Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.
Berkouk, K; Carpenter, P W; Lucey, A D
2003-12-01
Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.
Carpenter, P W; Berkouk, K; Lucey, A D
2003-12-01
Our aim in this paper is to use a simple theoretical model of the intraspinal cerebrospinal-fluid system to investigate mechanisms proposed for the pathogenesis of syringomyelia. The model is based on an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. According to this model, the leading edge of a pressure pulse tends to steepen and form an elastic jump, as it propagates up the intraspinal cerebrospinal-fluid system. We show that when an elastic jump is incident on a stenosis of the spinal subarachnoid space, it reflects to form a transient, localized region of high pressure within the spinal cord that for a cough-induced pulse is estimated to be 50 to 70 mm Hg or more above the normal level in the spinal subarachnoid space. We propose this as a new mechanism whereby pressure pulses created by coughing or sneezing can generate syrinxes. We also use the same analysis to investigate Williams' suck mechanism. Our results do not support his concept, nor, in cases where the stenosis is severe, the differential-pressure-propagation mechanism recently proposed by Greitz et al. Our analysis does provide some support for the piston mechanism recently proposed by Oldfield et al. and Heiss et al. For instance, it shows clearly how the spinal cord is compressed by the formation of elastic jumps over part of the cardiac cycle. What appears to be absent for this piston mechanism is any means whereby the elastic jumps can be focused (e.g., by reflecting from a stenosis) to form a transient, localized region of high pressure within the spinal cord. Thus it would seem to offer a mechanism for syrinx progression, but not for its formation.
COUPLED CHEMOTAXIS FLUID MODEL
LORZ, ALEXANDER
2010-06-01
We consider a model system for the collective behavior of oxygen-driven swimming bacteria in an aquatic fluid. In certain parameter regimes, such suspensions of bacteria feature large-scale convection patterns as a result of the hydrodynamic interaction between bacteria. The presented model consist of a parabolicparabolic chemotaxis system for the oxygen concentration and the bacteria density coupled to an incompressible Stokes equation for the fluid driven by a gravitational force of the heavier bacteria. We show local existence of weak solutions in a bounded domain in d, d = 2, 3 with no-flux boundary condition and in 2 in the case of inhomogeneous Dirichlet conditions for the oxygen. Â© 2010 World Scientific Publishing Company.
Large co-axial pulse tube preliminary results
Emery, N.; Caughley, A.; Meier, J.; Nation, M.; Tanchon, J.; Trollier, T.; Ravex, A.
2014-01-01
We report that Callaghan Innovation, formally known as Industrial Research Ltd (IRL), has designed and built its largest of three high frequency single-stage co-axial pulse tubes, closely coupled to a metal diaphragm pressure wave generator (PWG). The previous pulse tube achieved 110 W of cooling power @ 77 K, with an electrical input power of 3.1 kW from a 90 cc swept volume PWG. The pulse tubes have all been tuned to operate at 50 Hz, with a mean helium working pressure of 2.5 MPa. Sage pulse tube simulation software was used to model the latest pulse tube and predicted 280 W of cooling power @ 77 K. The nominal 250 W cryocooler was designed to be an intermediate step to up-scale pulse tube technology for our 1000 cc swept-volume PWG, to provide liquefaction of gases and cooling for HTS applications. Details of the modeling, design, development and preliminary experimental results are discussed.
Fluid Model of Waveguide Transverse Coupling
Institute of Scientific and Technical Information of China (English)
æ—
2003-01-01
In this paper, optical fluid is firstly defined. By using the movement law of hydrodynamics, the transverse coupling of waveguides is discussed. The result fully coincides with the electromagnetic solution.
Mechanics of coupled granular/fluid flows
Vinningland, J.; Toussaint, R.; Johnsen, O.; Flekkoy, E. G.; Maloy, K. J.
2006-12-01
We introduce a hybrid numerical model for coupled flow of solid grains and intersticial fluid, which renders for complex hydrodynamic interactions between mobile grains. This model treats the solid phase as discrete particles, interacting mechanically with the other particles and with the intersticial flowing fluid. The fluid is described by continuum equations rendering for its advection by the local grains, superposed to a pressure diffusion ruled by a Darcy flow with a permeability depending on the local solid fraction. This model is aimed at describing accurately such coupled flow. This model is tested for two model situations, where it is compared to experimental results: 1/ Injection of a localized overpressure in a grain/fluid filled cell lying horizontally, where gravity is unimportant. 2/ Sedimentation of heavy grains falling into an initially grain-free fluid region. The development of pattern-forming instabilities is obtained in these two situations, corresponding to granular/fluid equivalents of the two-fluids Saffman-Taylor and Rayleigh-Taylor instabilities. Numerical and experimental results are shown to be consistent with each other.
Dark Viscous Fluid coupled with Dark Matter and future singularity
Sebastiani, Lorenzo
2010-01-01
We study effects of viscous fluid coupled with dark matter in our universe. We consider bulk viscosity in the cosmic fluid and we suppose the existence of a coupling between fluid and dark matter, in order to reproduce a stable de Sitter universe protected against future-time singularities. More general inhomogeneous fluids are studied related to future singularities.
Mechanics of couple-stress fluid coatings
Waxman, A. M.
1982-01-01
The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.
