped in the MTZ under the Pangean cell. Therefore, under Africa, almost all of the hotspot plumes originate from the base of the MTZ, where a large amount of TTG and/or oceanic crusts has accumulated. This conceptual model may explain the fact that almost all the hotspots around Africa are located on margins above the African LLSVP. It is also considered that some of the hotspot plumes under the South Pacific thread through the TTG/oceanic crusts accumulated around the bottom of the MTZ, and some have their roots in the South Pacific LLSVP while others originate from the MTZ. The numerical simulations

  6. Measurements on cooling tower plumes. Pt. 3

    International Nuclear Information System (INIS)

    Fortak, H.

    1975-11-01

    In this paper an extended field experiment is described in which cooling tower plumes were investigated by means of three-dimensional in situ measurements. The goal of this program was to obtain input data for numerical models of cooling tower plumes. Data for testing or developing assumptions for sub-grid parametrizations were of special interest. Utilizing modern systems for high-resolution aerology and small aircraft, four measuring campaigns were conducted: two campaigns (1974) at the cooling towers of the RWE power station at Neurath and also two (1975) at the single cooling tower of the RWE power station at Meppen. Because of the broad spectrum of weather situations, it can be assumed that the results are representative with regard to the interrelationship between the structure of cooling tower plumes and the large-scale meteorological situation. A large number of flights with a powered glider ASK 16 (more than 100 flight hours) crossing the plumes on orthogonal tracks was performed. All flights showed that the plume could be identified up to large downwind distances by discontinuous jumps of temperature and vapour pressure. Therefore a definite geometry of the plume could always be defined. In all cross sections a vertical circulation could be observed. At the plumes boundaries, which could be defined by the mentioned jumps of temperature and vapour pressure, a maximum of downward vertical motion was observed in most cases. Entrainment along the boundary of a cross section seems to be very small, except at the lower part of the plume. There, the mass entrainment is maximum and is responsible for plume rise as well as for enlargement of the cross section. The visible part of the plume (cloud) was only a small fraction of the whole plume. The discontinuities of temperature and vapour pressure show that the plume fills the space below the visible plume down to the ground. However, all effects decrease rapidly towards the ground. It turned out that high

  7. Sinking, merging and stationary plumes in a coupled chemotaxis-fluid model: a high-resolution numerical approach

    KAUST Repository

    Chertock, A.; Fellner, K.; Kurganov, A.; Lorz, A.; Markowich, P. A.

    2012-01-01

    examples, which illustrate (i) the formation of sinking plumes, (ii) the possible merging of neighbouring plumes and (iii) the convergence towards numerically stable stationary plumes. The examples with stable stationary plumes show how the surface

  8. Modeling the South American regional smoke plume: aerosol optical depth variability and surface shortwave flux perturbation

    Directory of Open Access Journals (Sweden)

    N. E. Rosário

    2013-03-01

    Full Text Available Intra-seasonal variability of smoke aerosol optical depth (AOD and downwelling solar irradiance at the surface during the 2002 biomass burning season in South America was modeled using the Coupled Chemistry-Aerosol-Tracers Transport model with the Brazilian developments on the Regional Atmospheric Modeling System (CCATT-BRAMS. Measurements of total and fine mode fraction (FMF AOD from the AErosol RObotic NETwork (AERONET and solar irradiance at the surface from the Solar Radiation Network (SolRad-NET were used to evaluate model results. In general, the major features associated with AOD evolution over the southern part of the Amazon basin and cerrado ecosystem are captured by the model. The main discrepancies were found for high aerosol loading events. In the northeastern portion of the Amazon basin the model systematically underestimated total AOD, as expected, since smoke contribution is not dominant as it is in the southern portion and emissions other than smoke were not considered in the simulation. Better agreement was obtained comparing the model results with observed FMF AOD, which pointed out the relevance of coarse mode aerosol emission in that region. Likewise, major discrepancies over cerrado during high AOD events were found to be associated with coarse mode aerosol omission in our model. The issue of high aerosol loading events in the southern part of the Amazon was related to difficulties in predicting the smoke AOD field, which was discussed in the context of emissions shortcomings. The Cuiabá cerrado site was the only one where the highest quality AERONET data were unavailable for both total and FMF AOD. Thus, lower quality data were used. Root-mean-square error (RMSE between the model and observed FMF AOD decreased from 0.34 to 0.19 when extreme AOD events (FMF AOD550 nm ≥ 1.0 and Cuiabá were excluded from the analysis. Downward surface solar irradiance comparisons also followed similar trends when extreme AOD were excluded

  9. Heat and mass transfer in the mushroom-shaped head of mantle plume

    Directory of Open Access Journals (Sweden)

    Kirdyashkin Anatoly

    2017-01-01

    Full Text Available The results of experimental and theoretical modeling of free-convection flows in the melt of the plume conduit and in the mushroom-shaped head are presented. It was shown that the plumes with the mushroom-shaped heads can be responsible for the batholith formation. The main parameters of such plumes are estimated.

  10. Modelling Photoelectron Production in the Enceladus Plume and Comparison with Observations by CAPS-ELS

    Science.gov (United States)

    Taylor, S. A.; Coates, A. J.; Jones, G.; Wellbrock, A.; Waite, J. H., Jr.

    2016-12-01

    The Electron Spectrometer (ELS) of the Cassini Plasma Spectrometer (CAPS) measures electrons in the energy range 0.6-28,000 eV with an energy resolution of 16.7%. ELS has observed photoelectrons produced in the plume of Enceladus. These photoelectrons are found during Enceladus encounters in the energetic particle shadow where the spacecraft is shielded from penetrating radiation by the moon [Coates et al, 2013]. Observable is a population of photoelectrons at 20-30eV, which are seen at other bodies in the solar system and are usually associated with ionisation by the strong solar He II (30.4 nm) line. We have identified secondary peaks at 40-50eV detected by ELS which are also interpreted as a warmer population of photoelectrons created through the ionisation of neutrals in the Enceladus torus. We have constructed a model of photoelectron production in the plume and compared it with ELS Enceladus flyby data using automated fitting procedures. This has yielded estimates for electron temperature and density as well as a spacecraft potential estimate which is corrected for.

  11. Estimating Sulfur Dioxide in Volcanic Plumes Using an Ultraviolet Camera. First Results from Lascar, Ollagüe and Irruputuncu Volcanoes

    Science.gov (United States)

    Geoffroy, C. A.; Amigo, A.

    2014-12-01

    Volcanic gas fluxes give important information on both the amount of degassing and magma reservoirs. In most of magmas, water vapor (H2O) and carbon dioxide (CO2) are major components of volcanic gas. However, sulfur dioxide (SO2) is one of the targets of remote sensing due to their low concentration in the environment and easy detection by ultraviolet spectroscopy. Accordingly, plume imaging using passive ultraviolet cameras is a relatively simple method to study volcanic degassing, expeditious manner and can be used up from distances of about 10 km from source of emissions. We estimated SO2 concentrations and fluxes in volcanic plumes with the ultraviolet camera Envicam-2, developed by Nicarnica Aviation, acquired by the Geological Survey of Chile (SERNAGEOMIN). The camera has filters that allow passage of ultraviolet radiation at wavelengths of interest. For determining whether there is absorption of radiation associated with the presence of SO2 the Beer-Lambert law was used for quantifying concentrations using appropriate calibration cells. SO2 emissions to the atmosphere were estimated using wind speed as an approximation to the plume transport. In this study we reported the implementation of a new methodology for using Envicam-2 and subsequent collection of SO2 concentrations and fluxes in passive degassing volcanoes. Measurements were done at Lascar, Ollagüe and Irruputuncu volcanoes, located in northern Chile. The volcanoes were chosen because of optimal atmospheric conditions for ultraviolet imaging. Results indicate concentrations within the expected ranges for three volcanoes generally between 400-1700 ppm•m. In the case of Láscar volcano, the emission rates of SO2 range from 250 to 500 tonnes/day for a same image of the plume. In particular, wind speed was determined from scaling images and are consistent with data from regional numerical models, as well as records of the meteorological stations installed at the ALMA astronomical center, located

  12. Sinking, merging and stationary plumes in a coupled chemotaxis-fluid model: a high-resolution numerical approach

    KAUST Repository

    Chertock, A.

    2012-02-02

    Aquatic bacteria like Bacillus subtilis are heavier than water yet they are able to swim up an oxygen gradient and concentrate in a layer below the water surface, which will undergo Rayleigh-Taylor-type instabilities for sufficiently high concentrations. In the literature, a simplified chemotaxis-fluid system has been proposed as a model for bio-convection in modestly diluted cell suspensions. It couples a convective chemotaxis system for the oxygen-consuming and oxytactic bacteria with the incompressible Navier-Stokes equations subject to a gravitational force proportional to the relative surplus of the cell density compared to the water density. In this paper, we derive a high-resolution vorticity-based hybrid finite-volume finite-difference scheme, which allows us to investigate the nonlinear dynamics of a two-dimensional chemotaxis-fluid system with boundary conditions matching an experiment of Hillesdon et al. (Bull. Math. Biol., vol. 57, 1995, pp. 299-344). We present selected numerical examples, which illustrate (i) the formation of sinking plumes, (ii) the possible merging of neighbouring plumes and (iii) the convergence towards numerically stable stationary plumes. The examples with stable stationary plumes show how the surface-directed oxytaxis continuously feeds cells into a high-concentration layer near the surface, from where the fluid flow (recurring upwards in the space between the plumes) transports the cells into the plumes, where then gravity makes the cells sink and constitutes the driving force in maintaining the fluid convection and, thus, in shaping the plumes into (numerically) stable stationary states. Our numerical method is fully capable of solving the coupled chemotaxis-fluid system and enabling a full exploration of its dynamics, which cannot be done in a linearised framework. © 2012 Cambridge University Press.

  13. Measurements at cooling tower plumes. Part 3. Three-dimensional measurements at cooling tower plumes

    International Nuclear Information System (INIS)

    Fortak, H.

    An extended field experiment is described in which cooling tower plumes were studied by means of three-dimensional in situ measurements. The goal was to obtain input data for numerical models of cooling tower plumes. Of special interest were data for testing or developing assumptions for sub-grid parametrizations. Utilizing modern systems for high-resolution aerology and small aircraft, four measuring campaigns were conducted: two campaigns (1974) at the cooling towers of the RWE power station Neurath and also two (1975) at the single cooling tower of the RWE power station Meppen. Because of the broad spectrum of weather situations it can be assumed that the results are representative with regard to the interrelationship between structure of cooling tower plume and large-scale meteorological situation. A large number of flights with a powered glider crossing the plumes on orthogonal tracks was performed. All flights showed that the plume could be identified up to large downwind distances by discontinuous jumps of temperature and vapor pressure. Therefore, a definite geometry of the plume could always be defined. In all cross sections a vertical circulation could be observed. At the boundary, which could be defined by the mentioned jumps of temperature and vapor pressure, a maximum of downward vertical motion could be observed in most cases. Entrainment along the boundary of a cross section seems to be very small, except at the lower part of the plume. There, the mass entrainment is maximum and is responsible for plume rise as well as for enlargement of the cross section. The visible part of the plume (cloud) was only a small fraction of the whole plume. High-resolution aerology is necessary in order to explain the structure and behavior of such plumes. This is especially the case in investigations regarding the dynamic break-through of temperature inversions. Such cases were observed frequently under various meteorological conditions and are described

  14. Sediment Plumes Resulting from the Port of Miami Dredging: Analysis and Interpretation Using Satellite Data and Long Term Monitoring Programs

    Science.gov (United States)

    Barnes, B. B.; Hu, C.; Kovach, C.; Silverstein, R. N.

    2016-02-01

    From November 2013 through mid-2015, large turbidity plumes were observed offshore the Port of Miami (Florida, USA), likely associated with a project to deepen and widen the Miami Harbor channels. Using data from local monitoring programs, however, it is difficult to estimate the size, duration, extent, and severity (relative to natural turbidity events) of these plumes. In contrast, satellite observing systems offer a platform from which these plumes can be monitored and placed in historical context. As such, turbidity plumes captured by MODIS (Aqua) and Landsat 8 reflectance data were manually outlined. For MODIS, these delineations were refined using reflectance anomaly thresholds, determined from pre-dredging data. Long term records of local environmental conditions were used to account for conditions (e.g., wind speed, tidal stage) for which elevated reflectance data might be expected in the absence of dredging. The spatial extent of turbidity plumes observed in the Port of Miami region during the dredging period ranged from 127 and 228 km2, at least 5 times that immediately prior to dredging. The frequency of observed plumes in satellite imagery increased from 23% to 84% after dredging began, while temporal differences in plume location, severity, and size were also observed. Turbidity plumes may have large adverse effects on coral communities, and this region is home to many species of coral (including some considered threatened by the US Endangered Species Act). Indeed, over 11 km2 of coral area was affected by these plumes, with some locations within plume delineations on nearly 40% of images. The approaches developed in this work, in particular the focus on historical norms after considering all perturbation factors, may be included in monitoring and assessment of this and future dredging activities, especially where fragile marine ecosystems may potentially be impacted.

  15. A numerical study of the Magellan Plume

    Science.gov (United States)

    Palma, Elbio D.; Matano, Ricardo P.

    2012-05-01

    In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume's waters and an offshore displacement of its salinity front. The interaction between tidal and wind-forcing reinforces the downstream and upstream buoyancy transports of the plume. The influence of the Malvinas Current on the Magellan Plume is more dominant north of 50°S, where it increases the along-shelf velocities and generates intrusions of saltier waters from the outer shelf, thus causing a reduction of the downstream buoyancy transport. Our experiments also indicate that the northern limit of the Magellan Plume is set by a high salinity discharge from the San Matias Gulf. Sensitivity experiments show that increments of the wind stress cause a decrease of the downstream buoyancy transport and an increase of the upstream buoyancy transport. Variations of the magnitude of the discharge produce substantial modifications in the downstream penetration of the plume and buoyancy transport. The Magellan discharge generates a northeastward current in the middle shelf, a recirculation gyre south of the inlet and a region of weak currents father north.

  16. Recommendations on dose buildup factors used in models for calculating gamma doses for a plume

    International Nuclear Information System (INIS)

    Hedemann Jensen, P.; Thykier-Nielsen, S.

    1980-09-01

    Calculations of external γ-doses from radioactivity released to the atmosphere have been made using different dose buildup factor formulas. Some of the dose buildup factor formulas are used by the Nordic countries in their respective γ-dose models. A comparison of calculated γ-doses using these dose buildup factors shows that the γ-doses can be significantly dependent on the buildup factor formula used in the calculation. Increasing differences occur for increasing plume height, crosswind distance, and atmospheric stability and also for decreasing downwind distance. It is concluded that the most accurate γ-dose can be calculated by use of Capo's polynomial buildup factor formula. Capo-coefficients have been calculated and shown in this report for γ-energies below the original lower limit given by Capo. (author)

  17. Studies of the environmental impact of evaporative cooling tower plumes

    International Nuclear Information System (INIS)

    Thomson, D.W.

    1978-01-01

    This ongoing research program of the environmental impact of natural-draft evaporative cooling tower plumes consists principally of a comprehensive series of airborne measurements of a variety of the physical characteristics of the plumes and, to a lesser extent, of preliminary studies of remote sodar plume probing techniques and the development of simplified dynamical numerical models suitable for use in conducting field measurement programs. The PSU Doppler sodar was used at the Keystone Power Plant in southwestern Pennsylvania for an extended series of remote measurements of the characteristics of plume turbulent temperature and velocity fluctuations and results are discussed

  18. Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) Plume Induced Environment Modelling

    Science.gov (United States)

    Mobley, B. L.; Smith, S. D.; Van Norman, J. W.; Muppidi, S.; Clark, I

    2016-01-01

    Provide plume induced heating (radiation & convection) predictions in support of the LDSD thermal design (pre-flight SFDT-1) Predict plume induced aerodynamics in support of flight dynamics, to achieve targeted freestream conditions to test supersonic deceleration technologies (post-flight SFDT-1, pre-flight SFDT-2)

  19. Chemistry in aircraft plumes

    Energy Technology Data Exchange (ETDEWEB)

    Kraabol, A.G.; Stordal, F.; Knudsen, S. [Norwegian Inst. for Air Research, Kjeller (Norway); Konopka, P. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    An expanding plume model with chemistry has been used to study the chemical conversion of NO{sub x} to reservoir species in aircraft plumes. The heterogeneous conversion of N{sub 2}O{sub 5} to HNO{sub 3}(s) has been investigated when the emissions take place during night-time. The plume from an B747 has been simulated. During a ten-hour calculation the most important reservoir species was HNO{sub 3} for emissions at noon. The heterogeneous reactions had little impact on the chemical loss of NO{sub x} to reservoir species for emissions at night. (author) 4 refs.

  20. Chemistry in aircraft plumes

    Energy Technology Data Exchange (ETDEWEB)

    Kraabol, A G; Stordal, F; Knudsen, S [Norwegian Inst. for Air Research, Kjeller (Norway); Konopka, P [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1998-12-31

    An expanding plume model with chemistry has been used to study the chemical conversion of NO{sub x} to reservoir species in aircraft plumes. The heterogeneous conversion of N{sub 2}O{sub 5} to HNO{sub 3}(s) has been investigated when the emissions take place during night-time. The plume from an B747 has been simulated. During a ten-hour calculation the most important reservoir species was HNO{sub 3} for emissions at noon. The heterogeneous reactions had little impact on the chemical loss of NO{sub x} to reservoir species for emissions at night. (author) 4 refs.

  1. Paducah Gaseous Diffusion Plant Northwest Plume interceptor system evaluation

    International Nuclear Information System (INIS)

    Laase, A.D.; Clausen, J.L.

    1998-01-01

    The Paducah Gaseous Diffusion Plant (PGDP) recently installed an interceptor system consisting of four wells, evenly divided between two well fields, to contain the Northwest Plume. As stated in the Northwest Plume Record of Decision (ROD), groundwater will be pumped at a rate to reduce further contamination and initiate control of the northwest contaminant plume. The objective of this evaluation was to determine the optimum (minimal) well field pumping rates required for plume hotspot containment. Plume hotspot, as defined in the Northwest Plume ROD and throughout this report, is that portion of the plume with trichloroethene (TCE) concentrations greater than 1,000 microg/L. An existing 3-dimensional groundwater model was modified and used to perform capture zone analyses of the north and south interceptor system well fields. Model results suggest that the plume hotspot is not contained at the system design pumping rate of 100 gallons per minute (gal/min) per well field. Rather, the modeling determined that north and south well field pumping rates of 400 and 150 gal/min, respectively, are necessary for plume hotspot containment. The difference between the design and optimal pumping rates required for containment can be attributed to the discovery of a highly transmissive zone in the vicinity of the two well fields

  2. Lithosphere erosion atop mantle plumes

    Science.gov (United States)

    Agrusta, R.; Arcay, D.; Tommasi, A.

    2012-12-01

    Mantle plumes are traditionally proposed to play an important role in lithosphere erosion. Seismic images beneath Hawaii and Cape Verde show a lithosphere-asthenosphere-boundary (LAB) up to 50 km shallower than the surroundings. However, numerical models show that unless the plate is stationary the thermo-mechanical erosion of the lithosphere does not exceed 30 km. We use 2D petrological-thermo-mechanical numerical models based on a finite-difference method on a staggered grid and marker in cell method to study the role of partial melting on the plume-lithosphere interaction. A homogeneous peridotite composition with a Newtonian temperature- and pressure-dependent viscosity is used to simulate both the plate and the convective mantle. A constant velocity, ranging from 5 to 12.5 cm/yr, is imposed at the top of the plate. Plumes are created by imposing a thermal anomaly of 150 to 350 K on a 50 km wide domain at the base of the model (700 km depth); the plate right above the thermal anomaly is 40 Myr old. Partial melting is modeled using batch-melting solidus and liquidus in anhydrous conditions. We model the progressive depletion of peridotite and its effect on partial melting by assuming that the melting degree only strictly increases through time. Melt is accumulated until a porosity threshold is reached and the melt in excess is then extracted. The rheology of the partially molten peridotite is determined using viscous constitutive relationship based on a contiguity model, which enables to take into account the effects of grain-scale melt distribution. Above a threshold of 1%, melt is instantaneously extracted. The density varies as a function of partial melting degree and extraction. Besides, we analyze the kinematics of the plume as it impacts a moving plate, the dynamics of time-dependent small-scale convection (SSC) instabilities developing in the low-viscosity layer formed by spreading of hot plume material at the lithosphere base, and the resulting thermal

  3. Modelling tools for integrating geological, geophysical and contamination data for characterization of groundwater plumes

    DEFF Research Database (Denmark)

    Balbarini, Nicola

    the contaminant plume in a shallow and a deep plume. These plumes have different chemical characteristics and different migration paths to the stream. This has implications for the risk assessment of the stream and groundwater in the area. The difficulty of determining groundwater flow paths means that it is also...... receptors, including streams. Key risk assessment parameters, such as contaminant mass discharge estimates, and tools are then used to evaluate the risk. The cost of drilling often makes investigations of large and/or deep contaminant plumes unfeasible. For this reason, it is important to develop cost...... organic compounds, including pharmaceutical compounds and chlorinated ethenes. The correlation between DCIP and organic compounds is indirect and depends on the chemical composition of the contaminant plume and the transport processes. Thus, the correlations are site specific and may change between...

  4. A Model for the Infrared Radiance of Optically Thin, Particulate Exhaust Plumes Generated by Pyrotechnic Flares Burning in a Vacuum

    National Research Council Canada - National Science Library

    Cohen, Douglas

    2000-01-01

    .... The model is used to predict how a magnesium-Teflon exhaust plume would look when viewed as an approximate point source by a distant infrared sensor and also to analyze the data acquired from three separate magnesium-Teflon flares burned in a large vacuum chamber.

  5. Solar Coronal Plumes

    Directory of Open Access Journals (Sweden)

    Giannina Poletto

    2015-12-01

    Full Text Available Polar plumes are thin long ray-like structures that project beyond the limb of the Sun polar regions, maintaining their identity over distances of several solar radii. Plumes have been first observed in white-light (WL images of the Sun, but, with the advent of the space era, they have been identified also in X-ray and UV wavelengths (XUV and, possibly, even in in situ data. This review traces the history of plumes, from the time they have been first imaged, to the complex means by which nowadays we attempt to reconstruct their 3-D structure. Spectroscopic techniques allowed us also to infer the physical parameters of plumes and estimate their electron and kinetic temperatures and their densities. However, perhaps the most interesting problem we need to solve is the role they cover in the solar wind origin and acceleration: Does the solar wind emanate from plumes or from the ambient coronal hole wherein they are embedded? Do plumes have a role in solar wind acceleration and mass loading? Answers to these questions are still somewhat ambiguous and theoretical modeling does not provide definite answers either. Recent data, with an unprecedented high spatial and temporal resolution, provide new information on the fine structure of plumes, their temporal evolution and relationship with other transient phenomena that may shed further light on these elusive features.

  6. On the validity of a Fickian diffusion model for the spreading of liquid infiltration plumes in partially saturated heterogeneous media

    International Nuclear Information System (INIS)

    Pruess, K.

    1994-01-01

    Localized infiltration of aqueous and -non-aqueous phase liquids (NAPLs) occurs in many circumstances. Examples include leaky underground pipelines and storage tanks, landfill and disposal sites, and surface spills. Because of ever-present heterogeneities on different scales such infiltration plumes are expected to disperse transversally and longitudinally. This paper examines recent suggestions that liquid plumes are being dispersed from medium heterogeneities in a manner that is analogous to Fickian diffusion. Numerical simulation experiments on liquid infiltration in heterogeneous media are performed to study the dispersive effects of small-scale heterogeneity. It is found that plume spreading indeed tends to be diffusive. Our results suggest that, as far as infiltration of liquids is concerned, broad classes of heterogeneous media behave as dispersive media with locally homogeneous (albeit anisotropic) permeability

  7. Modeling the regional impact of ship emissions on NOx and ozone levels over the Eastern Atlantic and Western Europe using ship plume parameterization

    Directory of Open Access Journals (Sweden)

    P. Pisoft

    2010-07-01

    Full Text Available In general, regional and global chemistry transport models apply instantaneous mixing of emissions into the model's finest resolved scale. In case of a concentrated source, this could result in erroneous calculation of the evolution of both primary and secondary chemical species. Several studies discussed this issue in connection with emissions from ships and aircraft. In this study, we present an approach to deal with the non-linear effects during dispersion of NOx emissions from ships. It represents an adaptation of the original approach developed for aircraft NOx emissions, which uses an exhaust tracer to trace the amount of the emitted species in the plume and applies an effective reaction rate for the ozone production/destruction during the plume's dilution into the background air. In accordance with previous studies examining the impact of international shipping on the composition of the troposphere, we found that the contribution of ship induced surface NOx to the total reaches 90% over remote ocean and makes 10–30% near coastal regions. Due to ship emissions, surface ozone increases by up to 4–6 ppbv making 10% contribution to the surface ozone budget. When applying the ship plume parameterization, we show that the large scale NOx decreases and the ship NOx contribution is reduced by up to 20–25%. A similar decrease was found in the case of O3. The plume parameterization suppressed the ship induced ozone production by 15–30% over large areas of the studied region. To evaluate the presented parameterization, nitrogen monoxide measurements over the English Channel were compared with modeled values and it was found that after activating the parameterization the model accuracy increases.

  8. Coupling of Realistic Rate Estimates with Genomics for Assessing Contaminant Attenuation and Long-Term Plume Containment - Task 4: Modeling - Final Report

    International Nuclear Information System (INIS)

    Robert C. Starr

    2005-01-01

    seven plumes at 24 DOE facilities were screened, and 14 plumes were selected for detailed examination. In the plumes selected for further study, spatial changes in the concentration of a conservative co-contaminant were used to compensate for the effects of mixing and temporal changes in TCE release from the contaminant source. Decline in TCE concentration along a flow path in excess of the co contaminant concentration decline was attributed to cometabolic degradation. This study indicated that TCE was degraded in 9 of the 14 plumes examined, with first order degradation half-lives ranging from about 1 to 12 years. TCE degradation in about two-thirds of the plumes examined suggests that cometabolism of TCE in aerobic groundwater is a common occurrence, in contrast to the conventional wisdom that TCE is recalcitrant in aerobic groundwater. The degradation half-life values calculated in this study are short enough that natural attenuation may be a viable remedy in many aerobic plumes. Computer modeling of groundwater flow and contaminant transport and degradation is frequently used to predict the evolution of groundwater plumes, and for evaluating natural attenuation and other remedial alternatives. An important aspect of a computer model is the mathematical approach for describing degradation kinetics. A common approach is to assume that degradation occurs as a first-order process. First order kinetics are easily incorporated into transport models and require only a single value (a degradation half-life) to describe reaction kinetics. The use of first order kinetics is justified in many cases because more elaborate kinetic equations often closely approximate first order kinetics under typical field conditions. A previous modeling study successfully simulated the INL TCE plume using first order degradation kinetics. TCE cometabolism is the result of TCE reacting with microbial enzymes that were produced for other purposes, such as oxidizing a growth substrate to obtain

  9. DSMC Simulations of Io's Pele Plume

    Science.gov (United States)

    McDoniel, William; Goldstein, D.; Varghese, P.; Trafton, L.

    2012-10-01

    Io’s Pele plume rises over 300km in altitude and leaves a deposition ring 1200km across on the surface of the moon. Material emerges from an irregularly-shaped vent, and this geometry gives rise to complex 3D flow features. The Direct Simulation Monte Carlo method is used to model the gas flow in the rarefied plume, demonstrating how the geometry of the source region is responsible for the asymmetric structure of the deposition ring and illustrating the importance of very small-scale vent geometry in explaining large observed features of interest. Simulations of small particles in the plume and comparisons to the black “butterfly wings” seen at Pele are used to constrain particle sizes and entrainment mechanisms. Preliminary results for the effects of plasma energy and momentum transfer to the plume will also be presented.

  10. Predictive geochemical modeling of contaminant concentrations in laboratory columns and in plumes migrating from uranium mill tailings waste impoundments

    International Nuclear Information System (INIS)

    Peterson, S.R.; Martin, W.J.; Serne, R.J.

    1986-04-01

    A computer-based conceptual chemical model was applied to predict contaminant concentrations in plumes migrating from a uranium mill tailings waste impoundment. The solids chosen for inclusion in the conceptual model were selected based on reviews of the literature, on ion speciation/solubility calculations performed on the column effluent solutions and on mineralogical characterization of the contacted and uncontacted sediments. The mechanism of adsorption included in the conceptual chemical model was chosen based on results from semiselective extraction experiments and from mineralogical characterization procedures performed on the sediments. This conceptual chemical model was further developed and partially validated in laboratory experiments where assorted acidic uranium mill tailings solutions percolated through various sediments. This document contains the results of a partial field and laboratory validation (i.e., test of coherence) of this chemical model. Macro constituents (e.g., Ca, SO 4 , Al, Fe, and Mn) of the tailings solution were predicted closely by considering their concentrations to be controlled by the precipitation/dissolution of solid phases. Trace elements, however, were generally predicted to be undersaturated with respect to plausible solid phase controls. The concentration of several of the trace elements were closely predicted by considering their concentrations to be controlled by adsorption onto the amorphous iron oxyhydroxides that precipitated

  11. A forward model for the helium plume effect and the interpretation of helium charge exchange measurements at ASDEX Upgrade

    Science.gov (United States)

    Kappatou, A.; McDermott, R. M.; Pütterich, T.; Dux, R.; Geiger, B.; Jaspers, R. J. E.; Donné, A. J. H.; Viezzer, E.; Cavedon, M.; the ASDEX Upgrade Team

    2018-05-01

    The analysis of the charge exchange measurements of helium is hindered by an additional emission contributing to the spectra, the helium ‘plume’ emission (Fonck et al 1984 Phys. Rev. A 29 3288), which complicates the interpretation of the measurements. The plume emission is indistinguishable from the active charge exchange signal when standard analysis of the spectra is applied and its intensity is of comparable magnitude for ASDEX Upgrade conditions, leading to a significant overestimation of the He2+ densities if not properly treated. Furthermore, the spectral line shape of the plume emission is non-Gaussian and leads to wrong ion temperature and flow measurements when not taken into account. A kinetic model for the helium plume emission has been developed for ASDEX Upgrade. The model is benchmarked against experimental measurements and is shown to capture the underlying physics mechanisms of the plume effect, as it can reproduce the experimental spectra and provides consistent values for the ion temperature, plasma rotation, and He2+ density.

  12. Hydrogen chloride heterogeneous chemistry on frozen water particles in subsonic aircraft plume. Laboratory studies and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Persiantseva, N.V.; Popovitcheva, O.B.; Rakhimova, T.V. [Moscow State Univ. (Russian Federation)

    1997-12-31

    Heterogeneous chemistry of HCl, as a main reservoir of chlorine content gases, has been considered after plume cooling and ice particle formation. The HCl, HNO{sub 3}, N{sub 2}O{sub 5} uptake efficiencies by frozen water were obtained in a Knudsen-cell flow reactor at the subsonic cruise conditions. The formation of ice particles in the plume of subsonic aircraft is simulated to describe the kinetics of gaseous HCl loss due to heterogeneous processes. It is shown that the HCl uptake by frozen water particles may play an important role in the gaseous HCl depletion in the aircraft plume. (author) 14 refs.

  13. Hydrogen chloride heterogeneous chemistry on frozen water particles in subsonic aircraft plume. Laboratory studies and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Persiantseva, N V; Popovitcheva, O B; Rakhimova, T V [Moscow State Univ. (Russian Federation)

    1998-12-31

    Heterogeneous chemistry of HCl, as a main reservoir of chlorine content gases, has been considered after plume cooling and ice particle formation. The HCl, HNO{sub 3}, N{sub 2}O{sub 5} uptake efficiencies by frozen water were obtained in a Knudsen-cell flow reactor at the subsonic cruise conditions. The formation of ice particles in the plume of subsonic aircraft is simulated to describe the kinetics of gaseous HCl loss due to heterogeneous processes. It is shown that the HCl uptake by frozen water particles may play an important role in the gaseous HCl depletion in the aircraft plume. (author) 14 refs.

  14. Implementing the Stochastic Model of Safety Assessment for the T.D.P. Plume Model

    International Nuclear Information System (INIS)

    Hurtado, A.; Eguilior, S.; Recreo, F.

    2015-01-01

    In this paper, it is continued with the first phase of the implementation of the ABACO2G methodology (Application of Bayes to CO2 Geological Storage ) which is a new methodological approach to solving the problem related with the determination of probabilistic component of CO2 geological storage risk assessment, through the application of Bayesian networks and MonteCarlo probability. This in itself is a fundalmental but complex task, inasmuch as the risk assessment requires the identification of those system performance influence variables and the probability distribution of occurrence of defined events, which is highly difficult when there is no significant casuistry and/or fully developed events. On this, at this stage it has been studied the CO2 plume stochastic evolution implementation during the injection period. This is an essential task because the CO2 geologic storage risks will rely primarily on the convolution of the CO2 plume wavefront probability function with the probability functions of system risk elements, such as wells or faults, that define the event space to estimate the CO2 geologic storage risks.

  15. Large-eddy simulation study of oil/gas plumes in stratified fluid with cross current

    Science.gov (United States)

    Yang, Di; Xiao, Shuolin; Chen, Bicheng; Chamecki, Marcelo; Meneveau, Charles

    2017-11-01

    Dynamics of the oil/gas plume from a subsea blowout are strongly affected by the seawater stratification and cross current. The buoyant plume entrains ambient seawater and lifts it up to higher elevations. During the rising process, the continuously increasing density difference between the entrained and ambient seawater caused by the stable stratification eventually results in a detrainment of the entrained seawater and small oil droplets at a height of maximum rise (peel height), forming a downward plume outside the rising inner plume. The presence of a cross current breaks the plume's axisymmetry and causes the outer plume to fall along the downstream side of the inner plume. The detrained seawater and oil eventually fall to a neutral buoyancy level (trap height), and disperse horizontally to form an intrusion layer. In this study, the complex plume dynamics is investigated using large-eddy simulation (LES). Various laboratory and field scale cases are simulated to explore the effect of cross current and stratification on the plume dynamics. Based on the LES data, various turbulence statistics of the plume are systematically quantified, leading to some useful insights for modeling the mean plume dynamics using integral plume models. This research is made possible by a RFP-V Grant from The Gulf of Mexico Research Initiative.

  16. Implementation of a micro-physical scheme for warm clouds in the meteorological model 'MERCURE': Application to cooling tower plumes and to orographic precipitation

    International Nuclear Information System (INIS)

    Bouzereau, Emmanuel

    2004-01-01

    A two-moment semi-spectral warm micro-physical scheme has been implemented inside the meteorological model 'MERCURE'. A new formulation of the buoyancy flux () is proposed, which is coherent with the corrigendum of Mellor (1977) but differs from Bougeault (1981). The non-precipitating cloud microphysics is validated by comparing the numerical simulations of fifteen cases of cooling tower plumes with data from a measurement campaign in Bugey in 1980. Satisfactory results are obtained on the plumes shape, on the temperature and vertical velocity fields and on the droplets spectrums, although the liquid water contents tend to be overestimated. The precipitating cloud microphysics is tested by reproducing the academical cases of orographic precipitation of Chaumerliac et al. (1987) and Richard and Chaumerliac (1989). The simulations allow a check of the action of different micro-physical terms. (author) [fr

  17. Evaluation of remedial alternative of a LNAPL plume utilizing groundwater modeling

    International Nuclear Information System (INIS)

    Johnson, T.; Way, S.; Powell, G.

    1997-01-01

    The TIMES model was utilized to evaluate remedial options for a large LNAPL spill that was impacting the North Platte River in Glenrock, Wyoming. LNAPL was found discharging into the river from the adjoining alluvial aquifer. Subsequent investigations discovered an 18 hectare plume extended across the alluvium and into a sandstone bedrock outcrop to the south of the river. The TIMES model was used to estimate the LNAPL volume and to evaluate options for optimizing LNAPL recovery. Data collected from recovery and monitoring wells were used for model calibration. A LNAPL volume of 5.5 million L was estimated, over 3.0 million L of which is in the sandstone bedrock. An existing product recovery system was evaluated for its effectiveness. Three alternative recovery scenarios were also evaluated to aid in selecting the most cost-effective and efficient recovery system for the site. An active wellfield hydraulically upgradient of the existing recovery system was selected as most appropriate to augment the existing system in recovering LNAPL efficiently

  18. Integration of plume and puff diffusion models/application of CFD

    Science.gov (United States)

    Mori, Akira

    The clinical symptoms of patients and other evidences of a gas poisoning accident inside an industrial building strongly suggested an abrupt influx of engine exhaust from a construction vehicle which was operating outside in the open air. But the obviously high level of gas concentration could not be well explained by any conventional steady-state gas diffusion models. The author used an unsteady-state continuous Puff Model to simulate the time-wise changes in air stream with the pollutant gas being continuously emitted, and successfully reproduced the observed phenomena. The author demonstrates that this diffusion formula can be solved analytically by the use of error function as long as the change in wind velocity is stepwise, and clarifies the accurate differences between the unsteady- and steady-states and their convergence profiles. Also, the relationship between the Puff and Plume Models is discussed. The case study included a computational fluid dynamics (CFD) analysis to estimate the steady-state air stream and the gas concentration pattern in the affected area. It is well known that clear definition of the boundary conditions is key to successful CFD analysis. The author describes a two-step use of CFD: the first step to define the boundary conditions and the second to determine the steady-state air stream and the gas concentration pattern.

  19. Appearance property and mechanism of plume produced by pulsed ultraviolet laser ablating copper

    International Nuclear Information System (INIS)

    Huang Qingju; Li Fuquan; Wang Honghua

    2008-01-01

    Time-resolved measurements of plume emission spectra by pulsed ultraviolet laser ablating copper in neon were analyzed, and the photographs of plume from laser ablating copper were taken. The experimental results show that plume has different colours in different ranges. At low pressure the centre layer and middle layer colours of plume are mixed colour, and the outer layer colours of plume are yellow and green. At middle pressure the centre layer and middle layer colours of plume are white, and the outer layer colour of plume is pea green. At high pressure the centre layer and middle layer colours of plume are white, and the outer layer colour of plume is faintness green. The plume range is pressed with the rising of ambient gas pressure, and the range colour gets thin with the rising of ambient gas pressure. The plume excitation radiation mechanism in pulsed ultraviolet laser ablating copper was discussed. The primary excitation radiation mechanism in plume is electron collision energy transfer and atom collision energy transfer at low pressure and middle pressure, and it is electrons Bremsstrahlung and recombination excitation radiation of electron and ion at high pressure. The model can be used to explain the experimental result qualitatively. (authors)

  20. Interactions Between Mantle Plumes and Mid-Ocean Ridges: Constraints from Geophysics, Geochemistry, and Geodynamical Modeling

    National Research Council Canada - National Science Library

    Georgen, Jennifer

    2001-01-01

    This thesis studies interactions between mid-ocean ridges and mantle plumes. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow spreading, highly-segmented Southwest Indian Ridge (SWIR...

  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. Electrical Evolution of a Dust Plume from a Low Energy Lunar Impact: A Model Analog to LCROSS

    Science.gov (United States)

    Farrell, W. M.; Stubbs, T. J.; Jackson, T. L.; Colaprete, A.; Heldmann, J. L.; Schultz, P. H.; Killen, R. M.; Delory, G. T.; Halekas, J. S.; Marshall, J. R.; hide

    2011-01-01

    A Monte Carlo test particle model was developed that simulates the charge evolution of micron and sub-micron sized dust grains ejected upon low-energy impact of a moderate-size object onto a lunar polar crater floor. Our analog is the LCROSS impact into Cabeus crater. Our primary objective is to model grain discharging as the plume propagates upwards from shadowed crater into sunlight.

  3. Investigations of the 0.020-scale 88-OTS Integrated Space Shuttle Vehicle Jet-Plume Model in the NASA/Ames Research Center 11 by11-Foot Unitary Plan Wind Tunnel (IA80). Volume 1

    Science.gov (United States)

    Nichols, M. E.

    1976-01-01

    The results are documented of jet plume effects wind tunnel test of the 0.020-scale 88-OTS launch configuration space shuttle vehicle model in the 11 x 11 foot leg of the NASA/Ames Research Center Unitary Plan Wind Tunnel. This test involved cold gas main propulsion system (MPS) and solid rocket motor (SRB) plume simulations at Mach numbers from 0.6 to 1.4. Integrated vehicle surface pressure distributions, elevon and rudder hinge moments, and wing and vertical tail root bending and torsional moments due to MPS and SRB plume interactions were determined. Nozzle power conditions were controlled per pretest nozzle calibrations. Model angle of attack was varied from -4 deg to +4 deg; model angle of sideslip was varied from -4 deg to +4 deg. Reynolds number was varied for certain test conditions and configurations, with the nominal freestream total pressure being 14.69 psia. Plotted force and pressure data are presented.

  4. Modelling exhaust plume mixing in the near field of an aircraft

    Directory of Open Access Journals (Sweden)

    F. Garnier

    Full Text Available A simplified approach has been applied to analyse the mixing and entrainment processes of the engine exhaust through their interaction with the vortex wake of an aircraft. Our investigation is focused on the near field, extending from the exit nozzle until about 30 s after the wake is generated, in the vortex phase. This study was performed by using an integral model and a numerical simulation for two large civil aircraft: a two-engine Airbus 330 and a four-engine Boeing 747. The influence of the wing-tip vortices on the dilution ratio (defined as a tracer concentration shown. The mixing process is also affected by the buoyancy effect, but only after the jet regime, when the trapping in the vortex core has occurred. In the early wake, the engine jet location (i.e. inboard or outboard engine jet has an important influence on the mixing rate. The plume streamlines inside the vortices are subject to distortion and stretching, and the role of the descent of the vortices on the maximum tracer concentration is discussed. Qualitative comparison with contrail photograph shows similar features. Finally, tracer concentration of inboard engine centreline of B-747 are compared with other theoretical analyses and measured data.

  5. Hydrogeological modeling constraints provided by geophysical and geochemical mapping of a chlorinated ethenes plume in northern France

    Science.gov (United States)

    Razafindratsima, Stephen; Guérin, Roger; Bendjoudi, Hocine; de Marsily, Ghislain

    2014-09-01

    A methodological approach is described which combines geophysical and geochemical data to delineate the extent of a chlorinated ethenes plume in northern France; the methodology was used to calibrate a hydrogeological model of the contaminants' migration and degradation. The existence of strong reducing conditions in some parts of the aquifer is first determined by measuring in situ the redox potential and dissolved oxygen, dissolved ferrous iron and chloride concentrations. Electrical resistivity imaging and electromagnetic mapping, using the Slingram method, are then used to determine the shape of the pollutant plume. A decreasing empirical exponential relation between measured chloride concentrations in the water and aquifer electrical resistivity is observed; the resistivity formation factor calculated at a few points also shows a major contribution of chloride concentration in the resistivity of the saturated porous medium. MODFLOW software and MT3D99 first-order parent-daughter chain reaction and the RT3D aerobic-anaerobic model for tetrachloroethene (PCE)/trichloroethene (TCE) dechlorination are finally used for a first attempt at modeling the degradation of the chlorinated ethenes. After calibration, the distribution of the chlorinated ethenes and their degradation products simulated with the model approximately reflects the mean measured values in the observation wells, confirming the data-derived image of the plume.

  6. PHREEQC integrated modelling of plutonium migration from alpha ILL radwaste: organic complexes, concrete degradation and alkaline plume

    International Nuclear Information System (INIS)

    Cochepin, B.; Munier, I.; Giffaut, E.; Grive, M.

    2010-01-01

    glutaric acids. (iii) A sensitivity study to the progressive organic release from the waste package with various kinetic laws. (iv) The plutonium release is congruent to the one of organic compounds following the local thermodynamic equilibrium, considering the redox competition between Pu(+IV) and Pu(+VI) species. On the solute transport aspect: (i) The solute transfer in concrete and argillites (mechanically disturbed or not) materials is controlled by diffusion. (ii) The difference of transport properties depending on the material (porosity and effective diffusion), but without any feedback of porosity variation. (iii) A sorption model of organic compounds in concrete materials following a Langmuir isotherm. (iv) A sorption model of plutonium in argillites based on the analogy of uranium sorption on the smectite phase composing the MX-80 bentonite. The migration of plutonium through the waste disposal cell in contact with the host rock is simulated with PHREEQC (v2.16) in 1D radial geometry over a period of 100,000 years. First results show that the extension of the alkaline plume after 100,000 years does not exceed 1 m in the argillites, which is in good agreement with the results published in the 'Dossier 2005 Argile'. The smectite dissolution resulting from the alkaline plume reduces the plutonium sorption capacity of the argillaceous host rock. The sensitivity study on the kinetic release shows a great dependency of plutonium migration extent with the quantity of organics released, through the sequestration of plutonium under aqueous complexes. A distribution coefficient (K d ) of Pu in argillites is estimated a posteriori and interpreted for performance assessment considerations. (authors)

  7. Modelling pollutants dispersion and plume rise from large hydrocarbon tank fires in neutrally stratified atmosphere

    Science.gov (United States)

    Argyropoulos, C. D.; Sideris, G. M.; Christolis, M. N.; Nivolianitou, Z.; Markatos, N. C.

    2010-02-01

    Petrochemical industries normally use storage tanks containing large amounts of flammable and hazardous substances. Therefore, the occurrence of a tank fire, such as the large industrial accident on 11th December 2005 at Buncefield Oil Storage Depots, is possible and usually leads to fire and explosions. Experience has shown that the continuous production of black smoke from these fires due to the toxic gases from the combustion process, presents a potential environmental and health problem that is difficult to assess. The goals of the present effort are to estimate the height of the smoke plume, the ground-level concentrations of the toxic pollutants (smoke, SO 2, CO, PAHs, VOCs) and to characterize risk zones by comparing the ground-level concentrations with existing safety limits. For the application of the numerical procedure developed, an external floating-roof tank has been selected with dimensions of 85 m diameter and 20 m height. Results are presented and discussed. It is concluded that for all scenarios considered, the ground-level concentrations of smoke, SO 2, CO, PAHs and VOCs do not exceed the safety limit of IDLH and there are no "death zones" due to the pollutant concentrations.

  8. Experimental investigation of bubble plume structure instability

    Energy Technology Data Exchange (ETDEWEB)

    Marco Simiano; Robert Zboray; Francois de Cachard [Thermal-Hydraulics Laboratory, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Djamel Lakehal; George Yadigaroglu [Institute of Energy Technology, Swiss Federal Institute of Technology, ETH-Zentrum/CLT, 8092 Zurich (Switzerland)

    2005-07-01

    cameras at a right angle provided instantaneous projections of the plume shape on two perpendicular planes. Image processing techniques were applied to determine the plume width and position and their fluctuations in time. Triggering the video recording process with the STPF-PIV system allowed to correlate the measured velocity fields with the plume position with respect to the vessel axis. Then, the velocity fields were ensemble - averaged for a given plume position. The results may significantly differ from the time - averaged velocity fields in a fixed plane, which were used in the past for code assessment. The present results should allow to better discriminate between effective plume spreading, due e.g. to turbulent dispersion, and superimposed, apparent spreading due to plume motion. Beyond this aspect, the achievement of local measurements of most flow parameters in fairly large bubble plumes is a unique tool for model validation. (authors)

  9. Calculation of doses received while crossing a plume of radioactive material

    International Nuclear Information System (INIS)

    Scherpelz, R.I.; Desrosiers, A.E.

    1981-04-01

    A method has been developed for determining the dose received by a person while crossing a plume of radioactive material. The method uses a Gaussian plume model to arrive at a dose rate on the plume centerline at the position of the plume crossing. This dose rate may be due to any external or internal dose pathway. An algebraic formula can then be used to convert the plume centerline dose rate to a total dose integrated over the total time of plume crossing. Correction factors are presented for dose pathways in which the dose rate is not normally distributed about the plume centerline. The method is illustrated by a study done at the Pacific Northwest Laboratory, and results of this study are presented

  10. Ocean outfall plume characterization using an Autonomous Underwater Vehicle.

    Science.gov (United States)

    Rogowski, Peter; Terrill, Eric; Otero, Mark; Hazard, Lisa; Middleton, William

    2013-01-01

    A monitoring mission to map and characterize the Point Loma Ocean Outfall (PLOO) wastewater plume using an Autonomous Underwater Vehicle (AUV) was performed on 3 March 2011. The mobility of an AUV provides a significant advantage in surveying discharge plumes over traditional cast-based methods, and when combined with optical and oceanographic sensors, provides a capability for both detecting plumes and assessing their mixing in the near and far-fields. Unique to this study is the measurement of Colored Dissolved Organic Matter (CDOM) in the discharge plume and its application for quantitative estimates of the plume's dilution. AUV mission planning methodologies for discharge plume sampling, plume characterization using onboard optical sensors, and comparison of observational data to model results are presented. The results suggest that even under variable oceanic conditions, properly planned missions for AUVs equipped with an optical CDOM sensor in addition to traditional oceanographic sensors, can accurately characterize and track ocean outfall plumes at higher resolutions than cast-based techniques.

  11. Understanding CO2 Plume Behavior and Basin-Scale Pressure Changes during Sequestration Projects through the use of Reservoir Fluid Modeling

    Science.gov (United States)

    Leetaru, H.E.; Frailey, S.M.; Damico, J.; Mehnert, E.; Birkholzer, J.; Zhou, Q.; Jordan, P.D.

    2009-01-01

    permeability anisotropy, the CO2 injected into the Mt. Simon are expected to migrate less than 3 km. After 30 years of continuous injection followed by 100 years of shut-in, the plume from a 1 million tonnes a year injection rate is expected to migrate 1.6 km for a 0 degree dip reservoir and over 3 km for a 5 degree dip reservoir. The region where reservoir pressure increases in response to CO2 injection is typically much larger than the CO2 plume. It can thus be anticipated that there will be basin wide interactions between different CO2 injection sources if multiple, large volume sites are developed. This interaction will result in asymmetric plume migration that may be contrary to reservoir dip. A basin- scale simulation model is being developed to predict CO2 plume migration, brine displacement, and pressure buildup for a possible future sequestration scenario featuring multiple CO2 storage sites within the Illinois Basin Mt. Simon Sandstone. Interactions between different sites will be evaluated with respect to impacts on pressure and CO2 plume migration patterns. ?? 2009 Elsevier Ltd. All rights reserved.

  12. Modelling of Far-Field Mixing of Industrial Effluent Plume in Ambient ...

    African Journals Online (AJOL)

    This study sought to describe the dynamics of advective and dispersive transport of the effluent plume in the river and also ascertain the extent of its effect from discharge location to downstream far-field region. A homogenous differential equation was used as analytics to describe the physical process that describes the ...

  13. Modeling and validation of Ku-band signal attenuation through rocket plumes

    NARCIS (Netherlands)

    Veek, van der B.J.; Chintalapati, S.; Kirk, D.R.; Gutierrez, H.; Bun, R.F.

    2013-01-01

    Communications to and from a launch vehicle during ascent are of critical importance to the success of rocket-launch operations. During ascent, the rocket's exhaust plume causes significant interference in the radio communications between the vehicle and ground station. This paper presents an

  14. Modelling of N2-Thruster Plumes Based on Experiments in STG

    National Research Council Canada - National Science Library

    Plaehn, Klaus

    2000-01-01

    ... (no chemical reactions, constant ratio of specific heats). The essential parameter to be varied was the nozzle flow Reynolds number, the quantities to be measured were the Pitot pressure at the nozzle exit and the molecule number flux in the plume...

  15. Reservoir Characterization and CO2 Plume Migration Modeling Based on Bottom-hole Pressure Data: An Example from the AEP Mountaineer Geological Storage Project

    Science.gov (United States)

    Mishra, Srikanta; Kelley, Mark; Oruganti, YagnaDeepika; Bhattacharya, Indra; Spitznogle, Gary

    2014-05-01

    -invasive strategy for inferring the extent of the CO2 plume from the analysis of pressure monitoring data. Application of this methodology to the Rose Run data indicates a two-zone permeability model for the undisturbed formation, as well as an estimate of CO2 front movement over time. For reservoir modeling, a 2-D radial-cylindrical model based on "average" conditions in the study area was developed from integration of well-log and seismic data. STOMP-CO2 simulations were carried out to calibrate the observed pressure response using a trial-and-error procedure. This involved varying: (1) permeability near the injection well, (2) permeability of the far-field region, and (3) relative permeability model coefficients. Non-unique combinations of these parameters were found to produce similar pressure match, but different estimates of plume migration. Excellent matches were obtained for the bottom-hole pressures both at the injection well and the monitoring well using a two-zone permeability model, which corroborates the transient pressure analysis results. Estimates of radial plume migration, using the calibrated model, also agree well with those from the front tracking method described earlier.

  16. Model calculations of the chemical processes occurring in the plume of a coal-fired power plant

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, J F; Luria, M

    1982-02-01

    Computer simulations of the homogeneous, gas phase chemical reactions which occur in the plume of a coal-fired power plant were conducted in an effort to understand the influence of various environmental parameters on the production of secondary pollutants. Input data for the model were selected to reproduce the dilution of a plume from a medium-sized power plant. The environmental conditions chosen were characteristic of those found during mid-August in the south-eastern United States. Under most conditions examined, it was found that hydroxyl radicals were the most important species in the homogeneous conversion of stack gases into secondary pollutants. Other free radicals, such as HO/sub 2/ and CH/sub 3/O/sub 2/, exceeded the contribution of HO radicals only when high background hydrocarbon concentrations are used. The conversion rates calculated for the oxidation of SO/sub 2/ to SO/sub 4//sup 2 -/ in these plumes were consistent with those determined experimentally. The concentrations and relative proportions of NO/sub x/ (from the power plant) and reactive hydrocarbons (from the background air) determine, to a large extent, the plume reactivity. Free radical production is suppressed during the initial stages of dilution due to the high NO/sub x/ levels. Significant dilution is required before a suitable mix is attained which can sustain the free radical chain processes common to smog chemistry. In most cases, the free radical concentrations were found to pass through maxima and return to background levels. Under typical summertime conditions, the hyroxyl radical concentration was found to reach a maximum at a HC/NO/sub x/ ratio of approximately 20.

  17. Seismic Imaging of Mantle Plumes

    Science.gov (United States)

    Nataf, Henri-Claude

    The mantle plume hypothesis was proposed thirty years ago by Jason Morgan to explain hotspot volcanoes such as Hawaii. A thermal diapir (or plume) rises from the thermal boundary layer at the base of the mantle and produces a chain of volcanoes as a plate moves on top of it. The idea is very attractive, but direct evidence for actual plumes is weak, and many questions remain unanswered. With the great improvement of seismic imagery in the past ten years, new prospects have arisen. Mantle plumes are expected to be rather narrow, and their detection by seismic techniques requires specific developments as well as dedicated field experiments. Regional travel-time tomography has provided good evidence for plumes in the upper mantle beneath a few hotspots (Yellowstone, Massif Central, Iceland). Beneath Hawaii and Iceland, the plume can be detected in the transition zone because it deflects the seismic discontinuities at 410 and 660 km depths. In the lower mantle, plumes are very difficult to detect, so specific methods have been worked out for this purpose. There are hints of a plume beneath the weak Bowie hotspot, as well as intriguing observations for Hawaii. Beneath Iceland, high-resolution tomography has just revealed a wide and meandering plume-like structure extending from the core-mantle boundary up to the surface. Among the many phenomena that seem to take place in the lowermost mantle (or D''), there are also signs there of the presence of plumes. In this article I review the main results obtained so far from these studies and discuss their implications for plume dynamics. Seismic imaging of mantle plumes is still in its infancy but should soon become a turbulent teenager.

  18. Numerical modeling of the effects of fire-induced convection and fire-atmosphere interactions on wildfire spread and fire plume dynamics

    Science.gov (United States)

    Sun, Ruiyu

    It is possible due to present day computing power to produce a fluid dynamical physically-based numerical solution to wildfire behavior, at least in the research mode. This type of wildfire modeling affords a flexibility and produces details that are not available in either current operational wildfire behavior models or field experiments. However before using these models to study wildfire, validation is necessary, and model results need to be systematically and objectively analyzed and compared to real fires. Plume theory and data from the Meteotron experiment, which was specially designed to provide results from measurements for the theoretical study of a convective plume produced by a high heat source at the ground, are used here to evaluate the fire plume properties simulated by two numerical wildfire models, the Fire Dynamics Simulator or FDS, and the Clark coupled atmosphere-fire model. The study indicates that the FDS produces good agreement with the plume theory and the Meteotron results. The study also suggests that the coupled atmosphere-fire model, a less explicit and ideally less computationally demanding model than the FDS; can produce good agreement, but that the agreement is sensitive to the method of putting the energy released from the fire into the atmosphere. The WFDS (Wildfire and wildland-urban interface FDS), an extension of the FDS to the vegetative fuel, and the Australian grass fire experiments are used to evaluate and improve the UULES-wildfire coupled model. Despite the simple fire parameterization in the UULES-wildfire coupled model, the fireline is fairly well predicted in terms of both shape and location in the simulation of Australian grass fire experiment F19. Finally, the UULES-wildfire coupled model is used to examine how the turbulent flow in the atmospheric boundary layer (ABL) affects the growth of the grass fires. The model fires showed significant randomness in fire growth: Fire spread is not deterministic in the ABL, and a

  19. Identifying key controls on the behavior of an acidic-U(VI) plume in the Savannah River Site using reactive transport modeling.

    Science.gov (United States)

    Bea, Sergio A; Wainwright, Haruko; Spycher, Nicolas; Faybishenko, Boris; Hubbard, Susan S; Denham, Miles E

    2013-08-01

    Acidic low-level waste radioactive waste solutions were discharged to three unlined seepage basins at the F-Area of the Department of Energy (DOE) Savannah River Site (SRS), South Carolina, USA, from 1955 through 1989. Despite many years of active remediation, the groundwater remains acidic and contaminated with significant levels of U(VI) and other radionuclides. Monitored Natural Attenuation (MNA) is a desired closure strategy for the site, based on the premise that regional flow of clean background groundwater will eventually neutralize the groundwater acidity, immobilizing U(VI) through adsorption. An in situ treatment system is currently in place to accelerate this in the downgradient portion of the plume and similar measures could be taken upgradient if necessary. Understanding the long-term pH and U(VI) adsorption behavior at the site is critical to assess feasibility of MNA along with the in-situ remediation treatments. This paper presents a reactive transport (RT) model and uncertainty quantification (UQ) analyses to explore key controls on the U(VI)-plume evolution and long-term mobility at this site. Two-dimensional numerical RT simulations are run including the saturated and unsaturated (vadose) zones, U(VI) and H(+) adsorption (surface complexation) onto sediments, dissolution and precipitation of Al and Fe minerals, and key hydrodynamic processes are considered. UQ techniques are applied using a new open-source tool that is part of the developing ASCEM reactive transport modeling and analysis framework to: (1) identify the complex physical and geochemical processes that control the U(VI) plume migration in the pH range where the plume is highly mobile, (2) evaluate those physical and geochemical parameters that are most controlling, and (3) predict the future plume evolution constrained by historical, chemical and hydrological data. The RT simulation results show a good agreement with the observed historical pH and concentrations of U(VI), nitrates

  20. Thermal-Chemical Model Of Subduction: Results And Tests

    Science.gov (United States)

    Gorczyk, W.; Gerya, T. V.; Connolly, J. A.; Yuen, D. A.; Rudolph, M.

    2005-12-01

    Seismic structures with strong positive and negative velocity anomalies in the mantle wedge above subduction zones have been interpreted as thermally and/or chemically induced phenomena. We have developed a thermal-chemical model of subduction, which constrains the dynamics of seismic velocity structure beneath volcanic arcs. Our simulations have been calculated over a finite-difference grid with (201×101) to (201×401) regularly spaced Eulerian points, using 0.5 million to 10 billion markers. The model couples numerical thermo-mechanical solution with Gibbs energy minimization to investigate the dynamic behavior of partially molten upwellings from slabs (cold plumes) and structures associated with their development. The model demonstrates two chemically distinct types of plumes (mixed and unmixed), and various rigid body rotation phenomena in the wedge (subduction wheel, fore-arc spin, wedge pin-ball). These thermal-chemical features strongly perturb seismic structure. Their occurrence is dependent on the age of subducting slab and the rate of subduction.The model has been validated through a series of test cases and its results are consistent with a variety of geological and geophysical data. In contrast to models that attribute a purely thermal origin for mantle wedge seismic anomalies, the thermal-chemical model is able to simulate the strong variations of seismic velocity existing beneath volcanic arcs which are associated with development of cold plumes. In particular, molten regions that form beneath volcanic arcs as a consequence of vigorous cold wet plumes are manifest by > 20% variations in the local Poisson ratio, as compared to variations of ~ 2% expected as a consequence of temperature variation within the mantle wedge.

  1. Numerically Modeling the Erosion of Lunar Soil by Rocket Exhaust Plumes

    Science.gov (United States)

    2008-01-01

    In preparation for the Apollo program, Leonard Roberts of the NASA Langley Research Center developed a remarkable analytical theory that predicts the blowing of lunar soil and dust beneath a rocket exhaust plume. Roberts assumed that the erosion rate was determined by the excess shear stress in the gas (the amount of shear stress greater than what causes grains to roll). The acceleration of particles to their final velocity in the gas consumes a portion of the shear stress. The erosion rate continues to increase until the excess shear stress is exactly consumed, thus determining the erosion rate. Roberts calculated the largest and smallest particles that could be eroded based on forces at the particle scale, but the erosion rate equation assumed that only one particle size existed in the soil. He assumed that particle ejection angles were determined entirely by the shape of the terrain, which acts like a ballistic ramp, with the particle aerodynamics being negligible. The predicted erosion rate and the upper limit of particle size appeared to be within an order of magnitude of small-scale terrestrial experiments but could not be tested more quantitatively at the time. The lower limit of particle size and the predictions of ejection angle were not tested. We observed in the Apollo landing videos that the ejection angles of particles streaming out from individual craters were time-varying and correlated to the Lunar Module thrust, thus implying that particle aerodynamics dominate. We modified Roberts theory in two ways. First, we used ad hoc the ejection angles measured in the Apollo landing videos, in lieu of developing a more sophisticated method. Second, we integrated Roberts equations over the lunar-particle size distribution and obtained a compact expression that could be implemented in a numerical code. We also added a material damage model that predicts the number and size of divots which the impinging particles will cause in hardware surrounding the landing

  2. Buoyant plume calculations

    International Nuclear Information System (INIS)

    Penner, J.E.; Haselman, L.C.; Edwards, L.L.

    1985-01-01

    Smoke from raging fires produced in the aftermath of a major nuclear exchange has been predicted to cause large decreases in surface temperatures. However, the extent of the decrease and even the sign of the temperature change, depend on how the smoke is distributed with altitude. We present a model capable of evaluating the initial distribution of lofted smoke above a massive fire. Calculations are shown for a two-dimensional slab version of the model and a full three-dimensional version. The model has been evaluated by simulating smoke heights for the Hamburg firestorm of 1943 and a smaller scale oil fire which occurred in Long Beach in 1958. Our plume heights for these fires are compared to those predicted by the classical Morton-Taylor-Turner theory for weakly buoyant plumes. We consider the effect of the added buoyancy caused by condensation of water-laden ground level air being carried to high altitude with the convection column as well as the effects of background wind on the calculated smoke plume heights for several fire intensities. We find that the rise height of the plume depends on the assumed background atmospheric conditions as well as the fire intensity. Little smoke is injected into the stratosphere unless the fire is unusually intense, or atmospheric conditions are more unstable than we have assumed. For intense fires significant amounts of water vapor are condensed raising the possibility of early scavenging of smoke particles by precipitation. 26 references, 11 figures

  3. Modelling of coastal current and thermal plume dispersion - A case study off Nagapattinam, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, M.T.; Vethamony, P.; Suryanarayana, A.; Gouveia, A.D.

    representing the monsoons and the transition periods are selected to study the seasonal variability of simulated currents and thermal plumes. The plume showed northward spreading during March and July and southward during December. During October the spreading...

  4. Modelling of transport and biogeochemical processes in pollution plumes: Literature review of model development

    DEFF Research Database (Denmark)

    Brun, A.; Engesgaard, Peter Knudegaard

    2002-01-01

    A literature survey shows how biogeochemical (coupled organic and inorganic reaction processes) transport models are based on considering the complete biodegradation process as either a single- or as a two-step process. It is demonstrated that some two-step process models rely on the Partial...... Equilibrium Approach (PEA). The PEA assumes the organic degradation step, and not the electron acceptor consumption step, is rate limiting. This distinction is not possible in one-step process models, where consumption of both the electron donor and acceptor are treated kinetically. A three-dimensional, two......-step PEA model is developed. The model allows for Monod kinetics and biomass growth, features usually included only in one-step process models. The biogeochemical part of the model is tested for a batch system with degradation of organic matter under the consumption of a sequence of electron acceptors...

  5. Is the 'Fast Halo' around Hawaii as imaged in the PLUME experiment direct evidence for buoyant plume-fed asthenosphere?

    Science.gov (United States)

    Morgan, J. P.; Shi, C.; Hasenclever, J.

    2010-12-01

    An intriguing spatial pattern of variations in shear-wave arrival times has been mapped in the PLUME ocean bottom experiment (Wolfe et al., 2009) around Hawaii. The pattern consists of a halo of fast travel times surrounding a disk of slow arrivals from waves traveling up though the plume. We think it is directly sensing the pattern of dynamic uplift of the base of a buoyant asthenosphere - the buoyancy of the plume conduit lifting a 'rim' of the cooler, denser mantle that the plume rises through. The PLUME analysis inverted for lateral shear velocity variations beneath the lithosphere, after removing the assumed 1-D model velocity structure IASP91. They found that a slow plume-conduit extends to at least 1200 km below the Hawaiian hotspot. In this inversion the slow plume conduit is — quite surprisingly - surrounded by a fast wavespeed halo. A fast halo is impossible to explain as a thermal halo around the plume; this should lead to a slow wavespeed halo, not a fast one. Plume-related shearwave anisotropy also cannot simply explain this pattern — simple vertical strain around the plume conduit would result in an anisotropic slow shear-wavespeed halo, not a fast one. (Note the PLUME experiment’s uniform ‘fast-halo’ structure from 50-400km is likely to have strong vertical streaking in the seismic image; Pacific Plate-driven shear across a low-viscosity asthenosphere would be expected to disrupt and distort any cold sheet of vertical downwelling structure between 50-400km depths so that it would no longer be vertical as it is in the 2009 PLUME image with its extremely poor vertical depth control.) If the asthenosphere is plume-fed, hence more buoyant than underlying mantle, then there can be a simple explanation for this pattern. The anomaly would be due to faster traveltimes resulting from dynamic relief at the asthenosphere-mesosphere interface; uplift of the denser mesosphere by the buoyancy of the rising plume increases the distance a wave travels

  6. The effect of sediments on turbulent plume dynamics in a stratified fluid

    Science.gov (United States)

    Stenberg, Erik; Ezhova, Ekaterina; Brandt, Luca

    2017-11-01

    We report large eddy simulation results of sediment-loaded turbulent plumes in a stratified fluid. The configuration, where the plume is discharged from a round source, provides an idealized model of subglacial discharge from a submarine tidewater glacier and is a starting point for understanding the effect of sediments on the dynamics of the rising plume. The transport of sediments is modeled by means of an advection-diffusion equation where sediment settling velocity is taken into account. We initially follow the experimental setup of Sutherland (Phys. Rev. Fluids, 2016), considering uniformly stratified ambients and further extend the work to pycnocline-type stratifications typical of Greenland fjords. Apart from examining the rise height, radial spread and intrusion of the rising plume, we gain further insights of the plume dynamics by extracting turbulent characteristics and the distribution of the sediments inside the plume.

  7. Biodegradation at Dynamic Plume Fringes: Mixing Versus Reaction Control

    Science.gov (United States)

    Cirpka, O. A.; Eckert, D.; Griebler, C.; Haberer, C.; Kürzinger, P.; Bauer, R.; Mellage, A.

    2014-12-01

    Biodegradation of continuously emitted plumes is known to be most pronounced at the plume fringe, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. Under steady-state conditions, physical mixing of contaminant and electron acceptor by transverse dispersion was shown to be the major bottleneck for biodegradation, with plume lengths scaling inversely with the bulk transverse dispersivity in quasi two-dimensional settings. Under these conditions, the presence of suitable microbes is essential but the biokinetic parameters do not play an important role. When the location of the plume shifts (caused, e.g., by a fluctuating groundwater table), however, the bacteria are no more situated at the plume fringe and biomass growth, decay, activation and deactivation determine the time lag until the fringe-controlled steady state is approached again. During this time lag, degradation is incomplete. The objective of the presented study was to analyze to which extent flow and transport dynamics diminish effectiveness of fringe-controlled biodegradation and which microbial processes and related biokinetic parameters determine the system response in overall degradation to hydraulic fluctuations. We performed experiments in quasi-two-dimensional flow through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth and maintenance (often subsumed as "biomass decay") microbial dormancy (that is, change into a metabolically inactive state) and

  8. Plume rise from multiple sources

    International Nuclear Information System (INIS)

    Briggs, G.A.

    1975-01-01

    A simple enhancement factor for plume rise from multiple sources is proposed and tested against plume-rise observations. For bent-over buoyant plumes, this results in the recommendation that multiple-source rise be calculated as [(N + S)/(1 + S)]/sup 1/3/ times the single-source rise, Δh 1 , where N is the number of sources and S = 6 (total width of source configuration/N/sup 1/3/ Δh 1 )/sup 3/2/. For calm conditions a crude but simple method is suggested for predicting the height of plume merger and subsequent behavior which is based on the geometry and velocity variations of a single buoyant plume. Finally, it is suggested that large clusters of buoyant sources might occasionally give rise to concentrated vortices either within the source configuration or just downwind of it

  9. Experimental Melting Study of Basalt-Peridotite Hybrid Source: Melting model of Hawaiian plume

    Science.gov (United States)

    Takahashi, E.; Gao, S.

    2015-12-01

    Eclogite component entrained in ascending plume is considered to be essentially important in producing flood basalts (e.g., Columbia River basalt, Takahashi et al., 1998 EPSL), alkalic OIBs (e.g., Kogiso et al.,2003), ferro-picrites (Tuff et al.,2005) and Hawaiian shield lavas (e.g., Hauri, 1996; Takahashi & Nakajima, 2002, Sobolev et al.,2005). Size of the entrained eclogite, which controls the reaction rates with ambient peridotite, however, is very difficult to constrain using geophysical observation. Among Hawaiian shield volcanoes, Koolau is the most enriched end-member in eclogite component (Frey et al, 1994). Reconstruction of Koolau volcano based on submarine study on Nuuanu landslide (AGU Monograph vol.128, 2002, Takahashi Garcia Lipman eds.) revealed that silica-rich tholeiite appeared only at the last stage (Makapuu stage) of Koolau volcano. Chemical compositions of lavas as well as isotopes change abruptly and coherently across a horizon (Shinozaki et al. and Tanaka et al. ibid.). Based on these observation, Takahashi & Nakajima (2002 ibid) proposed that the Makapuu stage lava in Koolau volcano was supplied from a single large eclogite block. In order to study melting process in Hawaiian plume, high-pressure melting experiments were carried out under dry and hydrous conditions with layered eclogite/peridotite starting materials. Detail of our experiments will be given by Gao et al (2015 AGU). Combined previous field observation with new set of experiments, we propose that variation in SiO2 among Hawaiian tholeiites represent varying degree of wall-rock interaction between eclogite and ambient peridotite. Makapuu stage lavas in Koolau volcano represents eclogite partial melts formed at ~3 GPa with various amount of xenocrystic olivines derived from Pacific plate. In other words, we propose that "primary magma" in the melting column of Hawaiian plume ranges from basaltic andesite to ferro-picrite depending on the lithology of the source. Solidus of

  10. Dynamics of Mantle Plume Controlled by both Post-spinel and Post-garnet Phase Transitions

    Science.gov (United States)

    Liu, H.; Leng, W.

    2017-12-01

    Mineralogical studies indicate that two major phase transitions occur near 660 km depth in the Earth's pyrolitic mantle: the ringwoodite (Rw) to perovskite (Pv) + magnesiowüstite (Mw) and majorite (Mj) to perovskite (Pv) phase transitions. Seismological results also show a complicated phase boundary structure for plume regions at this depth, including broad pulse, double reflections and depressed 660 km discontinuity beneath hot regions etc… These observations have been attributed to the co-existence of these two phase transformations. However, previous geodynamical modeling mainly focused on the effects of Rw-Pv+Mw phase transition on the plume dynamics and largely neglected the effects of Mj-Pv phase transition. Here we develop a 3-D regional spherical geodynamic model to study the influence of the combination of Rw - Pv+Mw and Mj - Pv phase transitions on plume dynamics, including the topography fluctuation of 660 km discontinuity, plume shape and penetration capability of plume. Our results show that (1) a double phase boundary occurs at the hot center area of plume while for other regions with relatively lower temperature the phase boundary is single and flat, which respectively corresponds to the double reflections in the seismic observations and a high velocity prism-like structure at the top of 660 km discontinuity; (2) a large amount of low temperature plume materials could be trapped to form a complex trapezoid overlying the 660 km depth; (3) Mj - Pv phase change strongly enhances the plume penetration capability at 660 km depth, which significantly increases the plume mass flux due to the increased plume radius, but significantly reduces plume heat flux due to the decreased plume temperature in the upper mantle. Our model results provide new enlightenments for better constraining seismic structure and mineral reactions at 660 km phase boundaries.

  11. Vapor plume oscillation mechanisms in transient keyhole during tandem dual beam fiber laser welding

    Science.gov (United States)

    Chen, Xin; Zhang, Xiaosi; Pang, Shengyong; Hu, Renzhi; Xiao, Jianzhong

    2018-01-01

    Vapor plume oscillations are common physical phenomena that have an important influence on the welding process in dual beam laser welding. However, until now, the oscillation mechanisms of vapor plumes remain unclear. This is primarily because mesoscale vapor plume dynamics inside a millimeter-scale, invisible, and time-dependent keyhole are difficult to quantitatively observe. In this paper, based on a developed three-dimensional (3D) comprehensive model, the vapor plume evolutions in a dynamical keyhole are directly simulated in tandem dual beam, short-wavelength laser welding. Combined with the vapor plume behaviors outside the keyhole observed by high-speed imaging, the vapor plume oscillations in dynamical keyholes at different inter-beam distances are the first, to our knowledge, to be quantitatively analyzed. It is found that vapor plume oscillations outside the keyhole mainly result from vapor plume instabilities inside the keyhole. The ejection velocity at the keyhole opening and dynamical behaviors outside the keyhole of a vapor plume both violently oscillate with the same order of magnitude of high frequency (several kHz). Furthermore, the ejection speed at the keyhole opening and ejection area outside the keyhole both decrease as the beam distance increases, while the degree of vapor plume instability first decreases and then increases with increasing beam distance from 0.6 to 1.0 mm. Moreover, the oscillation mechanisms of a vapor plume inside the dynamical keyhole irradiated by dual laser beams are investigated by thoroughly analyzing the vapor plume occurrence and flow process. The vapor plume oscillations in the dynamical keyhole are found to mainly result from violent local evaporations and severe keyhole geometry variations. In short, the quantitative method and these findings can serve as a reference for further understanding of the physical mechanisms in dual beam laser welding and of processing optimizations in industrial applications.

  12. Biogeochemical and isotopic gradients in a BTEX/PAH contaminant plume: Model-based interpretation of a high-resolution field data set

    DEFF Research Database (Denmark)

    Prommer, H.; Anneser, B.; Rolle, Massimo

    2009-01-01

    of toluene, which is the most rapidly degrading compound and the most important reductant at the site. The resulting depth profiles at the observation well show distinct differences between the small isotopic enrichment in the contaminant plume core and the much stronger enrichment of up to 3.3 parts per......A high spatial resolution data set documenting carbon and sulfur isotope fractionation at a tar oil-contaminated, sulfate-reducing field site was analyzed with a reactive transport model. Within a comprehensive numerical model, the study links the distinctive observed isotope depth profiles...... with the degradation of various monoaromatic and polycyclic aromatic hydrocarbon compounds (BTEX/PAHs) under sulfate-reducing conditions. In the numerical model, microbial dynamics were simulated explicitly and isotope fractionation was directly linked to the differential microbial uptake of lighter and heavier carbon...

  13. Simulation of plume rise: Study the effect of stably stratified turbulence layer on the rise of a buoyant plume from a continuous source by observing the plume centroid

    Science.gov (United States)

    Bhimireddy, Sudheer Reddy; Bhaganagar, Kiran

    2016-11-01

    Buoyant plumes are common in atmosphere when there exists a difference in temperature or density between the source and its ambience. In a stratified environment, plume rise happens until the buoyancy variation exists between the plume and ambience. In a calm no wind ambience, this plume rise is purely vertical and the entrainment happens because of the relative motion of the plume with ambience and also ambient turbulence. In this study, a plume centroid is defined as the plume mass center and is calculated from the kinematic equation which relates the rate of change of centroids position to the plume rise velocity. Parameters needed to describe the plume are considered as the plume radius, plumes vertical velocity and local buoyancy of the plume. The plume rise velocity is calculated by the mass, momentum and heat conservation equations in their differential form. Our study focuses on the entrainment velocity, as it depicts the extent of plume growth. This entrainment velocity is made up as sum of fractions of plume's relative velocity and ambient turbulence. From the results, we studied the effect of turbulence on the plume growth by observing the variation in the plume radius at different heights and the centroid height reached before loosing its buoyancy.

  14. Plume and Dose Modeling Performed to Assess Waste Management Enhancements Associated with Envirocare's Decision to Purchase of an Engineered Rail Rollover Facility Enclosure

    International Nuclear Information System (INIS)

    Rogers, T.; Clayman, B.

    2003-01-01

    This paper describes the modeling performed on a proposed enclosure for the existing railcar rollover facility located in Clive, Utah at a radioactive waste disposal site owned and operated by Envirocare of Utah, Inc. (Envirocare). The dose and plume modeling information was used as a tool to justify the decision to make the capital purchase and realize the modeled performance enhancements

  15. A Monte Carlo simulation method for assessing biotransformation effects on groundwater fuel hydrocarbon plume lengths

    International Nuclear Information System (INIS)

    McNab, W.W. Jr.

    2000-01-01

    Biotransformation of dissolved groundwater hydrocarbon plumes emanating from leaking underground fuel tanks should, in principle, result in plume length stabilization over relatively short distances, thus diminishing the environmental risk. However, because the behavior of hydrocarbon plumes is usually poorly constrained at most leaking underground fuel tank sites in terms of release history, groundwater velocity, dispersion, as well as the biotransformation rate, demonstrating such a limitation in plume length is problematic. Biotransformation signatures in the aquifer geochemistry, most notably elevated bicarbonate, may offer a means of constraining the relationship between plume length and the mean biotransformation rate. In this study, modeled plume lengths and spatial bicarbonate differences among a population of synthetic hydrocarbon plumes, generated through Monte Carlo simulation of an analytical solute transport model, are compared to field observations from six underground storage tank (UST) sites at military bases in California. Simulation results indicate that the relationship between plume length and the distribution of bicarbonate is best explained by biotransformation rates that are consistent with ranges commonly reported in the literature. This finding suggests that bicarbonate can indeed provide an independent means for evaluating limitations in hydrocarbon plume length resulting from biotransformation. (Author)

  16. Gaussian plume model for the SO{sub 2} in a thermoelectric power plant; Modelo de pluma gaussiano para el SO{sub 2} en una central termoelectrica

    Energy Technology Data Exchange (ETDEWEB)

    Reyes L, C; Munoz Ledo, C R [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1993-12-31

    The Gaussian Plume Model is an analytical extension to simulate the dispersion of the SO{sub 2} concentration at ground level as a function of the emission changes in the spot sources, as well as the pollutant dispersion in the Wind Rose, when the necessary parameters are fed. The model was elaborated in a personal computer and the results produced are generated in text form. [Espanol] El modelo de pluma gaussiano es una extension analitica para simular la dispersion de las concentraciones de SO{sub 2} a nivel del piso en funcion de los cambios de las emisiones en las fuentes puntuales, asi como, la dispersion del contaminante en la rosa de los vientos cuando se le alimentan los parametros necesarios. El modelo fue elaborado en una computadora personal y los resultados que proporciona los genera en modo texto.

  17. Gaussian plume model for the SO{sub 2} in a thermoelectric power plant; Modelo de pluma gaussiano para el SO{sub 2} en una central termoelectrica

    Energy Technology Data Exchange (ETDEWEB)

    Reyes L, C.; Munoz Ledo, C. R. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1992-12-31

    The Gaussian Plume Model is an analytical extension to simulate the dispersion of the SO{sub 2} concentration at ground level as a function of the emission changes in the spot sources, as well as the pollutant dispersion in the Wind Rose, when the necessary parameters are fed. The model was elaborated in a personal computer and the results produced are generated in text form. [Espanol] El modelo de pluma gaussiano es una extension analitica para simular la dispersion de las concentraciones de SO{sub 2} a nivel del piso en funcion de los cambios de las emisiones en las fuentes puntuales, asi como, la dispersion del contaminante en la rosa de los vientos cuando se le alimentan los parametros necesarios. El modelo fue elaborado en una computadora personal y los resultados que proporciona los genera en modo texto.

  18. Lithosphere erosion and continental breakup : Interaction of extension, plume upwelling and melting

    NARCIS (Netherlands)

    Lavecchia, Alessio; Thieulot, Cedric; Beekman, Fred; Cloetingh, Sierd; Clark, Stuart

    2017-01-01

    We present the results of thermo-mechanical modelling of extension and breakup of a heterogeneous continental lithosphere, subjected to plume impingement in presence of intraplate stress field. We incorporate partial melting of the extending lithosphere, underlying upper mantle and plume, caused by

  19. Modeling of 2008 Kasatochi Volcanic Sulfate Direct Radiative Forcing: Assimilation of OMI SO2 Plume Height Data and Comparison with MODIS and CALIOP Observations

    Science.gov (United States)

    Wang, J.; Park, S.; Zeng, J.; Ge, C.; Yang, K.; Carn, S.; Krotkov, N.; Omar, A. H.

    2013-01-01

    Volcanic SO2 column amount and injection height retrieved from the Ozone Monitoring Instrument (OMI) with the Extended Iterative Spectral Fitting (EISF) technique are used to initialize a global chemistry transport model (GEOS-Chem) to simulate the atmospheric transport and lifecycle of volcanic SO2 and sulfate aerosol from the 2008 Kasatochi eruption, and to subsequently estimate the direct shortwave, top-of-the-atmosphere radiative forcing of the volcanic sulfate aerosol. Analysis shows that the integrated use of OMI SO2 plume height in GEOS-Chem yields: (a) good agreement of the temporal evolution of 3-D volcanic sulfate distributions between model simulations and satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarisation (CALIOP), and (b) an e-folding time for volcanic SO2 that is consistent with OMI measurements, reflecting SO2 oxidation in the upper troposphere and stratosphere is reliably represented in the model. However, a consistent (approx. 25 %) low bias is found in the GEOS-Chem simulated SO2 burden, and is likely due to a high (approx.20 %) bias of cloud liquid water amount (as compared to the MODIS cloud product) and the resultant stronger SO2 oxidation in the GEOS meteorological data during the first week after eruption when part of SO2 underwent aqueous-phase oxidation in clouds. Radiative transfer calculations show that the forcing by Kasatochi volcanic sulfate aerosol becomes negligible 6 months after the eruption, but its global average over the first month is -1.3W/sq m, with the majority of the forcing-influenced region located north of 20degN, and with daily peak values up to -2W/sq m on days 16-17. Sensitivity experiments show that every 2 km decrease of SO2 injection height in the GEOS-Chem simulations will result in a approx.25% decrease in volcanic sulfate forcing; similar sensitivity but opposite sign also holds for a 0.03 m increase of geometric radius of

  20. Effects of wildland fire smoke on a tree-roosting bat: integrating a plume model, field measurements, and mammalian dose-response relationships

    Science.gov (United States)

    M.B. Dickinson; J.C. Norris; A.S. Bova; R.L. Kremens; V. Young; M.J. Lacki

    2010-01-01

    Faunal injury and mortality in wildland fires is a concern for wildlife and fire management although little work has been done on the mechanisms by which exposures cause their effects. In this paper, we use an integral plume model, field measurements, and models of carbon monoxide and heat effects to explore risk to tree-roosting bats during prescribed fires in mixed-...

  1. Modeling Multiple-Core Updraft Plume Rise for an Aerial Ignition Prescribed Burn by Coupling Daysmoke with a Cellular Automata Fire Model

    Science.gov (United States)

    G. L Achtemeier; S. L. Goodrick; Y. Liu

    2012-01-01

    Smoke plume rise is critically dependent on plume updraft structure. Smoke plumes from landscape burns (forest and agricultural burns) are typically structured into “sub-plumes” or multiple-core updrafts with the number of updraft cores depending on characteristics of the landscape, fire, fuels, and weather. The number of updraft cores determines the efficiency of...

  2. Particle Simulation of Pulsed Plasma Thruster Plumes

    National Research Council Canada - National Science Library

    Boyd, Ian

    2002-01-01

    .... Our modeling had made progress in al aspects of simulating these complex devices including Teflon ablation, plasma formation, electro-magnetic acceleration, plume expansion, and particulate transport...

  3. Wintertime Overnight NOx Removal in a Southeastern United States Coal-fired Power Plant Plume: A Model for Understanding Winter NOx Processing and its Implications

    Science.gov (United States)

    Fibiger, Dorothy L.; McDuffie, Erin E.; Dubé, William P.; Aikin, Kenneth C.; Lopez-Hilfiker, Felipe D.; Lee, Ben H.; Green, Jaime R.; Fiddler, Marc N.; Holloway, John S.; Ebben, Carlena; Sparks, Tamara L.; Wooldridge, Paul; Weinheimer, Andrew J.; Montzka, Denise D.; Apel, Eric C.; Hornbrook, Rebecca S.; Hills, Alan J.; Blake, Nicola J.; DiGangi, Josh P.; Wolfe, Glenn M.; Bililign, Solomon; Cohen, Ronald C.; Thornton, Joel A.; Brown, Steven S.

    2018-01-01

    Nitric oxide (NO) is emitted in large quantities from coal-burning power plants. During the day, the plumes from these sources are efficiently mixed into the boundary layer, while at night, they may remain concentrated due to limited vertical mixing during which they undergo horizontal fanning. At night, the degree to which NO is converted to HNO3 and therefore unable to participate in next-day ozone (O3) formation depends on the mixing rate of the plume, the composition of power plant emissions, and the composition of the background atmosphere. In this study, we use observed plume intercepts from the Wintertime INvestigation of Transport, Emissions and Reactivity campaign to test sensitivity of overnight NOx removal to the N2O5 loss rate constant, plume mixing rate, background O3, and background levels of volatile organic compounds using a 2-D box model of power plant plume transport and chemistry. The factor that exerted the greatest control over NOx removal was the loss rate constant of N2O5. At the lowest observed N2O5 loss rate constant, no other combination of conditions converts more than 10% of the initial NOx to HNO3. The other factors did not influence NOx removal to the same degree.

  4. Wintertime Overnight NOx Removal in a Southeastern United States Coal-Fired Power Plant Plume: A Model for Understanding Winter NOx Processing and Its Implications

    Science.gov (United States)

    Fibiger, Dorothy L.; McDuffie, Erin E.; Dube, William P.; Aikin, Kenneth C.; Lopez-Hilifiker, Felipe D.; Lee, Ben H.; Green, Jaime R.; Fiddler, Marc N.; Holloway, John S.; Ebben, Carlena; hide

    2018-01-01

    Nitric oxide (NO) is emitted in large quantities from coal-�burning power plants. During the day, the plumes from these sources are efficiently mixed into the boundary layer, while at night, they may remain concentrated due to limited vertical mixing during which they undergo horizontal fanning. At night, the degree to which NO is converted to HNO3 and therefore unable to participate in next-�day ozone (O3) formation depends on the mixing rate of the plume, the composition of power plant emissions, and the composition of the background atmosphere. In this study, we use observed plume intercepts from the Wintertime INvestigation of Transport, Emissions and Reactivity (WINTER) campaign to test sensitivity of overnight NOx removal to the N2O5 loss rate constant, plume mixing rate, background O3, and background levels of volatile organic compounds using a 2-�D box model of power plant plume transport and chemistry. The factor that exerted the greatest control over NOx removal was the loss rate constant of N2O5. At the lowest observed N2O5 loss rate constant, no other combination of conditions converts more than 10 percent of the initial NOx to HNO3. The other factors did not influence NOx removal to the same degree.

  5. A simple modeling approach to study the regional impact of a Mediterranean forest isoprene emission on anthropogenic plumes

    Directory of Open Access Journals (Sweden)

    J. Cortinovis

    2005-01-01

    Full Text Available Research during the past decades has outlined the importance of biogenic isoprene emission in tropospheric chemistry and regional ozone photo-oxidant pollution. The first part of this article focuses on the development and validation of a simple biogenic emission scheme designed for regional studies. Experimental data sets relative to Boreal, Tropical, Temperate and Mediterranean ecosystems are used to estimate the robustness of the scheme at the canopy scale, and over contrasted climatic and ecological conditions. A good agreement is generally found when comparing field measurements and simulated emission fluxes, encouraging us to consider the model suitable for regional application. Limitations of the scheme are nevertheless outlined as well as further on-going improvements. In the second part of the article, the emission scheme is used on line in the broader context of a meso-scale atmospheric chemistry model. Dynamically idealized simulations are carried out to study the chemical interactions of pollutant plumes with realistic isoprene emissions coming from a Mediterranean oak forest. Two types of anthropogenic sources, respectively representative of the Marseille (urban and Martigues (industrial French Mediterranean sites, and both characterized by different VOC/NOx are considered. For the Marseille scenario, the impact of biogenic emission on ozone production is larger when the forest is situated in a sub-urban configuration (i.e. downwind distance TOWN-FOREST -1. In this case the enhancement of ozone production due to isoprene can reach +37% in term of maximum surface concentrations and +11% in term of total ozone production. The impact of biogenic emission decreases quite rapidly when the TOWN-FOREST distance increases. For the Martigues scenario, the biogenic impact on the plume is significant up to TOWN-FOREST distance of 90km where the ozone maximum surface concentration enhancement can still reach +30%. For both cases, the

  6. Bio-Physical Coupling of Seabirds and Prey with a Dynamic River Plume

    Science.gov (United States)

    Phillips, E. M.; Horne, J. K.; Zamon, J. E.; Adams, J.