Dynamics of non-minimally coupled perfect fluids
Bettoni, Dario
2015-01-01
We present a general formulation of the theory for a non-minimally coupled perfect fluid in which both conformal and disformal couplings are present. We discuss how such non-minimal coupling is compatible with the assumptions of a perfect fluid and derive both the Einstein and the fluid equations for such model. We found that, while the Euler equation is significantly modified with the introduction of an extra force related to the local gradients of the curvature, the continuity equation is unaltered, thus allowing for the definition of conserved quantities along the fluid flow. As an application to cosmology and astrophysics we compute the effects of the non-minimal coupling on a Friedmann--Lema\\^itre--Robertson--Walker background metric and on the Newtonian limit of our theory.
Fluid coupling in a discrete model of cochlear mechanics.
Elliott, Stephen J; Lineton, Ben; Ni, Guangjian
2011-09-01
A discrete model of cochlear mechanics is introduced that includes a full, three-dimensional, description of fluid coupling. This formulation allows the fluid coupling and basilar membrane dynamics to be analyzed separately and then coupled together with a simple piece of linear algebra. The fluid coupling is initially analyzed using a wavenumber formulation and is separated into one component due to one-dimensional fluid coupling and one comprising all the other contributions. Using the theory of acoustic waves in a duct, however, these two components of the pressure can also be associated with a far field, due to the plane wave, and a near field, due to the evanescent, higher order, modes. The near field components are then seen as one of a number of sources of additional longitudinal coupling in the cochlea. The effects of non-uniformity and asymmetry in the fluid chamber areas can also be taken into account, to predict both the pressure difference between the chambers and the mean pressure. This allows the calculation, for example, of the effect of a short cochlear implant on the coupled response of the cochlea.
Investigation of multipactor breakdown in communication satellite microwave co-axial systems
Indian Academy of Sciences (India)
S K Nagesh; D Revannasiddiah; S V K Shastry
2005-01-01
Multipactor breakdown or multipactor discharge is a form of high frequency discharge that may occur in microwave components operating at very low pressures. Some RF components of multi-channel communication satellites have co-axial geometry and handle high RF power under near-vacuum conditions. The breakdown occurs due to secondary electron resonance, wherein electrons move back and forth in synchronism with the RF voltage across the gap between the inner and outer conductors of the co-axial structure. If the yield of secondary electrons from the walls of the co-axial structure is greater than unity, then the electron density increases with time and eventually leads to the breakdown. In this paper, the current due to the oscillating electrons in the co-axial geometry has been treated as a radially oriented Hertzian dipole. The electric field, due to this dipole, at any point in the coaxial structure, may then be determined by employing the dyadic Greenâ€™s function technique. This field has been compared with the field that would exist in the absence of multipactor.
Modal analysis of two identical circular plates coupled with fluid
Energy Technology Data Exchange (ETDEWEB)
Jeong, Kyeong Hoon; Lee, Gyu Mahn; Park, Keun Bae; Chang, Moon Hee
2001-01-01
An analytical method for evaluating the free vibration of two identical circular plates coupled with fluid was developed by assuming the clamped boundary condition of the plates and an ideal fluid. The method was based upon the finite Fourier-Bessel series expansion and the Rayleigh-Riz method. The proposed method is verified by finite element analyses using commercial software, ANSYS (release 5.6) with good accuracy. Two transverse vibration modes, namely in-phase and out-of-phase, are observed alternately in the fluid-coupled system when the number of nodal circles increases for the fixed nodal diameter. It is found that the normalized natural frequency of the fluid-coupled system monotonically increases with an increase in the number of nodal diameters and circles by virtue of a decrease in relative hydrodynamic mass. The effect of distance between the circular plates and the effect of fluid bounding on the fluid-coupled natural frequencies are also investigated. The theory developed in this report can be applicable to the dynamic analysis of a bottom screen assembly in SMART integral reactor.
Fluid lipid bilayers: Intermonolayer coupling and its thermodynamic manifestations
DEFF Research Database (Denmark)
Hansen, Per Lyngs; Miao, Ling; Ipsen, John Hjorth
1998-01-01
A fluid membrane of lipid bilayer consists of two individual molecular monolayers physically opposed to each other. This unique molecular architecture naturally necessitates the need to treat a lipid-bilayer membrane as one entity of two coupled two-dimensional systems (monolayers), each of which...
Co-axial multicusp source for low axial energy spread ion beam production
Lee, Y; Leung, K N; Vujic, J L; Williams, M D; Zahir, N
1999-01-01
A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projects.
Co-axial multicusp source for low axial energy spread ion beam production
Energy Technology Data Exchange (ETDEWEB)
Lee, Y. E-mail: yylee@lbl.gov; Gough, R.A.; Leung, K.N.; Vujic, J.; Williams, M.D.; Zahir, N
1999-09-01
A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projects.
Co-axial multicusp source for low axial energy spread ion beam production
Lee, Y.; Gough, R. A.; Leung, K. N.; Vujic, J.; Williams, M. D.; Zahir, N.
1999-09-01
A co-axial multicusp ion source has been designed and tested. This source uses a new magnetic filter configuration. This magnetic filter is efficient in modifying the plasma potential distribution which can reduce the axial energy spread of the extracted ion beam. Energy spreads as low as 0.6 eV have been obtained. The electron temperature in this source has also been found to be about 0.1 eV. Furthermore, the new source configuration is capable of adjusting the radial plasma potential distribution which can improve the transverse ion energy, which results in a low beam emittance. The co-axial source can be used for a number of different applications such as ion projection lithography and radioactive ion beam projets.