    2016-02-01

    Freshwater plumes and plume density fronts are important regions of bio-physical coupling. On the west coast of North America, discharge from the Columbia River into the northern California Current creates a large, dynamic plume and multiple plume fronts. These nutrient-rich, productive waters fuel primary and secondary production, supporting a wide variety of small pelagic prey fish, large populations of Pacific salmon, seabirds, and marine mammals. To determine the influence of the Columbia River plume on marine predators, we analyzed at-sea seabird counts, in situ environmental data, surface trawl densities of prey fish, and acoustic backscatter measurements collected from research vessels in May and June 2010-2012. Concurrent distribution patterns of satellite-tagged sooty shearwaters (Puffinus griseus) and common murres (Uria aalge) were compared with seabird counts from ship surveys. To evaluate plume use by satellite-tagged birds, daily surface salinity values from SELFE hindcast models were extracted at each tag location. Both seabird species occurred in plume waters disproportionate to the total surveyed area, concentrating in the river plume when river flow and plume volume decreased. Murres were consistently within 20 km of the geographic mean center of the river plume. In contrast, shearwaters consistently occurred 100 km to the north of the plume center, where high densities of prey fish occur. Although acoustically detected prey also occurred in greater densities within the plume when volume decreased, surface catches of prey in the plume did not vary with changing plume conditions. Geographic indices of colocation (GIC) were low between murres and prey species caught in surface trawls, whereas GICs were >0.5 between shearwaters and prey species including squid (Loligo opalescens), juvenile Chinook salmon (Oncorhynchus tshawytscha), and coho (O. kisutch) salmon. We conclude that the river plume and associated fronts are identifiable, predictable, and

  7. Plume rise measurements at Turbigo

    Energy Technology Data Exchange (ETDEWEB)

    Anfossi, D

    1982-01-01

    This paper presents analyses of plume measurements obtained during that campaign by the ENEL ground-based Lidar. The five stacks of Turbigo Power Plant have different heights and emission parameters and their plumes usually combine, so a model for multiple sources was used to predict the plume rises. These predictions are compared with the observations. Measurements of sigma/sub v/ and sigma/sub z/ over the first 1000 m are compared with the curves derived from other observations in the Po Valley, using the no-lift balloon technique over the same range of downwind distance. Skewness and kurtosis distributions are shown, both along the vertical and the horizontal directions. In order to show the plume structure in more detail, we present two examples of Lidar-derived cross sections and the corresponding vertically and horizontally integrated concentration profiles.

  8. East Asian SO2 pollution plume over Europe – Part 1: Airborne trace gas measurements and source identification by particle dispersion model simulations

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2009-07-01

    Full Text Available A large SO2-rich pollution plume of East Asian origin was detected by aircraft based CIMS (Chemical Ionization Mass Spectrometry measurements at 3–7.5 km altitude over the North Atlantic. The measurements, which took place on 3 May 2006 aboard of the German research aircraft Falcon, were part of the INTEX-B (Intercontinental Chemical Transport Experiment-B campaign. Additional trace gases (NO, NOy, CO, H2O were measured and used for comparison and source identification. The atmospheric SO2 mole fraction was markedly increased inside the plume and reached up to 900 pmol/mol. Accompanying lagrangian FLEXPART particle dispersion model simulations indicate that the probed pollution plume originated at low altitudes from densely populated and industrialized regions of East Asia, primarily China, about 8–12 days prior to the measurements.

  9. Modeling crop residue burning experiments to evaluate smoke emissions and plume transport

    Science.gov (United States)

    Crop residue burning is a common land management practice that results in emissions of a variety of pollutants with negative health impacts. Modeling systems are used to estimate air quality impacts of crop residue burning to support retrospective regulatory assessments and also ...

  10. Modeling crop residue burning experiments to evaluate smoke emissions and plume transport

    Science.gov (United States)

    Luxi Zhou; Kirk R. Baker; Sergey L. Napelenok; George Pouliot; Robert Elleman; Susan M. O' Neill; Shawn P. Urbanski; David C. Wong

    2018-01-01

    Crop residue burning is a common land management practice that results in emissions of a variety of pollutants with negative health impacts. Modeling systems are used to estimate air quality impacts of crop residue burning to support retrospective regulatory assessments and also for forecasting purposes. Ground and airborne measurements from a recent field experiment...

  11. Stereo Photogrammetry Measurements of the Position and Attitude of a Nozzle-Plume/Shock-Wave Interaction Model in the NASA Ames 9- by 7-Ft Supersonic Wind Tunnel

    Science.gov (United States)

    Schairer, Edward T.; Kushner, Laura K.; Drain, Bethany A.; Heineck, James T.; Durston, Donald A.

    2017-01-01

    Stereo photogrammetry was used to measure the position and attitude of a slender body of revolution during nozzle-plume/shock-wave interaction tests in the NASA Ames 9- by 7-Ft Supersonic Wind Tunnel. The model support system was designed to allow the model to be placed at many locations in the test section relative to a pressure rail on one sidewall. It included a streamwise traverse as well as a thin blade that offset the model axis from the sting axis. With these features the support system was more flexible than usual resulting in higher-than-usual uncertainty in the position and attitude of the model. Also contributing to this uncertainty were the absence of a balance, so corrections for sting deflections could not be applied, and the wings-vertical orientation of the model, which precluded using a gravity-based accelerometer to measure pitch angle. Therefore, stereo photogrammetry was chosen to provide independent measures of the model position and orientation. This paper describes the photogrammetry system and presents selected results from the test.

  12. Application of data assimilation to improve the forecasting capability of an atmospheric dispersion model for a radioactive plume

    International Nuclear Information System (INIS)

    Jeong, H.J.; Han, M.H.; Hwang, W.T.; Kim, E.H.

    2008-01-01

    Modeling an atmospheric dispersion of a radioactive plume plays an influential role in assessing the environmental impacts caused by nuclear accidents. The performance of data assimilation techniques combined with Gaussian model outputs and measurements to improve forecasting abilities are investigated in this study. Tracer dispersion experiments are performed to produce field data by assuming a radiological emergency. Adaptive neuro-fuzzy inference system (ANFIS) and linear regression filter are considered to assimilate the Gaussian model outputs with measurements. ANFIS is trained so that the model outputs are likely to be more accurate for the experimental data. Linear regression filter is designed to assimilate measurements similar to the ANFIS. It is confirmed that ANFIS could be an appropriate method for an improvement of the forecasting capability of an atmospheric dispersion model in the case of a radiological emergency, judging from the higher correlation coefficients between the measured and the assimilated ones rather than a linear regression filter. This kind of data assimilation method could support a decision-making system when deciding on the best available countermeasures for public health from among emergency preparedness alternatives

  13. Fully coupled modeling of radionuclide migration in a clayey rock disturbed by alkaline plume

    International Nuclear Information System (INIS)

    Pellegrni, D.; Windt, L. de; Lee, J.V.D.

    2002-03-01

    The disposal of radioactive wastes in clayey formations may require the use of large amounts of concrete and cement as a barrier to minimize corrosion of steel containers and radionuclide migration and for supporting drifts and disposal vaults. In this context, reactive transport modeling of the interactions between cement or concrete and the argillaceous host rock aims at estimating the evolution in time of the containment properties of the multi-barriers system. The objectives of the paper are to demonstrate that integrating radionuclides migration in the modeling of strongly coupled geochemical processes of cement-clay stone interactions is feasible and that it represents an efficient way to assess the sensitivity and modification of the classical Kd and solubility parameters with respect to the chemical evolutions. Two types of modeling are considered in the paper: i): calculation of intrinsic solubility limits and Kd values backing up on the results of modeling of cement/clay stone interactions (radionuclides are assumed to be present over the whole domain at any time whatever the scenario), ii) full mechanistic modeling which explicitly introduces radionuclides in the calculation with ad hoc assumptions on radionuclide inventory, canister failure, migration pathway, etc. The reactive transport code HYTEC, based on the geochemical code CHESS, is used to simulate both the cement-clay stone interaction processes and the radionuclide migration in 1-D and 2-D configurations. Convective/dispersive and diffuse transport can be simulated for solutes and colloids. A wide range of processes such as aqueous chemistry, redox, dissolution/precipitation, surface complexation and ion exchange can be modeled at equilibrium or with kinetic control. In addition, HYTEC is strongly coupled, i.e. the hydrology (flow and diffusion) may change when mineral precipitation or dissolution changes the local porosity. (authors)

  14. Groundwater contaminant plume ranking

    International Nuclear Information System (INIS)

    1988-08-01

    Containment plumes at Uranium Mill Tailings Remedial Action (UMTRA) Project sites were ranked to assist in Subpart B (i.e., restoration requirements of 40 CFR Part 192) compliance strategies for each site, to prioritize aquifer restoration, and to budget future requests and allocations. The rankings roughly estimate hazards to the environment and human health, and thus assist in determining for which sites cleanup, if appropriate, will provide the greatest benefits for funds available. The rankings are based on the scores that were obtained using the US Department of Energy's (DOE) Modified Hazard Ranking System (MHRS). The MHRS and HRS consider and score three hazard modes for a site: migration, fire and explosion, and direct contact. The migration hazard mode score reflects the potential for harm to humans or the environment from migration of a hazardous substance off a site by groundwater, surface water, and air; it is a composite of separate scores for each of these routes. For ranking the containment plumes at UMTRA Project sites, it was assumed that each site had been remediated in compliance with the EPA standards and that relict contaminant plumes were present. Therefore, only the groundwater route was scored, and the surface water and air routes were not considered. Section 2.0 of this document describes the assumptions and procedures used to score the groundwater route, and Section 3.0 provides the resulting scores for each site. 40 tabs

  15. Plume structure in high-Rayleigh-number convection

    Science.gov (United States)

    Puthenveettil, Baburaj A.; Arakeri, Jaywant H.

    2005-10-01

    Near-wall structures in turbulent natural convection at Rayleigh numbers of 10^{10} to 10^{11} at A Schmidt number of 602 are visualized by a new method of driving the convection across a fine membrane using concentration differences of sodium chloride. The visualizations show the near-wall flow to consist of sheet plumes. A wide variety of large-scale flow cells, scaling with the cross-section dimension, are observed. Multiple large-scale flow cells are seen at aspect ratio (AR)= 0.65, while only a single circulation cell is detected at AR= 0.435. The cells (or the mean wind) are driven by plumes coming together to form columns of rising lighter fluid. The wind in turn aligns the sheet plumes along the direction of shear. the mean wind direction is seen to change with time. The near-wall dynamics show plumes initiated at points, which elongate to form sheets and then merge. Increase in rayleigh number results in a larger number of closely and regularly spaced plumes. The plume spacings show a common log normal probability distribution function, independent of the rayleigh number and the aspect ratio. We propose that the near-wall structure is made of laminar natural-convection boundary layers, which become unstable to give rise to sheet plumes, and show that the predictions of a model constructed on this hypothesis match the experiments. Based on these findings, we conclude that in the presence of a mean wind, the local near-wall boundary layers associated with each sheet plume in high-rayleigh-number turbulent natural convection are likely to be laminar mixed convection type.

  16. Analysis of dissolved benzene plumes and methyl tertiary butyl ether (MTBE) plumes in ground water at leaking underground fuel tank (LUFT) sites

    International Nuclear Information System (INIS)

    Happel, A.M.; Rice, D.; Beckenbach, E.; Savalin, L.; Temko, H.; Rempel, R.; Dooher, B.

    1996-11-01

    The 1990 Clean Air Act Amendments mandate the addition of oxygenates to gasoline products to abate air pollution. Currently, many areas of the country utilize oxygenated or reformulated fuel containing 15- percent and I I-percent MTBE by volume, respectively. This increased use of MTBE in gasoline products has resulted in accidental point source releases of MTBE containing gasoline products to ground water. Recent studies have shown MTBE to be frequently detected in samples of shallow ground water from urban areas throughout the United States (Squillace et al., 1995). Knowledge of the subsurface fate and transport of MTBE in ground water at leaking underground fuel tank (LUFT) sites and the spatial extent of MTBE plumes is needed to address these releases. The goal of this research is to utilize data from a large number of LUFT sites to gain insights into the fate, transport, and spatial extent of MTBE plumes. Specific goals include defining the spatial configuration of dissolved MTBE plumes, evaluating plume stability or degradation over time, evaluating the impact of point source releases of MTBE to ground water, and attempting to identify the controlling factors influencing the magnitude and extent of the MTBE plumes. We are examining the relationships between dissolved TPH, BTEX, and MTBE plumes at LUFT sites using parallel approaches of best professional judgment and a computer-aided plume model fitting procedure to determine plume parameters. Here we present our initial results comparing dissolved benzene and MTBE plumes lengths, the statistical significance of these results, and configuration of benzene and MTBE plumes at individual LUFT sites

  17. Plume-induced dynamic instabilities near cratonic blocks: Implications for P-T-t paths and metallogeny

    NARCIS (Netherlands)

    Guillou-Frottier, L.; Burov, E.; Cloetingh, S.; Le Goff, E.; Deschamps, Y.; Huet, B.; Bouchot, V.

    2012-01-01

    Plume head - lithosphere interactions around cratonic blocks result in thermo-mechanical disturbances that lead to heating and burial phases of crustal rocks. We present results from numerical models of plume head - cratonic blocks interactions where a free upper surface condition and realistic

  18. Mount Etna-Iblean volcanism caused by rollback-induced upper mantle upwelling around the Ionian slab edge : An alternative to the plume model

    NARCIS (Netherlands)

    Schellart, W. P.

    Volcanism in Sicily (Italy) at Mount Etna (0.5 Ma to present) and the Iblean Plateau (ca. 7.0-1.1 Ma) remains enigmatic, because it is located in close proximity to, but is laterally offset from, the Calabrian subduction zone. Previous work suggests that the volcanism results from a plume or from

  19. The planet beyond the plume hypothesis

    Science.gov (United States)

    Smith, Alan D.; Lewis, Charles

    1999-12-01

    Acceptance of the theory of plate tectonics was accompanied by the rise of the mantle plume/hotspot concept which has come to dominate geodynamics from its use both as an explanation for the origin of intraplate volcanism and as a reference frame for plate motions. However, even with a large degree of flexibility permitted in plume composition, temperature, size, and depth of origin, adoption of any limited number of hotspots means the plume model cannot account for all occurrences of the type of volcanism it was devised to explain. While scientific protocol would normally demand that an alternative explanation be sought, there have been few challenges to "plume theory" on account of a series of intricate controls set up by the plume model which makes plumes seem to be an essential feature of the Earth. The hotspot frame acts not only as a reference but also controls plate tectonics. Accommodating plumes relegates mantle convection to a weak, sluggish effect such that basal drag appears as a minor, resisting force, with plates having to move themselves by boundary forces and continents having to be rifted by plumes. Correspondingly, the geochemical evolution of the mantle is controlled by the requirement to isolate subducted crust into plume sources which limits potential buffers on the composition of the MORB-source to plume- or lower mantle material. Crustal growth and Precambrian tectonics are controlled by interpretations of greenstone belts as oceanic plateaus generated by plumes. Challenges to any aspect of the plume model are thus liable to be dismissed unless a counter explanation is offered across the geodynamic spectrum influenced by "plume theory". Nonetheless, an alternative synthesis can be made based on longstanding petrological evidence for derivation of intraplate volcanism from volatile-bearing sources (wetspots) in conjunction with concepts dismissed for being incompatible or superfluous to "plume theory". In the alternative Earth, the sources for

  20. Thermomechanical Modeling of the Formation of a Multilevel, Crustal-Scale Magmatic System by the Yellowstone Plume

    Science.gov (United States)

    Colón, D. P.; Bindeman, I. N.; Gerya, T. V.

    2018-05-01

    Geophysical imaging of the Yellowstone supervolcano shows a broad zone of partial melt interrupted by an amagmatic gap at depths of 15-20 km. We reproduce this structure through a series of regional-scale magmatic-thermomechanical forward models which assume that magmatic dikes stall at rheologic discontinuities in the crust. We find that basaltic magmas accumulate at the Moho and at the brittle-ductile transition, which naturally forms at depths of 5-10 km. This leads to the development of a 10- to 15-km thick midcrustal sill complex with a top at a depth of approximately 10 km, consistent with geophysical observations of the pre-Yellowstone hot spot track. We show a linear relationship between melting rates in the mantle and rhyolite eruption rates along the hot spot track. Finally, melt production rates from our models suggest that the Yellowstone plume is 175°C hotter than the surrounding mantle and that the thickness of the overlying lithosphere is 80 km.

  1. Phased Array Noise Source Localization Measurements of an F404 Nozzle Plume at Both Full and Model Scale

    Science.gov (United States)

    Podboy, Gary G.; Bridges, James E.; Henderson, Brenda S.

    2010-01-01

    A 48-microphone planar phased array system was used to acquire jet noise source localization data on both a full-scale F404-GE-F400 engine and on a 1/4th scale model of a F400 series nozzle. The full-scale engine test data show the location of the dominant noise sources in the jet plume as a function of frequency for the engine in both baseline (no chevron) and chevron configurations. Data are presented for the engine operating both with and without afterburners. Based on lessons learned during this test, a set of recommendations are provided regarding how the phased array measurement system could be modified in order to obtain more useful acoustic source localization data on high-performance military engines in the future. The data obtained on the 1/4th scale F400 series nozzle provide useful insights regarding the full-scale engine jet noise source mechanisms, and document some of the differences associated with testing at model-scale versus fullscale.

  2. Tropical biomass burning smoke plume size, shape, reflectance, and age based on 2001–2009 MISR imagery of Borneo

    Directory of Open Access Journals (Sweden)

    C. S. Zender

    2012-04-01

    values about 3% and 10% greater than at the origin, respectively. The initially oblong plumes become brighter and more circular with time, increasingly resembling smoke clouds. Wind speed does not explain a significant fraction of the variation in plume geometry. We provide a parameterization of plume shape that can help atmospheric models estimate the effects of plumes on weather, climate, and air quality. Plume age, the age of smoke furthest down-plume, is lognormally distributed with a median of 2.8 h (25th and 75th percentiles at 1.3 h and 4.0 h, different from the median ages reported in other studies. Intercomparison of our results with previous studies shows that the shape, height, optical depth, and lifetime characteristics reported for tropical biomass burning plumes on three continents are dissimilar and distinct from the same characteristics of non-tropical wildfire plumes.

  3. Simulations of the Effects of Jupiter's Plasma Torus on Io's Pele Plume

    Science.gov (United States)

    McDoniel, William; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence M.

    2014-11-01

    Io’s plumes rise hundreds of kilometers above its surface and sublimation atmosphere, presenting large targets for incoming ions from Jupiter’s plasma torus. The direct simulation Monte Carlo method is used to model the gas plume at Pele and its interaction with the Jovian plasma torus. Chemical reactions resulting from ion impacts in a plume change its composition and energy from the impacts changes the plume’s structure (asymmetrically). The presence of non-condensible daughter species in a warmer plume canopy produces a more diffuse deposition ring on Io’s surface, compared to simulations without plasma. Energized molecules also escape from the plume, forming a diffuse cloud of fast particles above the plume’s canopy, which may function to resupply the plasma torus and which suggests a mechanism for lofting other species to very high altitudes.

  4. Generation of dense plume fingers in saturated-unsaturated homogeneous porous media

    Science.gov (United States)

    Cremer, Clemens J. M.; Graf, Thomas

    2015-02-01

    Flow under variable-density conditions is widespread, occurring in geothermal reservoirs, at waste disposal sites or due to saltwater intrusion. The migration of dense plumes typically results in the formation of vertical plume fingers which are known to be triggered by material heterogeneity or by variations in source concentration that causes the density variation. Using a numerical groundwater model, six perturbation methods are tested under saturated and unsaturated flow conditions to mimic heterogeneity and concentration variations on the pore scale in order to realistically generate dense fingers. A laboratory-scale sand tank experiment is numerically simulated, and the perturbation methods are evaluated by comparing plume fingers obtained from the laboratory experiment with numerically simulated fingers. Dense plume fingering for saturated flow can best be reproduced with a spatially random, time-constant perturbation of the solute source. For unsaturated flow, a spatially and temporally random noise of solute concentration or a random conductivity field adequately simulate plume fingering.

  5. CALIOP-based Biomass Burning Smoke Plume Injection Height

    Science.gov (United States)

    Soja, A. J.; Choi, H. D.; Fairlie, T. D.; Pouliot, G.; Baker, K. R.; Winker, D. M.; Trepte, C. R.; Szykman, J.

    2017-12-01

    to CMAQ modeled smoke plume injection. These results have the potential to provide value to national and international modeling communities (scientific and air quality) and to public land, fire, and air quality management and regulations communities.

  6. Vertical dispersion from surface and elevated releases: An investigation of a Non-Gaussian plume model

    International Nuclear Information System (INIS)

    Brown, M.J.; Arya, S.P.; Snyder, W.H.

    1993-01-01

    The vertical diffusion of a passive tracer released from surface and elevated sources in a neutrally stratified boundary layer has been studied by comparing field and laboratory experiments with a non-Gaussian K-theory model that assumes power-law profiles for the mean velocity and vertical eddy diffusivity. Several important differences between model predictions and experimental data were discovered: (1) the model overestimated ground-level concentrations from surface and elevated releases at distances beyond the peak concentration; (2) the model overpredicted vertical mixing near elevated sources, especially in the upward direction; (3) the model-predicted exponent α in the exponential vertical concentration profile for a surface release [bar C(z)∝ exp(-z α )] was smaller than the experimentally measured exponent. Model closure assumptions and experimental short-comings are discussed in relation to their probable effect on model predictions and experimental measurements. 42 refs., 13 figs., 3 tabs

  7. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus

    2013-10-01

    Full Text Available We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

  8. Monitoring and forecasting Etna volcanic plumes

    Directory of Open Access Journals (Sweden)

    S. Scollo

    2009-09-01

    Full Text Available In this paper we describe the results of a project ongoing at the Istituto Nazionale di Geofisica e Vulcanologia (INGV. The objective is to develop and implement a system for monitoring and forecasting volcanic plumes of Etna. Monitoring is based at present by multispectral infrared measurements from the Spin Enhanced Visible and Infrared Imager on board the Meteosat Second Generation geosynchronous satellite, visual and thermal cameras, and three radar disdrometers able to detect ash dispersal and fallout. Forecasting is performed by using automatic procedures for: i downloading weather forecast data from meteorological mesoscale models; ii running models of tephra dispersal, iii plotting hazard maps of volcanic ash dispersal and deposition for certain scenarios and, iv publishing the results on a web-site dedicated to the Italian Civil Protection. Simulations are based on eruptive scenarios obtained by analysing field data collected after the end of recent Etna eruptions. Forecasting is, hence, supported by plume observations carried out by the monitoring system. The system was tested on some explosive events occurred during 2006 and 2007 successfully. The potentiality use of monitoring and forecasting Etna volcanic plumes, in a way to prevent threats to aviation from volcanic ash, is finally discussed.

  9. Development of a fluid model for DC arc plasma torches and its integration with downstream models of atmospheric plasma spray particle plumes

    Science.gov (United States)

    Cannamela, Michael J., III

    The plasma spray process uses plasma flames to melt micron sized particles of e.g. ceramic and propel the droplets to impinge upon and freeze to the target workpiece, forming a functional coating. Variations in the process arise from many sources, and because sensing of the process is imperfect one is motivated to pursue a modeling approach. This dissertation models the major elements of the process; the torch that produces the plasma flame, the jet of hot plasma issuing from the torch, and the plume of particles conveyed and heated by the jet. The plasma in the torch is modeled by a one-fluid magnetohydrodynamic (MHD) approach and it is found that the MHD equations can accurately predict the power dissipated in the bulk of the plasma, while special treatment is required in regions near the electrodes. Treatment of the cathode region is eased since it can be de-coupled from the bulk flow. Treatment of the anode region aims to extract the correct amount of power from the plasma. With MHD in the bulk and these special conditions at the electrode boundaries, the net power into the plasma can be matched with experiment. For one simulation of an SG-100 torch operating at 500A, the measured net power was 7.0kW while the computed net power was 7.1kW. Using outlet information from the torch, the impact of plasma arc oscillations on the free jet and on the in-flight particle states is predicted. The model of the plasma jet is validated against the existing LAVA code, and is able to predict the fraction of entrained air in the jet to within 20% of the experimental value. The variations in particle states due to the arc fluctuations are found to be similar in size to variations due to changes in particle injection velocity, and so cannot be neglected when considering particle state distributions. The end result of this work is to make available a complete chain of models for the plasma spray process, from torch input conditions to in-flight particle state.

  10. Numerical study of single and two interacting turbulent plumes in atmospheric cross flow

    Science.gov (United States)

    Mokhtarzadeh-Dehghan, M. R.; König, C. S.; Robins, A. G.

    The paper presents a numerical study of two interacting full-scale dry plumes issued into neutral boundary layer cross flow. The study simulates plumes from a mechanical draught cooling tower. The plumes are placed in tandem or side-by-side. Results are first presented for plumes with a density ratio of 0.74 and plume-to-crosswind speed ratio of 2.33, for which data from a small-scale wind tunnel experiment were available and were used to assess the accuracy of the numerical results. Further results are then presented for the more physically realistic density ratio of 0.95, maintaining the same speed ratio. The sensitivity of the results with respect to three turbulence models, namely, the standard k- ɛ model, the RNG k- ɛ model and the Differential Flux Model (DFM) is presented. Comparisons are also made between the predicted rise height and the values obtained from existing integral models. The formation of two counter-rotating vortices is well predicted. The results show good agreement for the rise height predicted by different turbulence models, but the DFM predicts temperature profiles more accurately. The values of predicted rise height are also in general agreement. However, discrepancies between the present results for the rise height for single and multiple plumes and the values obtained from known analytical relations are apparent and possible reasons for these are discussed.

  11. Nighttime NOx Chemistry in Coal-Fired Power Plant Plumes

    Science.gov (United States)

    Fibiger, D. L.; McDuffie, E. E.; Dube, W. P.; Veres, P. R.; Lopez-Hilfiker, F.; Lee, B. H.; Green, J. R.; Fiddler, M. N.; Ebben, C. J.; Sparks, T.; Weinheimer, A. J.; Montzka, D.; Campos, T. L.; Cohen, R. C.; Bililign, S.; Holloway, J. S.; Thornton, J. A.; Brown, S. S.

    2015-12-01

    Nitrogen oxides (NOx = NO + NO2) play a key role in atmospheric chemistry. During the day, they catalyze ozone (O3) production, while at night they can react to form nitric acid (HNO3) and nitryl chloride (ClNO2) and remove O3 from the atmosphere. These processes are well studied in the summer, but winter measurements are more limited. Coal-fired power plants are a major source of NOx to the atmosphere, making up approximately 30% of emissions in the US (epa.gov). NOx emissions can vary seasonally, as well as plant-to-plant, with important impacts on the details of the plume chemistry. In particular, due to inefficient plume dispersion, nighttime NOx emissions from power plants are held in concentrated plumes, where rates of mixing with ambient O3 have a strong influence on plume evolution. We will show results from the aircraft-based WINTER campaign over the northeastern United States, where several nighttime intercepts of power plant plumes were made. Several of these intercepts show complete O3 titration, which can have a large influence on NOx lifetime, and thus O3 production, in the plume. When power plant NO emissions exceed background O3 levels, O3 is completely consumed converting NO to NO2. In the presence of O3, NO2 will be oxidized to NO3, which will then react with NO2 to form N2O5, which can then form HNO3 and/or ClNO2 and, ultimately, remove NOx from the atmosphere or provide next-day oxidant sources. If there is no O3 present, however, no further chemistry can occur and NO and NO2 will be transported until mixing with sufficient O3 for higher oxidation products. Modeling results of plume development and mixing, which can tell us more about this transport, will also be presented.

  12. Puff-plume atmospheric deposition model for use at SRP in emergency-response situations

    International Nuclear Information System (INIS)

    Garrett, A.J.; Murphy, C.E. Jr.

    1981-05-01

    An atmospheric transport and diffusion model developed for real-time calculation of the location and concentration of toxic or radioactive materials during an accidental release was improved by including deposition calculations

  13. Satellite-based empirical models linking river plume dynamics with hypoxic area andvolume

    Science.gov (United States)

    Satellite-based empirical models explaining hypoxic area and volume variation were developed for the seasonally hypoxic (O2 < 2 mg L−1) northern Gulf of Mexico adjacent to the Mississippi River. Annual variations in midsummer hypoxic area and ...

  14. Multiscale Approach to Small River Plumes off California

    Science.gov (United States)

    Basdurak, N. B.; Largier, J. L.; Nidzieko, N.

    2012-12-01

    While larger scale plumes have received significant attention, the dynamics of plumes associated with small rivers typical of California are little studied. Since small streams are not dominated by a momentum flux, their plumes are more susceptible to conditions in the coastal ocean such as wind and waves. In order to correctly model water transport at smaller scales, there is a need to capture larger scale processes. To do this, one-way nested grids with varying grid resolution (1 km and 10 m for the parent and the child grid respectively) were constructed. CENCOOS (Central and Northern California Ocean Observing System) model results were used as boundary conditions to the parent grid. Semi-idealized model results for Santa Rosa Creek, California are presented from an implementation of the Regional Ocean Modeling System (ROMS v3.0), a three-dimensional, free-surface, terrain-following numerical model. In these preliminary results, the interaction between tides, winds, and buoyancy forcing in plume dynamics is explored for scenarios including different strengths of freshwater flow with different modes (steady and pulsed). Seasonal changes in transport dynamics and dispersion patterns are analyzed.

  15. Laboratory Study of Dispersion of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Petersen, Ole; Larsen, Torben

    1990-01-01

    -differences. Other methods as infra-red sensing are used for visualizing purpose. The results are used to calibrate an integral model of the dispersion. Conclusions are that the dispersion of a buoyant surface plume can be treated the superposition of a buoyancy induced stretching and turbulent diffusion, reduced...

  16. Understanding convective extreme precipitation scaling using observations and an entraining plume model

    NARCIS (Netherlands)

    Loriaux, J.M.; Lenderink, G.; De Roode, S.R.; Siebesma, A.P.

    2013-01-01

    Previously observed twice-Clausius–Clapeyron (2CC) scaling for extreme precipitation at hourly time scales has led to discussions about its origin. The robustness of this scaling is assessed by analyzing a subhourly dataset of 10-min resolution over the Netherlands. The results confirm the validity

  17. Groundwater modeling of source terms and contaminant plumes for DOE low-level waste performance assessments

    International Nuclear Information System (INIS)

    McDowell-Boyer, L.M.; Wilson, J.E.

    1994-01-01

    Under US Department of Energy (DOE) Order 5820.2A, all sites within the DOE complex must analyze the performance of planned radioactive waste disposal facilities before disposal takes place through the radiological performance assessment process. These assessments consider both exposures to the public from radionuclides potentially released from disposal facilities and protection of groundwater resources. Compliance with requirements for groundwater protection is often the most difficult to demonstrate as these requirements are generally more restrictive than those for other pathways. Modeling of subsurface unsaturated and saturated flow and transport was conducted for two such assessments for the Savannah River site. The computer code PORFLOW was used to evaluate release and transport of radionuclides from different types of disposal unit configurations: vault disposal and trench disposal. The effectiveness of engineered barriers was evaluated in terms of compliance with groundwater protection requirements. The findings suggest that, due to the limited lifetime of engineered barriers, overdesign of facilities for long-lived radionuclides is likely to occur if compliance must be realized for thousands of years

  18. An Updated Model for the Anomalous Resistivity of LNAPL Plumes in Sandy Environments

    Science.gov (United States)

    Sauck, W. A.; Atekwana, E. A.; Werkema, D. D.

    2006-05-01

    Anomalously low resistivities have been observed at some sites contaminated by light non-aqueous phase liquid (LNAPL) since. The model that has been used to explain this phenomenon was published in 2000. This working hypothesis invokes both physical mixing and bacterial action to explain the low resistivities near the base of the vadose zone and the upper part of the aquifer. The hydrocarbon-degrading bacteria (of which there are numerous species found in soils) produce organic acids and carbonic acids. The acidic pore waters dissolve readily soluble ions from the native soil grains and grain coatings, to produce a leachate high in total dissolved solids. The free product LNAPL is initially a wetting phase, although not generally more than 50% extent, and seasonal water table fluctuations mix the hydrocarbons vertically through the upper water saturated zone and transition zone. This update introduces several new aspects of the conductive model. The first is that, in addition to the acids being produced by the oil-degrading bacteria, they also produce surfactants. Surfactants act similarly to detergents in detaching the oil phase from the solid substrate, and forming an emulsion of oil droplets within the water. This has helped to explain how continuous, high-TDS capillary paths can develop and pass vertically through what appears to be a substantial free product layer, thus providing easy passage for electrical current during electrical resistivity measurements. Further, it has also been shown that the addition of organic acids and biosurfactants to pore fluids can directly contribute to the conductivity of the pore fluids. A second development is that large-diameter column experiments were conducted for nearly two years (8 columns for 4 experiments). The columns had a vertical row of eletrodes for resistivity measurements, ports for extracting water samples with a syringe, and sample tubes for extracting soil samples. Water samples were used for chemical analysis

  19. Modelling of contaminant migration in acidic groundwater plumes at uranium tailings impoundments: ADNEUT3

    International Nuclear Information System (INIS)

    Cherry, J.A.; Morin, K.A.; Dubrovsky, N.M.

    1984-06-01

    This report describes the creation and application of ADNEUT3, the latest addition to the ADNEUT (Acid-Drainage NEUTralization) family of computer programs for simulating acid-drainage transport and neutralization. The creation of ADNEUT3 involved the expansion of ADNEUT1 to allow variable input conditions such as changing input solution with time, variable initial amounts of minerals through the simulated streamtube, variable velocities through the streamtube, and variable solubilities for relevant minerals dependent on aqueous chemical composition. Concepts for simulating acid-drainage neutralization are reviewed and ADNEUT3 is then applied to a field-study site of acidic contaminant migration from the Nordic Main uranium-tailings impoundment near Elliot Lake, Ontario. A sensitivity study is first implemented to calibrate ADNEUT3 to the results of the 1979 to 1983 field studies. Then ADNEUT3 is used to define probable past conditions at the site which are not reliably known. In particular, ADNEUT3 is used to help identify: 1) the approximate year when acidic seepage began leaving the tailings impoundment (1966-1967), 2) the past chemical composition of the seepage (somewhat more acidic for a short period of time), and 3) the location of the source area within the tailings for the acidic seepage (near the impoundment dam, close to the field site). Finally, ADNEUT3 is used to predict future contaminant migration. Results indicate that hundreds of years are required under present conditions for the most acidic water with associated high levels of contaminants to migrate about 100 m from the tailings impoundment. The cause of this slow movement is the significant neutralization capacity of the aquifer. If acid production within the tailings decreases in the future, migration rates of contaminants will also decrease

  20. Characterizing the solar reflection from wildfire smoke plumes using airborne multiangle measurements

    Science.gov (United States)

    Gatebe, C. K.; Varnai, T.; Gautam, R.; Poudyal, R.; Singh, M. K.

    2016-12-01

    To help better understand forest fire smoke plumes, this study examines sunlight reflected from plumes that were observed over Canada during the ARCTAS campaign in summer 2008. In particular, the study analyzes multiangle and multispectral measurements of smoke scattering by the airborne Cloud Absorption Radiometer (CAR). In combination with other in-situ and remote sensing information and radiation modeling, CAR data is used for characterizing the radiative properties and radiative impact of smoke particles—which inherently depend on smoke particle properties that influence air quality. In addition to estimating the amount of reflected and absorbed sunlight, the work includes using CAR data to create spectral and broadband top-of-atmosphere angular distribution models (ADMs) of solar radiation reflected by smoke plumes, and examining the sensitivity of such angular models to scene parameters. Overall, the results help better understand the radiative properties and radiative effects of smoke particles, and are anticipated to help better interpret satellite data on smoke plumes.

  1. Scaling for turbulent viscosity of buoyant plumes in stratified fluids: PIV measurement with implications for submarine hydrothermal plume turbulence

    Science.gov (United States)

    Zhang, Wei; He, Zhiguo; Jiang, Houshuo

    2017-11-01

    Time-resolved particle image velocimetry (PIV) has been used to measure instantaneous two-dimensional velocity vector fields of laboratory-generated turbulent buoyant plumes in linearly stratified saltwater over extended periods of time. From PIV-measured time-series flow data, characteristics of plume mean flow and turbulence have been quantified. To be specific, maximum plume penetration scaling and entrainment coefficient determined from the mean flow agree well with the theory based on the entrainment hypothesis for buoyant plumes in stratified fluids. Besides the well-known persistent entrainment along the plume stem (i.e., the 'plume-stem' entrainment), the mean plume velocity field shows persistent entrainment along the outer edge of the plume cap (i.e., the 'plume-cap' entrainment), thereby confirming predictions from previous numerical simulation studies. To our knowledge, the present PIV investigation provides the first measured flow field data in the plume cap region. As to measured plume turbulence, both the turbulent kinetic energy field and the turbulence dissipation rate field attain their maximum close to the source, while the turbulent viscosity field reaches its maximum within the plume cap region; the results also show that maximum turbulent viscosity scales as νt,max = 0.030(B/N)1/2, where B is source buoyancy flux and N is ambient buoyancy frequency. These PIV data combined with previously published numerical simulation results have implications for understanding the roles of hydrothermal plume turbulence, i.e. plume turbulence within the cap region causes the 'plume-cap' entrainment that plays an equally important role as the 'plume-stem' entrainment in supplying the final volume flux at the plume spreading level.

  2. Temperature profile retrieval in axisymmetric combustion plumes using multilayer perceptron modeling and spectral feature selection in the infrared CO2 emission band.

    Science.gov (United States)

    García-Cuesta, Esteban; de Castro, Antonio J; Galván, Inés M; López, Fernando

    2014-01-01

    In this work, a methodology based on the combined use of a multilayer perceptron model fed using selected spectral information is presented to invert the radiative transfer equation (RTE) and to recover the spatial temperature profile inside an axisymmetric flame. The spectral information is provided by the measurement of the infrared CO2 emission band in the 3-5 μm spectral region. A guided spectral feature selection was carried out using a joint criterion of principal component analysis and a priori physical knowledge of the radiative problem. After applying this guided feature selection, a subset of 17 wavenumbers was selected. The proposed methodology was applied over synthetic scenarios. Also, an experimental validation was carried out by measuring the spectral emission of the exhaust hot gas plume in a microjet engine with a Fourier transform-based spectroradiometer. Temperatures retrieved using the proposed methodology were compared with classical thermocouple measurements, showing a good agreement between them. Results obtained using the proposed methodology are very promising and can encourage the use of sensor systems based on the spectral measurement of the CO2 emission band in the 3-5 μm spectral window to monitor combustion processes in a nonintrusive way.

  3. Investigation of CO, C2H6 and aerosols in a boreal fire plume over eastern Canada during BORTAS 2011 using ground- and satellite-based observations and model simulations

    Directory of Open Access Journals (Sweden)

    D. Griffin

    2013-10-01

    Full Text Available We present the results of total column measurements of CO, C2H6 and fine-mode aerosol optical depth (AOD during the "Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS-B campaign over eastern Canada. Ground-based observations, using Fourier transform spectrometers (FTSs and sun photometers, were carried out in July and August 2011. These measurements were taken in Halifax, Nova Scotia, which is an ideal location to monitor the outflow of boreal fires from North America, and also in Toronto, Ontario. Measurements of fine-mode AOD enhancements were highly correlated with enhancements in coincident trace gas (CO and C2H6 observations between 19 and 21 July 2011, which is typical for a smoke plume event. In this paper, we focus on the identification of the origin and the transport of this smoke plume. We use back trajectories calculated by the Canadian Meteorological Centre as well as FLEXPART forward trajectories to demonstrate that the enhanced CO, C2H6 and fine-mode AOD seen near Halifax and Toronto originated from forest fires in northwestern Ontario that occurred between 17 and 19 July 2011. In addition, total column measurements of CO from the satellite-borne Infrared Atmospheric Sounding Interferometer (IASI have been used to trace the smoke plume and to confirm the origin of the CO enhancement. Furthermore, the enhancement ratio – that is, in this case equivalent to the emission ratio (ERC2H6/CO – was estimated from these ground-based observations. These C2H6 emission results from boreal fires in northwestern Ontario agree well with C2H6 emission measurements from other boreal regions, and are relatively high compared to fires from other geographical regions. The ground-based CO and C2H6 observations were compared with outputs from the 3-D global chemical transport model GEOS-Chem, using the Fire Locating And Modeling of Burning Emissions (FLAMBE inventory

  4. Investigation of CO, C2H6 and aerosols in a boreal fire plume over eastern Canada during BORTAS 2011 using ground- and satellite-based observations and model simulations

    Science.gov (United States)

    Griffin, D.; Walker, K. A.; Franklin, J. E.; Parrington, M.; Whaley, C.; Hopper, J.; Drummond, J. R.; Palmer, P. I.; Strong, K.; Duck, T. J.; Abboud, I.; Bernath, P. F.; Clerbaux, C.; Coheur, P.-F.; Curry, K. R.; Dan, L.; Hyer, E.; Kliever, J.; Lesins, G.; Maurice, M.; Saha, A.; Tereszchuk, K.; Weaver, D.

    2013-10-01

    We present the results of total column measurements of CO, C2H6 and fine-mode aerosol optical depth (AOD) during the "Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS-B) campaign over eastern Canada. Ground-based observations, using Fourier transform spectrometers (FTSs) and sun photometers, were carried out in July and August 2011. These measurements were taken in Halifax, Nova Scotia, which is an ideal location to monitor the outflow of boreal fires from North America, and also in Toronto, Ontario. Measurements of fine-mode AOD enhancements were highly correlated with enhancements in coincident trace gas (CO and C2H6) observations between 19 and 21 July 2011, which is typical for a smoke plume event. In this paper, we focus on the identification of the origin and the transport of this smoke plume. We use back trajectories calculated by the Canadian Meteorological Centre as well as FLEXPART forward trajectories to demonstrate that the enhanced CO, C2H6 and fine-mode AOD seen near Halifax and Toronto originated from forest fires in northwestern Ontario that occurred between 17 and 19 July 2011. In addition, total column measurements of CO from the satellite-borne Infrared Atmospheric Sounding Interferometer (IASI) have been used to trace the smoke plume and to confirm the origin of the CO enhancement. Furthermore, the enhancement ratio - that is, in this case equivalent to the emission ratio (ERC2H6/CO) - was estimated from these ground-based observations. These C2H6 emission results from boreal fires in northwestern Ontario agree well with C2H6 emission measurements from other boreal regions, and are relatively high compared to fires from other geographical regions. The ground-based CO and C2H6 observations were compared with outputs from the 3-D global chemical transport model GEOS-Chem, using the Fire Locating And Modeling of Burning Emissions (FLAMBE) inventory. Agreement within the

  5. Advances in Monitoring, Modelling and Forecasting Volcanic Ash Plumes over the Past 5 Years and the Impact on Preparedness from the London VAAC Perspective

    Science.gov (United States)

    Lee, D. S.; Lisk, I.

    2015-12-01

    Hosted and run by the Met Office, the London VAAC (Volcanic Ash Advisory Centre) is responsible for issuing advisories on the location and likely dispersion of ash clouds originating from volcanoes in the North East Atlantic, primarily from Iceland. These advisories and additional guidance products are used by the civil aviation community to make decisions on airspace flight management. London VAAC has specialist forecasters who use a combination of volcano source data, satellite-based, ground-based and aircraft observations, weather forecast models and dispersion models. Since the eruption of the Icelandic volcano Eyjafjallajökull in 2010, which resulted in the decision by many northern European countries to impose significant restrictions on the use of their airspace, London VAAC has been active in further developing its volcanic ash monitoring, modelling and forecasting capabilities, collaborating with research organisations, industry, other VAACs, Meteorological Services and the Volcano Observatory in Iceland. It has been necessary to advance operational capabilities to address evolving requirements, including for more quantitative assessments of volcanic ash in the atmosphere. Here we summarise advances in monitoring, modelling and forecasting of volcanic ash plumes over the past 5 years from the London VAAC perspective, and the realization of science into operations. We also highlight the importance of collaborative activities, such as the 'VAAC Best Practice' Workshop, where information is exchanged between all nine VAACs worldwide on the operational practices in monitoring and forecasting volcanic ash, with the aim of working toward a more harmonized service for decision makers in the aviation community. We conclude on an evaluation of how better we are prepared for the next significant ash-rich Icelandic eruption, and the challenges still remaining.

  6. Plume tracer experiments at Hinkley Point 'A' [Nuclear Power Station] during 1987

    International Nuclear Information System (INIS)

    Foster, P.M.