Perfect fluids coupled to inhomogeneities in the late Universe
Zhuk, Alexander
2016-01-01
We consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. At such scales, the Universe is highly inhomogeneous and is filled with inhomogeneities in the form of galaxies and the groups of galaxies. We also suggest that the Universe is filled with a perfect fluid, and its fluctuations have peculiar velocities of the same (non-relativistic) order of magnitude as for the inhomogeneities. In this sense, the inhomogeneities (e.g. galaxies) and fluctuations of perfect fluids are coupled with each other. We clarify some important points of this approach and present a brief review of previous studies (e.g. CPL model and Chaplygin gas). We demonstrate that considered perfect fluids which satisfy our approach are really coupled to galaxies concentrating around them. The averaged (over the whole Universe) value of their fluctuations is equal to zero.
Fluid migration in the subduction zone: a coupled fluid flow approach
Wang, Hongliang; Huismans, Ritske; Rondenay, StÃ©phane
2016-04-01
Subduction zone are the main entry point of water into earth's mantle and play an important role in the global water cycle. The progressive release of water by metamorphic dehydration induce important physical-chemical process in the subduction zone, such as hydrous melting, hydration and weakening of the mantle wedge, creation of pore fluid pressures that may weaken the subduction interface and induce earthquakes. Most previous studies on the role of fluids in subduction zones assume vertical migration or migration according to the dynamic pressure in the solid matrix without considering the pore fluid pressure effect on the deformation of the solid matrix. Here we investigate this interaction by explicitly modeling two-phase coupled poro-plastic flow during subduction. In this approach, the fluid migrates by compaction and decompaction of the solid matrix and affects the subduction dynamics through pore fluid pressure dependent frictional-plastic yield. Our preliminary results indicate that: 1) the rate of fluid migration depends strongly on the permeability and the bulk viscosity of the solid matrix, 2) fluid transfer occurs preferentially along the slab and then propagates into the mantle wedge by viscous compaction driven fluid flow, 3) fluid transport from the surface to depth is a prerequisite for producing high fluid pore pressures and associated hydration induced weakening of the subduction zone interface.
Zhang, Minxin; Chen, Jiafu; Chen, Bingjing; Cao, Jingjing; Hong, Min; Zhou, Chenxu; Xu, Qun
2016-03-01
Hollow tubing polystyrene (PS) fibers (HFs) with porous shell were successfully fabricated through co-axial electrospinning and selectively dissolving and removing polyvinyl pyrrolidone (PVP) core of the co-axial PS/PVP fibers using C2H5OH at room temperature. The size of co-axial hollow tubing structure (CHTS) and the thickness of shell can be controlled by varying the feed rate ratio of the core solution to the shell solution. The oil-sorption results show that the oil-sorption capacity increases with the increasing of the size of CHTS in the HFs, and the HFs have higher oil-sorption capacities than the porous PS fibers (PFs) without CHTS. It is noticeable that the diesel sorption capacity (66 g/g) of the HFs is approximately 1.74 times as much as that (38 g/g) of the PFs. The motor oil sorption capacity (147 g/g) of the HFs is approximately 1.55 times as much as that (95 g/g) of the PFs. It is suggested that the HFs have a better oil-sorption performance than the PFs, especially for the low viscosity oil, which is contributed to large CHTS and high porosity.
Directory of Open Access Journals (Sweden)
Youssef Emam Youssef
2010-04-01
Full Text Available The Bain's co-axial circuit system is fully established in general anaesthesia practice. It is favoured for its light weight and suitability for head and neck surgery. However, there are numerous published reports of malfunction of the inner tube of the Bain's co-axial circuit, with potentially lethal complications for the patient. This report presents a case in which a patient connected to a reused Bain's circuit (Datex-Ohmeda developed severe hypercapnia in the early intraoperative period due to unusual defect of the inner tube. This report tests and outlines the integrity of co-axial circuits and also reviews the available literature.
Cerroni, D.; Fancellu, L.; Manservisi, S.; Menghini, F.
2016-06-01
In this work we propose to study the behavior of a solid elastic object that interacts with a multiphase flow. Fluid structure interaction and multiphase problems are of great interest in engineering and science because of many potential applications. The study of this interaction by coupling a fluid structure interaction (FSI) solver with a multiphase problem could open a large range of possibilities in the investigation of realistic problems. We use a FSI solver based on a monolithic approach, while the two-phase interface advection and reconstruction is computed in the framework of a Volume of Fluid method which is one of the more popular algorithms for two-phase flow problems. The coupling between the FSI and VOF algorithm is efficiently handled with the use of MEDMEM libraries implemented in the computational platform Salome. The numerical results of a dam break problem over a deformable solid are reported in order to show the robustness and stability of this numerical approach.
Modeling Chemical Mechanical Polishing with Couple Stress Fluids
Institute of Scientific and Technical Information of China (English)
å¼ æœè¾‰; é›’å»ºæ–Œ; æ¸©è¯—é“¸
2004-01-01
Chemical mechanical polishing (CMP) is a manufacturing process used to achieve high levels of global and local planarity.Currently, the slurries used in CMP usually contain nanoscale particles to accelerate the removal ratio and to optimize the planarity, whose rheological properties can no longer be accurately modeled with Newtonian fluids.The Reynolds equation, including the couple stress effects, was derived in this paper.The equation describes the mechanism to solve the CMP lubrication equation with the couple stress effects.The effects on load and moments resulting from the various parameters, such as pivot height, roll angle, and pitch angle, were subsequently simulated.The results show that the couple stress can provide higher load and angular moments.This study sheds some lights into the mechanism of the CMP process.