    1988-11-01

    The results of the first part of a programme of plume dispersion measurements at the Hinkley Point Nuclear Power Station are described. Using SF 6 gas and pyrotechnic smoke tracer techniques developed during an earlier study at Oldbury, measurements of ground level plume behaviour out to about 4 km and elevated plume behaviour out to about 1 km have been made in a series of twelve 1 hour trials and one 15 minute trial. Whereas the Oldbury study considered passive emissions, attention in this study has been focussed on the behaviour of the buoyant shield cooling air emission. Data on plume rise and the degree of plume entrainment by the building wake and on the effects of entrainment and wind meander on plume width and concentration, are presented and discussed in relation to current modelling recommendations. A limited number of 10 minute averaged measurements of plume concentration and 41-Ar decay gamma count were also made at 2 km range and their correlation and variability examined. (author)

  7. CFD investigation of balcony spill plumes in atria

    International Nuclear Information System (INIS)

    McCartney, C.J.; Lougheed, G.D.; Weckman, E.J.

    2004-01-01

    Smoke management in buildings during fire events often uses mechanical ventilation systems to maintain smoke layer elevation above a safe evacuation path. Design of these systems requires accurate correlations for the smoke production rate of the buoyant fire plume. One design issue is the smoke production rate of fire plumes which spill out from a fire compartment, under a balcony and up through an atrium or other large volume. Current engineering correlations for these balcony spill plumes are based on a combination of one-tenth scale test data and theoretical analysis. Questions have arisen over the suitability of these correlations for real-scale designs. A combined program of full-scale experimentation and CFD modeling is being conducted to analyze the accuracy of these correlations. A full-scale experimental facility was constructed with a 5 m by 5 m by 15 m fire compartment connected to a four-story atrium. Propane fires in the compartment produce balcony spill plumes which form steady-state smoke layers in the atrium. Experimental variables include fire size, compartment opening width, balcony depth and compartment fascia depth. A variable exhaust system was used to achieve various smoke layer heights for each of 100 compartment configurations. Temperature, smoke obscuration and gas concentrations were measured in the compartment, atrium and exhaust system. The experimental data was used to determine the atrium smoke layer elevation and balcony spill plume smoke production rate for each configuration and fire size. Comparison of this data with zone model results and design correlations for atrium smoke management systems will be performed to evaluate their accuracy. A CFD model of the experimental facility was implemented using the Fire Dynamics Simulator software (Version 3). Large-eddy simulations of the flow were performed with a constant radiative fraction and an infinitely fast mixture fraction combustion model. A grid sensitivity analysis was

  8. Characterizing Io’s Pele, Tvashtar and Pillan plumes: Lessons learned from Hubble

    Science.gov (United States)

    Jessup, Kandis Lea; Spencer, John R.

    2012-03-01

    almost equivalent corresponding to ∼2-6 × 1016 cm-2 and 3-5 × 1015 cm-2, respectively, producing SO2 and S2 gas resurfacing rates ∼0.04-0.2 cm yr-1 and 0.007-0.01 cm yr-1; and SO2 and S2 gas masses ∼1-4 × 1010 g and ∼2-3 × 109 g; for a total dust to gas ratio in the plumes ∼10-1-10-2. The 2007 Tvashtar plume was detected by HST at ∼380 ± 40 km in both reflected sunlight and absorbed jovian light; in 1999, the detected Pele plume altitude was 500 km in absorbed jovian light, but in reflected sunlight the detected height was ∼2× lower. Thus, for the 1999 Pele plume, similar to the 1979 Voyager Pele plume observations, the most efficient dust reflections occurred in the region closest to the plume vent. The 0.33-0.42 μm brightness of the 1997 Pillan plume was 10-20× greater than the Pele or Tvashtar plumes, exceeding by a factor of 3 the average brightness levels observed within 200 km of 1979 Loki eruption vent. But, the 0.26 μm brightness of the 1997 Pillan plume in reflected sunlight was significantly lower than would be predicted by the dust scattering model. Presuming that the 0.26 μm brightness of the 1997 Pillan plume was attenuated by the eruption plume’s gas component, then an SO2 gas density ∼3-6 × 1018 cm-2 is inferred from the data (for S2/SO2 ratios ⩽4%), comparable to the 0.3-2 × 1018 cm-2 SO2 density detected at Loki in 1979 (Pearl, J.C. et al. [1979]. Nature 280, 755; Lellouch et al., 1992), and producing an SO2 gas mass ∼3-8 × 1011 g and an SO2 resurfacing rate ∼8-23 cm yr-1. These results confirm the connection between high (⩾1017 cm-2) SO2 gas content and plumes that scatter strongly at nearly blue wavelengths, and it validates the occurrence of high density SO2 gas eruptions on Io. Noting that the SO2 gas content inferred from a spectrum of the 2003 Pillan plume was significantly lower ∼2 × 1016 cm-2 (Jessup, K.L., Spencer, J., Yelle, R. [2007]. Icarus 192, 24-40); and that the Pillan caldera was flooded with

  9. Elucidation of Metallic Plume and Spatter Characteristics Based on SVM During High-Power Disk Laser Welding

    International Nuclear Information System (INIS)

    Gao Xiangdong; Liu Guiqian

    2015-01-01

    During deep penetration laser welding, there exist plume (weak plasma) and spatters, which are the results of weld material ejection due to strong laser heating. The characteristics of plume and spatters are related to welding stability and quality. Characteristics of metallic plume and spatters were investigated during high-power disk laser bead-on-plate welding of Type 304 austenitic stainless steel plates at a continuous wave laser power of 10 kW. An ultraviolet and visible sensitive high-speed camera was used to capture the metallic plume and spatter images. Plume area, laser beam path through the plume, swing angle, distance between laser beam focus and plume image centroid, abscissa of plume centroid and spatter numbers are defined as eigenvalues, and the weld bead width was used as a characteristic parameter that reflected welding stability. Welding status was distinguished by SVM (support vector machine) after data normalization and characteristic analysis. Also, PCA (principal components analysis) feature extraction was used to reduce the dimensions of feature space, and PSO (particle swarm optimization) was used to optimize the parameters of SVM. Finally a classification model based on SVM was established to estimate the weld bead width and welding stability. Experimental results show that the established algorithm based on SVM could effectively distinguish the variation of weld bead width, thus providing an experimental example of monitoring high-power disk laser welding quality. (plasma technology)

  10. Synergistic use of Lagrangian dispersion and radiative transfer modelling with satellite and surface remote sensing measurements for the investigation of volcanic plumes: the Mount Etna eruption of 25–27 October 2013

    Directory of Open Access Journals (Sweden)

    P. Sellitto

    2016-06-01

    Full Text Available In this paper we combine SO2 and ash plume dispersion modelling with satellite and surface remote sensing observations to study the regional influence of a relatively weak volcanic eruption from Mount Etna on the optical and micro-physical properties of Mediterranean aerosols. We analyse the Mount Etna eruption episode of 25–27 October 2013. The evolution of the plume along the trajectory is investigated by means of the FLEXible PARTicle Lagrangian dispersion (FLEXPART model. The satellite data set includes true colour images, retrieved values of volcanic SO2 and ash, estimates of SO2 and ash emission rates derived from MODIS (MODerate resolution Imaging Spectroradiometer observations and estimates of cloud top pressure from SEVIRI (Spinning Enhanced Visible and InfraRed Imager. Surface remote sensing measurements of aerosol and SO2 made at the ENEA Station for Climate Observations (35.52° N, 12.63° E; 50 m a.s.l. on the island of Lampedusa are used in the analysis. The combination of these different data sets suggests that SO2 and ash, despite the initial injection at about 7.0 km altitude, reached altitudes around 10–12 km and influenced the column average aerosol particle size distribution at a distance of more than 350 km downwind. This study indicates that even a relatively weak volcanic eruption may produce an observable effect on the aerosol properties at the regional scale. The impact of secondary sulfate particles on the aerosol size distribution at Lampedusa is discussed and estimates of the clear-sky direct aerosol radiative forcing are derived. Daily shortwave radiative forcing efficiencies, i.e. radiative forcing per unit AOD (aerosol optical depth, are calculated with the LibRadtran model. They are estimated between −39 and −48 W m−2 AOD−1 at the top of the atmosphere and between −66 and −49 W m−2 AOD−1 at the surface, with the variability in the estimates mainly depending on the

  11. Influences of source condition and dissolution on bubble plume in a stratified environment

    Science.gov (United States)

    Chu, Shigan; Prosperetti, Andrea

    2017-11-01

    A cross-sectionally averaged model is used to study a bubble plume rising in a stratified quiescent liquid. Scaling analyses for the peel height, at which the plume momentum vanishes, and the neutral height, at which its average density equals the ambient density, are presented. Contrary to a widespread practice in the literature, it is argued that the neutral height cannot be identified with the experimentally reported intrusion height. Recognizing this difference provides an explanation of the reason why the intrusion height is found so frequently to lie so much above predictions, and brings the theoretical results in line with observations. The mathematical model depends on three dimensionless parameters, some of which are related to the inlet conditions at the plume source. Their influence on the peel and neutral heights is illustrated by means of numerical results. Aside from the source parameters, we incorporate dissolution of bubbles and the corresponding density change of plume into the model. Contrary to what's documented in literature, density change of plume due to dissolution plays an important role in keeping the total buoyancy of plume, thus alleviating the rapid decrease of peel height because of dissolution.

  12. Radioactive Plumes Monitoring Simulator

    International Nuclear Information System (INIS)

    Kapelushnik, I.; Sheinfeld, M.; Avida, R.; Kadmon, Y.; Ellenbogen, M.; Tirosh, D.

    1999-01-01

    The Airborne Radiation Monitoring System (ARMS) monitors air or ground radioactive contamination. The contamination source can be a radioactive plume or an area contaminated with radionuclides. The system is based on two major parts, an airborne unit carried by a helicopter and a ground station carried by a truck. The system enables real time measurement and analysis of radioactive plumes as well as post flight processing. The Radioactive Plumes Monitoring Simulator purpose is to create a virtual space where the trained operators experience full radiation field conditions, without real radiation hazard. The ARMS is based on a flying platform and hence the simulator allows a significant reduction of flight time costs

  13. Teaching the Mantle Plumes Debate

    Science.gov (United States)

    Foulger, G. R.

    2010-12-01

    There is an ongoing debate regarding whether or not mantle plumes exist. This debate has highlighted a number of issues regarding how Earth science is currently practised, and how this feeds into approaches toward teaching students. The plume model is an hypothesis, not a proven fact. And yet many researchers assume a priori that plumes exist. This assumption feeds into teaching. That the plume model is unproven, and that many practising researchers are skeptical, may be at best only mentioned in passing to students, with most teachers assuming that plumes are proven to exist. There is typically little emphasis, in particular in undergraduate teaching, that the origin of melting anomalies is currently uncertain and that scientists do not know all the answers. Little encouragement is given to students to become involved in the debate and to consider the pros and cons for themselves. Typically teachers take the approach that “an answer” (or even “the answer”) must be taught to students. Such a pedagogic approach misses an excellent opportunity to allow students to participate in an important ongoing debate in Earth sciences. It also misses the opportunity to illustrate to students several critical aspects regarding correct application of the scientific method. The scientific method involves attempting to disprove hypotheses, not to prove them. A priori assumptions should be kept uppermost in mind and reconsidered at all stages. Multiple working hypotheses should be entertained. The predictions of a hypothesis should be tested, and unpredicted observations taken as weakening the original hypothesis. Hypotheses should not be endlessly adapted to fit unexpected observations. The difficulty with pedagogic treatment of the mantle plumes debate highlights a general uncertainty about how to teach issues in Earth science that are not yet resolved with certainty. It also represents a missed opportunity to let students experience how scientific theories evolve, warts

  14. Predicted and observed cooling tower plume rise and visible plume length at the John E. Amos power plant

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, S R

    1976-01-01

    A one-dimensional numerical cloud growth model and several empirical models for plume rise and cloud growth are compared with twenty-seven sets of observations of cooling tower plumes from the 2900 MW John E. Amos power plant in West Virginia. The three natural draft cooling towers are 200 m apart. In a cross wind, the plumes begin to merge at a distance of about 500 m downwind. In calm conditions, with reduced entrainment, the plumes often do not merge until heights of 1000 m. The average plume rise, 750 m, is predicted well by the models, but day-to-day variations are simulated with a correlation coefficient of about 0.5. Model predictions of visible plume length agree, on the average, with observations for visible plumes of short to moderate length (less than about 1 km). The prediction of longer plumes is hampered by our lack of knowledge of plume spreading after the plumes level off. Cloud water concentrations predicted by the numerical model agree with those measured in natural cumulus clouds (about 0.1 to 1 g kg/sup -1/).

  15. Simulating Fine-Scale Marine Pollution Plumes for Autonomous Robotic Environmental Monitoring

    Directory of Open Access Journals (Sweden)

    Muhammad Fahad

    2018-05-01

    Full Text Available Marine plumes exhibit characteristics such as intermittency, sinuous structure, shape and flow field coherency, and a time varying concentration profile. Due to the lack of experimental quantification of these characteristics for marine plumes, existing work often assumes marine plumes exhibit behavior similar to aerial plumes and are commonly modeled by filament based Lagrangian models. Our previous field experiments with Rhodamine dye plumes at Makai Research Pier at Oahu, Hawaii revealed that marine plumes show similar characteristics to aerial plumes qualitatively, but quantitatively they are disparate. Based on the field data collected, this paper presents a calibrated Eulerian plume model that exhibits the qualitative and quantitative characteristics exhibited by experimentally generated marine plumes. We propose a modified model with an intermittent source, and implement it in a Robot Operating System (ROS based simulator. Concentration time series of stationary sampling points and dynamic sampling points across cross-sections and plume fronts are collected and analyzed for statistical parameters of the simulated plume. These parameters are then compared with statistical parameters from experimentally generated plumes. The comparison validates that the simulated plumes exhibit fine-scale qualitative and quantitative characteristics similar to experimental plumes. The ROS plume simulator facilitates future evaluations of environmental monitoring strategies by marine robots, and is made available for community use.

  16. Comparison of in situ observations of air traffic emission signatures in the North Atlantic flight corridor with simulations using a Gaussian plume model

    Energy Technology Data Exchange (ETDEWEB)

    Konopka, P; Schlager, H; Schulte, P; Schumann, U; Ziereis, H [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Hagen, D; Whitefield, P [Missouri Univ., Rolla, MO (United States). Lab. for Cloud and Aerosol Science

    1998-12-31

    Focussed aircraft measurements including NO, NO{sub 2}, O{sub 3}, and aerosols (CN) have been carried out over the Eastern North Atlantic as part of the POLINAT (Pollution from Aircraft Emissions in the North Atlantic Flight Corridor) project to search for small and large scale signals of air traffic emissions in the corridor region. Here, the experimental data measured at cruising altitudes on November, 6, 1994 close to peak traffic hours are considered. Observed peak concentrations in small scale NO{sub x} spikes exceed background level of about 50 pptv by up to two orders of magnitude. The measured NO{sub x} concentration field is compared with simulations obtained with a plume dispersion model using collected air traffic data and wind measurements. Additionally, the measured and calculated NO/NO{sub x} ratios are considered. The comparison with the model shows that the observed (multiple-)peaks can be understood as a superposition of several aircraft plumes with ages up to 3 hours. (author) 12 refs.

  17. Comparison of in situ observations of air traffic emission signatures in the North Atlantic flight corridor with simulations using a Gaussian plume model

    Energy Technology Data Exchange (ETDEWEB)

    Konopka, P.; Schlager, H.; Schulte, P.; Schumann, U.; Ziereis, H. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Hagen, D.; Whitefield, P. [Missouri Univ., Rolla, MO (United States). Lab. for Cloud and Aerosol Science

    1997-12-31

    Focussed aircraft measurements including NO, NO{sub 2}, O{sub 3}, and aerosols (CN) have been carried out over the Eastern North Atlantic as part of the POLINAT (Pollution from Aircraft Emissions in the North Atlantic Flight Corridor) project to search for small and large scale signals of air traffic emissions in the corridor region. Here, the experimental data measured at cruising altitudes on November, 6, 1994 close to peak traffic hours are considered. Observed peak concentrations in small scale NO{sub x} spikes exceed background level of about 50 pptv by up to two orders of magnitude. The measured NO{sub x} concentration field is compared with simulations obtained with a plume dispersion model using collected air traffic data and wind measurements. Additionally, the measured and calculated NO/NO{sub x} ratios are considered. The comparison with the model shows that the observed (multiple-)peaks can be understood as a superposition of several aircraft plumes with ages up to 3 hours. (author) 12 refs.

  18. Influence of plume rise on the consequences of radioactive material releases

    International Nuclear Information System (INIS)

    Russo, A.J.; Wayland, J.R.; Ritchie, L.T.

    1977-01-01

    Estimates of health consequences resulting from a postulated nuclear reactor accident can be strongly dependent on the buoyant rise of the plume of released radioactive material. The sensitivity of the consequences of a postulated accident to two different plume rise models has been investigated. The results of these investigations are the subject of this report. One of the models includes the effects of emission angle, momentum, and radioactive heating of the released material. The difference in the consequence estimates from the two models can exceed an order of magnitude under some conditions, but in general the results are similar

  19. Comparison of the 1981 INEL dispersion data with results from a number of different models

    Energy Technology Data Exchange (ETDEWEB)

    Lewellen, W S; Sykes, R I; Parker, S F

    1985-05-01

    The results from simulations by 12 different dispersion models are compared with observations from an extensive field experiment conducted by the Nuclear Regulatory Commission at the Idaho National Engineering Laboratory in July, 1981. Comparisons were made on the bases of hourly SF/sub 6/ samples taken at the surface, out to approximately 10 km from the 46 m release tower, both during and following 7 different 8-hour releases. Comparisons are also made for total integrated doses collected out to approximately 40 km. Three classes of models are used. Within the limited range appropriate for Class A models this data comparison shows that neither the puff models or the transport and diffusion models agree with the data any better than the simple Gaussian plume models. The puff and transport and diffusion models do show a slight edge in performance in comparison with the total dose over the extended range approximate for class B models. The best model results for the hourly samples show approximately 40% calculated within a factor of two when a 15/sup 0/ uncertainty in plume position is permitted and it is assumed that higher data samples may occur at stations between the actual sample sites. This is increased to 60% for the 12 hour integrated dose and 70% for the total integrated dose when the same performance measure is used. None of the models reproduce the observed patchy dose patterns. This patchiness is consistent with the discussion of the inherent uncertainty associated with time averaged plume observations contained in our companion reports on the scientific critique of available models.

  20. Gaussian Plume Model Parameters for Ground-Level and Elevated Sources Derived from the Atmospheric Diffusion Equation in the Neutral and Stable Conditions

    International Nuclear Information System (INIS)

    Essa, K.S.M.

    2009-01-01

    The analytical solution of the atmospheric diffusion equation for a point source gives the ground-level concentration profiles. It depends on the wind speed ua nd vertical dispersion coefficient σ z expressed by Pasquill power laws. Both σ z and u are functions of downwind distance, stability and source elevation, while for the ground-level emission u is constant. In the neutral and stable conditions, the Gaussian plume model and finite difference numerical methods with wind speed in power law and the vertical dispersion coefficient in exponential law are estimated. This work shows that the estimated ground-level concentrations of the Gaussian model for high-level source and numerical finite difference method are very match fit to the observed ground-level concentrations of the Gaussian model

  1. New insights on entrainment and condensation in volcanic plumes: Constraints from independent observations of explosive eruptions and implications for assessing their impacts

    Science.gov (United States)

    Aubry, Thomas J.; Jellinek, A. Mark

    2018-05-01

    The turbulent entrainment of atmosphere and the condensation of water vapor govern the heights of explosive volcanic plumes. These processes thus determine the delivery and the lifetime of volcanic ash and aerosols into the atmosphere. Predictions of plume heights using one-dimensional "integral" models of volcanic plumes, however, suffer from very large uncertainties, related to parameterizations for entrainment and condensation. In particular, the wind entrainment coefficient β, which governs the contribution of crosswinds to turbulent entrainment, is subject to uncertainties of one order of magnitude, leading to relative uncertainties of the order of 50% on plume height. In this study, we use a database of 94 eruptive phases with independent estimates of mass eruption rate and plume height to constrain and evaluate four popular 1D models. We employ re-sampling methods to account for observational uncertainties. We show that plume height predictions are significantly improved when: i) the contribution of water vapor condensation to the plume buoyancy flux is excluded; and ii) the wind entrainment coefficient β is held constant between 0.1 and 0.4. We explore implications of these results for predicting the climate impacts of explosive eruptions and the likelihood that eruptions will form stable umbrella clouds or devastating pyroclastic flows. Last, we discuss the sensitivity of our results to the definition of plume height in the model in light of a recent set of laboratory experiments and draw conclusions for improving future databases of eruption parameters.

  2. Lévy-taxis: a novel search strategy for finding odor plumes in turbulent flow-dominated environments

    Science.gov (United States)

    Pasternak, Zohar; Bartumeus, Frederic; Grasso, Frank W.

    2009-10-01

    Locating chemical plumes in aquatic or terrestrial environments is important for many economic, conservation, security and health related human activities. The localization process is composed mainly of two phases: finding the chemical plume and then tracking it to its source. Plume tracking has been the subject of considerable study whereas plume finding has received little attention. We address here the latter issue, where the searching agent must find the plume in a region often many times larger than the plume and devoid of the relevant chemical cues. The probability of detecting the plume not only depends on the movements of the searching agent but also on the fluid mechanical regime, shaping plume intermittency in space and time; this is a basic, general problem when exploring for ephemeral resources (e.g. moving and/or concealing targets). Here we present a bio-inspired search strategy named Lévy-taxis that, under certain conditions, located odor plumes significantly faster and with a better success rate than other search strategies such as Lévy walks (LW), correlated random walks (CRW) and systematic zig-zag. These results are based on computer simulations which contain, for the first time ever, digitalized real-world water flow and chemical plume instead of their theoretical model approximations. Combining elements of LW and CRW, Lévy-taxis is particularly efficient for searching in flow-dominated environments: it adaptively controls the stochastic search pattern using environmental information (i.e. flow) that is available throughout the course of the search and shows correlation with the source providing the cues. This strategy finds natural application in real-world search missions, both by humans and autonomous robots, since it accomodates the stochastic nature of chemical mixing in turbulent flows. In addition, it may prove useful in the field of behavioral ecology, explaining and predicting the movement patterns of various animals searching for

  3. Levy-taxis: a novel search strategy for finding odor plumes in turbulent flow-dominated environments

    International Nuclear Information System (INIS)

    Pasternak, Zohar; Grasso, Frank W; Bartumeus, Frederic

    2009-01-01

    Locating chemical plumes in aquatic or terrestrial environments is important for many economic, conservation, security and health related human activities. The localization process is composed mainly of two phases: finding the chemical plume and then tracking it to its source. Plume tracking has been the subject of considerable study whereas plume finding has received little attention. We address here the latter issue, where the searching agent must find the plume in a region often many times larger than the plume and devoid of the relevant chemical cues. The probability of detecting the plume not only depends on the movements of the searching agent but also on the fluid mechanical regime, shaping plume intermittency in space and time; this is a basic, general problem when exploring for ephemeral resources (e.g. moving and/or concealing targets). Here we present a bio-inspired search strategy named Levy-taxis that, under certain conditions, located odor plumes significantly faster and with a better success rate than other search strategies such as Levy walks (LW), correlated random walks (CRW) and systematic zig-zag. These results are based on computer simulations which contain, for the first time ever, digitalized real-world water flow and chemical plume instead of their theoretical model approximations. Combining elements of LW and CRW, Levy-taxis is particularly efficient for searching in flow-dominated environments: it adaptively controls the stochastic search pattern using environmental information (i.e. flow) that is available throughout the course of the search and shows correlation with the source providing the cues. This strategy finds natural application in real-world search missions, both by humans and autonomous robots, since it accommodates the stochastic nature of chemical mixing in turbulent flows. In addition, it may prove useful in the field of behavioral ecology, explaining and predicting the movement patterns of various animals searching for food

  4. Levy-taxis: a novel search strategy for finding odor plumes in turbulent flow-dominated environments

    Energy Technology Data Exchange (ETDEWEB)

    Pasternak, Zohar; Grasso, Frank W [BioMimetic and Cognitive Robotics Laboratory, Department of Psychology, Brooklyn College, The City University of New York, 2900 Bedford Avenue, Brooklyn 11210, NY (United States); Bartumeus, Frederic [Department of Ecology and Evolutionary Biology and Princeton Environmental Institute, 106 Guyot Hall, Princeton University, Princeton 08544, NJ (United States)], E-mail: zpast@yahoo.com

    2009-10-30

    Locating chemical plumes in aquatic or terrestrial environments is important for many economic, conservation, security and health related human activities. The localization process is composed mainly of two phases: finding the chemical plume and then tracking it to its source. Plume tracking has been the subject of considerable study whereas plume finding has received little attention. We address here the latter issue, where the searching agent must find the plume in a region often many times larger than the plume and devoid of the relevant chemical cues. The probability of detecting the plume not only depends on the movements of the searching agent but also on the fluid mechanical regime, shaping plume intermittency in space and time; this is a basic, general problem when exploring for ephemeral resources (e.g. moving and/or concealing targets). Here we present a bio-inspired search strategy named Levy-taxis that, under certain conditions, located odor plumes significantly faster and with a better success rate than other search strategies such as Levy walks (LW), correlated random walks (CRW) and systematic zig-zag. These results are based on computer simulations which contain, for the first time ever, digitalized real-world water flow and chemical plume instead of their theoretical model approximations. Combining elements of LW and CRW, Levy-taxis is particularly efficient for searching in flow-dominated environments: it adaptively controls the stochastic search pattern using environmental information (i.e. flow) that is available throughout the course of the search and shows correlation with the source providing the cues. This strategy finds natural application in real-world search missions, both by humans and autonomous robots, since it accommodates the stochastic nature of chemical mixing in turbulent flows. In addition, it may prove useful in the field of behavioral ecology, explaining and predicting the movement patterns of various animals searching for food

  5. Seismic Evidence for Lower Mantle Plume Under the Yellowstone Hotspot

    Science.gov (United States)

    Nelson, P.; Grand, S.

    2017-12-01

    The mantle plume hypothesis for the origin of intraplate volcanism has been controversial since its inception in the 1970s. The hypothesis proposes hot narrow upwelling of rock rooted at the core mantle boundary (CMB) rise through the mantle and interact with the base of the lithosphere forming linear volcanic systems such as Hawaii and Yellowstone. Recently, broad lower mantle (>500 km in diameter) slow velocity conduits, most likely thermochemical in origin, have been associated with some intraplate volcanic provinces (French and Romanowicz, 2015). However, the direct detection of a classical thin thermal plume in the lower mantle using travel time tomography has remained elusive (Anderson and Natland, 2014). Here we present a new shear wave tomography model for the mantle beneath the western United States that is optimized to find short wavelength, sub-vertical structures in the lower mantle. Our approach uses carefully measured SKS and SKKS travel times recorded by dense North American seismic networks in conjunction with finite frequency kernels to build on existing tomography models. We find the presence of a narrow ( 300 km diameter) well isolated cylindrically shaped slow anomaly in the lower most mantle which we associate with the Yellowstone Hotspot. The conduit has a 2% reduction in shear velocity and is rooted at the CMB near the California/Arizona/Nevada border. A cross sectional view through the anomaly shows that it is slightly tilted toward the north until about 1300 km depth where it appears to weaken and deflect toward the surficial positon of the hotspot. Given the anomaly's strength, proximity to the Yellowstone Hotspot, and morphology we argue that a thermal plume interpretation is the most reasonable. Our results provide strong support for a lower mantle plume origin of the Yellowstone hotspot and more importantly the existence of deep thermal plumes.

  6. The 2016 Case for Mantle Plumes and a Plume-Fed Asthenosphere (Augustus Love Medal Lecture)

    Science.gov (United States)

    Morgan, Jason P.

    2016-04-01

    The process of science always returns to weighing evidence and arguments for and against a given hypothesis. As hypotheses can only be falsified, never universally proved, doubt and skepticism remain essential elements of the scientific method. In the past decade, even the hypothesis that mantle plumes exist as upwelling currents in the convecting mantle has been subject to intense scrutiny; from geochemists and geochronologists concerned that idealized plume models could not fit many details of their observations, and from seismologists concerned that mantle plumes can sometimes not be 'seen' in their increasingly high-resolution tomographic images of the mantle. In the place of mantle plumes, various locally specific and largely non-predictive hypotheses have been proposed to explain the origins of non-plate boundary volcanism at Hawaii, Samoa, etc. In my opinion, this debate has now passed from what was initially an extremely useful restorative from simply 'believing' in the idealized conventional mantle plume/hotspot scenario to becoming an active impediment to our community's ability to better understand the dynamics of the solid Earth. Having no working hypothesis at all is usually worse for making progress than having an imperfect and incomplete but partially correct one. There continues to be strong arguments and strong emerging evidence for deep mantle plumes. Furthermore, deep thermal plumes should exist in a mantle that is heated at its base, and the existence of Earth's (convective) geodynamo clearly indicates that heat flows from the core to heat the mantle's base. Here I review recent seismic evidence by French, Romanowicz, and coworkers that I feel lends strong new observational support for the existence of deep mantle plumes. I also review recent evidence consistent with the idea that secular core cooling replenishes half the mantle's heat loss through its top surface, e.g. that the present-day mantle is strongly bottom heated. Causes for

  7. Magnetotelluric Detection Thresholds as a Function of Leakage Plume Depth, TDS and Volume

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buscheck, T. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mansoor, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carroll, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-21

    We conducted a synthetic magnetotelluric (MT) data analysis to establish a set of specific thresholds of plume depth, TDS concentration and volume for detection of brine and CO2 leakage from legacy wells into shallow aquifers in support of Strategic Monitoring Subtask 4.1 of the US DOE National Risk Assessment Partnership (NRAP Phase II), which is to develop geophysical forward modeling tools. 900 synthetic MT data sets span 9 plume depths, 10 TDS concentrations and 10 plume volumes. The monitoring protocol consisted of 10 MT stations in a 2×5 grid laid out along the flow direction. We model the MT response in the audio frequency range of 1 Hz to 10 kHz with a 50 Ωm baseline resistivity and the maximum depth up to 2000 m. Scatter plots show the MT detection thresholds for a trio of plume depth, TDS concentration and volume. Plumes with a large volume and high TDS located at a shallow depth produce a strong MT signal. We demonstrate that the MT method with surface based sensors can detect a brine and CO2 plume so long as the plume depth, TDS concentration and volume are above the thresholds. However, it is unlikely to detect a plume at a depth larger than 1000 m with the change of TDS concentration smaller than 10%. Simulated aquifer impact data based on the Kimberlina site provides a more realistic view of the leakage plume distribution than rectangular synthetic plumes in this sensitivity study, and it will be used to estimate MT responses over simulated brine and CO2 plumes and to evaluate the leakage detectability. Integration of the simulated aquifer impact data and the MT method into the NRAP DREAM tool may provide an optimized MT survey configuration for MT data collection. This study presents a viable approach for sensitivity study of geophysical monitoring methods for leakage detection. The results come in handy for rapid assessment of leakage detectability.

  8. N Reactor thermal plume characterization during Pu-only mode of operation

    Energy Technology Data Exchange (ETDEWEB)

    Ecker, R.M.; Thompson, F.L.; Whelan, G.

    1983-04-01

    Pacific Northwest Laboratories (PNL) performed field and modeling studies -from March 1982 through June 1983 to characterize the thermal plume from the N Reactor heated water outfall while the N Reactor operated in the Pu-only mode. Part 1 of this report deals with the field studies conducted to characterize the N Reactor thermal plume while in the Pu-only mode of operation. It includes a description of the study area, a description of field tasks and procedures, and data collection results and discussion. Part 2 describes the computer simulation of the thermal plume under different flow conditions and the calibration of the model used. It includes a description of the computer model and the assumptions on which it is based, a presentation of the input data used in this application, and a discussion of modeling results. Because the field studies were restricted by the NPOES permit variance to the spring months when high Columbia River flows prevail the mathematical modeling of the N Reactor thermal plume while the reactor operates in the Pu-only mode is instrumental in characterizing the plume during low Columbia River flows.

  9. Mathematical and numerical modeling of the turbulent dispersion of reactive pollutant plumes; Modelacion matematica y numerica de la dispersion turbulenta de plumas de contaminantes reactivos

    Energy Technology Data Exchange (ETDEWEB)

    Rodas Grapain, Arturo

    1999-07-01

    One of the main problems involved in air quality models to calculate the pollutant concentration in a single point in the space and time, is the complexity of the numerical method. Even though the numerical methods are based on sophisticated and elaborated mathematics. They present two important and inevitable drawbacks: the stability of the numerical method. This means that its capacity to obtain reliable convergency in relation to the calculated values and real values is limited. The time and memory consumption. The high machine memory used to perform the numerical procedures and the time needed to prepare such procedures. Another problem is the mathematical basis of the structure of the air quality model. Commonly, simple models can perform quick estimations; however they are not exact contrary to the complex and elaborated models. In order to employ these complex models a high speed computer (workstations or Cray computer) is required. For this reason, this work presents a model approach with a relatively simple theoretical structure. The structure of this model named MOTTQUIP (modelo de transporte turbulento y quimica de plumas) can provide good results in point concentration operations. These results are compared with those obtained by two moderately complex mathematical models (Georgopoulos-Seinfeld and Lipphardt reactive plume models). The model developed in this work, shows a special feature where the solution of the differential equations are not involved explicitly. Therefore, it does not present the typical difficult in solving this kind of equations with the traditional numerical methods. [Spanish] Uno de los principales problemas que se presentan en los modelos de calidad del aire para el calculo de la concentracion de un cierto contaminante, para un punto dado en el espacio y en el tiempo, es la complejidad del metodo numerico involucrado para este fin, debido a que dichos metodos de calculo estan basados en matematicas sofisticadas y muy

  10. Measurements at cooling tower plumes. Pt. 1

    International Nuclear Information System (INIS)

    Gassmann, F.; Haschke, D.; Solfrian, W.

    1976-04-01

    Referring to the present status of knowledge model conceptions, assumptions and approaches are summarized, which can lead to mathematical models for the simulation of dry or wet cooling tower plumes. By developing a one-dimensional plume model (FOG) the most important problems are considered in detail. It is shown that for the calibration of the necessary parameters as well as for the development of models full scale measurements are of decisive importance. After a discussion of different possibilities of measurement the organisation of a campaign of measurement is described. (orig.) [de

  11. Engineering model cryocooler test results

    International Nuclear Information System (INIS)

    Skimko, M.A.; Stacy, W.D.; McCormick, J.A.

    1992-01-01

    This paper reports that recent testing of diaphragm-defined, Stirling-cycle machines and components has demonstrated cooling performance potential, validated the design code, and confirmed several critical operating characteristics. A breadboard cryocooler was rebuilt and tested from cryogenic to near-ambient cold end temperatures. There was a significant increase in capacity at cryogenic temperatures and the performance results compared will with code predictions at all temperatures. Further testing on a breadboard diaphragm compressor validated the calculated requirement for a minimum axial clearance between diaphragms and mating heads

  12. Advancing Land-Sea Conservation Planning: Integrating Modelling of Catchments, Land-Use Change, and River Plumes to Prioritise Catchment Management and Protection

    Science.gov (United States)

    Álvarez-Romero, Jorge G.; Pressey, Robert L.; Ban, Natalie C.; Brodie, Jon

    2015-01-01

    Human-induced changes to river loads of nutrients and sediments pose a significant threat to marine ecosystems. Ongoing land-use change can further increase these loads, and amplify the impacts of land-based threats on vulnerable marine ecosystems. Consequently, there is a need to assess these threats and prioritise actions to mitigate their impacts. A key question regarding prioritisation is whether actions in catchments to maintain coastal-marine water quality can be spatially congruent with actions for other management objectives, such as conserving terrestrial biodiversity. In selected catchments draining into the Gulf of California, Mexico, we employed Land Change Modeller to assess the vulnerability of areas with native vegetation to conversion into crops, pasture, and urban areas. We then used SedNet, a catchment modelling tool, to map the sources and estimate pollutant loads delivered to the Gulf by these catchments. Following these analyses, we used modelled river plumes to identify marine areas likely influenced by land-based pollutants. Finally, we prioritised areas for catchment management based on objectives for conservation of terrestrial biodiversity and objectives for water quality that recognised links between pollutant sources and affected marine areas. Our objectives for coastal-marine water quality were to reduce sediment and nutrient discharges from anthropic areas, and minimise future increases in coastal sedimentation and eutrophication. Our objectives for protection of terrestrial biodiversity covered species of vertebrates. We used Marxan, a conservation planning tool, to prioritise interventions and explore spatial differences in priorities for both objectives. Notable differences in the distributions of land values for terrestrial biodiversity and coastal-marine water quality indicated the likely need for trade-offs between catchment management objectives. However, there were priority areas that contributed to both sets of objectives. Our

  13. Advancing Land-Sea Conservation Planning: Integrating Modelling of Catchments, Land-Use Change, and River Plumes to Prioritise Catchment Management and Protection.

    Directory of Open Access Journals (Sweden)

    Jorge G Álvarez-Romero

    Full Text Available Human-induced changes to river loads of nutrients and sediments pose a significant threat to marine ecosystems. Ongoing land-use change can further increase these loads, and amplify the impacts of land-based threats on vulnerable marine ecosystems. Consequently, there is a need to assess these threats and prioritise actions to mitigate their impacts. A key question regarding prioritisation is whether actions in catchments to maintain coastal-marine water quality can be spatially congruent with actions for other management objectives, such as conserving terrestrial biodiversity. In selected catchments draining into the Gulf of California, Mexico, we employed Land Change Modeller to assess the vulnerability of areas with native vegetation to conversion into crops, pasture, and urban areas. We then used SedNet, a catchment modelling tool, to map the sources and estimate pollutant loads delivered to the Gulf by these catchments. Following these analyses, we used modelled river plumes to identify marine areas likely influenced by land-based pollutants. Finally, we prioritised areas for catchment management based on objectives for conservation of terrestrial biodiversity and objectives for water quality that recognised links between pollutant sources and affected marine areas. Our objectives for coastal-marine water quality were to reduce sediment and nutrient discharges from anthropic areas, and minimise future increases in coastal sedimentation and eutrophication. Our objectives for protection of terrestrial biodiversity covered species of vertebrates. We used Marxan, a conservation planning tool, to prioritise interventions and explore spatial differences in priorities for both objectives. Notable differences in the distributions of land values for terrestrial biodiversity and coastal-marine water quality indicated the likely need for trade-offs between catchment management objectives. However, there were priority areas that contributed to both

  14. Advancing Land-Sea Conservation Planning: Integrating Modelling of Catchments, Land-Use Change, and River Plumes to Prioritise Catchment Management and Protection.

    Science.gov (United States)

    Álvarez-Romero, Jorge G; Pressey, Robert L; Ban, Natalie C; Brodie, Jon

    2015-01-01

    Human-induced changes to river loads of nutrients and sediments pose a significant threat to marine ecosystems. Ongoing land-use change can further increase these loads, and amplify the impacts of land-based threats on vulnerable marine ecosystems. Consequently, there is a need to assess these threats and prioritise actions to mitigate their impacts. A key question regarding prioritisation is whether actions in catchments to maintain coastal-marine water quality can be spatially congruent with actions for other management objectives, such as conserving terrestrial biodiversity. In selected catchments draining into the Gulf of California, Mexico, we employed Land Change Modeller to assess the vulnerability of areas with native vegetation to conversion into crops, pasture, and urban areas. We then used SedNet, a catchment modelling tool, to map the sources and estimate pollutant loads delivered to the Gulf by these catchments. Following these analyses, we used modelled river plumes to identify marine areas likely influenced by land-based pollutants. Finally, we prioritised areas for catchment management based on objectives for conservation of terrestrial biodiversity and objectives for water quality that recognised links between pollutant sources and affected marine areas. Our objectives for coastal-marine water quality were to reduce sediment and nutrient discharges from anthropic areas, and minimise future increases in coastal sedimentation and eutrophication. Our objectives for protection of terrestrial biodiversity covered species of vertebrates. We used Marxan, a conservation planning tool, to prioritise interventions and explore spatial differences in priorities for both objectives. Notable differences in the distributions of land values for terrestrial biodiversity and coastal-marine water quality indicated the likely need for trade-offs between catchment management objectives. However, there were priority areas that contributed to both sets of objectives. Our

  15. Ozone Depletion in Tropospheric Volcanic Plumes: From Halogen-Poor to Halogen-Rich Emissions

    Directory of Open Access Journals (Sweden)

    Tjarda J. Roberts

    2018-02-01

    Full Text Available Volcanic halogen emissions to the troposphere undergo a rapid plume chemistry that destroys ozone. Quantifying the impact of volcanic halogens on tropospheric ozone is challenging, only a few observations exist. This study presents measurements of ozone in volcanic plumes from Kīlauea (HI, USA, a low halogen emitter. The results are combined with published data from high halogen emitters (Mt Etna, Italy; Mt Redoubt, AK, USA to identify controls on plume processes. Ozone was measured during periods of relatively sustained Kīlauea plume exposure, using an Aeroqual instrument deployed alongside Multi-Gas SO2 and H2S sensors. Interferences were accounted for in data post-processing. The volcanic H2S/SO2 molar ratio was quantified as 0.03. At Halema‘uma‘u crater-rim, ozone was close to ambient in the emission plume (at 10 ppmv SO2. Measurements in grounding plume (at 5 ppmv SO2 about 10 km downwind of Pu‘u ‘Ō‘ō showed just slight ozone depletion. These Kīlauea observations contrast with substantial ozone depletion reported at Mt Etna and Mt Redoubt. Analysis of the combined data from these three volcanoes identifies the emitted Br/S as a strong but non-linear control on the rate of ozone depletion. Model simulations of the volcanic plume chemistry highlight that the proportion of HBr converted into reactive bromine is a key control on the efficiency of ozone depletion. This underlines the importance of chemistry in the very near-source plume on the fate and atmospheric impacts of volcanic emissions to the troposphere.

  16. Io Pele plume

    Science.gov (United States)

    2000-01-01

    Voyager 1 took this narrow-angle camera image on 5 March 1979 from a distance of 450,000 kilometers. At this geometry, the camera looks straight down through a volcanic plume at one of Io's most active volcanos, Pele. The large heart-shaped feature is the region where Pele's plume falls to the surface. At the center of the 'heart' is the small dark fissure that is the source of the eruption. The Voyager Project is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science.

  17. Mantle plumes on Venus revisited

    Science.gov (United States)

    Kiefer, Walter S.

    1992-01-01

    The Equatorial Highlands of Venus consist of a series of quasicircular regions of high topography, rising up to about 5 km above the mean planetary radius. These highlands are strongly correlated with positive geoid anomalies, with a peak amplitude of 120 m at Atla Regio. Shield volcanism is observed at Beta, Eistla, Bell, and Atla Regiones and in the Hathor Mons-Innini Mons-Ushas Mons region of the southern hemisphere. Volcanos have also been mapped in Phoebe Regio and flood volcanism is observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in many of these regions. It is now widely accepted that at least Beta, Atla, Eistla, and Bell Regiones are the surface expressions of hot, rising mantel plumes. Upwelling plumes are consistent with both the volcanism and the extensional tectonism observed in these regions. The geoid anomalies and topography of these four regions show considerable variation. Peak geoid anomalies exceed 90 m at Beta and Atla, but are only 40 m at Eistla and 24 m at Bell. Similarly, the peak topography is greater at Beta and Atla than at Eistla and Bell. Such a range of values is not surprising because terrestrial hotspot swells also have a side range of geoid anomalies and topographic uplifts. Kiefer and Hager used cylindrical axisymmetric, steady-state convection calculations to show that mantle plumes can quantitatively account for both the amplitude and the shape of the long-wavelength geoid and topography at Beta and Atla. In these models, most of the topography of these highlands is due to uplift by the vertical normal stress associated with the rising plume. Additional topography may also be present due to crustal thickening by volcanism and crustal thinning by rifting. Smrekar and Phillips have also considered the geoid and topography of plumes on Venus, but they restricted themselves to considering only the geoid-topography ratio and did not

  18. FINAL TECHNICAL REPORT-THE ECOLOGY AND GENOMICS OF CO2 FIXATIION IN OCEANIC RIVER PLUMES

    Energy Technology Data Exchange (ETDEWEB)

    PAUL, JOHN H

    2013-06-21

    nutrient input. The offshore ORP was characterized by haptophyte and in places Prochlorococcus carbon fixation gene expression in surface water, with greater heterokont rbcL RNA at SCM depths. MODIS satellite chlorophyll-a data implied a plume of high chlorophyll water far into the eastern Caribbean, yet field observations did not support this, most likely because of high levels of colored dissolved organic matter (cDOM) in the ORP. The presence of pelagic nitrogen fixers (Trichodesmium and cyanobacterial diatom endosymbionts) most likely provided N for the offshore MRP production. The results underscore the importance of oceanic river plumes as sinks for CO2 and the need for their incorporation in global carbon models as well as estimates of CO2 sequestration.