Peristaltic Transport of a Couple Stress Fluid : Some Physiological Applications
Maiti, S
2010-01-01
The present paper deals with a theoretical investigation of the peristaltic transport of a couple stress fluid in a porous channel. The study is motivated towards the physiological flow of blood in the micro-circulatory system, by taking account of the particle size effect. The velocity, pressure gradient, stream function and frictional force of blood are investigated, when the Reynolds number is small and the wavelength is large, by using appropriate analytical and numerical methods. Effects of different physical parameters reflecting porosity, Darcy number, couple stress parameter as well as amplitude ratio on velocity profiles, pumping action and frictional force, streamlines pattern and trapping of blood are studied with particular emphasis. The computational results are presented in graphical form. The results are found to be in good agreement with those of Shapiro et. al \\cite{r25} that was carried out for a non-porous channel in the absence of couple stress effect. The present study puts forward an imp...
DEFF Research Database (Denmark)
JÃ¸rgensen, Lars; Qvortrup, Klaus; Chronakis, Ioannis S.
2015-01-01
Asolectin phospholipid nano-microfibers were prepared using electrospinning processing. The asolectin fibers were studied by scanning electron microscopy, and the fiber morphology was found to be strongly dependent on the phospholipid concentration and the solvents used. The solvents studied were...... does not follow the theoretically predicted value of similar to 0.35 mu m because of the intermolecular aggregation between the reverse micelles formed in the highly concentrated asolectin solutions. However, when co-axial solvent electrospinning was applied, where the outer needle contains a pure...
High-precision efficiency calibration of a high-purity co-axial germanium detector
Energy Technology Data Exchange (ETDEWEB)
Blank, B., E-mail: blank@cenbg.in2p3.fr [Centre d' Etudes NuclÃ©aires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, UniversitÃ© de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Souin, J.; Ascher, P.; Audirac, L.; Canchel, G.; Gerbaux, M.; GrÃ©vy, S.; Giovinazzo, J.; GuÃ©rin, H.; Nieto, T. Kurtukian; Matea, I. [Centre d' Etudes NuclÃ©aires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, UniversitÃ© de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Bouzomita, H.; Delahaye, P.; Grinyer, G.F.; Thomas, J.C. [Grand AccÃ©lÃ©rateur National d' Ions Lourds, CEA/DSM, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, F-14076 CAEN Cedex 5 (France)
2015-03-11
A high-purity co-axial germanium detector has been calibrated in efficiency to a precision of about 0.15% over a wide energy range. High-precision scans of the detector crystal and Î³-ray source measurements have been compared to Monte-Carlo simulations to adjust the dimensions of a detector model. For this purpose, standard calibration sources and short-lived online sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed Î² decays for tests of the weak-interaction standard model.
Coupling fluid-structure interaction with phase-field fracture
Wick, Thomas
2016-12-01
In this work, a concept for coupling fluid-structure interaction with brittle fracture in elasticity is proposed. The fluid-structure interaction problem is modeled in terms of the arbitrary Lagrangian-Eulerian technique and couples the isothermal, incompressible Navier-Stokes equations with nonlinear elastodynamics using the Saint-Venant Kirchhoff solid model. The brittle fracture model is based on a phase-field approach for cracks in elasticity and pressurized elastic solids. In order to derive a common framework, the phase-field approach is re-formulated in Lagrangian coordinates to combine it with fluid-structure interaction. A crack irreversibility condition, that is mathematically characterized as an inequality constraint in time, is enforced with the help of an augmented Lagrangian iteration. The resulting problem is highly nonlinear and solved with a modified Newton method (e.g., error-oriented) that specifically allows for a temporary increase of the residuals. The proposed framework is substantiated with several numerical tests. In these examples, computational stability in space and time is shown for several goal functionals, which demonstrates reliability of numerical modeling and algorithmic techniques. But also current limitations such as the necessity of using solid damping are addressed.
Coupled Vlasov and two-fluid codes on GPUs
Rieke, M; Grauer, R
2014-01-01
We present a way to combine Vlasov and two-fluid codes for the simulation of a collisionless plasma in large domains while keeping full information of the velocity distribution in localized areas of interest. This is made possible by solving the full Vlasov equation in one region while the remaining area is treated by a 5-moment two-fluid code. In such a treatment, the main challenge of coupling kinetic and fluid descriptions is the interchange of physically correct boundary conditions between the different plasma models. In contrast to other treatments, we do not rely on any specific form of the distribution function, e.g. a Maxwellian type. Instead, we combine an extrapolation of the distribution function and a correction of the moments based on the fluid data. Thus, throughout the simulation both codes provide the necessary boundary conditions for each other. A speed-up factor of around 20 is achieved by using GPUs for the computationally expensive solution of the Vlasov equation and an overall factor of a...
Global Solutions to the Coupled Chemotaxis-Fluid Equations
Duan, Renjun
2010-08-10
In this paper, we are concerned with a model arising from biology, which is a coupled system of the chemotaxis equations and the viscous incompressible fluid equations through transport and external forcing. The global existence of solutions to the Cauchy problem is investigated under certain conditions. Precisely, for the Chemotaxis-Navier-Stokes system over three space dimensions, we obtain global existence and rates of convergence on classical solutions near constant states. When the fluid motion is described by the simpler Stokes equations, we prove global existence of weak solutions in two space dimensions for cell density with finite mass, first-order spatial moment and entropy provided that the external forcing is weak or the substrate concentration is small. Â© Taylor & Francis Group, LLC.
A Strongly Coupled Anisotropic Fluid From Dilaton Driven Holography
Jain, Sachin; Sen, Kallol; Sinha, Aninda; Trivedi, Sandip P
2014-01-01
We consider a system consisting of $5$ dimensional gravity with a negative cosmological constant coupled to a massless scalar, the dilaton. We construct a black brane solution which arises when the dilaton satisfies linearly varying boundary conditions in the asymptotically $AdS_5$ region. The geometry of this black brane breaks rotational symmetry while preserving translational invariance and corresponds to an anisotropic phase of the system. Close to extremality, where the anisotropy is big compared to the temperature, some components of the viscosity tensor become parametrically small compared to the entropy density. We study the quasi normal modes in considerable detail and find no instability close to extremality. We also obtain the equations for fluid mechanics for an anisotropic driven system in general, working upto first order in the derivative expansion for the stress tensor, and identify additional transport coefficients which appear in the constitutive relation. For the fluid of interest we find t...
Coupling lattice Boltzmann and molecular dynamics models for dense fluids
Dupuis, A.; Kotsalis, E. M.; Koumoutsakos, P.
2007-04-01
We propose a hybrid model, coupling lattice Boltzmann (LB) and molecular dynamics (MD) models, for the simulation of dense fluids. Time and length scales are decoupled by using an iterative Schwarz domain decomposition algorithm. The MD and LB formulations communicate via the exchange of velocities and velocity gradients at the interface. We validate the present LB-MD model in simulations of two- and three-dimensional flows of liquid argon past and through a carbon nanotube. Comparisons with existing hybrid algorithms and with reference MD solutions demonstrate the validity of the present approach.
A coupled chemotaxis-fluid model: Global existence
Liu, Jian-Guo
2011-09-01
We consider a model arising from biology, consisting of chemotaxis equations coupled to viscous incompressible fluid equations through transport and external forcing. Global existence of solutions to the Cauchy problem is investigated under certain conditions. Precisely, for the chemotaxis-Navier- Stokes system in two space dimensions, we obtain global existence for large data. In three space dimensions, we prove global existence of weak solutions for the chemotaxis-Stokes system with nonlinear diffusion for the cell density.Â© 2011 Elsevier Masson SAS. All rights reserved.
Fluid Lifestyles: Dink Couples (Double Income, no Kids
Directory of Open Access Journals (Sweden)
Iara Silva da Silva
2013-03-01
Full Text Available In contemporaneity, new family arrangements arise, such as couples with dual income and no kids (DINK.Â The DINK family arrangement is the object of this study. Their lifestyle is investigated through the triangulation of methods and techniques using qualitative and quantitative research. As evidence, we can single out a fluid lifestyle, typical of post-modernity, that values freedom to follow unconventional paths. Even if it is a specific subculture, heterosexual couples without children have diverse lifestyles: the cocooned prioritize their homes; the resigned have a moderate affinity for their houses, do not take care of their health, and love technology; and the espoused, who among the in-groups, prioritize their spouse.Â DOI: 10.5585/remark.v12i1.2385
Numerical Simulation and Flow Behaviors of Taylor Flow in Co-Axial Rotating Cylinder
Directory of Open Access Journals (Sweden)
Sheng Chung Tzeng
2014-04-01
Full Text Available This work uses the incense as the trace of flow to perform flow visualization of Taylor-Couette flow. The test section was made of a rotational inner cylinder and a stationary outer cylinder. Two modes of inner cylinder were employed. One had a smooth wall, and the other had an annular ribbed wall. Clear and complete Taylor vortices were investigated in both smooth and ribbed wall of co-axial rotating cylinder. Besides, a steady-state, axis-symmetrical numerical model was provided to simulate the present flow field. The Taylor vortices could be also successfully predicted. However, the assumption of steady-state flow might reduce some flow perturbations, resulting in an over-predicted critical Taylor number. A transient simulation is suggested to be performed in the future.
VIBRATION ANALYSIS OF TURBINE BASED ON FLUID-STRUCTURE COUPLING
Institute of Scientific and Technical Information of China (English)
LIU Demin; LIU Xiaobing
2008-01-01
The vibration of a Francis turbine is analyzed with the additional quality matrix method based on fluid-structure coupling (FSC). Firstly, the vibration frequency and mode of blade and runner in air and water are calculated. Secondly, the influences to runner frequency domain by large flow, small flow and design flow working conditions are compared. Finally the influences to runner modes by centrifugal forces under three rotating speeds of 400 r/min, 500 r/min and 600 r/min are compared. The centrifugal force and small flow working condition have greatly influence on the vibration of small runner. With the increase of centrifugal force, the vibration frequency of the runner is sharply increased. Some order frequencies are even close to the runner natural frequency in the air. Because the low frequency vibration will severely damage the stability of the turbine, low frequency vibration of units should be avoided as soon as possible.