  19. Dilution in Transition Zone between Rising Plumes and Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben

    2004-01-01

    The papers presents some physical experiments with the dilution of sea outfall plumes with emphasize on the transition zone where the relative fast flowing vertical plume turns to a horizontal surface plume following the slow sea surface currents. The experiments show that a considerable dilution...

  20. A buoyant plume adjacent to a headland-Observations of the Elwha River plume

    Science.gov (United States)

    Warrick, J.A.; Stevens, A.W.

    2011-01-01

    Small rivers commonly discharge into coastal settings with topographic complexities - such as headlands and islands - but these settings are underrepresented in river plume studies compared to more simplified, straight coasts. The Elwha River provides a unique opportunity to study the effects of coastal topography on a buoyant plume, because it discharges into the Strait of Juan de Fuca on the western side of its deltaic headland. Here we show that this headland induces flow separation and transient eddies in the tidally dominated currents (O(100. cm/s)), consistent with other headlands in oscillatory flow. These flow conditions are observed to strongly influence the buoyant river plume, as predicted by the "small-scale" or "narrow" dynamical classification using Garvine's (1995) system. Because of the transient eddies and the location of the river mouth on the headland, flow immediately offshore of the river mouth is directed eastward twice as frequently as it is westward. This results in a buoyant plume that is much more frequently "bent over" toward the east than the west. During bent over plume conditions, the plume was attached to the eastern shoreline while having a distinct, cuspate front along its westernmost boundary. The location of the front was found to be related to the magnitude and direction of local flow during the preceding O(1. h), and increases in alongshore flow resulted in deeper freshwater mixing, stronger baroclinic anomalies, and stronger hugging of the coast. During bent over plume conditions, we observed significant convergence of river plume water toward the frontal boundary within 1. km of the river mouth. These results show how coastal topography can strongly influence buoyant plume behavior, and they should assist with understanding of initial coastal sediment dispersal pathways from the Elwha River during a pending dam removal project. ?? 2010.

  1. On predicting mantle mushroom plumes

    Directory of Open Access Journals (Sweden)

    Ka-Kheng Tan

    2011-04-01

    Top cooling may produce plunging plumes of diameter of 585 km and at least 195 Myr old. The number of cold plumes is estimated to be 569, which has not been observed by seismic tomography or as cold spots. The cold plunging plumes may overwhelm and entrap some of the hot rising plumes from CMB, so that together they may settle in the transition zone.

  2. Turbulent buoyant jets and plumes

    CERN Document Server

    Rodi, Wolfgang

    The Science & Applications of Heat and Mass Transfer: Reports, Reviews, & Computer Programs, Volume 6: Turbulent Buoyant Jets and Plumes focuses on the formation, properties, characteristics, and reactions of turbulent jets and plumes. The selection first offers information on the mechanics of turbulent buoyant jets and plumes and turbulent buoyant jets in shallow fluid layers. Discussions focus on submerged buoyant jets into shallow fluid, horizontal surface or interface jets into shallow layers, fundamental considerations, and turbulent buoyant jets (forced plumes). The manuscript then exami

  3. Evaluating the quantity of native H2 in Enceladus' plumes with the Cassini-INMS closed source data: constraints from modeling of ice grains impact in the instrument

    Science.gov (United States)

    Bouquet, A.; Brockwell, T.; Waite, J. H., Jr.; Chocron, S.; Teolis, B. D.; Perryman, R.; Walker, J. D.

    2016-12-01

    The data from the closed source of the Cassini Ion and Neutral Mass Spectrometer (INMS) at Enceladus' plumes shows a signal of H2 in significant quantities (15% mole fraction for low speed flybys). H2 would be considered a "smoking gun" for the suspected hydrothermal activity in Enceladus' ocean. However the H2 quantity varies with the speed of the flyby, which is attributed to the presence of ice grains in the plumes hitting the walls of the titanium antechamber of INMS and exposing fresh titanium that may react with water to form hydrogen. The large number of small ice grains arriving during a single INMS integration period creates a back-ground signal in addition to large grains causing punctual spikes. We have developed a surface chemistry model of the INMS, taking into account adsorption and chemisorption of species of interest to determine how much H2 is produced from the expected ice grains distribution for each flyby (given by Cassini CAPS data ). CTH simulations have been used to assess the contribution of grains of different size in terms of titanium produced. We show that the spikes in the mass 2 channel can be explained by microns-sized grains, and that smaller grains (below 500 nm) are the major contributors to reactions with titanium, accounting for most of the non-spike signal. We find that the mass 2 background signal due to titanium is strongly driven by the water available, and therefore its shape versus time can't follow the sharp rises in the data (see Figure). This makes the structures seen in flyby E18 either the product of several big grains or the observation of locally high density of H2 (jets). We will analyze the effect of grains on other mass channels and comparison to CDA data to de-termine whether the peaks can be attributed to multiple ice grains or to native H2. The work will be extended to the E17 and E14 flybys to reach a definitive assessment of the native H2 abundance in the Enceladus plume.

  4. PLUME and research sotware

    Science.gov (United States)

    Baudin, Veronique; Gomez-Diaz, Teresa

    2013-04-01

    The PLUME open platform (https://www.projet-plume.org) has as first goal to share competences and to value the knowledge of software experts within the French higher education and research communities. The project proposes in its platform the access to more than 380 index cards describing useful and economic software for this community, with open access to everybody. The second goal of PLUME focuses on to improve the visibility of software produced by research laboratories within the higher education and research communities. The "development-ESR" index cards briefly describe the main features of the software, including references to research publications associated to it. The platform counts more than 300 cards describing research software, where 89 cards have an English version. In this talk we describe the theme classification and the taxonomy of the index cards and the evolution with new themes added to the project. We will also focus on the organisation of PLUME as an open project and its interests in the promotion of free/open source software from and for research, contributing to the creation of a community of shared knowledge.

  5. SAMI3 Simulations of the Persistent May 1994 Plasmasphere Plume

    Science.gov (United States)

    Krall, J.; Huba, J.; Borovsky, J.

    2017-12-01

    We use the Naval Research Laboratory SAMI3 ionosphere/plasmasphere model[1] to explore the physics of a long-lived plasmasphere plume. A plasmasphere plume is a storm feature that extends the cold plasma that is normally trapped by the geomagnetic field (the plasmasphere) outward towards the bow shock. In the case of the May 1994 storm, the storm and the plume continued for 12 days. For the model storm, we imposed a Kp-driven Volland/Stern-Maynard/Chen potential [2-4]. Results are compared to measurements of the cold ion density from the 1989-046 spacecraft in geosynchronous orbit [5]. We find that many details of the observed plume are reproduced by SAMI3, but only if a background magnetosphere density is included as a boundary condition. We also find that high-speed, field aligned plasma flows contribute significantly to the observed plume density. [1] Huba, J. and J. Krall (2013), Modeling the plasmasphere with SAMI3, Geophys. Res. Lett., 40, 6-10, doi:10.1029/2012GL054300 [2] Volland, H. (1973), A semiempirical model of large-scale magnetospheric electric fields, Journal of Geophysical Research, 78, 171-180, doi:10.1029/JA078i001p00171 [3] Stern, D.P. (1975), The motion of a proton in the equatorial magnetosphere, Journal of Geophysical Research, 80, 595-599, doi:10.1029/JA080i004p00595 [4] Maynard, N.C., and A.J. Chen (1975), Isolated cold plasma regions: Observations and their relation to possible production mechanisms, Journal of Geophysical Research, 80, 1009-1013, doi:10.1029/JA080i007p01009 [5] Borovsky, J.E., D.T. Welling, M.F. Thomsen, and M.H. Denton (2014), Long-lived plasmaspheric drainage plumes: Where does the plasma come from?, Journal of Geophysical Research: Space Physics, 119, 6496-6520, doi:10.1002/2014JA020228 Research supported by NRL base funds.

  6. Methane Emission Estimates from Landfills Obtained with Dynamic Plume Measurements

    International Nuclear Information System (INIS)

    Hensen, A.; Scharff, H.

    2001-01-01

    Methane emissions from 3 different landfills in the Netherlands were estimated using a mobile Tuneable Diode Laser system (TDL). The methane concentration in the cross section of the plume is measured downwind of the source on a transect perpendicular to the wind direction. A gaussian plume model was used to simulate the concentration levels at the transect. The emission from the source is calculated from the measured and modelled concentration levels.Calibration of the plume dispersion model is done using a tracer (N 2 O) that is released from the landfill and measured simultaneously with the TDL system. The emission estimates for the different locations ranged from 3.6 to 16 m 3 ha -1 hr -1 for the different sites. The emission levels were compared to emission estimates based on the landfill gas production models. This comparison suggests oxidation rates that are up to 50% in spring and negligible in November. At one of the three sites measurements were performed in campaigns in 3 consecutive years. Comparison of the emission levels in the first and second year showed a reduction of the methane emission of about 50% due to implementation of a gas extraction system. From the second to the third year emissions increased by a factor of 4 due to new land filling. Furthermore measurements were performed in winter when oxidation efficiency was reduced. This paper describes the measurement technique used, and discusses the results of the experimental sessions that were performed

  7. Dust Plume Modeling from Ranges and Maneuver Areas on Fort Bliss and the White Sands Missile Range: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Elaine G.; Barnard, James C.; Rutz, Frederick C.; Pekour, Mikhail S.; Rishel, Jeremy P.; Shaw, William J.

    2009-05-04

    The potential for air quality impacts from heavy mechanized vehicles operating on and between the unpaved main supply routes at Fort Bliss and White Sands Missile Range was investigated. This report details efforts by the staff of Pacific Northwest National Laboratory for the Fort Bliss Directorate of Environment in this investigation. Dust emission and dispersion from typical move-out activities occurring on the installations were simulated using the atmospheric modeling system DUSTRAN. Major assumptions associated with designing the modeling scenarios are summarized and results of simulations conducted under these assumptions are presented for four representative meteorological periods.

  8. Dispersion of Chernobyl radioactive plume over Europe

    International Nuclear Information System (INIS)

    Albergel, A.

    1988-01-01

    A long-range pollutant transport and removal model, is used to analyse the Chernobyl radioactive plume dispersion over the Europe Continent. Model predictions are compared to field measurements of Cs-137 activity in the air from April 26th, to May 5th 1986 [fr

  9. The timescales of plume generation caused by continental aggregation

    Science.gov (United States)

    Honda, Satoru; Yoshida, Masaki; Ootorii, Sakie; Iwase, Yasuyuki

    2000-02-01

    To understand the thermal evolution of the mantle following the aggregation of non-subductable thick continental lithosphere, we study a numerical model in which a supercontinent, simulated by high viscosity raft, HVR, covers a part of the top surface of a convection layer. We model infinite Prandtl number convection either in a three-dimensional (3D) spherical shell, 3D rectangular box (aspect ratios: 8 and 4) or two-dimensional (2D) rectangular box (aspect ratio: 8) and except for the HVR, we specify a constant viscosity. The HVR, which has a viscosity higher than that of its surrounding, is instantaneously placed on the top surface of a well-developed convection layer and its position is fixed. Our results from 3D spherical shell cases with and without phase transitions show the emergence of a large plume characterized by a long wavelength thermal anomaly (a degree one pattern) for a Pangea-like geometry. We analyze the volume averaged temperature under the HVR (=) the remaining (oceanic) area (=) and total area (=) to determine the timescale of plume generation. The difference between and (=Δ TCO) and show the existence of two characteristic timescales.Δ TCO exhibits an initial rapid increase and may become constant or continue to gradually increase. Meanwhile, shows a similar behavior but with a longer timescale. We find that these timescales associated with the increase of Δ TCO and can be attributed to the formation of large scale flow (i.e. plume) and response of the whole system to the emplacement of the HVR, respectively. For 3D spherical cases, we find that the timescale of plume generation is 1-2 Gyr, if the Rayleigh number is 10 6. To determine the effects of the viscosity of the HVR, 2D versus 3D modeling and the effects of the internal heating, we have also studied 2D and 3D rectangular box cases. A factor of about two variation exists in the timescale of plume generation. It appears that the timescale becomes greater for a smaller amount of

  10. Dynamics of the Sediment Plume Over the Yangtze Bank in the Yellow and East China Seas

    Science.gov (United States)

    Luo, Zhifa; Zhu, Jianrong; Wu, Hui; Li, Xiangyu

    2017-12-01

    A distinct sediment plume exists over the Yangtze Bank in the Yellow and East China Seas (YECS) in winter, but it disappears in summer. Based on satellite color images, there are two controversial viewpoints about the formation mechanism for the sediment plume. One viewpoint is that the sediment plume forms because of cross-shelf sediment advection of highly turbid water along the Jiangsu coast. The other viewpoint is that the formation is caused by local bottom sediment resuspension and diffused to the surface layer through vertical turbulent mixing. The dynamic mechanism of the sediment plume formation has been unclear until now. This issue was explored by using a numerical sediment model in the present paper. Observed wave, current, and sediment data from 29 December 2016 to 16 January 2017 were collected near the Jiangsu coast and used to validate the model. The results indicated that the model can reproduce the hydrodynamic and sediment processes. Numerical experiments showed that the bottom sediment could be suspended by the bottom shear stress and diffuse to the surface layer by vertical mixing in winter; however, the upward diffusion is restricted by the strong stratification in summer. The sediment plume is generated locally due to bottom sediment resuspension primarily via tide-induced bottom shear stress rather than by cross-shelf sediment advection over the Yangtze Bank.

  11. Three-dimensional simulation of gas and dust in Io's Pele plume

    Science.gov (United States)

    McDoniel, William J.; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence M.

    2015-09-01

    Io's giant Pele plume rises high above the moon's surface and produces a complex deposition pattern. We use the direct simulation Monte Carlo (DSMC) method to model the flow of SO2 gas and silicate ash from the surface of the lava lake, into the umbrella-shaped canopy of the plume, and eventually onto the surface where the flow leaves black "butterfly wings" surrounded by a large red ring. We show how the geometry of the lava lake, from which the gas is emitted, is responsible for significant asymmetry in the plume and for the shape of the red deposition ring by way of complicated gas-dynamic interactions between parts of the gas flow arising from different areas in the lava lake. We develop a model for gas flow in the immediate vicinity of the lava lake and use it to show that the behavior of ash particles of less than about 2 μm in diameter in the plume is insensitive to the details of how they are introduced into the flow because they are coupled to the gas at low altitudes. We simulate dust particles in the plume to show how particle size determines the distance from the lava lake at which particles deposit on the surface, and we use this dependence to find a size distribution of black dust particles in the plume that provides the best explanation for the observed black fans to the east and west of the lava lake. This best-fit particle size distribution suggests that there may be two distinct mechanisms of black dust creation at Pele, and when two log-normal distributions are fit to our results we obtain a mean particle diameter of 88 nm. We also propose a mechanism by which the condensible plume gas might overlay black dust in areas where black coloration is not observed and compare this to the observed overlaying of Pillanian dust by Pele's red ring.

  12. Experimental Investigation of Large-Scale Bubbly Plumes

    Energy Technology Data Exchange (ETDEWEB)

    Zboray, R.; Simiano, M.; De Cachard, F

    2004-03-01

    Carefully planned and instrumented experiments under well-defined boundary conditions have been carried out on large-scale, isothermal, bubbly plumes. The data obtained is meant to validate newly developed, high-resolution numerical tools for 3D transient, two-phase flow modelling. Several measurement techniques have been utilised to collect data from the experiments: particle image velocimetry, optical probes, electromagnetic probes, and visualisation. Bubble and liquid velocity fields, void-fraction distributions, bubble size and interfacial-area-concentration distributions have all been measured in the plume region, as well as recirculation velocities in the surrounding pool. The results obtained from the different measurement techniques have been compared. In general, the two-phase flow data obtained from the different techniques are found to be consistent, and of high enough quality for validating numerical simulation tools for 3D bubbly flows. (author)

  13. Experimental Investigation of Large-Scale Bubbly Plumes

    International Nuclear Information System (INIS)

    Zboray, R.; Simiano, M.; De Cachard, F.

    2004-01-01

    Carefully planned and instrumented experiments under well-defined boundary conditions have been carried out on large-scale, isothermal, bubbly plumes. The data obtained is meant to validate newly developed, high-resolution numerical tools for 3D transient, two-phase flow modelling. Several measurement techniques have been utilised to collect data from the experiments: particle image velocimetry, optical probes, electromagnetic probes, and visualisation. Bubble and liquid velocity fields, void-fraction distributions, bubble size and interfacial-area-concentration distributions have all been measured in the plume region, as well as recirculation velocities in the surrounding pool. The results obtained from the different measurement techniques have been compared. In general, the two-phase flow data obtained from the different techniques are found to be consistent, and of high enough quality for validating numerical simulation tools for 3D bubbly flows. (author)

  14. Ablation plume dynamics in a background gas

    DEFF Research Database (Denmark)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2010-01-01

    The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during the expa......The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during...... the expansion. The model also leads to an insightful treatment of the stopping behavior in dimensionless units for plumes and background gases of different atomic/molecular masses. The energetics of the plume dynamics can also be treated with this model. Experimental time-of-flight data of silver ions in a neon...... background gas show a fair agreement with predictions from the PM-model. Finally we discuss the validity of the model, if the work done by the pressure of the background gas is neglected....

  15. Non-equilibrium processes in ash-laden volcanic plumes: new insights from 3D multiphase flow simulations

    Science.gov (United States)

    Esposti Ongaro, Tomaso; Cerminara, Matteo

    2016-10-01

    In the framework of the IAVCEI (International Association of Volcanology and Chemistry of the Earth Interior) initiative on volcanic plume models intercomparison, we discuss three-dimensional numerical simulations performed with the multiphase flow model PDAC (Pyroclastic Dispersal Analysis Code). The model describes the dynamics of volcanic and atmospheric gases (in absence of wind) and two pyroclastic phases by adopting a non-equilibrium Eulerian-Eulerian formulation. Accordingly, gas and particulate phases are treated as interpenetrating fluids, interacting with each other through momentum (drag) and heat exchange. Numerical results describe the time-wise and spatial evolution of weak (mass eruption rate: 1.5 × 106 kg/s) and strong (mass eruption rate: 1.5 × 109 kg/s) plumes. The two tested cases display a remarkably different phenomenology, associated with the different roles of atmospheric stratification, compressibility and mechanism of buoyancy reversal, reflecting in a different structure of the plume, of the turbulent eddies and of the atmospheric circulation. This also brings about different rates of turbulent mixing and atmospheric air entrainment. The adopted multiphase flow model allows to quantify temperature and velocity differences between the gas and particles, including settling, preferential concentration by turbulence and thermal non-equilibrium, as a function of their Stokes number, i.e., the ratio between their kinetic equilibrium time and the characteristic large-eddy turnover time of the turbulent plume. As a result, the spatial and temporal distribution of coarse ash in the atmosphere significantly differs from that of the fine ash, leading to a modification of the plume shape. Finally, three-dimensional numerical results have been averaged in time and across horizontal slices in order to obtain a one-dimensional picture of the plume in a stationary regime. For the weak plume, the results are consistent with one-dimensional models, at

  16. Plume dispersion from the MVP field experiment. Analysis of surface concentration and its fluctuations

    Science.gov (United States)

    Ma, Yimin; Boybeyi, Zafer; Hanna, Steven; Chayantrakom, Kittisak

    Surface concentration and its fluctuations from plume dispersion under unstable conditions in a coastal environment are investigated using the model validation program field experimental data. The goal of this study is to better understand plume dispersion under such conditions. Procedures are described to derive the plume surface concentration from moving vehicle measurements. Convective boundary layer scalings are applied and cumulative density functions (CDF) are studied. The results indicate that the relative concentration fluctuation intensity ( σc/C(y)) decreases with the normalized downwind distance ( X) and that it is relatively small at the plume central line and largely increased at the plume edges, consistent with other field and laboratory results. The relation between σc/C(y) at the plume centerline ( σc/C) and X for elevated sources can be described by σc/C=a+b/X. The crosswind plume spread ( σy) is found to satisfy Deardorff and Willis's (J. Appl. Meteorol., 14 (1975) 1451) form of σy/h=a1X/(1+a2X) scaled with convective layer depth h. For elevated sources, the normalized crosswind integrated concentration ( Cy) is found to satisfy a relation of Cy=16X, with Yaglom's (Izr. Atmos. Oceanic Phys., 8 (1972) 333) scaling rule on the free convective layer being applied. Empirical CDFs based on the gamma and the clipped probability density functions show agreements with the experimental CDFs, with the former being better than the latter when (c-C)/σc>0.5. A new clipped-gamma CDF form is proposed based on the analysis of the present data, showing a better agreement. We suggest that a parameter u0*(12-0.5h/L), with combined efforts of surface friction velocity ( u0*), Monin-Obukhov stability length ( L) and unstable boundary layer height ( h), replace the convective velocity scale ( w*) under weak convective conditions in a coastal environment.

  17. Inhomogeneous distribution of Chlamydomonas in a cylindrical container with a bubble plume

    Science.gov (United States)

    Nonaka, Yuki; Kikuchi, Kenji; Numayama-Tsuruta, Keiko; Kage, Azusa; Ueno, Hironori; Ishikawa, Takuji

    2016-01-01

    ABSTRACT Swimming microalgae show various taxes, such as phototaxis and gravitaxis, which sometimes result in the formation of a cell-rich layer or a patch in a suspension. Despite intensive studies on the effects of shear flow and turbulence on the inhomogeneous distribution of microalgae, the effect of a bubble plume has remained unclear. In this study, we used Chlamydomonas as model microalgae, and investigated the spatial distribution of cells in a cylindrical container with a bubble plume. The results illustrate that cells become inhomogeneously distributed in the suspension due to their motility and photo-responses. A vortical ring distribution was observed below the free surface when the bubble flow rate was sufficiently small. We performed a scaling analysis on the length scale of the vortical ring, which captured the main features of the experimental results. These findings are important in understanding transport phenomena in a microalgae suspension with a bubble plume. PMID:26787679

  18. Simulating Irregular Source Geometries for Ionian Plumes

    Science.gov (United States)

    McDoniel, W. J.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.; Buchta, D. A.; Freund, J.; Kieffer, S. W.

    2011-05-01

    Volcanic plumes on Io respresent a complex rarefied flow into a near-vacuum in the presence of gravity. A 3D Direct Simulation Monte Carlo (DSMC) method is used to investigate the gas dynamics of such plumes, with a focus on the effects of source geometry on far-field deposition patterns. A rectangular slit and a semicircular half annulus are simulated to illustrate general principles, especially the effects of vent curvature on deposition ring structure. Then two possible models for the giant plume Pele are presented. One is a curved line source corresponding to an IR image of a particularly hot region in the volcano's caldera and the other is a large area source corresponding to the entire caldera. The former is seen to produce the features seen in observations of Pele's ring, but with an error in orientation. The latter corrects the error in orientation, but loses some structure. A hybrid simulation of 3D slit flow is also discussed.

  19. Simulating Irregular Source Geometries for Ionian Plumes

    International Nuclear Information System (INIS)

    McDoniel, W. J.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.; Buchta, D. A.; Freund, J.; Kieffer, S. W.

    2011-01-01

    Volcanic plumes on Io respresent a complex rarefied flow into a near-vacuum in the presence of gravity. A 3D Direct Simulation Monte Carlo (DSMC) method is used to investigate the gas dynamics of such plumes, with a focus on the effects of source geometry on far-field deposition patterns. A rectangular slit and a semicircular half annulus are simulated to illustrate general principles, especially the effects of vent curvature on deposition ring structure. Then two possible models for the giant plume Pele are presented. One is a curved line source corresponding to an IR image of a particularly hot region in the volcano's caldera and the other is a large area source corresponding to the entire caldera. The former is seen to produce the features seen in observations of Pele's ring, but with an error in orientation. The latter corrects the error in orientation, but loses some structure. A hybrid simulation of 3D slit flow is also discussed.

  20. Study of Plume Impingement Effects in the Lunar Lander Environment

    Science.gov (United States)

    Marichalar, Jeremiah; Prisbell, A.; Lumpkin, F.; LeBeau, G.

    2010-01-01

    Plume impingement effects from the descent and ascent engine firings of the Lunar Lander were analyzed in support of the Lunar Architecture Team under the Constellation Program. The descent stage analysis was performed to obtain shear and pressure forces on the lunar surface as well as velocity and density profiles in the flow field in an effort to understand lunar soil erosion and ejected soil impact damage which was analyzed as part of a separate study. A CFD/DSMC decoupled methodology was used with the Bird continuum breakdown parameter to distinguish the continuum flow from the rarefied flow. The ascent stage analysis was performed to ascertain the forces and moments acting on the Lunar Lander Ascent Module due to the firing of the main engine on take-off. The Reacting and Multiphase Program (RAMP) method of characteristics (MOC) code was used to model the continuum region of the nozzle plume, and the Direct Simulation Monte Carlo (DSMC) Analysis Code (DAC) was used to model the impingement results in the rarefied region. The ascent module (AM) was analyzed for various pitch and yaw rotations and for various heights in relation to the descent module (DM). For the ascent stage analysis, the plume inflow boundary was located near the nozzle exit plane in a region where the flow number density was large enough to make the DSMC solution computationally expensive. Therefore, a scaling coefficient was used to make the DSMC solution more computationally manageable. An analysis of the effectiveness of this scaling technique was performed by investigating various scaling parameters for a single height and rotation of the AM. Because the inflow boundary was near the nozzle exit plane, another analysis was performed investigating three different inflow contours to determine the effects of the flow expansion around the nozzle lip on the final plume impingement results.

  1. Linking lowermost mantle structure, core-mantle boundary heat flux and mantle plume formation

    Science.gov (United States)

    Li, Mingming; Zhong, Shijie; Olson, Peter

    2018-04-01

    The dynamics of Earth's lowermost mantle exert significant control on the formation of mantle plumes and the core-mantle boundary (CMB) heat flux. However, it is not clear if and how the variation of CMB heat flux and mantle plume activity are related. Here, we perform geodynamic model experiments that show how temporal variations in CMB heat flux and pulses of mantle plumes are related to morphologic changes of the thermochemical piles of large-scale compositional heterogeneities in Earth's lowermost mantle, represented by the large low shear velocity provinces (LLSVPs). We find good correlation between the morphologic changes of the thermochemical piles and the time variation of CMB heat flux. The morphology of the thermochemical piles is significantly altered during the initiation and ascent of strong mantle plumes, and the changes in pile morphology cause variations in the local and the total CMB heat flux. Our modeling results indicate that plume-induced episodic variations of CMB heat flux link geomagnetic superchrons to pulses of surface volcanism, although the relative timing of these two phenomena remains problematic. We also find that the density distribution in thermochemical piles is heterogeneous, and that the piles are denser on average than the surrounding mantle when both thermal and chemical effects are included.

  2. Buoyant plumes from solute gradients generated by non-motile Escherichia coli

    International Nuclear Information System (INIS)

    Benoit, M R; Brown, R B; Todd, P; Klaus, D M; Nelson, E S

    2008-01-01

    The effect of hydrodynamic mixing in bacterial populations due to bacterial chemotaxis is a well-described phenomenon known as bioconvection. Here we report the observation of buoyant plumes that result in hydrodynamic mixing, but in contrast to bioconvection the plumes form in the absence of bacterial motility. We propose that the buoyant flow originates from solute gradients created by bacterial metabolism, similar to solute-induced buoyant flow around growing protein crystals. In our experiments, metabolically-active non-motile Escherichia coli were layered along the bottom of flat-bottomed containers. The E. coli consumed glucose in the medium creating a lighter fluid beneath a heavier fluid. The situation is an example of Rayleigh–Taylor instability, in which a lighter fluid pushes on a heavier one. We developed a numerical model to study the effect of E. coli nutrient consumption and by-product excretion on extracellular solute gradients. The model solutions showed reduced-density fluid along the bottom of the fluid domain leading to buoyant plumes, which were qualitatively similar to the experimental plumes. We also used scaling analyses to study the dependence of plume formation on container size and cell size, and to investigate the effect of reduced gravity, such as the microgravity conditions encountered during spaceflight

  3. The Ensemble Kalman Filter for Groundwater Plume Characterization: A Case Study.

    Science.gov (United States)

    Ross, James L; Andersen, Peter F

    2018-04-17

    The Kalman filter is an efficient data assimilation tool to refine an estimate of a state variable using measured data and the variable's correlations in space and/or time. The ensemble Kalman filter (EnKF) (Evensen, 2004, 2009) is a Kalman filter variant that employs Monte Carlo analysis to define the correlations that help to refine the updated state. While use of EnKF in hydrology is somewhat limited, it has been successfully applied in other fields of engineering (e.g. oil reservoir modeling, weather forecasting). Here, EnKF is used to refine a simulated groundwater TCE plume that underlies the Tooele Army Depot-North (TEAD-N) in Utah, based on observations of TCE in the aquifer. The resulting EnKF-based assimilated plume is simulated forward in time to predict future plume migration. The correlations that underpin EnKF updating implicitly contain information about how the plume developed over time under the influence of complex site hydrology and variable source history, as they are predicated on multiple realizations of a well-calibrated numerical groundwater flow and transport model. The EnKF methodology is compared to an ordinary kriging-based assimilation method with respect to the accurate representation of plume concentrations in order to determine the relative efficacy of EnKF for water quality data assimilation. This article is protected by copyright. All rights reserved.

  4. Plume rise from stacks with scrubbers: a state-of-the-art review

    International Nuclear Information System (INIS)

    Schatzmann, M.; Policastro, A.J.

    1984-01-01

    The state of the art of predicting plume rise from stacks with scrubbers is evaluated critically. The significant moisture content of the scrubbed plume upon exit leads to important thermodynamic effects during plume rise that are unaccounted for in the usual dry plume rise theories. For example, under conditionally unstable atmospheres, a wet scrubbed plume treated as completely dry acts as if the atmosphere were stable, whereas in reality the scrubbed plume behaves instead as if the atmosphere were unstable. Even the use of moist plume models developed for application to cooling tower plume rise is not valid since these models 1) employ the Boussinesq approximation, 2) use a number of additional simplifying approximations that require small exit temperature differences between tower exit and ambient temperatures, and 3) are not calibrated to stack data

  5. Preliminary Modelling of the Effect of Impurity in CO2 Streams on the Storage Capacity and the Plume Migration in Pohang Basin, Korea

    Science.gov (United States)

    Park, Yongchan; Choi, Byoungyoung; Shinn, Youngjae

    2015-04-01

    Captured CO2 streams contain various levels of impurities which vary depending on the combustion technology and CO2 sources such as a power plant and iron and steel production processes. Common impurities or contaminants are non-condensable gases like nitrogen, oxygen and hydrogen, and are also air pollutants like sulphur and nitrogen oxides. Specifically for geological storage, the non-condensable gases in CO2 streams are not favourable because they can decrease density of the injected CO2 stream and can affect buoyancy of the plume. However, separation of these impurities to obtain the CO2 purity higher than 99% would greatly increase the cost of capture. In 2010, the Korean Government announced a national framework to develop CCS, with the aim of developing two large scale integrated CCS projects by 2020. In order to achieve this goal, a small scale injection project into Pohang basin near shoreline has begun which is seeking the connection with a capture project, especially at a steel company. Any onshore sites that are suitable for the geological storage are not identified by this time so we turned to the shallow offshore Pohang basin where is close to a large-scale CO2 source. Currently, detailed site surveys are being undertaken and the collected data were used to establish a geological model of the basin. In this study, we performed preliminary modelling study on the effect of impurities on the geological storage using the geological model. Using a potential compositions of impurities in CO2 streams from the steel company, we firstly calculated density and viscosity of CO2 streams as a function of various pressure and temperature conditions with CMG-WINPROP and then investigated the effect of the non-condensable gases on storage capacity, injectivity and plume migrations with CMG-GEM. Further simulations to evaluate the areal and vertical sweep efficiencies by impurities were perform in a 2D vertical cross section as well as in a 3D simulation grid. Also

  6. Evaluation of plume potential and plume abatement of evaporative cooling towers in a subtropical region

    International Nuclear Information System (INIS)

    Xu Xinhua; Wang Shengwei; Ma Zhenjun

    2008-01-01

    Hong Kong is a typical subtropical region with frequently high humidity in late spring and summer seasons. Plume from evaporative cooling towers, which service air-conditioning systems of civil buildings, has aroused public concerns since 2000 when the fresh water evaporative cooling towers were allowed to be used for high energy efficiency and environmental issues. This paper presents the evaluation of the plume potential and its effect on the sizing of the plume abatement system in a large commercial office building in Hong Kong for practical application. This evaluation was conducted based on a dynamic simulation platform using the typical meteorological year of Hong Kong since the occurrence of the plume heavily depends on the state conditions of the exhaust air from cooling towers and the ambient air, while the state condition of the exhaust air is determined by the total building cooling load and the control strategies of cooling towers employed mainly for improving energy efficiency. The results show that the control strategies have a significant effect on the plume potential and further affect the system design and sizing of the plume abatement system

  7. Thermal plumes in ventilated rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    1990-01-01

    The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects. Free...... above a point heat source cannot be used. This is caused either by the way of generating the plume including a long intermediate region or by the environmental conditions where vertical temperature gradients are present. The flow has a larger angle of spread and the entrainment factor is greather than...... turbulent plumes from different heated bodies are investigated. The measurements have taken place in a full-scale test room where the vertical temperature gradient have been changed. The velocity and the temperature distribution in the plume are measured. Large scale plume axis wandering is taken...

  8. Thermal History of CBb Chondrules and Cooling Rate Distributions of Ejecta Plumes

    Science.gov (United States)

    Hewins, R. H.; Condie, C.; Morris, M.; Richardson, M. L. A.; Ouellette, N.; Metcalf, M.

    2018-03-01

    It has been proposed that some meteorites, CB and CH chondrites, contain material formed as a result of a protoplanetary collision during accretion. Their melt droplets (chondrules) and FeNi metal are proposed to have formed by evaporation and condensation in the resulting impact plume. We observe that the skeletal olivine (SO) chondrules in CBb chondrites have a blebby texture and an enrichment in refractory elements not found in normal chondrules. Because the texture requires complete melting, their maximum liquidus temperature of 1928 K represents a minimum temperature for the putative plume. Dynamic crystallization experiments show that the SO texture can be created only by brief reheating episodes during crystallization, giving a partial dissolution of olivine. The ejecta plume formed in a smoothed particle hydrodynamics simulation served as the basis for 3D modeling with the adaptive mesh refinement code FLASH4.3. Tracer particles that move with the fluid cells are used to measure the in situ cooling rates. Their cooling rates are ∼10,000 K hr‑1 briefly at peak temperature and, in the densest regions of the plume, ∼100 K hr‑1 for 1400–1600 K. A small fraction of cells is seen to be heating at any one time, with heating spikes explained by the compression of parcels of gas in a heterogeneous patchy plume. These temperature fluctuations are comparable to those required in crystallization experiments. For the first time, we find an agreement between experiments and models that supports the plume model specifically for the formation of CBb chondrules.

  9. Identifying the European fossil fuel plumes in the atmosphere over the Northeast Atlantic Region through isotopic observations and numerical modelling

    DEFF Research Database (Denmark)

    Geels, C.; Christensen, J.H.; Hansen, A.W.

    2006-01-01

    Atmospheric transport, C-14. fossil fuel CO_2, numerical modeling, the north East Atlantic Region Udgivelsesdato: 18 August......Atmospheric transport, C-14. fossil fuel CO_2, numerical modeling, the north East Atlantic Region Udgivelsesdato: 18 August...

  10. Observation of the volcanic plume of Eyjafjallajoekull over continental Europe by MAX-DOAS

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, S.; Bobrowski, N.; Friess, U.; Platt, U. [IUP, University of Heidelberg (Germany); Flentje, H. [DWD, Hohenpeissenberg (Germany); Hoermann, C.; Sihler, H. [IUP, University of Heidelberg (Germany); MPI, Mainz (Germany); Kern, C. [USGS, Vancouver (Canada); Wagner, T. [MPI, Mainz (Germany)

    2011-07-01

    The recent eruption of Eyjafjallajoekull Volcano (Iceland) and the emitted ash plume which disrupted commercial air traffic over Europe has led to an exhaustive debate on how to improve our ability to quantitatively determine the ash load in the atmosphere as a function of time and geographical location. Satellite instruments detecting ash and SO{sub 2} and ground-based LIDAR stations can help constrain atmospheric transport and meteorology models used to predict ash dispersion. However, MAX-DOAS represents an additional tool with considerable potential for the quantitative detection of elevated volcanic ash and SO{sub 2} plumes. It performs especially well during weather conditions in which satellites and LIDARs are impeded in their effectiveness, e.g. in the case of dense clouds above or below the plume, respectively. Here, the advantages and disadvantages of the DOAS technique are discussed, and its potential for monitoring of volcanic ash hazards explored. Results of ash and SO{sub 2} measurements of the Eyjafjallajoekull plume as it passed over Heidelberg are presented as an example of a positive detection of a highly diluted volcanic plume. Their low cost and complementary nature makes MAX-DOAS a promising technology in the field of aviation hazard detection and management.

  11. Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

    Directory of Open Access Journals (Sweden)

    E. Real

    2008-12-01

    Full Text Available The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O3 production is estimated to be −5 ppbv/day leading to low O3 by the time the plume reached Europe. Model runs with no wet deposition of HNO3 predicted much lower average net destruction of −1 ppbv/day O3, arising from increased levels of NOx via photolysis of HNO3. This indicates that wet deposition of HNO3 is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with O3 concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O3/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O3 production as is often assumed.

  12. Results of the naive quark model

    International Nuclear Information System (INIS)

    Gignoux, C.

    1987-10-01

    The hypotheses and limits of the naive quark model are recalled and results on nucleon-nucleon scattering and possible multiquark states are presented. Results show that with this model, ropers do not come. For hadron-hadron interactions, the model predicts Van der Waals forces that the resonance group method does not allow. Known many-body forces are not found in the model. The lack of mesons shows up in the absence of a far reaching force. However, the model does have strengths. It is free from spuriousness of center of mass, and allows a democratic handling of flavor. It has few parameters, and its predictions are very good [fr

  13. River plume patterns and dynamics within the Southern California Bight

    Science.gov (United States)

    Warrick, J.A.; DiGiacomo, P.M.; Weisberg, S.B.; Nezlin, N.P.; Mengel, M.; Jones, B.H.; Ohlmann, J.C.; Washburn, L.; Terrill, E.J.; Farnsworth, K.L.

    2007-01-01

    Stormwater river plumes are important vectors of marine contaminants and pathogens in the Southern California Bight. Here we report the results of a multi-institution investigation of the river plumes across eight major river systems of southern California. We use in situ water samples from multi-day cruises in combination with MODIS satellite remote sensing, buoy meteorological observations, drifters, and HF radar current measurements to evaluate the dispersal patterns and dynamics of the freshwater plumes. River discharge was exceptionally episodic, and the majority of storm discharge occurred in a few hours. The combined plume observing techniques revealed that plumes commonly detach from the coast and turn to the left, which is the opposite direction of Coriolis influence. Although initial offshore velocity of the buoyant plumes was ∼50 cm/s and was influenced by river discharge inertia (i.e., the direct momentum of the river flux) and buoyancy, subsequent advection of the plumes was largely observed in an alongshore direction and dominated by local winds. Due to the multiple day upwelling wind conditions that commonly follow discharge events, plumes were observed to flow from their respective river mouths to down-coast waters at rates of 20–40 km/d. Lastly, we note that suspended-sediment concentration and beam-attenuation were poorly correlated with plume salinity across and within the sampled plumes (mean r2=0.12 and 0.25, respectively), while colored dissolved organic matter (CDOM) fluorescence was well correlated (mean r2=0.56), suggesting that CDOM may serve as a good tracer of the discharged freshwater in subsequent remote sensing and monitoring efforts of plumes.

  14. A study of space shuttle plumes in the lower thermosphere

    Science.gov (United States)

    Meier, R. R.; Stevens, Michael H.; Plane, John M. C.; Emmert, J. T.; Crowley, G.; Azeem, I.; Paxton, L. J.; Christensen, A. B.

    2011-12-01

    During the space shuttle main engine burn, some 350 t of water vapor are deposited at between 100 and 115 km. Subsequent photodissociation of water produces large plumes of atomic hydrogen that can expand rapidly and extend for thousands of kilometers. From 2002 to 2007, the Global Ultraviolet Imager (GUVI) on NASA's Thermosphere Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) satellite imaged many of these hydrogen plumes at Lyman α (121.567 nm) while viewing in the nadir. The images reveal rapid plume expansion and occasional very fast transport to both north and south polar regions. Some plumes persist for up to 6 d. Near-simultaneous direct detections of water vapor were made with the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) instrument, also on TIMED. We compare the spreading of the hydrogen plume with a two-dimensional model that includes photodissociation as well as both vertical and horizontal diffusion. Molecular diffusion appears to be sufficient to account for the horizontal expansion, although wind shears and turbulent mixing may also contribute. We compare the bulk motion of the observed plumes with wind climatologies derived from satellite observations. The plumes can move much faster than predictions of wind climatologies. But dynamical processes not contained in wind climatologies, such as the quasi-two-day wave, can account for at least some of the high speed observations. The plume phenomena raise a number of important questions about lower thermospheric and mesospheric processes, ranging from dynamics and chemistry to polar mesospheric cloud formation and climatology.

  15. A new tectono-magmatic model for the Lofoten/Vesterålen Margin at the outer limit of the Iceland Plume influence

    Science.gov (United States)

    Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R.; Murai, Yoshio

    2017-10-01

    The Early Eocene continental breakup was magma-rich and formed part of the North Atlantic Igneous Province. Extrusive and intrusive magmatism was abundant on the continental side, and a thick oceanic crust was produced up to a few m.y. after breakup. However, the extensive magmatism at the Vøring Plateau off mid-Norway died down rapidly northeastwards towards the Lofoten/Vesterålen Margin. In 2003 an Ocean Bottom Seismometer profile was collected from mainland Norway, across Lofoten, and into the deep ocean. Forward/inverse velocity modeling by raytracing reveals a continental margin transitional between magma-rich and magma-poor rifting. For the first time a distinct lower-crustal body typical for volcanic margins has been identified at this outer margin segment, up to 3.5 km thick and ∼50 km wide. On the other hand, expected extrusive magmatism could not be clearly identified here. Strong reflections earlier interpreted as the top of extensive lavas may at least partly represent high-velocity sediments derived from the shelf, and/or fault surfaces. Early post-breakup oceanic crust is moderately thickened (∼8 km), but is reduced to 6 km after 1 m.y. The adjacent continental crystalline crust is extended down to a minimum of 4.5 km thickness. Early plate spreading rates derived from the Norway Basin and the northern Vøring Plateau were used to calculate synthetic magnetic seafloor anomalies, and compared to our ship magnetic profile. It appears that continental breakup took place at ∼53.1 Ma, ∼1 m.y. later than on the Vøring Plateau, consistent with late strong crustal extension. The low interaction between extension and magmatism indicates that mantle plume material was not present at the Lofoten Margin during initial rifting, and that the observed excess magmatism was created by late lateral transport from a nearby pool of plume material into the lithospheric rift zone at breakup time.

  16. Hot rocket plume experiment - Survey and conceptual design. [of rhenium-iridium bipropellants

    Science.gov (United States)

    Millard, Jerry M.; Luan, Taylor W.; Dowdy, Mack W.

    1992-01-01

    Attention is given to a space-borne engine plume experiment study to fly an experiment which will both verify and quantify the reduced contamination from advanced rhenium-iridium earth-storable bipropellant rockets (hot rockets) and provide a correlation between high-fidelity, in-space measurements and theoretical plume and surface contamination models. The experiment conceptual design is based on survey results from plume and contamination technologists throughout the U.S. With respect to shuttle use, cursory investigations validate Hitchhiker availability and adaptability, adequate remote manipulator system (RMS) articulation and dynamic capability, acceptable RMS attachment capability, adequate power and telemetry capability, and adequate flight altitude and attitude/orbital capability.

  17. Numerical simulation of helicopter engine plume in forward flight

    Science.gov (United States)

    Dimanlig, Arsenio C. B.; Vandam, Cornelis P.; Duque, Earl P. N.

    1994-01-01

    Flowfields around helicopters contain complex flow features such as large separated flow regions, vortices, shear layers, blown and suction surfaces and an inherently unsteady flow imposed by the rotor system. Another complicated feature of helicopters is their infrared signature. Typically, the aircraft's exhaust plume interacts with the rotor downwash, the fuselage's complicated flowfield, and the fuselage itself giving each aircraft a unique IR signature at given flight conditions. The goal of this project was to compute the flow about a realistic helicopter fuselage including the interaction of the engine air intakes and exhaust plume. The computations solve the Think-Layer Navier Stokes equations using overset type grids and in particular use the OVERFLOW code by Buning of NASA Ames. During this three month effort, an existing grid system of the Comanche Helicopter was to be modified to include the engine inlet and the hot engine exhaust. The engine exhaust was to be modeled as hot air exhaust. However, considerable changes in the fuselage geometry required a complete regriding of the surface and volume grids. The engine plume computations have been delayed to future efforts. The results of the current work consists of a complete regeneration of the surface and volume grids of the most recent Comanche fuselage along with a flowfield computation.