Zhou, Lingkang; Hua, Wei; Zhang, Gan
2017-05-01
In this paper, power distribution between the inner and outer machines of a co-axial dual-mechanical-port flux-switching permanent magnet (CADMP-FSPM) machine is investigated for fuel-based extended range electric vehicle (ER-EV). Firstly, the topology and operation principle of the CADMP-FSPM machine are introduced, which consist of an inner FSPM machine used for high-speed, an outer FSPM machine for low-speed, and a magnetic isolation ring between them. Then, the magnetic field coupling of the inner and outer FSPM machines is analyzed with more attention paid to the optimization of the isolation ring thickness. Thirdly, the power-dimension (PD) equations of the inner and outer FSPM machines are derived, respectively, and thereafter, the PD equation of the whole CADMP-FSPM machine can be given. Finally, the PD equations are validated by finite element analysis, which supplies the guidance on the design of this type of machines.
Salt tectonics and shallow subseafloor fluid convection: models of coupled fluid-heat-salt transport
Wilson, A.; Ruppel, C.
2007-01-01
Thermohaline convection associated with salt domes has the potential to drive significant fluid flow and mass and heat transport in continental margins, but previous studies of fluid flow associated with salt structures have focused on continental settings or deep flow systems of importance to petroleum exploration. Motivated by recent geophysical and geochemical observations that suggest a convective pattern to near-seafloor pore fluid flow in the northern Gulf of Mexico (GoMex), we devise numerical models that fully couple thermal and chemical processes to quantify the effects of salt geometry and seafloor relief on fluid flow beneath the seafloor. Steady-state models that ignore halite dissolution demonstrate that seafloor relief plays an important role in the evolution of shallow geothermal convection cells and that salt at depth can contribute a thermal component to this convection. The inclusion of faults causes significant, but highly localized, increases in flow rates at seafloor discharge zones. Transient models that include halite dissolution show the evolution of flow during brine formation from early salt-driven convection to later geothermal convection, characteristics of which are controlled by the interplay of seafloor relief and salt geometry. Predicted flow rates are on the order of a few millimeters per year or less for homogeneous sediments with a permeability of 10âˆ’15 m2, comparable to compaction-driven flow rates. Sediment permeabilities likely fall below 10âˆ’15 m2 at depth in the GoMex basin, but such thermohaline convection can drive pervasive mass transport across the seafloor, affecting sediment diagenesis in shallow sediments. In more permeable settings, such flow could affect methane hydrate stability, seafloor chemosynthetic communities, and the longevity of fluid seeps.
Fluid-structure coupled analysis of underwater cylindrical shells
Institute of Scientific and Technical Information of China (English)
AI Shang-mao; SUN Li-ping
2008-01-01
Underwater cylindrical shell structures have been found a wide of application in many engineering fields,such as the element of marine,oil platforms,etc.The coupled vibration analysis is a hot issue for these underwater structures.The vibration characteristics of underwater structures are influenced not only by hydrodynamic pressure but also by hydrostatic pressure corresponding to different water depths.In this study,an acoustic finite element method was used to evaluate the underwater structures.Taken the hydrostatic pressure into account in terms of initial stress stiffness,an acoustical fluid-structure coupled analysis of underwater cylindrical shells has been made to study the effect of hydrodynamic pressures on natural frequency and sound radiation.By comparing with the frequencies obtained by the acoustic finite element method and by the added mass method based on the Bessel function,the validity of present analysis was checked.Finally,test samples of the sound radiation of stiffened cylindrical shells were acquired by a harmonic acoustic analysis.The results showed that hydrostatic pressure plays an important role in determining a large submerged body motion,and the characteristics of sound radiation change with water depth. Furthermore,the analysis methods and the results are of significant reference value for studies of other complicated submarine structures.
Tomohara, Keisuke; Kasamatsu, Koji; Yoshimura, Tomoyuki; Furuta, Takumi; Kawabata, Takeo
2016-07-01
Enantioselective intramolecular conjugate addition reactions of short-lived C-O axially chiral enolates have been developed. The reactions proceeded with inversion of the configuration and provided dihydrobenzofurans with contiguous tetra- and trisubstituted carbon centers in up to 96% enantiomeric excess (ee).
Partitioned fluid-solid coupling for cardiovascular blood flow: left-ventricular fluid mechanics.
Krittian, Sebastian; Janoske, Uwe; Oertel, Herbert; BÃ¶hlke, Thomas
2010-04-01
We present a 3D code-coupling approach which has been specialized towards cardiovascular blood flow. For the first time, the prescribed geometry movement of the cardiovascular flow model KaHMo (Karlsruhe Heart Model) has been replaced by a myocardial composite model. Deformation is driven by fluid forces and myocardial response, i.e., both its contractile and constitutive behavior. Whereas the arbitrary Lagrangian-Eulerian formulation (ALE) of the Navier-Stokes equations is discretized by finite volumes (FVM), the solid mechanical finite elasticity equations are discretized by a finite element (FEM) approach. Taking advantage of specialized numerical solution strategies for non-matching fluid and solid domain meshes, an iterative data-exchange guarantees the interface equilibrium of the underlying governing equations. The focus of this work is on left-ventricular fluid-structure interaction based on patient-specific magnetic resonance imaging datasets. Multi-physical phenomena are described by temporal visualization and characteristic FSI numbers. The results gained show flow patterns that are in good agreement with previous observations. A deeper understanding of cavity deformation, blood flow, and their vital interaction can help to improve surgical treatment and clinical therapy planning.