  18. Hybrid cooling tower Neckarwestheim 2 cooling function, emission, plume dispersion

    International Nuclear Information System (INIS)

    Braeuning, G.; Ernst, G.; Maeule, R.; Necker, P.

    1990-01-01

    The fan-assisted hybrid cooling tower of the 1300 MW power plant Gemeinschafts-Kernkraftwerk Neckarwestheim 2 was designed and constructed based on results from theoretical and experimental studies and experiences from a smaller prototype. The wet part acts in counterflow. The dry part is arranged above the wet part. Each part contains 44 fans. Special attention was payed to the ducts which mix the dry into the wet plume. The cooling function and state, mass flow and contents of the emission were measured. The dispersion of the plume in the atmosphere was observed. The central results are presented in this paper. The cooling function corresponds to the predictions. The content of drifted cooling water in the plume is extremely low. The high velocity of the plume in the exit causes an undisturbed flow into the atmosphere. The hybrid operation reduces visible plumes strongly, especially in warmer and drier ambient air

  19. Critical Magnetic Field Strengths for Unipolar Solar Coronal Plumes In Quiet Regions and Coronal Holes?

    Science.gov (United States)

    Avallone, Ellis; Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.; Winebarger, Amy

    2017-01-01

    Coronal plumes are bright magnetic funnels that are found in quiet regions and coronal holes that extend high into the solar corona whose lifetimes can last from hours to days. The heating processes that make plumes bright involve the magnetic field at the base of the plume, but their intricacies remain mysterious. Raouafi et al. (2014) infer from observation that plume heating is a consequence of magnetic reconnection at the base, whereas Wang et al. (2016) infer that plume heating is a result of convergence of the magnetic flux at the plume's base, or base flux. Both papers suggest that the base flux in their plumes is of mixed polarity, but do not quantitatively measure the base flux or consider whether a critical magnetic field strength is required for plume production. To investigate the magnetic origins of plume heating, we track plume luminosity in the 171 Å wavelength as well as the abundance and strength of the base flux over the lifetimes of six unipolar coronal plumes. Of these, three are in coronal holes and three are in quiet regions. For this sample, we find that plume heating is triggered when convergence of the base flux surpasses a field strength of approximately 300 - 500 Gauss, and that the luminosity of both quiet region and coronal hole plumes respond similarly to the strength of the magnetic field in the base.

  20. Non-Maxwellian electron energy probability functions in the plume of a SPT-100 Hall thruster

    Science.gov (United States)

    Giono, G.; Gudmundsson, J. T.; Ivchenko, N.; Mazouffre, S.; Dannenmayer, K.; Loubère, D.; Popelier, L.; Merino, M.; Olentšenko, G.

    2018-01-01

    We present measurements of the electron density, the effective electron temperature, the plasma potential, and the electron energy probability function (EEPF) in the plume of a 1.5 kW-class SPT-100 Hall thruster, derived from cylindrical Langmuir probe measurements. The measurements were taken on the plume axis at distances between 550 and 1550 mm from the thruster exit plane, and at different angles from the plume axis at 550 mm for three operating points of the thruster, characterized by different discharge voltages and mass flow rates. The bulk of the electron population can be approximated as a Maxwellian distribution, but the measured distributions were seen to decline faster at higher energy. The measured EEPFs were best modelled with a general EEPF with an exponent α between 1.2 and 1.5, and their axial and angular characteristics were studied for the different operating points of the thruster. As a result, the exponent α from the fitted distribution was seen to be almost constant as a function of the axial distance along the plume, as well as across the angles. However, the exponent α was seen to be affected by the mass flow rate, suggesting a possible relationship with the collision rate, especially close to the thruster exit. The ratio of the specific heats, the γ factor, between the measured plasma parameters was found to be lower than the adiabatic value of 5/3 for each of the thruster settings, indicating the existence of non-trivial kinetic heat fluxes in the near collisionless plume. These results are intended to be used as input and/or testing properties for plume expansion models in further work.

  1. Dispersion under low wind speed conditions using Gaussian Plume approach

    International Nuclear Information System (INIS)

    Rakesh, P.T.; Srinivas, C.V.; Baskaran, R.; Venkatesan, R.; Venkatraman, B.

    2018-01-01

    For radioactive dose computation due to atmospheric releases, dispersion models are essential requirement. For this purpose, Gaussian plume model (GPM) is used in the short range and advanced particle dispersion models are used in all ranges. In dispersion models, other than wind speed the most influential parameter which determines the fate of the pollutant is the turbulence diffusivity. In GPM the diffusivity is represented using empirical approach. Studies show that under low wind speed conditions, the existing diffusivity relationships are not adequate in estimating the diffusion. An important phenomenon that occurs during the low wind speed is the meandering motions. It is found that under meandering motions the extent of plume dispersion is more than the estimated value using conventional GPM and particle transport models. In this work a set of new turbulence parameters for the horizontal diffusion of the plume is suggested and using them in GPM, the plume is simulated and is compared against observation available from Hanford tracer release experiment

  2. Heat flow study of the Emeishan large igneous province region: Implications for the geodynamics of the Emeishan mantle plume

    Science.gov (United States)

    Jiang, Qiang; Qiu, Nansheng; Zhu, Chuanqing

    2018-01-01

    The Emeishan large igneous province (ELIP) is widely considered to be a consequence of a mantle plume. The supporting evidence includes rapid emplacement, voluminous flood basalt eruptions, and high mantle potential temperature estimates. Several studies have suggested that there was surface uplift prior to the eruption of the Emeishan flood basalts. Additionally, the plume's lateral extent is hard to constrain and has been variously estimated to be 800-1400 km in diameter. In this study, we analyzed present-day heat flow data and reconstructed the Permian paleo-heat flow using vitrinite reflectance and zircon (U-Th)/He thermochronology data in the ELIP region and discussed implications for the geodynamics of the Emeishan mantle plume. The present-day heat flow is higher in the inner and intermediate zones than in the outer zone, with a decrease of average heat flow from 76 mW/m2 to 51 mW/m2. Thermal history modeling results show that an abnormal high paleo-heat flow of 90-110 mW/m2 was caused by the Emeishan mantle plume activity. Based on the present-day heat flow data, we can calculate that there is lithospheric thinning in the central ELIP region, which may be due to the destruction of the lithosphere by mantle plume upwelling and magmatic underplating. The Permian paleo-heat flow anomaly implies that there was a temperature anomaly in the mantle. The ascending high-temperature mantle plume and the thinned lithosphere may have induced the large-scale uplift in the ELIP region. According to the range of the surface heat flow anomaly, it can be estimated that the diameter of the flattened head of the Emeishan mantle plume could have reached 1600-1800 km. Our research provides new insights into the geodynamics of the Emeishan mantle plume through study of heat flow.

  3. First Results of Modeling Radiation Belt Electron Dynamics with the SAMI3 Plasmasphere Model

    Science.gov (United States)

    Komar, C. M.; Glocer, A.; Huba, J.; Fok, M. C. H.; Kang, S. B.; Buzulukova, N.

    2017-12-01

    The radiation belts were one of the first discoveries of the Space Age some sixty years ago and radiation belt models have been improving since the discovery of the radiation belts. The plasmasphere is one region that has been critically important to determining the dynamics of radiation belt populations. This region of space plays a critical role in describing the distribution of chorus and magnetospheric hiss waves throughout the inner magnetosphere. Both of these waves have been shown to interact with energetic electrons in the radiation belts and can result in the energization or loss of radiation belt electrons. However, radiation belt models have been historically limited in describing the distribution of cold plasmaspheric plasma and have relied on empirically determined plasmasphere models. Some plasmasphere models use an azimuthally symmetric distribution of the plasmasphere which can fail to capture important plasmaspheric dynamics such as the development of plasmaspheric drainage plumes. Previous work have coupled the kinetic bounce-averaged Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model used to model ring current and radiation belt populations with the Block-adaptive Tree Solar wind Roe-type Upwind Scheme (BATSRUS) global magnetohydrodynamic model to self-consistently obtain the magnetospheric magnetic field and ionospheric potential. The present work will utilize this previous coupling and will additionally couple the SAMI3 plasmasphere model to better represent the dynamics on the plasmasphere and its role in determining the distribution of waves throughout the inner magnetosphere. First results on the relevance of chorus, hiss, and ultralow frequency waves on radiation belt electron dynamics will be discussed in context of the June 1st, 2013 storm-time dropout event.

  4. Plume Splitting in a Two-layer Stratified Ambient Fluid

    Science.gov (United States)

    Ma, Yongxing; Flynn, Morris; Sutherland, Bruce

    2017-11-01

    A line-source plume descending into a two-layer stratified ambient fluid in a finite sized tank is studied experimentally. Although the total volume of ambient fluid is fixed, lower- and upper-layer fluids are respectively removed and added at a constant rate mimicking marine outfall through diffusers and natural and hybrid ventilated buildings. The influence of the plume on the ambient depends on the value of λ, defined as the ratio of the plume buoyancy to the buoyancy loss of the plume as it crosses the ambient interface. Similar to classical filling-box experiments, the plume can always reach the bottom of the tank if λ > 1 . By contrast, if λ < 1 , an intermediate layer eventually forms as a result of plume splitting. Eventually all of the plume fluid spreads within the intermediate layer. The starting time, tv, and the ending time, tt, of the transition process measured from experiments correlate with the value of λ. A three-layer ambient fluid is observed after transition, and the mean value of the measured densities of the intermediate layer fluid is well predicted using plume theory. Acknowledgments: Funding for this study was provided by NSERC.

  5. Interpreting Results from the Multinomial Logit Model

    DEFF Research Database (Denmark)

    Wulff, Jesper

    2015-01-01

    This article provides guidelines and illustrates practical steps necessary for an analysis of results from the multinomial logit model (MLM). The MLM is a popular model in the strategy literature because it allows researchers to examine strategic choices with multiple outcomes. However, there see...... suitable for both interpretation and communication of results. The pratical steps are illustrated through an application of the MLM to the choice of foreign market entry mode.......This article provides guidelines and illustrates practical steps necessary for an analysis of results from the multinomial logit model (MLM). The MLM is a popular model in the strategy literature because it allows researchers to examine strategic choices with multiple outcomes. However, there seem...... to be systematic issues with regard to how researchers interpret their results when using the MLM. In this study, I present a set of guidelines critical to analyzing and interpreting results from the MLM. The procedure involves intuitive graphical representations of predicted probabilities and marginal effects...

  6. Aquifer test results, 200-UP-1 operable unit IRM plume: Wells 299-W19-39 and 299-W19-36

    International Nuclear Information System (INIS)

    Swanson, L.C.

    1996-03-01

    An aquifer test was conducted at 200-UP-1 extraction well 299-W19-39 from September 6 to 8, 1995. The testing process consisted of pumping groundwater from the extraction well, using the surface treatment system to purify the water, and reinjecting the water through well 299-W19-36. Multiple observation wells were used to measure the response of the aquifer during the pumping and recovery phases of the test. Tables 1 and 2 list each well monitored and give well location and configuration information. Pretest monitoring initiated on August 31, 1995 was used to establish water-level trends and barometric pressure responses in the extraction, injection, and observation wells. Water-level monitoring continued for about 2 weeks after pumping ceased. The objectives of the aquifer test were to determine large-scale aquifer properties to confirm hydraulic conductivity input values used in previous numerical modeling work, to evaluate the long-term performance of the extraction and monitoring wells, and to estimate the radial extent of the drawdown cone (i.e., the expected capture area and depth). All of the test objectives were met. A discussion of the test results follows

  7. The study on spatial distribution features of radiological plume discharged from Nuclear Power Plant based on C4ISRE

    Science.gov (United States)

    Ma, Yunfeng; Shen, Yue; Feng, Bairun; Yang, Fan; Li, Qiangqiang; Du, Boying; Bian, Yushan; Hu, Qiongqong; Wang, Qi; Hu, Xiaomin; Yin, Hang

    2018-02-01

    When the nuclear emergency accident occurs, it is very important to estimate three-dimensional space feature of the radioactive plume discharged from the source term for the emergency organization, as well as for better understanding of atmospheric dispersion processes. So, taking the Hongyanhe Nuclear Power Plant for example, the study for three-dimensional space feature of the radioactive plume is accomplished by applying atmospheric transport model (coupling of WRF-HYSPLIT) driven by FNL meteorological data of NCEP (04/01/2014-04/02/2014) based on the C4ISRE (Command, Control, Communications, Computer, Intelligence, Surveillance, Reconnaissance, Environmental Impact Assessment).The results show that the whole shape of three-dimensional plume was about irregular cloth influenced by wind; In the spatial domain (height > 16000m),the distribution of radiological plume, which looked more like horseshoe-shaped, presented irregular polygons of which the total length was 2258.7km, where covered the area of 39151km2; In the airspace from 4000m to 16000m, the plume, covered the area of 116269 km2, showed a triangle and the perimeter of that was 2280.4km; The shape of the plume was more like irregular quadrilateral, its perimeter was 2941.8km and coverage area of the plume was 131534km2;The overall distribution of the wind field showed a rectangular shape; Within the area along the horizontal direction 400m from origin to east and under height (lower than 2000m),the closer the distance coordinate (0,0), the denser the plume particles; Within the area of horizontal distance(500m-1000m) and height (4000m- 16000m), the particle density were relatively sparse and the spread extent of the plume particles from west to East was relatively large and the plume particles were mainly in the suspended state without obvious dry sedimentation; Within the area of horizontal distance (800m-1100m) and height (>16000m), there were relatively gentle horizontal diffusion of plume particles

  8. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects....

  9. Optimized Field Sampling and Monitoring of Airborne Hazardous Transport Plumes; A Geostatistical Simulation Approach

    International Nuclear Information System (INIS)

    Chen, DI-WEN

    2001-01-01

    Airborne hazardous plumes inadvertently released during nuclear/chemical/biological incidents are mostly of unknown composition and concentration until measurements are taken of post-accident ground concentrations from plume-ground deposition of constituents. Unfortunately, measurements often are days post-incident and rely on hazardous manned air-vehicle measurements. Before this happens, computational plume migration models are the only source of information on the plume characteristics, constituents, concentrations, directions of travel, ground deposition, etc. A mobile ''lighter than air'' (LTA) system is being developed at Oak Ridge National Laboratory that will be part of the first response in emergency conditions. These interactive and remote unmanned air vehicles will carry light-weight detectors and weather instrumentation to measure the conditions during and after plume release. This requires a cooperative computationally organized, GPS-controlled set of LTA's that self-coordinate around the objectives in an emergency situation in restricted time frames. A critical step before an optimum and cost-effective field sampling and monitoring program proceeds is the collection of data that provides statistically significant information, collected in a reliable and expeditious manner. Efficient aerial arrangements of the detectors taking the data (for active airborne release conditions) are necessary for plume identification, computational 3-dimensional reconstruction, and source distribution functions. This report describes the application of stochastic or geostatistical simulations to delineate the plume for guiding subsequent sampling and monitoring designs. A case study is presented of building digital plume images, based on existing ''hard'' experimental data and ''soft'' preliminary transport modeling results of Prairie Grass Trials Site. Markov Bayes Simulation, a coupled Bayesian/geostatistical methodology, quantitatively combines soft information

  10. Analysis of Nozzle Jet Plume Effects on Sonic Boom Signature

    Science.gov (United States)

    Bui, Trong

    2010-01-01

    An axisymmetric full Navier-Stokes computational fluid dynamics (CFD) study was conducted to examine nozzle exhaust jet plume effects on the sonic boom signature of a supersonic aircraft. A simplified axisymmetric nozzle geometry, representative of the nozzle on the NASA Dryden NF-15B Lift and Nozzle Change Effects on Tail Shock (LaNCETS) research airplane, was considered. The highly underexpanded nozzle flow is found to provide significantly more reduction in the tail shock strength in the sonic boom N-wave pressure signature than perfectly expanded and overexpanded nozzle flows. A tail shock train in the sonic boom signature, similar to what was observed in the LaNCETS flight data, is observed for the highly underexpanded nozzle flow. The CFD results provide a detailed description of the nozzle flow physics involved in the LaNCETS nozzle at different nozzle expansion conditions and help in interpreting LaNCETS flight data as well as in the eventual CFD analysis of a full LaNCETS aircraft. The current study also provided important information on proper modeling of the LaNCETS aircraft nozzle. The primary objective of the current CFD research effort was to support the LaNCETS flight research data analysis effort by studying the detailed nozzle exhaust jet plume s imperfect expansion effects on the sonic boom signature of a supersonic aircraft. Figure 1 illustrates the primary flow physics present in the interaction between the exhaust jet plume shock and the sonic boom coming off of an axisymmetric body in supersonic flight. The steeper tail shock from highly expanded jet plume reduces the dip of the sonic boom N-wave signature. A structured finite-volume compressible full Navier-Stokes CFD code was used in the current study. This approach is not limited by the simplifying assumptions inherent in previous sonic boom analysis efforts. Also, this study was the first known jet plume sonic boom CFD study in which the full viscous nozzle flow field was modeled, without

  11. NW Iberia Shelf Dynamics. Study of the Douro River Plume.

    Directory of Open Access Journals (Sweden)

    Isabel Iglesias

    2014-06-01

    Full Text Available River plumes are one of the most important mechanisms that transport the terrestrial materials to the coast and the ocean. Some examples of those materials are pollutants, essential nutrients, which enhance the phytoplankton productivity or sediments, which settle on the seabed producing modifications on the bathymetry affecting the navigation channels. The mixing between the riverine and the oceanic waters can induce instabilities, which might generate bulges, filaments, and buoyant currents over the continental shelf. Offshore, the buoyant riverine water could form a front with the oceanic waters often related with the occurrence of current-jets, eddies and strong mixing. The study and modelling of the river plumes is a key factor for the complete understanding of sediment transport mechanisms and patterns, and of coastal physics and dynamic processes. On this study the Douro River plume will be simulated. The Douro River is located on the north-west Iberian coast and its daily averaged freshwater discharge can range values from 0 to 13000 m3/s. This variability impacts the formation of the river plumes and its dispersion along the continental shelf. This study builds on the long-term objective of generate a Douro River plume forecasting system as part of the RAIA and RAIA.co projects. Satellite imagery was analyzed showing that the river Douro is one of the main sources of suspended particles, dissolved material and chlorophyll in the NW Iberian Shelf. The Regional Oceanic Modeling System (ROMS model was selected to reproduce scenarios of plume generation, retention and dispersion. Whit this model, three types of simulations were performed: (i schematic winds simulations with prescribed river flow, wind speed and direction; (ii multi-year climatological simulation, with river flow and temperature change for each month; (iii extreme case simulation, based on the Entre-os-Rios accident situation. The schematic wind case-studies suggest that the

  12. Plume rise predictions

    International Nuclear Information System (INIS)

    Briggs, G.A.

    1976-01-01

    Anyone involved with diffusion calculations becomes well aware of the strong dependence of maximum ground concentrations on the effective stack height, h/sub e/. For most conditions chi/sub max/ is approximately proportional to h/sub e/ -2 , as has been recognized at least since 1936 (Bosanquet and Pearson). Making allowance for the gradual decrease in the ratio of vertical to lateral diffusion at increasing heights, the exponent is slightly larger, say chi/sub max/ approximately h/sub e/ - 2 . 3 . In inversion breakup fumigation, the exponent is somewhat smaller; very crudely, chi/sub max/ approximately h/sub e/ -1 . 5 . In any case, for an elevated emission the dependence of chi/sub max/ on h/sub e/ is substantial. It is postulated that a really clever ignorant theoretician can disguise his ignorance with dimensionless constants. For most sources the effective stack height is considerably larger than the actual source height, h/sub s/. For instance, for power plants with no downwash problems, h/sub e/ is more than twice h/sub s/ whenever the wind is less than 10 m/sec, which is most of the time. This is unfortunate for anyone who has to predict ground concentrations, for he is likely to have to calculate the plume rise, Δh. Especially when using h/sub e/ = h/sub s/ + Δh instead of h/sub s/ may reduce chi/sub max/ by a factor of anywhere from 4 to infinity. Factors to be considered in making plume rise predictions are discussed

  13. Results of steel containment vessel model test

    International Nuclear Information System (INIS)

    Luk, V.K.; Ludwigsen, J.S.; Hessheimer, M.F.; Komine, Kuniaki; Matsumoto, Tomoyuki; Costello, J.F.

    1998-05-01

    A series of static overpressurization tests of scale models of nuclear containment structures is being conducted by Sandia National Laboratories for the Nuclear Power Engineering Corporation of Japan and the US Nuclear Regulatory Commission. Two tests are being conducted: (1) a test of a model of a steel containment vessel (SCV) and (2) a test of a model of a prestressed concrete containment vessel (PCCV). This paper summarizes the conduct of the high pressure pneumatic test of the SCV model and the results of that test. Results of this test are summarized and are compared with pretest predictions performed by the sponsoring organizations and others who participated in a blind pretest prediction effort. Questions raised by this comparison are identified and plans for posttest analysis are discussed

  14. Saharan dust plume charging observed over the UK

    Science.gov (United States)

    Harrison, R. Giles; Nicoll, Keri A.; Marlton, Graeme J.; Ryder, Claire L.; Bennett, Alec J.

    2018-05-01

    A plume of Saharan dust and Iberian smoke was carried across the southern UK on 16th October 2017, entrained into an Atlantic cyclone which had originated as Hurricane Ophelia. The dust plume aloft was widely noticed as it was sufficiently dense to redden the visual appearance of the sun. Time series of backscatter from ceilometers at Reading and Chilbolton show two plumes: one carried upwards to 2.5 km, and another below 800 m into the boundary layer, with a clear slot between. Steady descent of particles at about 50 cm s‑1 continued throughout the morning, and coarse mode particles reached the surface. Plumes containing dust are frequently observed to be strongly charged, often through frictional effects. This plume passed over atmospheric electric field sensors at Bristol, Chilbolton and Reading. Consistent measurements at these three sites indicated negative plume charge. The lower edge plume charge density was (‑8.0 ± 3.3) nC m‑2, which is several times greater than that typical for stratiform water clouds, implying an active in situ charge generation mechanism such as turbulent triboelectrification. A meteorological radiosonde measuring temperature and humidity was launched into the plume at 1412 UTC, specially instrumented with charge and turbulence sensors. This detected charge in the boundary layer and in the upper plume region, and strong turbulent mixing was observed throughout the atmosphere’s lowest 4 km. The clear slot region, through which particles sedimented, was anomalously dry compared with modelled values, with water clouds forming intermittently in the air beneath. Electrical aspects of dust should be included in numerical models, particularly the charge-related effects on cloud microphysical properties, to accurately represent particle behaviour and transport.

  15. Showmaker-Levy 9 and plume-forming collisions on Earth

    Energy Technology Data Exchange (ETDEWEB)

    Boslough, M.B.E.; Crawford, D.A.

    1995-12-31

    Computational models for the July, 1994 collision of comet Shoemaker-Levy 9 with Jupiter have provided a framework for interpreting the observational data. Imaging, photometry, and spectroscopy data from ground-based, Hubble Space Telescope, and Galileo spacecraft instruments are consistent with phenomena that were dominated by the generation of incandescent fireballs that were ballistically ejected to high altitudes, where they formed plumes that subsequently collapsed over large areas of Jupiter`s atmosphere. Applications of similar computational models to collisions into Earth`s atmosphere show that a very similar sequence of events should take place for NEO impacts with energies as low as 3 megatons, recurring on 100 year timescales or less. This result suggests that the 1908 Tunguska event was a plume-forming atmospheric explosion, and that some of the phenomena associated with it might be related to the ejection and collapse of a high plume. Hazards associated with plume growth and collapse should be included in the evaluation of the impact threat to Earth, and opportunities should be sought for observational validation of atmospheric impact models by exploiting data already being collected from the natural flux of multi-kiloton to megaton sized objects that constantly enter Earth`s atmosphere on annual to decadal timescales.

  16. A distribution-based parametrization for improved tomographic imaging of solute plumes

    Science.gov (United States)

    Pidlisecky, Adam; Singha, K.; Day-Lewis, F. D.

    2011-01-01

    Difference geophysical tomography (e.g. radar, resistivity and seismic) is used increasingly for imaging fluid flow and mass transport associated with natural and engineered hydrologic phenomena, including tracer experiments, in situ remediation and aquifer storage and recovery. Tomographic data are collected over time, inverted and differenced against a background image to produce 'snapshots' revealing changes to the system; these snapshots readily provide qualitative information on the location and morphology of plumes of injected tracer, remedial amendment or stored water. In principle, geometric moments (i.e. total mass, centres of mass, spread, etc.) calculated from difference tomograms can provide further quantitative insight into the rates of advection, dispersion and mass transfer; however, recent work has shown that moments calculated from tomograms are commonly biased, as they are strongly affected by the subjective choice of regularization criteria. Conventional approaches to regularization (Tikhonov) and parametrization (image pixels) result in tomograms which are subject to artefacts such as smearing or pixel estimates taking on the sign opposite to that expected for the plume under study. Here, we demonstrate a novel parametrization for imaging plumes associated with hydrologic phenomena. Capitalizing on the mathematical analogy between moment-based descriptors of plumes and the moment-based parameters of probability distributions, we design an inverse problem that (1) is overdetermined and computationally efficient because the image is described by only a few parameters, (2) produces tomograms consistent with expected plume behaviour (e.g. changes of one sign relative to the background image), (3) yields parameter estimates that are readily interpreted for plume morphology and offer direct insight into hydrologic processes and (4) requires comparatively few data to achieve reasonable model estimates. We demonstrate the approach in a series of

  17. SO2 plume height retrieval from direct fitting of GOME-2 backscattered radiance measurements

    Science.gov (United States)

    van Gent, J.; Spurr, R.; Theys, N.; Lerot, C.; Brenot, H.; Van Roozendael, M.

    2012-04-01

    The use of satellite measurements for SO2 monitoring has become an important aspect in the support of aviation control. Satellite measurements are sometimes the only information available on SO2 concentrations from volcanic eruption events. The detection of SO2 can furthermore serve as a proxy for the presence of volcanic ash that poses a possible hazard to air traffic. In that respect, knowledge of both the total vertical column amount and the effective altitude of the volcanic SO2 plume is valuable information to air traffic control. The Belgian Institute for Space Aeronomy (BIRA-IASB) hosts the ESA-funded Support to Aviation Control Service (SACS). This system provides Volcanic Ash Advisory Centers (VAACs) worldwide with near real-time SO2 and volcanic ash data, derived from measurements from space. We present results from our algorithm for the simultaneous retrieval of total vertical columns of O3 and SO2 and effective SO2 plume height from GOME-2 backscattered radiance measurements. The algorithm is an extension to the GODFIT direct fitting algorithm, initially developed at BIRA-IASB for the derivation of improved total ozone columns from satellite data. The algorithm uses parameterized vertical SO2 profiles which allow for the derivation of the peak height of the SO2 plume, along with the trace gas total column amounts. To illustrate the applicability of the method, we present three case studies on recent volcanic eruptions: Merapi (2010), Grímsvotn (2011), and Nabro (2011). The derived SO2 plume altitude values are validated with the trajectory model FLEXPART and with aerosol altitude estimations from the CALIOP instrument on-board the NASA A-train CALIPSO platform. We find that the effective plume height can be obtained with a precision as fine as 1 km for moderate and strong volcanic events. Since this is valuable information for air traffic, we aim at incorporating the plume height information in the SACS system.

  18. Radiatively-driven processes in forest fire and desert dust plumes

    Energy Technology Data Exchange (ETDEWEB)

    Weinzierl, Bernadett Barbara

    2008-07-01

    plume lifetime. This study combines experimental data, modelling of optical parameters and calculated heating rates to assess the role of forest fire and desert dust plumes. The microphysical, optical and chemical properties of forest fire and desert dust aerosol, and their vertical distribution, were measured with multiple instruments on the DLR Falcon 20-E5 research aircraft during ITOP and SAMUM. Aerosol size information and absorption data were analysed with respect to the aerosol mixing state, effective diameter and parameterisation of forest fire and dust size distributions. Altogether, about 90 size distributions for particles from different sources were extracted from multiple instruments and parameterised with multimodal log-normal distributions. Subsequently, the optical properties were calculated for the different aerosol layers and compared with other independent measurements of the optical properties like the extinction coefficient determined with a High Spectral Resolution Lidar. The aerosol optical properties serve as the basis for the radiative transfer calculations with libRadtran (library for radiative transfer). Finally, the aerosol microphysical and optical properties, the meteorological data and the heating rates are examined to investigate the proposed self-stabilising and sealed ageing effects. The investigation of numerous forest fire and desert dust plumes in this study revealed characteristic aerosol properties: the aged (age: 4-13 days) forest fire aerosol is characterised by the absence of a nucleation mode, a depleted Aitken mode and an enhanced accumulation mode. In addition, more than 80% of the particles in the Aitken mode and nearly all particles in the accumulation mode of the forest fire plumes are internally mixed with a solid core. The desert dust aerosol exhibits two size regimes of different mixing states: below 0.5 {mu}m, particles have a non-volatile core and a volatile coating; larger particles above 0.5 {mu}m consist of non

  19. Argonne National Laboratory's thermal plume measurements: instruments and techniques

    International Nuclear Information System (INIS)

    Van Loon, L.S.; Frigo, A.A.; Paddock, R.A.

    1977-12-01

    Instrumentation and techniques were developed at Argonne National Laboratory for measuring the three-dimensional temperature structure of thermal plumes from power plants, along with the limnological, meteorological, and plant operating conditions affecting their behavior. The equipment and procedures were designed to provide field data for use in evaluating predictive models that describe thermal plume behavior, and over 100 sets of these data have been collected. The instrument systems and techniques employed in a typical thermal discharge survey are highly integrated. Continuous monitoring of ambient and plant conditions is coupled with plume mapping from a moving survey boat. The instantaneous location of the boat together with subsurface temperature measurements from a towed thermistor chain provide a quasisynoptic view of the plume structure. Real-time, onboard display of the boat path and vertical temperatures supply feedback to investigators for determining the extent and spatial resolution of measurements required. The unique design, reliability, accuracy, calibration, and historical development of the components of these integrated systems are described. Survey system interfaces with data handling and processing techniques are also explained. Special supportive studies to investigate plume dynamics, values of eddy diffusivities, time-temperature histories of water parcels in thermal plumes, and rapid changes in plume shape are also described along with instrumentation used

  20. The EURAD model: Design and first results

    International Nuclear Information System (INIS)

    1989-01-01

    The contributions are abridged versions of lectures delivered on the occasion of the presentation meeting of the EURAD project on the 20th and 21st of February 1989 in Cologne. EURAD stands for European Acid Deposition Model. The project takes one of the possible and necessary ways to search for scientific answers to the questions which the modifications of the atmosphere caused by anthropogenic influence raise. One of the objectives is to develop a realistic numeric model of long-distance transport of harmful substances in the troposphere over Europe and to use this model for the investigation of pollutant distribution but also for the support of their experimental study. The EURAD Model consists of two parts: a meteorologic mesoscale model and a chemical transport model. In the first part of the presentation, these parts are introduced and questions concerning the implementation of the entire model on the computer system CRAY X-MP/22 discussed. Afterwards it is reported upon the results of the test calculations for the cases 'Chernobyl' and 'Alpex'. Thereafter selected problems concerning the treatments of meteorological and air-chemistry processes as well as the parametrization of subscale processes within the model are discussed. The conclusion is made by two lectures upon emission evaluations and emission scenarios. (orig./KW) [de

  1. A physiological production model for cacao : results of model simulations

    NARCIS (Netherlands)

    Zuidema, P.A.; Leffelaar, P.A.

    2002-01-01

    CASE2 is a physiological model for cocoa (Theobroma cacao L.) growth and yield. This report introduces the CAcao Simulation Engine for water-limited production in a non-technical way and presents simulation results obtained with the model.

  2. Wet plume atop of the flattening slab: Insight into intraplate volcanism in East Asia

    Science.gov (United States)

    He, Lijuan

    2017-08-01

    Geophysical observations imply the intraplate volcanism in East Asia is related to dehydration of slab stagnating in the transition zone. To better understand the dynamics of such process, a thermochemical mantle convection model is constructed to simulate numerically the thermal evolution of slab and the transportation of water in the process of slab downgoing, flattening and stagnation. Equation of water transfer is included, and water effects on density and viscosity are considered. Model results indicate the warming of slab by surrounding mantle is rather slow. Water could be successfully dragged into the transition zone if the reference viscosity of the hydrous layer (with initial water of 2 wt%) is higher than 1017 Pa s and that of mantle is 1021 Pa s. Wet plumes could then originate in the flat-lying part of the slab, relatively far from the trench. Generally, the viscosity of the hydrous layer governs the initiation of wet plume, whereas the viscosity of the overlying mantle wedge controls the activity of the ascending wet plumes - they are more active in the weaker wedge. The complex fluid flow superposed by corner flow and free thermal convection influences greatly the water transport pattern in the upper mantle. Modeling results together with previous modeling infer three stages of water circulation in the big mantle wedge: 1) water is brought into the mantle transition zone by downward subducting slab under some specific thermo-rheological conditions, otherwise water is released at shallow depth near wedge tip; 2) wet plume generates from surface of the flattening slab warmed by surrounding mantle, and 3) water spreads over the big mantle wedge. Wet plume from the flattening Pacific Plate arrives at the lithospheric base and induces melting, which can explain the intraplate Cenozoic volcanoes in East Asia.

  3. Rise of a cold plume

    International Nuclear Information System (INIS)

    Kakuta, Michio

    1977-06-01

    The rise of smoke from the stacks of two research reactors in normal operation was measured by photogrametric method. The temperature of effluent gas is less than 20 0 C higher than that of the ambient air (heat emission of the order 10 4 cal s -1 ), and the efflux velocity divided by the wind speed is between 0.5 and 2.8 in all 16 smoke runs. The field data obtained within downwind distance of 150m are compared with those by plume rise formulas presently available. Considering the shape of bending-over plume, the Briggs' formula for 'jet' gives a reasonable explanation of the observed plume rise. (auth.)

  4. The Green Propellant Infusion Mission Thruster Performance Testing for Plume Diagnostics

    Science.gov (United States)

    Deans, Matthew C.; Reed, Brian D.; Arrington, Lynn A.; Williams, George J.; Kojima, Jun J.; Kinzbach, McKenzie I.; McLean, Christopher H.

    2014-01-01

    The Green Propellant Infusion Mission (GPIM) is sponsored by NASA's Space Technology Mission Directorate (STMD) Technology Demonstration Mission (TDM) office. The goal of GPIM is to advance the technology readiness level of a green propulsion system, specifically, one using the monopropellant, AF-M315E, by demonstrating ground handling, spacecraft processing, and on-orbit operations. One of the risks identified for GPIM is potential contamination of sensitive spacecraft surfaces from the effluents in the plumes of AF-M315E thrusters. NASA Glenn Research Center (GRC) is conducting activities to characterize the effects of AF-M315E plume impingement and deposition. GRC has established individual plume models of the 22-N and 1-N thrusters that will be used on the GPIM spacecraft. The model simulations will be correlated with plume measurement data from Laboratory and Engineering Model 22-N, AF-M315E thrusters. The thrusters are currently being tested in a small rocket, altitude facility at NASA GRC. A suite of diagnostics, including Raman spectroscopy, Rayleigh spectroscopy, and Schlieren imaging are being used to acquire plume measurements of AF-M315E thrusters. Plume data will include temperature, velocity, relative density, and species concentration. The plume measurement data will be compared to the corresponding simulations of the plume model. The GRC effort will establish a data set of AF-M315E plume measurements and a plume model that can be used for future AF-M315E applications.

  5. Modelling rainfall erosion resulting from climate change

    Science.gov (United States)

    Kinnell, Peter

    2016-04-01

    It is well known that soil erosion leads to agricultural productivity decline and contributes to water quality decline. The current widely used models for determining soil erosion for management purposes in agriculture focus on long term (~20 years) average annual soil loss and are not well suited to determining variations that occur over short timespans and as a result of climate change. Soil loss resulting from rainfall erosion is directly dependent on the product of runoff and sediment concentration both of which are likely to be influenced by climate change. This presentation demonstrates the capacity of models like the USLE, USLE-M and WEPP to predict variations in runoff and erosion associated with rainfall events eroding bare fallow plots in the USA with a view to modelling rainfall erosion in areas subject to climate change.

  6. On the relative motions of long-lived Pacific mantle plumes.

    Science.gov (United States)

    Konrad, Kevin; Koppers, Anthony A P; Steinberger, Bernhard; Finlayson, Valerie A; Konter, Jasper G; Jackson, Matthew G

    2018-02-27

    Mantle plumes upwelling beneath moving tectonic plates generate age-progressive chains of volcanos (hotspot chains) used to reconstruct plate motion. However, these hotspots appear to move relative to each other, implying that plumes are not laterally fixed. The lack of age constraints on long-lived, coeval hotspot chains hinders attempts to reconstruct plate motion and quantify relative plume motions. Here we provide 40 Ar/ 39 Ar ages for a newly identified long-lived mantle plume, which formed the Rurutu hotspot chain. By comparing the inter-hotspot distances between three Pacific hotspots, we show that Hawaii is unique in its strong, rapid southward motion from 60 to 50 Myrs ago, consistent with paleomagnetic observations. Conversely, the Rurutu and Louisville chains show little motion. Current geodynamic plume motion models can reproduce the first-order motions for these plumes, but only when each plume is rooted in the lowermost mantle.

  7. INTRAVAL test case 1b - modelling results

    International Nuclear Information System (INIS)

    Jakob, A.; Hadermann, J.

    1991-07-01

    This report presents results obtained within Phase I of the INTRAVAL study. Six different models are fitted to the results of four infiltration experiments with 233 U tracer on small samples of crystalline bore cores originating from deep drillings in Northern Switzerland. Four of these are dual porosity media models taking into account advection and dispersion in water conducting zones (either tubelike veins or planar fractures), matrix diffusion out of these into pores of the solid phase, and either non-linear or linear sorption of the tracer onto inner surfaces. The remaining two are equivalent porous media models (excluding matrix diffusion) including either non-linear sorption onto surfaces of a single fissure family or linear sorption onto surfaces of several different fissure families. The fits to the experimental data have been carried out by Marquardt-Levenberg procedure yielding error estimates of the parameters, correlation coefficients and also, as a measure for the goodness of the fits, the minimum values of the χ 2 merit function. The effects of different upstream boundary conditions are demonstrated and the penetration depth for matrix diffusion is discussed briefly for both alternative flow path scenarios. The calculations show that the dual porosity media models are significantly more appropriate to the experimental data than the single porosity media concepts. Moreover, it is matrix diffusion rather than the non-linearity of the sorption isotherm which is responsible for the tailing part of the break-through curves. The extracted parameter values for some models for both the linear and non-linear (Freundlich) sorption isotherms are consistent with the results of independent static batch sorption experiments. From the fits, it is generally not possible to discriminate between the two alternative flow path geometries. On the basis of the modelling results, some proposals for further experiments are presented. (author) 15 refs., 23 figs., 7 tabs

  8. Thermally-Driven Mantle Plumes Reconcile Hot-spot Observations

    Science.gov (United States)

    Davies, D.; Davies, J.

    2008-12-01

    Hot-spots are anomalous regions of magmatism that cannot be directly associated with plate tectonic processes (e.g. Morgan, 1972). They are widely regarded as the surface expression of upwelling mantle plumes. Hot-spots exhibit variable life-spans, magmatic productivity and fixity (e.g. Ito and van Keken, 2007). This suggests that a wide-range of upwelling structures coexist within Earth's mantle, a view supported by geochemical and seismic evidence, but, thus far, not reproduced by numerical models. Here, results from a new, global, 3-D spherical, mantle convection model are presented, which better reconcile hot-spot observations, the key modification from previous models being increased convective vigor. Model upwellings show broad-ranging dynamics; some drift slowly, while others are more mobile, displaying variable life-spans, intensities and migration velocities. Such behavior is consistent with hot-spot observations, indicating that the mantle must be simulated at the correct vigor and in the appropriate geometry to reproduce Earth-like dynamics. Thermally-driven mantle plumes can explain the principal features of hot-spot volcanism on Earth.

  9. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter

    Axisymmeric circular buoyant jets are treated both theoretically and experimentally. From a literature study the author concludes that the state of experimental knowledge is less satisfactory. Further three different measuring methods have been established to investigate the thermal plumes from...

  10. Novel plume deflection concept testing

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will explore the feasibility and effectiveness of utilizing an electrically driven thermal shield for use as part of rocket plume deflectors. To...

  11. Applying UV cameras for SO2 detection to distant or optically thick volcanic plumes

    Science.gov (United States)

    Kern, Christoph; Werner, Cynthia; Elias, Tamar; Sutton, A. Jeff; Lübcke, Peter

    2013-01-01

    Ultraviolet (UV) camera systems represent an exciting new technology for measuring two dimensional sulfur dioxide (SO2) distributions in volcanic plumes. The high frame rate of the cameras allows the retrieval of SO2 emission rates at time scales of 1 Hz or higher, thus allowing the investigation of high-frequency signals and making integrated and comparative studies with other high-data-rate volcano monitoring techniques possible. One drawback of the technique, however, is the limited spectral information recorded by the imaging systems. Here, a framework for simulating the sensitivity of UV cameras to various SO2 distributions is introduced. Both the wavelength-dependent transmittance of the optical imaging system and the radiative transfer in the atmosphere are modeled. The framework is then applied to study the behavior of different optical setups and used to simulate the response of these instruments to volcanic plumes containing varying SO2 and aerosol abundances located at various distances from the sensor. Results show that UV radiative transfer in and around distant and/or optically thick plumes typically leads to a lower sensitivity to SO2 than expected when assuming a standard Beer–Lambert absorption model. Furthermore, camera response is often non-linear in SO2 and dependent on distance to the plume and plume aerosol optical thickness and single scatter albedo. The model results are compared with camera measurements made at Kilauea Volcano (Hawaii) and a method for integrating moderate resolution differential optical absorption spectroscopy data with UV imagery to retrieve improved SO2 column densities is discussed.

  12. Assessment of Turbulence-Chemistry Interactions in Missile Exhaust Plume Signature Analysis

    National Research Council Canada - National Science Library

    Calhoon, W

    2002-01-01

    ... components and missile defense systems. Current engineering level models neglect turbulence chemistry interactions and typically underpredict the intensity of plume afterburning and afterburning burnout...

  13. How plume-ridge interaction shapes the crustal thickness pattern of the Réunion hotspot track

    Science.gov (United States)

    Bredow, Eva; Steinberger, Bernhard; Gassmöller, Rene; Dannberg, Juliane

    2017-08-01

    The Réunion mantle plume has shaped a large area of the Earth's surface over the past 65 million years: from the Deccan Traps in India along the hotspot track comprising the island chains of the Laccadives, Maldives, and Chagos Bank on the Indian plate and the Mascarene Plateau on the African plate up to the currently active volcanism at La Réunion Island. This study addresses the question how the Réunion plume, especially in interaction with the Central Indian Ridge, created the complex crustal thickness pattern of the hotspot track. For this purpose, the mantle convection code ASPECT was used to design three-dimensional numerical models, which consider the specific location of the plume underneath moving plates and surrounded by large-scale mantle flow. The results show the crustal thickness pattern produced by the plume, which altogether agrees well with topographic maps. Especially two features are consistently reproduced by the models: the distinctive gap in the hotspot track between the Maldives and Chagos is created by the combination of the ridge geometry and plume-ridge interaction; and the Rodrigues Ridge, a narrow crustal structure which connects the hotspot track and the Central Indian Ridge, appears as the surface expression of a long-distance sublithospheric flow channel. This study therefore provides further insight how small-scale surface features are generated by the complex interplay between mantle and lithospheric processes.

  14. Smoke plumes: Emissions and effects

    Science.gov (United States)

    Susan O' Neill; Shawn Urbanski; Scott Goodrick; Sim Larkin

    2017-01-01

    Smoke can manifest itself as a towering plume rising against the clear blue sky-or as a vast swath of thick haze, with fingers that settle into valleys overnight. It comes in many forms and colors, from fluffy and white to thick and black. Smoke plumes can rise high into the atmosphere and travel great distances across oceans and continents. Or smoke can remain close...

  15. Volcanic eruption plumes on Io

    International Nuclear Information System (INIS)

    Strom, R.G.; Terrile, R.J.; Masursky, H.; Hansen, C.

    1979-01-01

    The detection of an umbrella-shaped plume extending about 280 km above the bright limb of Io was one of the most important discoveries made during the Voyager 1 encounter with the jovian system. This discovery proves that Io is volcanically active at present, and the number and magnitude of these eruptions indicate that Io is the most volcanically active body so far discovered in the Solar System. Preliminary analyses of these eruptive plumes are presented. (U.K.)

  16. Anisotropic Signature of the Afar plume in the Upper Mantle.

    Science.gov (United States)

    Sicilia, D.; Montagner, J.; Debayle, E.; Leveque, J.; Cara, M.; Lepine, J.

    2002-12-01

    Plumes remain enigmatic geological objects and it is still unclear how they are formed and whether they act independently from plate tectonics. The role of plumes in mantle dynamics can be investigated by studying their interaction with lithosphere and crust and their perturbations on flow pattern in the mantle. The flow pattern can be derived from seismic anisotropy. An anisotropic surface wave tomography in the Horn of Africa was performed. The choice of the experiment in the Horn of Africa is motivated by the the presence of the Afar hotspot, one of the biggest continental hotspot. In the framework of the mantle degree 2 pattern, the Afar hotspot is the antipode of the Pacific superswell, but its origin at depth and its geodynamic importance are still debated. Data were collected from the permanent IRIS and GEOSCOPE networks and from the PASSCAL experiment in Tanzania and Saudi Arabia. We completed our data base with a French deployment of portable broadband stations surrounding the Afar Hotspot. Path average phase velocities are obtained by using a method based on a least-squares minimization (Beucler et al.,2002). A correction of the data is applied according to the a priori 3SMAC model (Nataf and Ricard, 1996). 3D-models of velocity, radial and azimuthal anisotropies are inverted for. Down to 250km, low velocities are found beneath the Red Sea, the Gulf of Aden, the South East of the Tanzania Craton, the Afar hotspot. High velocities are present in the eastern Arabia and the Tanzania Craton. These results are in agreement with the isotropic model of Debayle et al. (2002). The anisotropy model beneath Afar displays a complex pattern. The azimuthal anisotropy shows that the Afar plume might be interpreted as feeding other hotspots in central Africa. Deeper in the asthenosphere, a wide stem of positive radial anisotropy (VSH > VSV) comes up, where we might expect the reverse sign. The same observation was made below Iceland (Gaherty, 2001) and Hawaii (Montagner

  17. The controversy over plumes: Who is actually right?

    Science.gov (United States)

    Puchkov, V. N.

    2009-01-01

    The current state of the theory of mantle plumes and its relation to classic plate tectonics show that the “plume” line of geodynamic research is in a period of serious crisis. The number of publications criticizing this concept is steadily increasing. The initial suggestions of plumes’ advocates are disputed, and not without grounds. Questions have been raised as to whether all plumes are derived from the mantle-core interface; whether they all have a wide head and a narrow tail; whether they are always accompanied by uplifting of the Earth’s surface; and whether they can be reliably identified by geochemical signatures, e.g., by the helium-isotope ratio. Rather convincing evidence indicates that plumes cannot be regarded as a strictly fixed reference frame for moving lithospheric plates. More generally, the very existence of plumes has become the subject of debate. Alternative ideas contend that all plumes, or hot spots, are directly related to plate-tectonic mechanisms and appear as a result of shallow tectonic stress, subsequent decompression, and melting of the mantle enriched in basaltic material. Attempts have been made to explain the regular variation in age of volcanoes in ocean ridges by the crack propagation mechanism or by drift of melted segregations of enriched mantle in a nearly horizontal asthenospheric flow. In the author’s opinion, the crisis may be overcome by returning to the beginnings of the plume concept and by providing an adequate specification of plume attributes. Only mantle flows with sources situated below the asthenosphere should be referred to as plumes. These flows are not directly related to such plate-tectonic mechanisms as passive rifting and decompression melting in the upper asthenosphere and are marked by time-progressive volcanic chains; their subasthenospheric roots are detected in seismic tomographic images. Such plumes are mostly located at the margins of superswells, regions of attenuation of seismic waves at the

  18. Experiments on Plume Spreading by Engineered Injection and Extraction

    Science.gov (United States)

    Mays, D. C.; Jones, M.; Tigera, R. G.; Neupauer, R.

    2014-12-01

    The notion that groundwater remediation is transport-limited emphasizes the coupling between physical (i.e., hydrodynamic), geochemical, and microbiological processes in the subsurface. Here we leverage this coupling to promote groundwater remediation using the approach of engineered injection and extraction. In this approach, inspired by the literature on chaotic advection, uncontaminated groundwater is injected and extracted through a manifold of wells surrounding the contaminated plume. The potential of this approach lies in its ability to actively manipulate the velocity field near the contaminated plume, generating plume spreading above and beyond that resulting from aquifer heterogeneity. Plume spreading, in turn, promotes mixing and reaction by chemical and biological processes. Simulations have predicted that engineered injection and extraction generates (1) chaotic advection whose characteristics depend on aquifer heterogeneity, and (2) faster rates and increased extent of groundwater remediation. This presentation focuses on a complimentary effort to experimentally demonstrate these predictions experimentally. In preparation for future work using refractive index matched (RIM) porous media, the experiments reported here use a Hele-Shaw apparatus containing silicone oil. Engineered injection and extraction is used to manipulate the geometry of an initially circular plume of black pigment, and photographs record the plume geometry after each step of injection of extraction. Image analysis, using complimentary Eulerian and Lagrangian approaches, reveals the thickness and variability of the dispersion zone surrounding the deformed plume of black pigment. The size, shape, and evolution of this dispersion zone provides insight into the interplay between engineered injection and extraction, which generates plume structure, and dispersion (here Taylor dispersion), which destroys plume structure. These experiments lay the groundwork for application of engineered

  19. Asymmetric three-dimensional topography over mantle plumes.

    Science.gov (United States)

    Burov, Evgueni; Gerya, Taras

    2014-09-04

    The role of mantle-lithosphere interactions in shaping surface topography has long been debated. In general, it is supposed that mantle plumes and vertical mantle flows result in axisymmetric, long-wavelength topography, which strongly differs from the generally asymmetric short-wavelength topography created by intraplate tectonic forces. However, identification of mantle-induced topography is difficult, especially in the continents. It can be argued therefore that complex brittle-ductile rheology and stratification of the continental lithosphere result in short-wavelength modulation and localization of deformation induced by mantle flow. This deformation should also be affected by far-field stresses and, hence, interplay with the 'tectonic' topography (for example, in the 'active/passive' rifting scenario). Testing these ideas requires fully coupled three-dimensional numerical modelling of mantle-lithosphere interactions, which so far has not been possible owing to the conceptual and technical limitations of earlier approaches. Here we present new, ultra-high-resolution, three-dimensional numerical experiments on topography over mantle plumes, incorporating a weakly pre-stressed (ultra-slow spreading), rheologically realistic lithosphere. The results show complex surface evolution, which is very different from the smooth, radially symmetric patterns usually assumed as the canonical surface signature of mantle upwellings. In particular, the topography exhibits strongly asymmetric, small-scale, three-dimensional features, which include narrow and wide rifts, flexural flank uplifts and fault structures. This suggests a dominant role for continental rheological structure and intra-plate stresses in controlling dynamic topography, mantle-lithosphere interactions, and continental break-up processes above mantle plumes.

  20. Life Cycle of Mantle Plumes: A perspective from the Galapagos Plume (Invited)

    Science.gov (United States)

    Gazel, E.; Herzberg, C. T.

    2009-12-01

    Hotspots are localized sources of heat and magmatism considered as modern-day evidence of mantle plumes. Some hotspots are related to massive magmatic production that generated Large Igneous Provinces (LIPS), an initial-peak phase of plume activity with a mantle source hotter and more magmatically productive than present-day hotspots. Geological mapping and geochronological studies have shown much lower eruption rates for OIB compared to lavas from Large Igneous Provinces LIPS such as oceanic plateaus and continental flood provinces. Our study is the first quantitative petrological comparison of mantle source temperatures and extent of melting for OIB and LIP sources. The wide range of primary magma compositions and inferred mantle potential temperatures for each LIP and OIB occurrence suggest that this rocks originated form a hotspot, a spatially localized source of heat and magmatism restricted in time. Extensive outcrops of basalt, picrite, and sometimes komatiite with circa 65-95 Ma ages occupy portions of the pacific shore of Central and South America included in the Caribbean Large Igneous Province (CLIP). There is general consensus of a Pacific-origin of CLIP and most studies suggest that it was produced by melting in the Galapagos mantle plume. The Galapagos connection is consistent with isotopic and geochemical similarities with lavas from the present-day Galapagos hotspot. A Galapagos link for rocks in South American oceanic complexes (eg. the island of Gorgona) is more controversial and requires future work. The MgO and FeO contents of lavas from the Galapagos related lavas and their primary magmas have decreased since the Cretaceous. From petrological modeling we infer that these changes reflect a cooling of the Galapagos mantle plume from a potential temperature of 1560-1620 C in the Cretaceous to 1500 C at the present time. These temperatures are higher than 1350 C for ambient mantle associated with oceanic ridges, and provide support for the mantle

  1. Field experimental observations of highly graded sediment plumes

    DEFF Research Database (Denmark)

    Hjelmager Jensen, Jacob; Saremi, Sina; Jimenez, Carlos

    2015-01-01

    A field experiment in the waters off the south-eastern coast of Cyprus was carried out to study near-field formation of sediment plumes from dumping. Different loads of sediment were poured into calm and limpid waters one at the time from just above the sea surface. The associated plumes......-bed positions gives unique insight into the dynamics of the descending plume and near-field dispersion processes, and enables good understanding of flow and sediment transport processes involved from-release-to-deposition of the load in a non-scaled environment. The high resolution images and footages...... are available through the link provided herein. Observations support the development of a detailed multi-fractional sediment plume model....

  2. Can molecular diffusion explain Space Shuttle plume spreading?

    Science.gov (United States)

    Meier, R. R.; Plane, John M. C.; Stevens, Michael H.; Paxton, L. J.; Christensen, A. B.; Crowley, G.

    2010-04-01

    The satellite-borne Global Ultraviolet Imager (GUVI) has produced more than 20 images of NASA Space Shuttle main engine plumes in the lower thermosphere. These reveal atomic hydrogen and, by inference, water vapor transport over hemispherical-scale distances with speeds much faster than expected from models of thermospheric wind motions. Furthermore, the hydrogen plumes expand rapidly. We find rates that exceed the horizontal diffusion speed at nominal plume altitudes of 104-112 km. Kelley et al. (2009) have proposed a 2-D turbulence mechanism to explain the observed spreading rates (and rapid advection) of the plumes. But upon further investigation, we conclude that H atom diffusion can indeed account for the observed expansion rates by recognizing that vertical diffusion quickly conveys atoms to higher altitudes where horizontal diffusion is much more rapid. We also find evidence for H atom production directly during the Shuttle's main engine burn.

  3. Turbulent structure of thermal plume. Velocity field

    International Nuclear Information System (INIS)

    Guillou, B.; Brahimi, M.; Doan-kim-son

    1986-01-01

    An experimental investigation and a numerical study of the dynamics of a turbulent plume rising from a strongly heated source are described. This type of flow is met in thermal effluents (air, vapor) from, e.g., cooling towers of thermal power plants. The mean and fluctuating values of the vertical component of the velocity were determined using a Laser-Doppler anemometer. The measurements allow us to distinguish three regions in the plume-a developing region near the source, an intermediate region, and a self-preserving region. The characteristics of each zone have been determined. In the self-preserving zone, especially, the turbulence level on the axis and the entrainment coefficient are almost twice of the values observed in jets. The numerical model proposed takes into account an important phenomenon, the intermittency, observed in the plume. This model, established with the self-preserving hypothesis, brings out analytical laws. These laws and the predicted velocity profile are in agreement with the experimental evolutions [fr

  4. On the nature of the frontal zone of the Choctawhatchee Bay plume in the Gulf of Mexico

    Science.gov (United States)

    Huguenard, K. D.; Bogucki, D. J.; Ortiz-Suslow, D. G.; Laxague, N. J. M.; MacMahan, J. H.; Özgökmen, T. M.; Haus, B. K.; Reniers, A. J. H. M.; Hargrove, J.; Soloviev, A. V.; Graber, H.

    2016-02-01

    River plumes often feature turbulent processes in the frontal zone and interfacial region at base of the plume, which ultimately impact spreading and mixing rates with the ambient coastal ocean. The degree to which these processes govern overall plume mixing is yet to be quantified with microstructure observations. A field campaign was conducted in a river plume in the northeast Gulf of Mexico in December 2013, in order to assess mixing processes that could potentially impact transport and dispersion of surface material near coastal regions. Current velocity, density, and Turbulent Kinetic Energy Values, ɛ, were obtained using an Acoustic Doppler Current Profiler (ADCP), a Conductivity Temperature Depth (CTD) profiler, a Vertical Microstructure Profiler (VMP), and two Acoustic Doppler Velocimeters (ADVs). The frontal region contained ɛ values on the order of 10-5 m2 s-3, which were markedly larger than in the ambient water beneath (O 10-9 m2 s-3). An energetic wake of moderate ɛ values (O 10-6 m2 s-3) was observed trailing the frontal edge. The interfacial region of an interior section of the plume featured opposing horizontal velocities and a ɛ value on the order of 10-6 m2 s-3. A simplified mixing budget was used under significant assumptions to compare contributions from wind, tides, and frontal regions of the plume. The results from this order of magnitude analysis indicated that frontal processes (59%) dominated in overall mixing. This emphasizes the importance of adequate parameterization of river plume frontal processes in coastal predictive models.

  5. Ozone production efficiency of a ship-plume: ITCT 2K2 case study.

    Science.gov (United States)

    Kim, Hyun S; Kim, Yong H; Han, Kyung M; Kim, Jhoon; Song, Chul H

    2016-01-01

    Ozone production efficiency (OPE) of ship plume was first evaluated in this study, based on ship-plume photochemical/dynamic model simulations and the ship-plume composition data measured during the ITCT 2K2 (Intercontinental Transport and Chemical Transformation 2002) aircraft campaign. The averaged instantaneous OPEs (OPE(i)‾) estimated via the ship-plume photochemical/dynamic modeling for the ITCT 2K2 ship-plume ranged between 4.61 and 18.92, showing that the values vary with the extent of chemical evolution (or chemical stage) of the ship plume and the stability classes of the marine boundary layer (MBL). Together with OPE(i)‾, the equivalent OPEs (OPE(e)‾) for the entire ITCT 2K2 ship-plume were also estimated. The OPE(e)‾ values varied between 9.73 (for the stable MBL) and 12.73 (for the moderately stable MBL), which agreed well with the OPE(e)‾ of 12.85 estimated based on the ITCT 2K2 ship-plume observations. It was also found that both the model-simulated and observation-based OPE(e)‾ inside the ship-plume were 0.29-0.38 times smaller than the OPE(e)‾ calculated/measured outside the ITCT 2K2 ship-plume. Such low OPEs insides the ship plume were due to the high levels of NO and non-liner ship-plume photochemistry. Possible implications of this ship-plume OPE study in the global chemistry-transport modeling are also discussed. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Tracking of smokestack and cooling tower plumes using wind measurements at different levels

    International Nuclear Information System (INIS)

    Miller, R.L.; Patrinos, A.A.N.

    1980-08-01

    Relationships between cooling tower and smokestack plumes at the Bowen Electric Generating Plant in northwestern Georgia and wind direction measurements at levels from the surface at 850 mb (approx. 1.5 km) are examined. The wind measurements play an important role in estimating plume directions which in turn are utilized to establish control and target (upwind and downwind) areas for a study of plant-induced precipitation modification. Fifty-two plume observations were made during a three week period in December 1979. Results indicate that a windset (4.5 km from the plant) mounted at a level approximating that of the cooling tower plume is a better predictor of plume direction than surface windsets (1.0 km from the plant) or 850 mb level winds. However, an apparent topographical influence on the wind direction measurements at the plume-level windset site somewhat limits its plume tracking capability, at least for ambient winds from the SW quadrant

  7. Sediment plume response to surface melting and supraglacial lake drainages on the Greenland ice sheet

    DEFF Research Database (Denmark)

    Chu, Vena W.; Smith, Laurence C; Rennermalm, Asa K.

    2009-01-01

    ) supraglacial lake drainage events from MODIS. Results confirm that the origin of the sediment plume is meltwater release from the ice sheet. Interannual variations in plume area reflect interannual variations in surface melting. Plumes appear almost immediately with seasonal surface-melt onset, provided...... the estuary is free of landfast sea ice. A seasonal hysteresis between melt extent and plume area suggests late-season exhaustion in sediment supply. Analysis of plume sensitivity to supraglacial events is less conclusive, with 69% of melt pulses and 38% of lake drainage events triggering an increase in plume...... area. We conclude that remote sensing of sediment plume behavior offers a novel tool for detecting the presence, timing and interannual variability of meltwater release from the ice sheet....

  8. River Plumes in Sunglint, Sarawak, Borneo

    Science.gov (United States)

    1991-01-01

    The sunglint pattern along the coast of Sarawak (3.0N, 111.5E) delineates the boundry of fresh water river plumes as they flow into the South China Sea. The fresh water lens (boundry between fresh and sea water) overides the saline and more dense sea water and oils, both natural and man made, collect along the convergence zones and dampen wave action. As a result, the smoother sea surface appears bright in the sunglint pattern.

  9. Strategic Map for Enceladus Plume Biosignature Sample Return

    Science.gov (United States)

    Sherwood, B.

    2014-12-01

    The discovery of jets emitting salty water from the interior of Saturn's small moon Enceladus is one of the most astounding results of the Cassini mission to date. The measured presence of organic species in the resulting plume, the finding that the jet activity is valved by tidal stretching at apocrone, the modeled lifetime of E-ring particles, and gravitational inference of a long-lived, deep, large water reservoir all indicate that the textbook conditions for habitability are met at Enceladus today: liquid water, biologically available elements, source of energy, and longevity of conducive conditions. Enceladus may be the best place in our solar system to search for direct evidence of biomarkers, and the plume provides a way to sample, analyze, and even return them to Earth for detailed analysis. For example, it is straightforward to define a Stardust-like, fly-through, plume ice-particle, dust, and gas collection mission. Concept engineering and evaluation indicate that the associated technical, programmatic, regulatory, and cost issues are quite unlike the Stardust precedent however, not least because of such a mission's Category-V, Restricted Earth Return, classification. The poster presents a strategic framework for systematic integration of the enabling issues: cultivation of science advocacy, resolution of diverse stakeholder concerns, development of verifiable and affordable technical solutions, validation of cost estimation methods, alignment with other candidate astrobiology missions, complementarity of international agency goals, and finally the identification of appropriate research and flight-mission opportunities. A strategic approach is essential if we are to know the astrobiological state of Enceladus in our lifetime, and two international teams are already dedicated to implementing key steps on this roadmap.

  10. Discussion of gas trade model (GTM) results

    International Nuclear Information System (INIS)

    Manne, A.

    1989-01-01

    This is in response to your invitation to comment on the structure of GTM and also upon the differences between its results and those of other models participating in EMF9. First a word upon the structure. GTM was originally designed to provide both regional and sectoral detail within the North American market for natural gas at a single point in time, e.g. the year 2000. It is a spatial equilibrium model in which a solution is obtained by maximizing a nonlinear function, the sum of consumers and producers surplus. Since transport costs are included in producers cost, this formulation automatically ensures that geographical price differentials will not differ by more than transport costs. For purposes of EMF9, GTM was modified to allow for resource development and depletion over time

  11. Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

    Directory of Open Access Journals (Sweden)

    Peter G. Betts

    2015-01-01

    Full Text Available We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in: contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes flat subduction above the plume, resulting in a “bowed” shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau + plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the overriding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian

  12. Contrasted continental rifting via plume-craton interaction: Applications to Central East African Rift

    Directory of Open Access Journals (Sweden)

    Alexander Koptev

    2016-03-01

    Full Text Available The East African Rift system (EARS provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the pre-rift, syn-rift and post-rift far-field volcanic and tectonic activity show that the EARS formed in the context of the interaction between a deep mantle plume and a horizontally and vertically heterogeneous lithosphere under far-field tectonic extension. We bring quantitative insights into this evolution by implementing high-resolution 3D thermo-mechanical numerical deformation models of a lithosphere of realistic rheology. The models focus on the central part of the EARS. We explore scenarios of plume-lithosphere interaction with plumes of various size and initial position rising beneath a tectonically pre-stretched lithosphere. We test the impact of the inherited rheological discontinuities (suture zones along the craton borders, of the rheological structure, of lithosphere plate thickness variations, and of physical and mechanical contrasts between the craton and the embedding lithosphere. Our experiments indicate that the ascending plume material is deflected by the cratonic keel and preferentially channeled along one of its sides, leading to the formation of a large rift zone along the eastern side of the craton, with significant magmatic activity and substantial melt amount derived from the mantle plume material. We show that the observed asymmetry of the central EARS, with coeval amagmatic (western and magmatic (eastern branches, can be explained by the splitting of warm material rising from a broad plume head whose initial position is slightly shifted to the eastern side of the craton. In that case, neither a mechanical weakness of the contact between the craton and the embedding lithosphere nor the presence of second plume are required to

  13. Analysis of nonequilibrium chemical processes in the plume of subsonic and supersonic aircraft with hydrogen and hydrocarbon combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Starik, A.M.; Lebedev, A.B.; Titova, N.S. [Central Inst. of Aviation Motors, Moscow (Russian Federation)

    1997-12-31

    On the basic of quasi one dimensional mixing model the numerical analysis of nonequilibrium chemical processes in the plume of subsonic and hypersonic aircraft is presented. It was found that species HNO, HNO{sub 3}, HNO{sub 4}, N{sub 2}O{sub 5}, ClO{sub 2}, CH{sub 3}NO{sub 2} could be formed as a result of nonequilibrium processes in the plume and their concentrations can essentially exceed both background values in free stream of atmosphere and their values at the nozzle exit plane. (author) 10 refs.

  14. Analysis of nonequilibrium chemical processes in the plume of subsonic and supersonic aircraft with hydrogen and hydrocarbon combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Starik, A M; Lebedev, A B; Titova, N S [Central Inst. of Aviation Motors, Moscow (Russian Federation)

    1998-12-31

    On the basic of quasi one dimensional mixing model the numerical analysis of nonequilibrium chemical processes in the plume of subsonic and hypersonic aircraft is presented. It was found that species HNO, HNO{sub 3}, HNO{sub 4}, N{sub 2}O{sub 5}, ClO{sub 2}, CH{sub 3}NO{sub 2} could be formed as a result of nonequilibrium processes in the plume and their concentrations can essentially exceed both background values in free stream of atmosphere and their values at the nozzle exit plane. (author) 10 refs.

  15. Meteorology of the Southern Global Plume: African and South American Fires Pollute the South Pacific

    Science.gov (United States)

    Guo, Z.; Chatfield, R. B.

    1999-01-01

    An immense global plume of CO meanders widely around the world in the Southern Hemisphere. It arises over Southern America and Africa and flows eastward. The first emissions are in tropical Brazil, and the plume circulates around the world to South America again. The plume was largely unexpected until there were aircraft studies made in NASA's Pacific Exploratory Mission - Tropics (Part A). This paper describes the meteorology of the Global Plume, as our simulation, with a synoptic model adapted to global transport, reveals it with a tracer-CO simulation. The observations and their simulation require a particular set of conditions of pollutant accumulation, cumulonimbus venting with required strengths at a narrow range of altitude. Additionally, a particular subtropical conduction region, over the Indian Ocean, Australia, and the westeRNmost South Pacific, relatively free of storms, appears to be a key part of the mechanism. These conclusions are the results of a synoptic reconstruction of the PEMT-A period, September- October, 1996.

  16. The Danish national passenger modelModel specification and results

    DEFF Research Database (Denmark)

    Rich, Jeppe; Hansen, Christian Overgaard

    2016-01-01

    The paper describes the structure of the new Danish National Passenger model and provides on this basis a general discussion of large-scale model design, cost-damping and model validation. The paper aims at providing three main contributions to the existing literature. Firstly, at the general level......, the paper provides a description of a large-scale forecast model with a discussion of the linkage between population synthesis, demand and assignment. Secondly, the paper gives specific attention to model specification and in particular choice of functional form and cost-damping. Specifically we suggest...... a family of logarithmic spline functions and illustrate how it is applied in the model. Thirdly and finally, we evaluate model sensitivity and performance by evaluating the distance distribution and elasticities. In the paper we present results where the spline-function is compared with more traditional...

  17. Superconducting solenoid model magnet test results

    Energy Technology Data Exchange (ETDEWEB)

    Carcagno, R.; Dimarco, J.; Feher, S.; Ginsburg, C.M.; Hess, C.; Kashikhin, V.V.; Orris, D.F.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.A.; Terechkine, I.; /Fermilab

    2006-08-01

    Superconducting solenoid magnets suitable for the room temperature front end of the Fermilab High Intensity Neutrino Source (formerly known as Proton Driver), an 8 GeV superconducting H- linac, have been designed and fabricated at Fermilab, and tested in the Fermilab Magnet Test Facility. We report here results of studies on the first model magnets in this program, including the mechanical properties during fabrication and testing in liquid helium at 4.2 K, quench performance, and magnetic field measurements. We also describe new test facility systems and instrumentation that have been developed to accomplish these tests.

  18. Superconducting solenoid model magnet test results

    International Nuclear Information System (INIS)

    Carcagno, R.; Dimarco, J.; Feher, S.; Ginsburg, C.M.; Hess, C.; Kashikhin, V.V.; Orris, D.F.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.A.; Terechkine, I.; Tompkins, J.C.; Wokas, T.; Fermilab

    2006-01-01

    Superconducting solenoid magnets suitable for the room temperature front end of the Fermilab High Intensity Neutrino Source (formerly known as Proton Driver), an 8 GeV superconducting H- linac, have been designed and fabricated at Fermilab, and tested in the Fermilab Magnet Test Facility. We report here results of studies on the first model magnets in this program, including the mechanical properties during fabrication and testing in liquid helium at 4.2 K, quench performance, and magnetic field measurements. We also describe new test facility systems and instrumentation that have been developed to accomplish these tests

  19. FOOTPRINT: A New Tool to Predict the Potential Impact of Biofuels on BTEX Plumes

    Science.gov (United States)

    Ahsanuzzaman et al. (2008) used the Deeb et al. (2002) conceptual model to construct a simple screening model to estimate the area of a plume of benzene produced from a release of gasoline containing ethanol. The screening model estimates the plume area, or footprint of the plum...

  20. Chernobyl plume: commentary about a discharge

    International Nuclear Information System (INIS)

    Anon

    2011-01-01

    The Paris appeal court has dismissed the charges against P. Pellerin who was the head of the SCIRP (service of protection against the ionizing radiations) at the time of the Chernobyl accident. The appeal court confirms that P.Pellerin never said that the Chernobyl plume stopped at the French border but instead he said that the Chernobyl plume entered the French territory but the radioactivity level was so low that it was unnecessary to take sanitary steps. P.Pellerin based his decision on the results of 6500 controls performed by the SCIRP in May and June 1986. Seven other European countries recommended not to take sanitary measures. The increase of thyroid cancers that has happened in all industrialized countries and that affect only adults, can not due to Chernobyl contamination because child's thyroid is far more sensitive than adult's. The increase of thyroid cancer is mainly due to a better detection of the tumors. (A.C.)

  1. Relationship between eruption plume heights and seismic source amplitudes of eruption tremors and explosion events

    Science.gov (United States)

    Mori, A.; Kumagai, H.

    2016-12-01

    It is crucial to analyze and interpret eruption tremors and explosion events for estimating eruption size and understanding eruption phenomena. Kumagai et al. (EPS, 2015) estimated the seismic source amplitudes (As) and cumulative source amplitudes (Is) for eruption tremors and explosion events at Tungurahua, Ecuador, by the amplitude source location (ASL) method based on the assumption of isotropic S-wave radiation in a high-frequency band (5-10 Hz). They found scaling relations between As and Is for eruption tremors and explosion events. However, the universality of these relations is yet to be verified, and the physical meanings of As and Is are not clear. In this study, we analyzed the relations between As and Is for eruption tremors and explosion events at active volcanoes in Japan, and estimated As and Is by the ASL method. We obtained power-law relations between As and Is, in which the powers were different between eruption tremors and explosion events. These relations were consistent with the scaling relations at Tungurahua volcano. Then, we compared As with maximum eruption plume heights (H) during eruption tremors analyzed in this study, and found that H was proportional to 0.21 power of As. This relation is similar to the plume height model based on the physical process of plume rise, which indicates that H is proportional to 0.25 power of volumetric flow rate for plinian eruptions. This suggests that As may correspond to volumetric flow rate. If we assume a seismic source with volume changes and far-field S-wave, As is proportional to the source volume rate. This proportional relation and the plume height model give rise to the relation that H is proportional to 0.25 power of As. These results suggest that we may be able to estimate plume heights in realtime by estimating As during eruptions from seismic observations.

  2. Numerical studies of pulsating buoyant plume in isothermal and non isothermal situations

    International Nuclear Information System (INIS)

    Sharma, Pavan K.; Singh, R.K.; Mohanty, Ananya; Das, D.

    2014-01-01

    A computational study has been carried out for predicting the behaviour of buoyant plume in isothermal and non isothermal configuration. General simulation objectives of any buoyant flow simulation are macroscopic in nature and deals with the grass data in respect of buoyancy induced scalar transport. However, the accuracy of predicting such macroscopic parameters is a strong function of several other microscopic parameters which govern the overall macroscopic behaviour. Some of the microscopic parameters for analysis could be buoyancy induced stable/unstable flows, relative plume behaviour, baroclinic velocity distribution etc. Only the CFD based flow modelling approach is capable of calculating several of these aspects. LES based modelling scores over the conventional RANS based computational modelling. The primary objective of the present study was to model buoyant plume simulation of different types in order to explore the details regarding plume and flow structure, instabilities and puffing behaviour. One of the influencing parameters on the overall plume behaviour is the buoyancy resolution index i.e. fineness of chosen grid in relation to the buoyancy intensity and other hydrodynamic parameters. The grid sensitivity studies have been carried out to find out the optimum value grid size by way of buoyant pool fire simulations. Comparative simulation has also been made for a square and round pool fire and it was found that for engineering simulations equivalent area square pool modeling is sufficient. Using the optimum value of grid size and square pool shape simulations have been carried out for different value of fire intensity. The flame puffing frequency as calculated by the reported correlation was compared against the computationally observed puffing frequency and the agreement was generally found to be excellent. Besides these results the comparisons of predicted peak flames temperatures data for various case studies with the available experimental data

  3. Characterization of DNAPL Source Zone Architecture and Prediction of Associated Plume Response: Progress and Perspectives

    Science.gov (United States)

    Abriola, L. M.; Pennell, K. D.; Ramsburg, C. A.; Miller, E. L.; Christ, J.; Capiro, N. L.; Mendoza-Sanchez, I.; Boroumand, A.; Ervin, R. E.; Walker, D. I.; Zhang, H.

    2012-12-01

    concentration measurements. Finally, two-dimensional aquifer cell experiments for representative DNAPL release events were performed to explore the link between source zone metrics and plume development, and to demonstrate the utility of the developed estimation tools and upscaled models. Research results reveal that, for the subsurface scenarios examined, many metrics can be estimated at greater than 80% accuracy from concentration transect measurements. Partitioning tracer investigations demonstrate that push-pull tracer data cannot be accurately modeled using local equilibrium assumptions and that fitted upscaled mass transfer coefficients exhibit a strong dependence on DNAPL mass distribution, a dependence that can be exploited for local metric identification. Aquifer cell experiments demonstrate that upscaled screening model predictions can capture the multi-stage behavior of single component NAPL fluxes from source zone architectures initially characterized as ganglia-dominated, and that transitions from ganglia- to pool-dominated architecture can be predicted using source zone metrics such as pool fraction.

  4. Scale Model Thruster Acoustic Measurement Results

    Science.gov (United States)

    Vargas, Magda; Kenny, R. Jeremy

    2013-01-01

    The Space Launch System (SLS) Scale Model Acoustic Test (SMAT) is a 5% scale representation of the SLS vehicle, mobile launcher, tower, and launch pad trench. The SLS launch propulsion system will be comprised of the Rocket Assisted Take-Off (RATO) motors representing the solid boosters and 4 Gas Hydrogen (GH2) thrusters representing the core engines. The GH2 thrusters were tested in a horizontal configuration in order to characterize their performance. In Phase 1, a single thruster was fired to determine the engine performance parameters necessary for scaling a single engine. A cluster configuration, consisting of the 4 thrusters, was tested in Phase 2 to integrate the system and determine their combined performance. Acoustic and overpressure data was collected during both test phases in order to characterize the system's acoustic performance. The results from the single thruster and 4- thuster system are discussed and compared.

  5. CMS standard model Higgs boson results

    Directory of Open Access Journals (Sweden)

    Garcia-Abia Pablo

    2013-11-01

    Full Text Available In July 2012 CMS announced the discovery of a new boson with properties resembling those of the long-sought Higgs boson. The analysis of the proton-proton collision data recorded by the CMS detector at the LHC, corresponding to integrated luminosities of 5.1 fb−1 at √s = 7 TeV and 19.6 fb−1 at √s = 8 TeV, confirm the Higgs-like nature of the new boson, with a signal strength associated with vector bosons and fermions consistent with the expectations for a standard model (SM Higgs boson, and spin-parity clearly favouring the scalar nature of the new boson. In this note I review the updated results of the CMS experiment.

  6. Modelling Extortion Racket Systems: Preliminary Results

    Science.gov (United States)

    Nardin, Luis G.; Andrighetto, Giulia; Székely, Áron; Conte, Rosaria

    Mafias are highly powerful and deeply entrenched organised criminal groups that cause both economic and social damage. Overcoming, or at least limiting, their harmful effects is a societally beneficial objective, which renders its dynamics understanding an objective of both scientific and political interests. We propose an agent-based simulation model aimed at understanding how independent and combined effects of legal and social norm-based processes help to counter mafias. Our results show that legal processes are effective in directly countering mafias by reducing their activities and changing the behaviour of the rest of population, yet they are not able to change people's mind-set that renders the change fragile. When combined with social norm-based processes, however, people's mind-set shifts towards a culture of legality rendering the observed behaviour resilient to change.

  7. New results in the Dual Parton Model

    International Nuclear Information System (INIS)

    Van, J.T.T.; Capella, A.

    1984-01-01

    In this paper, the similarity between the x distribution for particle production and the fragmentation functions are observed in e+e- collisions and in deep inelastic scattering are presented. Based on the observation, the authors develop a complete approach to multiparticle production which incorporates the most important features and concepts learned about high energy collisions. 1. Topological expansion : the dominant diagram at high energy corresponds to the simplest topology. 2. Unitarity : diagrams of various topology contribute to the cross sections in a way that unitary is preserved. 3. Regge behaviour and Duality. 4. Partonic structure of hadrons. These general theoretical ideas, result from many joint experimental and theoretical efforts on the study of soft hadron physics. The dual parton model is able to explain all the experimental features from FNAL to SPS collider energies. It has all the properties of an S-matrix theory and provides a unified description of hadron-hadron, hadron-nucleus and nucleus-nucleus collisions

  8. Thermal turbulent convection: thermal plumes and fluctuations

    International Nuclear Information System (INIS)

    Gibert, M.

    2007-10-01

    In this study we investigate the phenomenon of thermal turbulent convection in new and unprecedented ways. The first system we studied experimentally is an infinite vertical channel, where a constant vertical mean gradient of temperature exists. Inside this channel the average mass flux is null. The results obtained from our measurements reveal that the flow is mainly inertial; indeed the dissipative coefficients (here the viscosity) play a role only to define a coherence length L. This length is the distance over which the thermal plumes can be considered as 'free falling' objects. The horizontal transport, of heat and momentum, is entirely due to fluctuations. The associated 'mixing length' is small compared to the channel width. In the other hand, the vertical heat transport is due to coherent structures: the heat plumes. Those objects were also investigated in a Lagrangian study of the flow in the bulk of a Rayleigh-Benard cell. The probe, which has the same density as the fluid used in this experiment, is a sphere of 2 cm in diameter with embarked thermometers and radio-emitter. The heat plumes transport it, which allows a statistical study of such objects. (author)

  9. Lidar sounding of volcanic plumes

    Science.gov (United States)

    Fiorani, Luca; Aiuppa, Alessandro; Angelini, Federico; Borelli, Rodolfo; Del Franco, Mario; Murra, Daniele; Pistilli, Marco; Puiu, Adriana; Santoro, Simone

    2013-10-01

    Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on remote sensing of volcanic plumes, reports on the current progress of the lidar system.

  10. Biogeochemistry of landfill leachate plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Kjeldsen, Peter; Bjerg, Poul Løgstrup

    2001-01-01

    are relatively narrow and do not in terms of width exceed the width of the landfill. The concept of redox zones being present in the plume has been confirmed by the reported composition of the leachate contaminated groundwater at several landfills and constitutes an important framework for understanding...... the behavior of the contaminants in the plume as the leachate migrates away from the landfill. Diverse microbial communities have been identified in leachate plumes and are believed to be responsible for the redox processes. Dissolved organic C in the leachate, although it appears to be only slowly degradable...... to be subject to anaerobic oxidation, but the mechanisms are not yet understood. Heavy metals do not seem to constitute a significant pollution problem at landfills, partly because the heavy metal concentrations in the leachate often are low, and partly because of strong attenuation by sorption...

  11. Constructional types of hybrid tower cells. First plume observations on experimental cells in the Gemeinschaftskernkraftwerk Neckar (GKN)

    International Nuclear Information System (INIS)

    Maeule, R.

    1977-01-01

    First experience with two experimental hybrid-cell cooling towers at the Gemeinschaftkernkraftwerk Neckar (GKN) concerning techniques and plume influence. In dependence of plume-determining parameters coinciding, noticeable plume reductions as well as situations without visible improvements are observed. These results, which are not quite clear, demonstrate that systematical analytical investigations are needed. (orig.) [de

  12. Mobile Bay turbidity plume study

    Science.gov (United States)

    Crozier, G. F.

    1976-01-01

    Laboratory and field transmissometer studies on the effect of suspended particulate material upon the appearance of water are reported. Quantitative correlations were developed between remotely sensed image density, optical sea truth data, and actual sediment load. Evaluation of satellite image sea truth data for an offshore plume projects contours of transmissivity for two different tidal phases. Data clearly demonstrate the speed of change and movement of the optical plume for water patterns associated with the mouth of Mobile bay in which relatively clear Gulf of Mexico water enters the bay on the eastern side. Data show that wind stress in excess of 15 knots has a marked impact in producing suspended sediment loads.

  13. Finiteness results for Abelian tree models

    NARCIS (Netherlands)

    Draisma, J.; Eggermont, R.H.

    2015-01-01

    Equivariant tree models are statistical models used in the reconstruction of phylogenetic trees from genetic data. Here equivariant refers to a symmetry group imposed on the root distribution and on the transition matrices in the model. We prove that if that symmetry group is Abelian, then the

  14. Finiteness results for Abelian tree models

    NARCIS (Netherlands)

    Draisma, J.; Eggermont, R.H.

    2012-01-01

    Equivariant tree models are statistical models used in the reconstruction of phylogenetic trees from genetic data. Here equivariant refers to a symmetry group imposed on the root distribution and on the transition matrices in the model. We prove that if that symmetry group is Abelian, then the

  15. Finiteness results for Abelian tree models

    NARCIS (Netherlands)

    Draisma, J.; Eggermont, R.H.

    2015-01-01

    Equivariant tree models are statistical models used in the reconstruction of phylogenetic trees from genetic data. Here equivariant§ refers to a symmetry group imposed on the root distribution and on the transition matrices in the model. We prove that if that symmetry group is Abelian, then the

  16. Simultaneous Sampling of Flow and Odorants by Crustaceans can Aid Searches within a Turbulent Plume

    Directory of Open Access Journals (Sweden)

    Swapnil Pravin

    2013-12-01

    Full Text Available Crustaceans such as crabs, lobsters and crayfish use dispersing odorant molecules to determine the location of predators, prey, potential mates and habitat. Odorant molecules diffuse in turbulent flows and are sensed by the olfactory organs of these animals, often using a flicking motion of their antennules. These antennules contain both chemosensory and mechanosensory sensilla, which enable them to detect both flow and odorants during a flick. To determine how simultaneous flow and odorant sampling can aid in search behavior, a 3-dimensional numerical model for the near-bed flow environment was created. A stream of odorant concentration was released into the flow creating a turbulent plume, and both temporally and spatially fluctuating velocity and odorant concentration were quantified. The plume characteristics show close resemblance to experimental measurements within a large laboratory flume. Results show that mean odorant concentration and it’s intermittency, computed as dc/dt, increase towards the plume source, but the temporal and spatial rate of this increase is slow and suggests that long measurement times would be necessary to be useful for chemosensory guidance. Odorant fluxes measured transverse to the mean flow direction, quantified as the product of the instantaneous fluctuation in concentration and velocity, v’c’, do show statistically distinct magnitude and directional information on either side of a plume centerline over integration times of <0.5 s. Aquatic animals typically have neural responses to odorant and velocity fields at rates between 50 and 500 ms, suggesting this simultaneous sampling of both flow and concentration in a turbulent plume can aid in source tracking on timescales relevant to aquatic animals.

  17. Overview of NASA GRCs Green Propellant Infusion Mission Thruster Testing and Plume Diagnostics

    Science.gov (United States)

    Deans, Matthew C.; Reed, Brian D.; Yim, John T.; Arrington, Lynn A.; Williams, George J.; Kojima, Jun J.; McLean, Christopher H.

    2014-01-01

    The Green Propellant Infusion Mission (GPIM) is sponsored by NASA's Space Technology Mission Directorate (STMD) Technology Demonstration Mission (TDM) office. The goal of GPIM is to advance the technology readiness level of a green propulsion system, specifically, one using the monopropellant, AF-M315E, by demonstrating ground handling, spacecraft processing, and on-orbit operations. One of the risks identified for GPIM is potential contamination of sensitive spacecraft surfaces from the effluents in the plumes of AF-M315E thrusters. NASA Glenn Research Center (GRC) is conducting activities to characterize the effects of AF-M315E plume impingement and deposition. GRC has established individual plume models of the 22-N and 1-N thrusters that will be used on the GPIM spacecraft. The models describe the pressure, temperature, density, Mach number, and species concentration of the AF-M315E thruster exhaust plumes. The models are being used to assess the impingement effects of the AF-M315E thrusters on the GPIM spacecraft. The model simulations will be correlated with plume measurement data from Laboratory and Engineering Model 22-N, AF-M315E thrusters. The thrusters will be tested in a small rocket, altitude facility at NASA GRC. The GRC thruster testing will be conducted at duty cycles representatives of the planned GPIM maneuvers. A suite of laser-based diagnostics, including Raman spectroscopy, Rayleigh spectroscopy, Schlieren imaging, and physical probes will be used to acquire plume measurements of AFM315E thrusters. Plume data will include temperature, velocity, relative density, and species concentration. The plume measurement data will be compared to the corresponding simulations of the plume model. The GRC effort will establish a data set of AF-M315E plume measurements and a plume model that can be used for future AF-M315E applications.

  18. Aircraft measurements over Europe of an air pollution plume from Southeast Asia – aerosol and chemical characterization

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2007-01-01

    Full Text Available An air pollution plume from Southern and Eastern Asia, including regions in India and China, was predicted by the FLEXPART particle dispersion model to arrive in the upper troposphere over Europe on 24–25 March 2006. According to the model, the plume was exported from Southeast Asia six days earlier, transported into the upper troposphere by a warm conveyor belt, and travelled to Europe in a fast zonal flow. This is confirmed by the retrievals of carbon monoxide (CO from AIRS satellite measurements, which are in excellent agreement with the model results over the entire transport history. The research aircraft DLR Falcon was sent into this plume west of Spain on 24 March and over Southern Europe on 25 March. On both days, the pollution plume was found close to the predicted locations and, thus, the measurements taken allowed the first detailed characterization of the aerosol content and chemical composition of an anthropogenic pollution plume after a nearly hemispheric transport event. The mixing ratios of CO, reactive nitrogen (NOy and ozone (O3 measured in the Asian plume were all clearly elevated over a background that was itself likely elevated by Asian emissions: CO by 17–34 ppbv on average (maximum 60 ppbv and O3 by 2–9 ppbv (maximum 22 ppbv. Positive correlations existed between these species, and a ΔO3/ΔCO slope of 0.25 shows that ozone was formed in this plume, albeit with moderate efficiency. Nucleation mode and Aitken particles were suppressed in the Asian plume, whereas accumulation mode aerosols were strongly elevated and correlated with CO. The suppression of the nucleation mode was likely due to the large pre-existing aerosol surface of the transported larger particles. Super-micron particles, likely desert dust, were found in part of the Asian pollution plume and also in surrounding cleaner air. The aerosol light absorption coefficient was enhanced in the plume (average values for individual plume encounters 0.25–0

  19. Immersive visualization of dynamic CFD model results

    International Nuclear Information System (INIS)

    Comparato, J.R.; Ringel, K.L.; Heath, D.J.

    2004-01-01

    With immersive visualization the engineer has the means for vividly understanding problem causes and discovering opportunities to improve design. Software can generate an interactive world in which collaborators experience the results of complex mathematical simulations such as computational fluid dynamic (CFD) modeling. Such software, while providing unique benefits over traditional visualization techniques, presents special development challenges. The visualization of large quantities of data interactively requires both significant computational power and shrewd data management. On the computational front, commodity hardware is outperforming large workstations in graphical quality and frame rates. Also, 64-bit commodity computing shows promise in enabling interactive visualization of large datasets. Initial interactive transient visualization methods and examples are presented, as well as development trends in commodity hardware and clustering. Interactive, immersive visualization relies on relevant data being stored in active memory for fast response to user requests. For large or transient datasets, data management becomes a key issue. Techniques for dynamic data loading and data reduction are presented as means to increase visualization performance. (author)

  20. Introducing students to ocean modeling via a web-based implementation for the Regional Ocean Modeling System (ROMS) river plume case study

    Science.gov (United States)

    Harris, C. K.; Overeem, I.; Hutton, E.; Moriarty, J.; Wiberg, P.