An investigation on co-axial water-jet assisted fiber laser cutting of metal sheets
Madhukar, Yuvraj K.; Mullick, Suvradip; Nath, Ashish K.
2016-02-01
Water assisted laser cutting has received significant attention in recent times with assurance of many advantages than conventional gas assisted laser cutting. A comparative study between co-axial water-jet and gas-jet assisted laser cutting of thin sheets of mild steel (MS) and titanium (Ti) by fiber laser is presented. Fiber laser (1.07 Î¼m wavelength) was utilised because of its low absorption in water. The cut quality was evaluated in terms of average kerf, projected dross height, heat affected zone (HAZ) and cut surface roughness. It was observed that a broad range process parameter could produce consistent cut quality in MS. However, oxygen assisted cutting could produce better quality only with optimised parameters at high laser power and high cutting speed. In Ti cutting the water-jet assisted laser cutting performed better over the entire range of process parameters compared with gas assisted cutting. The specific energy, defined as the amount of laser energy required to remove unit volume of material was found more in case of water-jet assisted laser cutting process. It is mainly due to various losses associated with water assisted laser processing such as absorption of laser energy in water and scattering at the interaction zone.
Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang
2016-06-01
A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mÎ© and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 Î¼F, an inductance of 11.7 nH, a resistance of 4.3 mÎ©, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10-2 Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physicsÂ® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak
Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang
2016-06-01
A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mÎ© and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 Î¼F, an inductance of 11.7 nH, a resistance of 4.3 mÎ©, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10(-2) Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physicsÂ® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak
Chen, M.; Ju, L. Y.; Hao, H. X.
2014-01-01
Small scale thermoacoustic heat engines have advantages in fields like space exploration and domestic applications considering small space occupation and ease of transport. In the present paper, the influence of resonator diameter on the general performance of a small thermoacoustic Stirling engine was experimentally investigated using helium as the working gas. Reducing the diameter of the resonator appropriately is beneficial for lower onset heating temperature, lower frequency and higher pressure amplitude. Based on the pressure distribution in the small thermoacoustic engine, an outlet for the acoustic work transmission was made to combine the engine and a miniature co-axial pulse tube cooler. The cooling performance of the whole refrigeration system without any moving part was tested. Experimental results showed that further efforts are required to optimize the engine performance and its match with the co-axial pulse tube cooler in order to obtain better cooling performance, compared with its original operating condition, driven by a traditional electrical linear compressor.
Finite element procedures for coupled linear analysis of heat transfer, fluid and solid mechanics
Sutjahjo, Edhi; Chamis, Christos C.
1993-01-01
Coupled finite element formulations for fluid mechanics, heat transfer, and solid mechanics are derived from the conservation laws for energy, mass, and momentum. To model the physics of interactions among the participating disciplines, the linearized equations are coupled by combining domain and boundary coupling procedures. Iterative numerical solution strategy is presented to solve the equations, with the partitioning of temporal discretization implemented.
Off-centered stagnation point flow of a couple stress fluid towards a rotating disk.
Khan, Najeeb Alam; Riaz, Fatima
2014-01-01
An investigation has been made to study the off-centered stagnation flow of a couple stress fluid over a rotating disk. The model developed for the governing problem in the form of partial differential equations has been converted to ordinary differential equations with the use of suitable similarity transformation. The analytical approximation has been made with the most promising analytical approach, homotopy analysis method (HAM). The convergence region of the obtained solution is determined and plotted. The effects of couple stress and nondimensional parameters have been observed on the flows of couple stress fluid. Also comparison has been made with the Newtonian fluid as the special case of considered problem.
Analytical solutions of couple stress fluid flows with slip boundary conditions
Directory of Open Access Journals (Sweden)
Devakar M.
2014-09-01
Full Text Available In the present article, the exact solutions for fundamental flows namely Couette, Poiseuille and generalized Couette flows of an incompressible couple stress fluid between parallel plates are obtained using slip boundary conditions. The effect of various parameters on velocity for each problem is discussed. It is found that, for each of the problems, the solution in the limiting case as couple stresses approaches to zero is similar to that of classical viscous Newtonian fluid. The results indicate that, the presence of couple stresses decreases the velocity of the fluid.
Coupling electrokinetics and rheology: Electrophoresis in non-Newtonian fluids.
Khair, Aditya S; Posluszny, Denise E; Walker, Lynn M
2012-01-01
We present a theoretical scheme to calculate the electrophoretic motion of charged colloidal particles immersed in complex (non-Newtonian) fluids possessing shear-rate-dependent viscosities. We demonstrate that this non-Newtonian rheology leads to an explicit shape and size dependence of the electrophoretic velocity of a uniformly charged particle in the thin-Debye-layer regime, in contrast to electrophoresis in Newtonian fluids. This dependence is caused by non-Newtonian stresses in the bulk (electroneutral) fluid outside the Debye layer, whose magnitude is naturally characterized in an electrophoretic Deborah number.
Dispersion of a solute in peristaltic motion of a couple stress fluid through a porous medium
National Research Council Canada - National Science Library
G. Radhakrishnamacharya; Habtu Alemayehu
2012-01-01
The paper presents an analytical solution for dispersion of a solute in the peristaltic motion of a couple stress fluid through a porous medium in the presence of both homogeneous and heterogeneous chemical reactions...