    2016-12-01

    Numerical models are increasingly used for both research and applied sciences, and it is important that we train students to run models and analyze model data. This is especially true within oceanographic sciences, many of which use hydrodynamic models to address oceanographic transport problems. These models, however, often require a fair amount of training and computer skills before a student can run the models and analyze the large data sets produced by the models. One example is the Regional Ocean Modeling System (ROMS), an open source, three-dimensional primitive equation hydrodynamic ocean model that uses a structured curvilinear horizontal grid. It currently has thousands of users worldwide, and the full model includes modules for sediment transport and biogeochemistry, and several options for turbulence closures and numerical schemes. Implementing ROMS can be challenging to students, however, in part because the code was designed to provide flexibility for the choice of model parameterizations and processes, and to run on a variety of High Performance Computing (HPC) platforms. To provide a more accessible tool for classroom use, we have modified an existing idealized ROMS implementation to be run on a High Performance Computer (HPC) via the WMT (Web Modeling Toolkit), and developed a series of lesson plans that explore sediment transport within the idealized model domain. This has addressed our goal to provide a relatively easy introduction to the numerical modeling process that can be used within upper level undergraduate and graduate classes to explore sediment transport on continental shelves. The model implementation includes wave forcing, along-shelf currents, a riverine source, and suspended sediment transport. The model calculates suspended transport and deposition of sediment delivered to the continental shelf by a riverine flood. Lesson plans lead the students through running the model on a remote HPC, modifying the standard model. The lesson

  1. New particle formation and growth in biomass burning plumes: An important source of cloud condensation nuclei

    Science.gov (United States)

    Hennigan, Christopher J.; Westervelt, Daniel M.; Riipinen, Ilona; Engelhart, Gabriella J.; Lee, Taehyoung; Collett, Jeffrey L., Jr.; Pandis, Spyros N.; Adams, Peter J.; Robinson, Allen L.

    2012-05-01

    Experiments were performed in an environmental chamber to characterize the effects of photo-chemical aging on biomass burning emissions. Photo-oxidation of dilute exhaust from combustion of 12 different North American fuels induced significant new particle formation that increased the particle number concentration by a factor of four (median value). The production of secondary organic aerosol caused these new particles to grow rapidly, significantly enhancing cloud condensation nuclei (CCN) concentrations. Using inputs derived from these new data, global model simulations predict that nucleation in photo-chemically aging fire plumes produces dramatically higher CCN concentrations over widespread areas of the southern hemisphere during the dry, burning season (Sept.-Oct.), improving model predictions of surface CCN concentrations. The annual indirect forcing from CCN resulting from nucleation and growth in biomass burning plumes is predicted to be -0.2 W m-2, demonstrating that this effect has a significant impact on climate that has not been previously considered.

  2. Remediating Contaminant Plumes in Groundwater with Shallow Excavations Containing Coarse Reactive Media.

    Science.gov (United States)

    Hudak, Paul F

    2018-02-01

    A groundwater flow and mass transport model tested the capability of shallow excavations filled with coarse, reactive media to remediate a hypothetical unconfined aquifer with a maximum saturated thickness of 5 m. Modeled as contaminant sinks, the rectangular excavations were 10 m downgradient of an initial contaminant plume originating from a source at the top of the aquifer. The initial plume was approximately 259 m long, 23 m wide, and 5 m thick, with a downgradient tip located approximately 100 m upgradient of the site boundary. The smallest trench capable of preventing offsite migration was 11 m long (measured perpendicular to groundwater flow), 4 m wide (measured parallel to groundwater flow), and 3 m deep. Results of this study suggest that shallow trenches filled with coarse filter media that partially penetrate unconfined aquifers may be a viable alternative for remediating contaminated groundwater at some sites.

  3. Linkage of PRA models. Phase 1, Results

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.L.; Knudsen, J.K.; Kelly, D.L.

    1995-12-01

    The goal of the Phase I work of the ``Linkage of PRA Models`` project was to postulate methods of providing guidance for US Nuclear Regulator Commission (NRC) personnel on the selection and usage of probabilistic risk assessment (PRA) models that are best suited to the analysis they are performing. In particular, methods and associated features are provided for (a) the selection of an appropriate PRA model for a particular analysis, (b) complementary evaluation tools for the analysis, and (c) a PRA model cross-referencing method. As part of this work, three areas adjoining ``linking`` analyses to PRA models were investigated: (a) the PRA models that are currently available, (b) the various types of analyses that are performed within the NRC, and (c) the difficulty in trying to provide a ``generic`` classification scheme to groups plants based upon a particular plant attribute.

  4. Linkage of PRA models. Phase 1, Results

    International Nuclear Information System (INIS)

    Smith, C.L.; Knudsen, J.K.; Kelly, D.L.

    1995-12-01

    The goal of the Phase I work of the ''Linkage of PRA Models'' project was to postulate methods of providing guidance for US Nuclear Regulator Commission (NRC) personnel on the selection and usage of probabilistic risk assessment (PRA) models that are best suited to the analysis they are performing. In particular, methods and associated features are provided for (a) the selection of an appropriate PRA model for a particular analysis, (b) complementary evaluation tools for the analysis, and (c) a PRA model cross-referencing method. As part of this work, three areas adjoining ''linking'' analyses to PRA models were investigated: (a) the PRA models that are currently available, (b) the various types of analyses that are performed within the NRC, and (c) the difficulty in trying to provide a ''generic'' classification scheme to groups plants based upon a particular plant attribute

  5. Engineering Glass Passivation Layers -Model Results

    Energy Technology Data Exchange (ETDEWEB)

    Skorski, Daniel C.; Ryan, Joseph V.; Strachan, Denis M.; Lepry, William C.

    2011-08-08

    The immobilization of radioactive waste into glass waste forms is a baseline process of nuclear waste management not only in the United States, but worldwide. The rate of radionuclide release from these glasses is a critical measure of the quality of the waste form. Over long-term tests and using extrapolations of ancient analogues, it has been shown that well designed glasses exhibit a dissolution rate that quickly decreases to a slow residual rate for the lifetime of the glass. The mechanistic cause of this decreased corrosion rate is a subject of debate, with one of the major theories suggesting that the decrease is caused by the formation of corrosion products in such a manner as to present a diffusion barrier on the surface of the glass. Although there is much evidence of this type of mechanism, there has been no attempt to engineer the effect to maximize the passivating qualities of the corrosion products. This study represents the first attempt to engineer the creation of passivating phases on the surface of glasses. Our approach utilizes interactions between the dissolving glass and elements from the disposal environment to create impermeable capping layers. By drawing from other corrosion studies in areas where passivation layers have been successfully engineered to protect the bulk material, we present here a report on mineral phases that are likely have a morphological tendency to encrust the surface of the glass. Our modeling has focused on using the AFCI glass system in a carbonate, sulfate, and phosphate rich environment. We evaluate the minerals predicted to form to determine the likelihood of the formation of a protective layer on the surface of the glass. We have also modeled individual ions in solutions vs. pH and the addition of aluminum and silicon. These results allow us to understand the pH and ion concentration dependence of mineral formation. We have determined that iron minerals are likely to form a complete incrustation layer and we plan

  6. CIEMAT model results for Esthwaite Water

    International Nuclear Information System (INIS)

    Aguero, A.; Garcia-Olivares, A.

    2000-01-01

    This study used the transfer model PRYMA-LO, developed by CIEMAT-IMA, Madrid, Spain, to simulate the transfer of Cs-137 in watershed scenarios. The main processes considered by the model include: transfer of the fallout to the ground, incorporation of the fallout radioisotopes into the water flow, and their removal from the system. The model was tested against observation data obtained in water and sediments of Esthwaite Water, Lake District, UK. This comparison made it possible to calibrate the parameters of the model to the specific scenario

  7. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, P.; Nielsen, Peter Vilhelm

    The main objective of ventilation is to provide good air quality for the occupants. For this purpose the necessary ventilating air change rate must be determined. Within displacement ventilation the estimation is closely related to the air flow rate in the thermal plumes when an air quality based...

  8. Ship exhaust gas plume cooling

    NARCIS (Netherlands)

    Schleijpen, H.M.A.; Neele, P.P.

    2004-01-01

    The exhaust gas plume is an important and sometimes dominating contributor to the infrared signature of ships. Suppression of the infrared ship signatures has been studied by TNO for the Royal Netherlands Navy over considerable time. This study deals with the suppression effects, which can be

  9. Groundwater contaminant plume maps and volumes, 100-K and 100-N Areas, Hanford Site, Washington

    Science.gov (United States)

    Johnson, Kenneth H.

    2016-09-27

    extents are shown graphically and in tabular form for comparison to previous estimates. Plume data also were interpolated to a finer grid (10 × 10 m) for some processing, particularly to estimate volumes of contaminated groundwater. However, hydrogeologic transport modeling was not considered for the interpolation. The compilation of plume extents for each contaminant also allowed estimates of overlap of the plumes or areas with more than one contaminant above regulatory standards.A mapping of saturated aquifer thickness also was derived across the 100-K and 100–N study area, based on the vertical difference between the groundwater level (water table) at the top and the altitude of the top of the Ringold Upper Mud geologic unit, considered the bottom of the uppermost unconfined aquifer. Saturated thickness was calculated for each cell in the finer (10 × 10 m) grid. The summation of the cells’ saturated thickness values within each polygon of plume regulatory exceedance provided an estimate of the total volume of contaminated aquifer, and the results also were checked using a SURFER® volumetric integration procedure. The total volume of contaminated groundwater in each plume was derived by multiplying the aquifer saturated thickness volume by a locally representative value of porosity (0.3).Estimates of the uncertainty of the plume delineation also are presented. “Upper limit” plume delineations were calculated for each contaminant using the same procedure as the “average” plume extent except with values at each well that are set at a 95-percent upper confidence limit around the log-normally transformed mean concentrations, based on the standard error for the distribution of the mean value in that well; “lower limit” plumes are calculated at a 5-percent confidence limit around the geometric mean. These upper- and lower-limit estimates are considered unrealistic because the statistics were increased or decreased at each well simultaneously and were not

  10. Do buoyant plumes enhance cross-shelf transport in the Black Sea?

    Science.gov (United States)

    Sedakov, Roman; Zavialov, Peter; Izhitsky, Alexander

    2017-04-01

    either constant and different within each layer or a linear function of depth. In each case we obtain an analytical solution and derive a relation between seaward/shoreward transport and eddy viscosity. Both 2D and 3D models indicate that the stratified conditions damping vertical mixing lead to an increase of transport in the surface layer. This result corresponds well with the in situ observations, showing that buoyant plumes may indeed enhance advection of plume waters across shelf areas.

  11. Characterization of redox conditions in pollution plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwart, Steven A.

    2000-01-01

    Evalution of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...

  12. Chesapeake Bay plume dynamics from LANDSAT

    Science.gov (United States)

    Munday, J. C., Jr.; Fedosh, M. S.

    1981-01-01

    LANDSAT images with enhancement and density slicing show that the Chesapeake Bay plume usually frequents the Virginia coast south of the Bay mouth. Southwestern (compared to northern) winds spread the plume easterly over a large area. Ebb tide images (compared to flood tide images) show a more dispersed plume. Flooding waters produce high turbidity levels over the shallow northern portion of the Bay mouth.

  13. Oil Spill Detection and Modelling: Preliminary Results for the Cercal Accident

    Science.gov (United States)

    da Costa, R. T.; Azevedo, A.; da Silva, J. C. B.; Oliveira, A.

    2013-03-01

    two-dimensional surface plume transport model VOILS [1] with the oil spreading formulation enabled. The remaining oil weathering processes (evaporation, emulsification, dispersion and dissolution in the water column) and shoreline retention were disregarded. The computational structure of the model is based on Eulerian-Lagrangian formulations, horizontal unstructured mesh discretization and it is soft-coupled with the tri-dimensional hydrodynamic model SELFE - Semi-Implicit Eulerian Lagrangian Finite Element [15] that uses hybrid sigma-Z coordinates in the vertical. The preliminary results of this hindcast simulation for the Cercal oil spill are presented and compared with available satellite SAR images. The forcings used play an important role in the final results. During the late stage spreading phases of the oil, about one month after the spill, the Douro River outflow is best seen in the SAR images. The morphology of the river outflow is discussed according to traditional coastal dynamics, and compared with model results. In addition to several interesting physical features that were identified, we report on the generation of Internal Solitary Waves (ISW) in the vicinity of the Douro River Plume (DRP). It is well known that trains of short-period internal waves can be generated by river plumes (such as the Columbia River). The internal structure of the observed internal waves (elevation waves or mode-2 versus mode-1 internal waves) is discussed based on the SAR signatures and available stratification. The present work has been conducted under an FCT - Fundaç ão para a Ciência e a Tecnologia / MCTES - Ministério da Ciência, Tecnologia e Ensino Superior (PIDDAC - Programa de Investimentos e Despesas de Desenvolvimento da Administraç ão Central) Portuguese funded project entitled PAC:MAN Pollution accidents in coastal areas: a Risk management system (PTDC/AACAMB/113469/2008).

  14. Flying Training Capacity Model: Initial Results

    National Research Council Canada - National Science Library

    Lynch, Susan

    2005-01-01

    OBJECTIVE: (1) Determine the flying training capacity for 6 bases: * Sheppard AFB * Randolph AFB * Moody AFB * Columbus AFB * Laughlin AFB * Vance AFB * (2) Develop versatile flying training capacity simulation model for AETC...

  15. The influence of atmospheric conditions on the cooling tower plume of nuclear power station; Uticaj atmosferskih uslova na perjanicu rashladnih tornjeva nuklearne elektrane

    Energy Technology Data Exchange (ETDEWEB)

    Vehauc, A [Boris Kidric Institute of nuclear sciences, Vinca, Belgrade (Yugoslavia)

    1978-07-01

    The paper deals with the effect of atmospheric conditions - relative humidity, wind velocity, temperature and temperature gradient on the visible plume. For estimating cooling tower plumes, used was made of verified mathematical model. (author)

  16. Resolving superimposed ground-water contaminant plumes characterized by chromium, nitrate, uranium, and technetium--99

    International Nuclear Information System (INIS)

    Hall, S.H.

    1990-02-01

    Leakage from a liquid waste storage and solar evaporation basin at the Hanford Site in southeastern Washington State has resulted in a ground-water contaminant plume characterized by nitrate, hexavalent chromium, uranium, and technetium-99. The plume is superimposed on a larger, pre-existing plume extending from upgradient sites and having the same suite of contaminants. However, the relative abundance of contaminant species is quite different for each plume source. Thus, characteristic concentration ratios, rather than concentrations of individual species, are used as geochemical tracers, with emphasis on graphical analysis. Accordingly, it has been possible to resolve the boundaries of the smaller plume and to estimate the contribution of each plume to the observed contamination downgradient from the storage basin. 11 refs., 7 figs

  17. Turbulent forces within river plumes affect spread

    Science.gov (United States)

    Bhattacharya, Atreyee

    2012-08-01

    When rivers drain into oceans through narrow mouths, hydraulic forces squeeze the river water into buoyant plumes that are clearly visible in satellite images. Worldwide, river plumes not only disperse freshwater, sediments, and nutrients but also spread pollutants and organisms from estuaries into the open ocean. In the United States, the Columbia River—the largest river by volume draining into the Pacific Ocean from North America—generates a plume at its mouth that transports juvenile salmon and other fish into the ocean. Clearly, the behavior and spread of river plumes, such as the Columbia River plume, affect the nation's fishing industry as well as the global economy.

  18. Microbial populations in contaminant plumes

    Science.gov (United States)

    Haack, Sheridan K.; Bekins, Barbara A.

    Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation. La biodégradation efficace des polluants souterrains requiert deux éléments: des populations microbiennes possédant les aptitudes nécessaires à la dégradation, et des conditions géochimiques et hydrologiques souterraines favorables. Des contraintes pratiques sur la conception et l'interprétation des expériences à la fois en microbiologie et en hydrogéologie ont conduit à une connaissance limitée des interactions entre les

  19. Base pressure and heat transfer tests of the 0.0225-scale space shuttle plume simulation model (19-OTS) in yawed flight conditions in the NASA-Lewis 10x10-foot supersonic wind tunnel (test IH83)

    Science.gov (United States)

    Foust, J. W.

    1979-01-01

    Wind tunnel tests were performed to determine pressures, heat transfer rates, and gas recovery temperatures in the base region of a rocket firing model of the space shuttle integrated vehicle during simulated yawed flight conditions. First and second stage flight of the space shuttle were simulated by firing the main engines in conjunction with the SRB rocket motors or only the SSME's into the continuous tunnel airstream. For the correct rocket plume environment, the simulated altitude pressures were halved to maintain the rocket chamber/altitude pressure ratio. Tunnel freestream Mach numbers from 2.2 to 3.5 were simulated over an altitude range of 60 to 130 thousand feet with varying angle of attack, yaw angle, nozzle gimbal angle and SRB chamber pressure. Gas recovery temperature data derived from nine gas temperature probe runs are presented. The model configuration, instrumentation, test procedures, and data reduction are described.

  20. Graphical interpretation of numerical model results

    International Nuclear Information System (INIS)

    Drewes, D.R.

    1979-01-01

    Computer software has been developed to produce high quality graphical displays of data from a numerical grid model. The code uses an existing graphical display package (DISSPLA) and overcomes some of the problems of both line-printer output and traditional graphics. The software has been designed to be flexible enough to handle arbitrarily placed computation grids and a variety of display requirements

  1. Lower-mantle plume beneath the Yellowstone hotspot revealed by core waves

    Science.gov (United States)

    Nelson, Peter L.; Grand, Stephen P.

    2018-04-01

    The Yellowstone hotspot, located in North America, is an intraplate source of magmatism the cause of which is hotly debated. Some argue that a deep mantle plume sourced at the base of the mantle supplies the heat beneath Yellowstone, whereas others claim shallower subduction or lithospheric-related processes can explain the anomalous magmatism. Here we present a shear wave tomography model for the deep mantle beneath the western United States that was made using the travel times of core waves recorded by the dense USArray seismic network. The model reveals a single narrow, cylindrically shaped slow anomaly, approximately 350 km in diameter that we interpret as a whole-mantle plume. The anomaly is tilted to the northeast and extends from the core-mantle boundary to the surficial position of the Yellowstone hotspot. The structure gradually decreases in strength from the deepest mantle towards the surface and if it is purely a thermal anomaly this implies an initial excess temperature of 650 to 850 °C. Our results strongly support a deep origin for the Yellowstone hotspot, and also provide evidence for the existence of thin thermal mantle plumes that are currently beyond the resolution of global tomography models.

  2. Laser beam-plasma plume interaction during laser welding

    Science.gov (United States)

    Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

    2003-10-01

    Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

  3. The Entrainment Rate for Buoyant Plumes in a Crossflow

    Science.gov (United States)

    Devenish, B. J.; Rooney, G. G.; Webster, H. N.; Thomson, D. J.

    2010-03-01

    We consider large-eddy simulations (LES) of buoyant plumes from a circular source with initial buoyancy flux F 0 released into a stratified environment with constant buoyancy frequency N and a uniform crossflow with velocity U. We make a systematic comparison of the LES results with the mathematical theory of plumes in a crossflow. We pay particular attention to the limits {tilde{U}≪1} and {tilde{U}≫ 1}, where {tilde{U}=U/(F_0 N)^{1/4}}, for which analytical results are possible. For {tilde{U}≫ 1}, the LES results show good agreement with the well-known two-thirds law for the rise in height of the plume. Sufficiently far above the source, the centreline vertical velocity of the LES plumes is consistent with the analytical z -1/3 and z -1/2 scalings for respectively {tilde{U}≪ 1} and {tilde{U}≫ 1}. In the general case, where the entrainment is assumed to be the sum of the contributions from the horizontal and vertical velocity components, we find that the discrepancy between the LES data and numerical solutions of the plume equations is largest for {tilde{U}=O(1)}. We propose a modified additive entrainment assumption in which the contributions from the horizontal and vertical velocity components are not equally weighted. We test this against observations of the plume generated by the Buncefield fire in the U.K. in December 2005 and find that the results compare favourably. We also show that the oscillations of the plume as it settles down to its final rise height may be attenuated by the radiation of gravity waves. For {tilde{U}≪ 1} the oscillations decay rapidly due to the transport of energy away from the plume by gravity waves. For {tilde{U}>rsim 1} the gravity waves travel in the same direction and at the same speed as the flow. In this case, the oscillations of the plume do not decay greatly by radiation of gravity waves.

  4. Subduction, Extension, and a Mantle Plume in the Pacific Northwest

    Science.gov (United States)

    Hawley, W. B.; Allen, R. M.; Richards, M. A.

    2016-12-01

    Subduction zones are some of the most important systems that control the dynamics and evolution of the earth. The Cascadia Subduction Zone offers a unique natural laboratory for understanding the subduction process, and how subduction interacts with other large-scale geodynamical phenomena. The small size of the Juan de Fuca (JdF) plate and the proximity of the system to the Yellowstone Hotspot and the extensional Basin and Range province allow for detailed study of the effects these important systems have on each other. We present both a P-wave and an S-wave tomographic model of the Pacific Northwestern United States using regional seismic arrays, including the amphibious Cascadia Initiative. These models share important features, such as the Yellowstone plume, the subducting JdF slab, a gap in the subducting slab, and a low-velocity feature beneath the shallowest portions of the slab. But subtle differences in these features between the models—the size of the gap in the subducting JdF slab and the shape of the Yellowstone plume shaft above the transition zone, for example—provide physical insight into the interpretation of these models. The physics that we infer from our seismic tomography and other studies of the region will refine our understanding of subduction zones worldwide, and will help to identify targets for future amphibious seismic array studies. The discovery of a pronounced low-velocity feature beneath the JdF slab as it subducts beneath the coastal Pacific Northwest is, thus far, the most surprising result from our imaging work, and implies a heretofore unanticipated regime of dynamical interaction between the sublithospheric oceanic asthenosphere and the subduction process. Such discoveries are made possible, and rendered interpretable, by ever-increasing resolution that the Cascadia Initiative affords seismic tomography models.

  5. Ignalina NPP Safety Analysis: Models and Results

    International Nuclear Information System (INIS)

    Uspuras, E.

    1999-01-01

    Research directions, linked to safety assessment of the Ignalina NPP, of the scientific safety analysis group are presented: Thermal-hydraulic analysis of accidents and operational transients; Thermal-hydraulic assessment of Ignalina NPP Accident Localization System and other compartments; Structural analysis of plant components, piping and other parts of Main Circulation Circuit; Assessment of RBMK-1500 reactor core and other. Models and main works carried out last year are described. (author)

  6. Field experimental observations of highly graded sediment plumes.

    Science.gov (United States)

    Jensen, Jacob Hjelmager; Saremi, Sina; Jimenez, Carlos; Hadjioannou, Louis

    2015-06-15

    A field experiment in the waters off the south-eastern coast of Cyprus was carried out to study near-field formation of sediment plumes from dumping. Different loads of sediment were poured into calm and limpid waters one at the time from just above the sea surface. The associated plumes, gravitating towards the seafloor, were filmed simultaneously by four divers situated at different depths in the water column, and facing the plume at different angles. The processes were captured using GoPro-Hero-series cameras. The high-quality underwater footage from near-surface, mid-depth and near-bed positions gives unique insight into the dynamics of the descending plume and near-field dispersion processes, and enables good understanding of flow and sediment transport processes involved from-release-to-deposition of the load in a non-scaled environment. The high resolution images and footages are available through the link provided herein. Observations support the development of a detailed multi-fractional sediment plume model. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Comparison of results from dispersion models for regulatory purposes based on Gaussian-and Lagrangian-algorithms: an evaluating literature study

    International Nuclear Information System (INIS)

    Walter, H.

    2004-01-01

    Powerful tools to describe atmospheric transport processes for radiation protection can be provided by meteorology; these are atmospheric flow and dispersion models. Concerning dispersion models, Gaussian plume models have been used since a long time to describe atmospheric dispersion processes. Advantages of the Gaussian plume models are short computation time, good validation and broad acceptance worldwide. However, some limitations and their implications on model result interpretation have to be taken into account, as the mathematical derivation of an analytic solution of the equations of motion leads to severe constraints. In order to minimise these constraints, various dispersion models for scientific and regulatory purposes have been developed and applied. Among these the Lagrangian particle models are of special interest, because these models are able to simulate atmospheric transport processes close to reality, e.g. the influence of orography, topography, wind shear and other meteorological phenomena. Within this study, the characteristics and computational results of Gaussian dispersion models as well as of Lagrangian models have been compared and evaluated on the base of numerous papers and reports published in literature. Special emphasis has been laid on the intention that dispersion models should comply with EU requests (Richtlinie 96/29/Euratom, 1996) on a more realistic assessment of the radiation exposure to the population. (orig.)

  8. Channelization of plumes beneath ice shelves

    KAUST Repository

    Dallaston, M.  C.; Hewitt, I. J.; Wells, A. J.

    2015-01-01

    © 2015 Cambridge University Press. We study a simplified model of ice-ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

  9. Channelization of plumes beneath ice shelves

    KAUST Repository

    Dallaston, M. C.

    2015-11-11

    © 2015 Cambridge University Press. We study a simplified model of ice-ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

  10. Multi-temporal dynamics of suspended particulate matter in a macro-tidal river Plume (the Gironde) as observed by satellite data

    Science.gov (United States)

    Constantin, Sorin; Doxaran, David; Derkacheva, Anna; Novoa, Stéfani; Lavigne, Héloïse

    2018-03-01

    The Gironde River plume area is unique in terms of Suspended Particulate Matter (SPM) dynamics. Multiple factors contribute to the variations of SPM at multiple time scales, from river outputs to wind stress, currents and tidal cycles. The formation and evolution of the Maximum Turbidity Zone (MTZ) inside the estuary also plays a significant role. Thus, detailed analyses and monitoring of the region is important for better understanding the mechanisms governing the turbid plume dynamics, for proper future management and monitoring of SPM export from the estuary to the coastal ocean. In this study we use an unprecedented volume of satellite data to capture and better understand the dynamics of the river plume. We combine two types of satellite information in order to achieve these goals: data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Spinning Enhanced Visible and Infrared Imager (SEVIRI) sensors. The integrated information allows accounting for multiple time scales, i.e. from seasonal to diurnal cycles. We show and parameterize the overall effects of river discharge rates over the plume extension. Seasonal variations are also analyzed and an overall relationship between river discharge rates and plume magnitude is computed. For the first time, we clearly observe and explain the diurnal cycle of SPM dynamics in the river plume. Despite the limited capabilities of the SEVIRI sensor, geostationary data was successfully used to derive such information and results similar to in-situ datasets were obtained. The same patterns are observed, with significant increase in SPM plume during spring/ebb tide periods. Results from our study can be further used to refine sediment transport models and to gain a better perspective on the ecological implications of the sediment output in the continental shelf area.

  11. Development of upwelling on pathway and freshwater transport of Pearl River plume in northeastern South China Sea

    Science.gov (United States)

    Chen, Zhaoyun; Jiang, Yuwu; Liu, James T.; Gong, Wenping

    2017-08-01

    In situ observations, satellite images, and numerical modeling results have shown that the Pearl River plume axis extends alongshore and passes through two separate upwelling regions—one off the Guangdong and Fujian coasts (the Yuedong upwelling) and the other in the Taiwan Bank during the initial and medium stages of the Yuedong upwelling, while it is directed offshore when the Yuedong upwelling is strong. Model experiments are conducted to examine the effects of wind strength and baroclinicity on the upwelling and the corresponding pathway and freshwater transport of the Pearl River plume. The baroclinic effect is important to intensifying the horizontal velocity at the upwelling front and freshwater transport in the northeastern South China Sea. The freshwater transport flux is further decomposed into advection, vertical shear, and tidal pumping components, and advection is the dominant contributor. As the Yuedong upwelling develops, the zone with a relatively high-pressure gradient moves offshore due to offshore Ekman transport and the shift in the upwelling front, which is responsible for the offshore transport of the river plume. When the river plume is transported to the outer-shelf, sometimes it can be further entrained into eddies, allowing its export to the open sea.

  12. Far-reaching transport of Pearl River plume water by upwelling jet in the northeastern South China Sea

    Science.gov (United States)

    Chen, Zhaoyun; Pan, Jiayi; Jiang, Yuwu; Lin, Hui

    2017-09-01

    Satellite images from the Moderate Resolution Imaging Spectroradiometer (MODIS) show that there was a belt of turbid water appearing along an upwelling front near the Chinese coast of Guangdong, and indicate that the turbid water of the Pearl River plume water could be transported to a far-reaching area east of the Taiwan Bank. Numerical modeling results are consistent with the satellite observations, and reveal that a strong jet exists at the upwelling front with a speed as high as 0.8 m s- 1, which acts as a pathway for transporting the high-turbidity plume water. The dynamical analysis suggests that geostrophic equilibrium dominates in the upwelling front and plume areas, and the baroclinicity of the upwelling front resulting from the horizontal density gradient is responsible for the generation of the strong jet, which enhances the far-reaching transport of the terrigenous nutrient-rich water of the Pearl River plume. Model sensitivity analyses also confirm that this jet persists as long as the upwelling front exists, even when the wind subsides and becomes insignificant. Further idealized numerical model experiments indicate that the formation and persistence of the upwelling front jet depend on the forcing strength of the upwelling-favorable wind. The formation time of the jet varies from 15 to 158 h as the stress of the upwelling-favorable wind changes from 0.2 to 0.01 N m- 2. With the persistent transport of the nutrient-rich plume water, biophysical activities can be promoted significantly in the far-reaching destination area of the oligotrophic water.

  13. Plume Mitigation: Soil Erosion and Lunar Prospecting Sensor Project

    Science.gov (United States)

    Metzger, Philip T.

    2014-01-01

    Demonstrate feasibility of the simplest, lowest-mass method of measuring density of a cloud of lunar soil ejected by rocket exhaust, using new math techniques with a small baseline laser/camera system. Focus is on exploring the erosion process that occurs when the exhaust plume of a lunar rocket impacts the regolith. Also, predicting the behavior of the lunar soil that would be blasted from a lunar landing/launch site shall assist in better design and protection of any future lunar settlement from scouring of structures and equipment. NASA is gathering experimental data to improve soil erosion models and understand how lunar particles enter the plume flow.

  14. Calculation of cooling tower plumes for high pressure wintry situations

    International Nuclear Information System (INIS)

    Gassmann, F.; Tinguely, M.; Haschke, D.

    1982-12-01

    The diffusion of the plumes of the projected nuclear power plants at Kaiseraugst and Schwoerstadt, during high pressure wintry conditions, has been examined using a mathematical model to simulate the plumes. For these calculations, microaerological measurements were made in the proximity of Kaiseraugst and Schwoerstadt. These give a typical image of the weather during high pressure wintry conditions, which is normally associated with an inversion, sometimes strong, at a low height. Dry cooling towers with natural draught, which offer an alternative solution to the wet cooling towers proposed for Kasieraugst, are examined equally. (Auth./G.T.H.)

  15. Magnetic Detachment and Plume Control in Escaping Magnetized Plasma

    International Nuclear Information System (INIS)

    Schmit, P.F.; Fisch, N.J.

    2008-01-01

    The model of two-fluid, axisymmetric, ambipolar magnetized plasma detachment from thruster guide fields is extended to include plasmas with non-zero injection angular velocity profiles. Certain plasma injection angular velocity profiles are shown to narrow the plasma plume, thereby increasing exhaust efficiency. As an example, we consider a magnetic guide field arising from a simple current ring and demonstrate plasma injection schemes that more than double the fraction of useful exhaust aperture area, more than halve the exhaust plume angle, and enhance magnetized plasma detachment

  16. Loire and Gironde turbid plumes: Characterization and influence on thermohaline properties

    Science.gov (United States)

    Costoya, X.; Fernández-Nóvoa, D.; deCastro, M.; Gómez-Gesteira, M.

    2017-12-01

    Knowledge and predictability of turbid river plumes is of great importance because they modulate the properties of the seawater adjacent to river mouths. The Loire and Gironde Rivers form the most important plumes in the Bay of Biscay, as they provide > 75% of total runoff. The development of the turbid plume under the influence of its main drivers was analyzed using Moderate Resolution Imaging Spectroradiometer satellite data from the period 2003-2015. River discharge was found to be the main driver, followed by wind, which also had an important effect in modulating the turbid plume during periods of high river discharge. Seaward and upwelling favorable winds enhanced the dispersion of plumes on seawater, whereas landward and downwelling favorable winds limited mixing with the adjacent ocean water. The maximum extension of the turbid plume was reached under landward winds. In addition, the spatio-temporal evolution of the East Atlantic pattern and the North Atlantic Oscillation was observed to affect the dynamics of plumes: positive values of both indices favored a greater extension of the plume. Thermohaline properties differed inside and outside the area affected by both rivers. In particular, these rivers maintain winter stratification inside the turbid plume, which results in a different warming ratio when compared with the adjacent ocean.

  17. Microplasticity of MMC. Experimental results and modelling

    International Nuclear Information System (INIS)

    Maire, E.; Lormand, G.; Gobin, P.F.; Fougeres, R.

    1993-01-01

    The microplastic behavior of several MMC is investigated by means of tension and compression tests. This behavior is assymetric : the proportional limit is higher in tension than in compression but the work hardening rate is higher in compression. These differences are analysed in terms of maxium of the Tresca's shear stress at the interface (proportional limit) and of the emission of dislocation loops during the cooling (work hardening rate). On another hand, a model is proposed to calculate the value of the yield stress, describing the composite as a material composed of three phases : inclusion, unaffected matrix and matrix surrounding the inclusion having a gradient in the density of the thermally induced dilocations. (orig.)

  18. Microplasticity of MMC. Experimental results and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Maire, E. (Groupe d' Etude de Metallurgie Physique et de Physique des Materiaux, INSA, 69 Villeurbanne (France)); Lormand, G. (Groupe d' Etude de Metallurgie Physique et de Physique des Materiaux, INSA, 69 Villeurbanne (France)); Gobin, P.F. (Groupe d' Etude de Metallurgie Physique et de Physique des Materiaux, INSA, 69 Villeurbanne (France)); Fougeres, R. (Groupe d' Etude de Metallurgie Physique et de Physique des Materiaux, INSA, 69 Villeurbanne (France))

    1993-11-01

    The microplastic behavior of several MMC is investigated by means of tension and compression tests. This behavior is assymetric : the proportional limit is higher in tension than in compression but the work hardening rate is higher in compression. These differences are analysed in terms of maxium of the Tresca's shear stress at the interface (proportional limit) and of the emission of dislocation loops during the cooling (work hardening rate). On another hand, a model is proposed to calculate the value of the yield stress, describing the composite as a material composed of three phases : inclusion, unaffected matrix and matrix surrounding the inclusion having a gradient in the density of the thermally induced dilocations. (orig.).

  19. ARCON96, Radioactive Plume Concentration in Reactor Control Rooms

    International Nuclear Information System (INIS)

    Ramsdell, J.V.; Simonen, C.A.

    2003-01-01

    1 - Description of program or function: ARCON96 was developed to calculate relative concentrations in plumes from nuclear power plants at control room air intakes in the vicinity of the release point. 2 - Methods: ARCON96 implements a straight-line Gaussian dispersion model with dispersion coefficients that are modified to account for low wind meander and building wake effects. Hourly, normalized concentrations (X/Q) are calculated from hourly meteorological data. The hourly values are averaged to form X/Qs for periods ranging from 2 to 720 hours in duration. The calculated values for each period are used to form cumulative frequency distributions. 3 - Restriction on the complexity of the problem: ARCON96 is a single user program. If expanded output is selected by the user, the file includes the hourly input and X/Qs and the intermediate computational results. The output file may exceed a megabyte size

  20. Numerical investigation of two interacting parallel thruster-plumes and comparison to experiment

    Science.gov (United States)

    Grabe, Martin; Holz, André; Ziegenhagen, Stefan; Hannemann, Klaus

    2014-12-01

    Clusters of orbital thrusters are an attractive option to achieve graduated thrust levels and increased redundancy with available hardware, but the heavily under-expanded plumes of chemical attitude control thrusters placed in close proximity will interact, leading to a local amplification of downstream fluxes and of back-flow onto the spacecraft. The interaction of two similar, parallel, axi-symmetric cold-gas model thrusters has recently been studied in the DLR High-Vacuum Plume Test Facility STG under space-like vacuum conditions, employing a Patterson-type impact pressure probe with slot orifice. We reproduce a selection of these experiments numerically, and emphasise that a comparison of numerical results to the measured data is not straight-forward. The signal of the probe used in the experiments must be interpreted according to the degree of rarefaction and local flow Mach number, and both vary dramatically thoughout the flow-field. We present a procedure to reconstruct the probe signal by post-processing the numerically obtained flow-field data and show that agreement to the experimental results is then improved. Features of the investigated cold-gas thruster plume interaction are discussed on the basis of the numerical results.

  1. A cold plasma plume with a highly conductive liquid electrode

    International Nuclear Information System (INIS)

    Chen Guangliang; Chen Wenxing; Chen Shihua; Yang Size

    2008-01-01

    A cold dielectric barrier discharge (DBD) plasma plume with one highly conductive liquid electrode has been developed to treat thermally sensitive materials, and its preliminary discharging characteristics have been studied. The averaged electron temperature and density is estimated to be 0.6eV and 10 11 /cm 3 , respectively. The length of plasma plume can reach 5 cm with helium gas (He), and the conductivity of the outer electrode affects the plume length obviously. This plasma plume could be touched by bare hand without causing any burning or painful sensation, which may provide potential application for safe aseptic skin care. Moreover, the oxidative particles (e.g., OH, O * , O 3 ) in the downstream oxygen (O2) gas of the plume have been applied to treat the landfill leachate. The results show that the activated O 2 gas can degrade the landfill leachate effectively, and the chemical oxygen demand (COD), conductivity, biochemical oxygen demand (BOD), and suspended solid (SS) can be decreased by 52%, 57%, 76% and 92%, respectively. (fluids, plasmas and electric discharges)

  2. Sewage outfall plume dispersion observations with an autonomous underwater vehicle.

    Science.gov (United States)

    Ramos, P; Cunha, S R; Neves, M V; Pereira, F L; Quintaneiro, I

    2005-01-01

    This work represents one of the first successful applications of Autonomous Underwater Vehicles (AUVs) for interdisciplinary coastal research. A monitoring mission to study the shape and estimate the initial dilution of the S. Jacinto sewage outfall plume using an AUV was performed on July 2002. An efficient sampling strategy enabling greater improvements in spatial and temporal range of detection demonstrated that the sewage effluent plume can be clearly traced using naturally occurring tracers in the wastewater. The outfall plume was found at the surface highly influenced by the weak stratification and low currents. Dilution varying with distance downstream was estimated from the plume rise over the outfall diffuser until a nearly constant value of 130:1, 60 m from the diffuser, indicating the near field end. Our results demonstrate that AUVs can provide high-quality measurements of physical properties of effluent plumes in a very effective manner and valuable considerations about the initial mixing processes under real oceanic conditions can be further investigated.

  3. Prediction of fluctuating pressure environments associated with plume-induced separated flow fields

    Science.gov (United States)

    Plotkin, K. J.

    1973-01-01

    The separated flow environment induced by underexpanded rocket plumes during boost phase of rocket vehicles has been investigated. A simple semi-empirical model for predicting the extent of separation was developed. This model offers considerable computational economy as compared to other schemes reported in the literature, and has been shown to be in good agreement with limited flight data. The unsteady pressure field in plume-induced separated regions was investigated. It was found that fluctuations differed from those for a rigid flare only at low frequencies. The major difference between plume-induced separation and flare-induced separation was shown to be an increase in shock oscillation distance for the plume case. The prediction schemes were applied to PRR shuttle launch configuration. It was found that fluctuating pressures from plume-induced separation are not as severe as for other fluctuating environments at the critical flight condition of maximum dynamic pressure.

  4. Infrared Imagery of Solid Rocket Exhaust Plumes

    Science.gov (United States)

    Moran, Robert P.; Houston, Janice D.

    2011-01-01

    The Ares I Scale Model Acoustic Test program consisted of a series of 18 solid rocket motor static firings, simulating the liftoff conditions of the Ares I five-segment Reusable Solid Rocket Motor Vehicle. Primary test objectives included acquiring acoustic and pressure data which will be used to validate analytical models for the prediction of Ares 1 liftoff acoustics and ignition overpressure environments. The test article consisted of a 5% scale Ares I vehicle and launch tower mounted on the Mobile Launch Pad. The testing also incorporated several Water Sound Suppression Systems. Infrared imagery was employed during the solid rocket testing to support the validation or improvement of analytical models, and identify corollaries between rocket plume size or shape and the accompanying measured level of noise suppression obtained by water sound suppression systems.

  5. Emissions lifetimes and ozone formation in power plant plumes

    International Nuclear Information System (INIS)

    Ryerson, T.B.; Buhr, M.P.; Frost, G.J.; Goldan, P.D.; Holloway, J.S.; Huebler, G.; Jobson, B.T.; Kuster, W.C.; McKeen, S.A.; Parrish, D.D.; Roberts, J.M.; Sueper, D.T.; Trainer, M.; Williams, J.; Fehsenfeld, F.C.

    1998-01-01

    The concept of ozone production efficiency (OPE) per unit NO x is based on photochemical models and provides a tool with which to assess potential regional tropospheric ozone control strategies involving NO x emissions reductions. An aircraft study provided data from which power plant emissions removal rates and measurement-based estimates of OPE are estimated. This study was performed as part of the Southern Oxidants Study - 1995 Nashville intensive and focuses on the evolution of NO x , SO 2 , and ozone concentrations in coal-fired power plant plumes during transport. Two approaches are examined. A mass balance approach accounts for mixing effects within the boundary layer and is used to calculate effective boundary layer removal rates for NO x and SO 2 and to estimate net OPE, Net OPE is more directly comparable to photochemical model results than previous measurement-based estimates. Derived net production efficiencies from mass balance range from 1 to 3 molecules of ozone produced per molecule of NO x emitted. A concentration ratio approach provides an estimate of removal rates of primary emissions relative to a tracer species. This approach can be combined with emissions ratio information to provide upper limit estimates of OPE that range from 2 to 7. Both approaches illustrate the dependence of ozone production on NO x source strength in these large point source plumes. The dependence of total ozone production, ozone production efficiency, and the rate of ozone production on NO x source strength is examined. These results are interpreted in light of potential ozone control strategies for the region. 42 refs., 8 figs., 5 tabs

  6. Emissions lifetimes and ozone formation in power plant plumes

    Energy Technology Data Exchange (ETDEWEB)

    Ryerson, T.B.; Buhr, M.P.; Frost, G.J.; Goldan, P.D.; Holloway, J.S.; Huebler, G.; Jobson, B.T.; Kuster, W.C.; McKeen, S.A.; Parrish, D.D.; Roberts, J.M.; Sueper, D.T.; Trainer, M.; Williams, J.; Fehsenfeld, F.C. [NOAA Aeronomy Laboratory, Boulder, CO (United States)

    1998-09-20

    The concept of ozone production efficiency (OPE) per unit NO{sub x} is based on photochemical models and provides a tool with which to assess potential regional tropospheric ozone control strategies involving NO{sub x} emissions reductions. An aircraft study provided data from which power plant emissions removal rates and measurement-based estimates of OPE are estimated. This study was performed as part of the Southern Oxidants Study - 1995 Nashville intensive and focuses on the evolution of NO{sub x}, SO{sub 2}, and ozone concentrations in coal-fired power plant plumes during transport. Two approaches are examined. A mass balance approach accounts for mixing effects within the boundary layer and is used to calculate effective boundary layer removal rates for NO{sub x} and SO{sub 2} and to estimate net OPE, Net OPE is more directly comparable to photochemical model results than previous measurement-based estimates. Derived net production efficiencies from mass balance range from 1 to 3 molecules of ozone produced per molecule of NO{sub x} emitted. A concentration ratio approach provides an estimate of removal rates of primary emissions relative to a tracer species. This approach can be combined with emissions ratio information to provide upper limit estimates of OPE that range from 2 to 7. Both approaches illustrate the dependence of ozone production on NO{sub x} source strength in these large point source plumes. The dependence of total ozone production, ozone production efficiency, and the rate of ozone production on NO{sub x} source strength is examined. These results are interpreted in light of potential ozone control strategies for the region. 42 refs., 8 figs., 5 tabs.

  7. Growth of plume ''resident'' fishes in Lake Michigan

    International Nuclear Information System (INIS)

    Spigarelli, S.A.; Smith, D.W.

    1974-01-01

    Brown trout, rainbow trout, and chinook salmon were collected from the Point Beach thermal discharge area, tagged with commercial dart tags and temperature-sensitive tags, and released back into the discharge area. RNA and DNA analyses were performed on epaxial muscle samples taken from each tagged fish recaptured in the plume area and from control fish. A table is presented to show mean weights, condition factors, and RNA-DNA ratios for each group of fish. Results indicated that the fish did not experience any severe growth abnormalities as a result of their residence in the thermal plume area