Co-axial electrospun polystyrene/polyurethane fibres for oil collection from water surface
Lin, Jinyou; Tian, Feng; Shang, Yanwei; Wang, Fujun; Ding, Bin; Yu, Jianyong; Guo, Zhi
2013-03-01
The pollution arising from oil spills is a matter of great concern due to its damaging impacts on the ecological environment, which has created a tremendous need to find more efficient materials for oil spill cleanup. In this work, we reported a sorbent for oil soak-up from a water surface with a high sorption capacity, good selectivity, and excellent reusability based on the hydrophobic-oleophilic fibrous mats that were fabricated via co-axial electrospinning polystyrene (PS) solution as the shell solution and polyurethane (PU) solution as the core solution. The fine structures of as-prepared fibers were regulated by manipulating the spinning voltages, core solution concentrations, and solvent compositions in shell solutions, which were also characterized by field emission scanning electron microscopy, transmission electron microscopy, nitrogen adsorption method, and synchrotron radiation small-angle X-ray scattering. The effects of inter-fiber voids and intra-fiber porosity on oil sorption capacities were well studied. A comparison of oil sorption capacity for the single fiber with different porous structures was also investigated with the help of scanning transmission X-ray microscopy. The results showed that the sorption capacities of the as-prepared sorbent with regards to motor oil and sunflower seed oil can be 64.40 and 47.48 g g-1, respectively, approximately 2-3 times that of conventional polypropylene (PP) fibers for these two same oils. Even after five sorption cycles, a comparable oil sorption capacity with PP fibers was still maintained, exhibiting an excellent reusability. We believe that the composite PS-PU fibrous mats have a great potential application in wastewater treatment, oil accident remediation and environmental protection.The pollution arising from oil spills is a matter of great concern due to its damaging impacts on the ecological environment, which has created a tremendous need to find more efficient materials for oil spill cleanup. In
Exact solutions for MHD flow of couple stress fluid with heat transfer
Directory of Open Access Journals (Sweden)
Najeeb Alam Khan
2016-01-01
Full Text Available This paper aims at presenting exact solutions for MHD flow of couple stress fluid with heat transfer. The governing partial differential equations (PDEs for an incompressible MHD flow of couple stress fluid are reduced to ordinary differential equations by employing wave parameter. The methodology is implemented for linearizing the flow equations without extra transformation and restrictive assumptions. Comparison is made with the result obtained previously.
Fluid powered linear piston motor with harmonic coupling
Energy Technology Data Exchange (ETDEWEB)
Raymond, David W.
2016-09-20
A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.
Fluid-particle flow and validation using two-way-coupled mesoscale SPH-DEM
Robinson, Martin; Luding, Stefan; Ramaioli, Marco
2013-01-01
First, a meshless simulation method is presented for multiphase fluid-particle flows with a two-way coupled Smoothed Particle Hydrodynamics (SPH) for the fluid and the Discrete Element Method (DEM) for the solid phase. The unresolved fluid model, based on the locally averaged Navier Stokes equations, is expected to be considerably faster than fully resolved models. Furthermore, in contrast to similar mesh-based Discrete Particle Methods (DPMs), our purely particle-based method enjoys the flex...
A Lattice Boltzmann Model for Fluid-Solid Coupling Heat Transfer in Fractal Porous Media
Institute of Scientific and Technical Information of China (English)
CAI Jun; HUAI Xiu-Lan
2009-01-01
We report a lattice Boltzmann model that can be used to simulate fluid-solid coupling heat transfer in fractal porous media.A numerical simulation is conducted to investigate the temperature evolution under different ratios of thermal conductivity of solid matrix of porous media to that of fluid.The accordance of our simulation results with the solutions from the conventional CFD method indicates the feasibility and the reliability for the developed lattice Boltzmann model to reveal the phenomena and rules of fluid-solid coupling heat transfer in complex porous structures.
Magneto-Fluid Coupling - Eruptive Events in the Solar Corona
Ohsaki, S; Yoshida, Z; Mahajan, S M; Ohsaki, Shuichi; Shatashvili, Nana L.; Yoshida, Zensho; Mahajan, Swadesh M.
2001-01-01
By modelling the coronal structures by "slowly" evolving Double-Beltrami two-fluid equilibria (created by the interaction of the magnetic and velocity fields), the conditions for catastrophic transformations of the original state are derived. It is shown that, at the transition, much of the magnetic energy of the original state is converted to the the flow kinetic energy.
On-line coupling of supercritical fluid extraction and chromatographic techniques.
SÃ¡nchez-Camargo, Andrea Del Pilar; Parada-Alfonso, FabiÃ¡n; IbÃ¡Ã±ez, Elena; Cifuentes, Alejandro
2017-01-01
This review summarizes and discusses recent advances and applications of on-line supercritical fluid extraction coupled to liquid chromatography, gas chromatography, and supercritical fluid chromatographic techniques. Supercritical fluids, due to their exceptional physical properties, provide unique opportunities not only during the extraction step but also in the separation process. Although supercritical fluid extraction is especially suitable for recovery of non-polar organic compounds, this technique can also be successfully applied to the extraction of polar analytes by the aid of modifiers. Supercritical fluid extraction process can be performed following "off-line" or "on-line" approaches and their main features are contrasted herein. Besides, the parameters affecting the supercritical fluid extraction process are explained and a "decision tree" is for the first time presented in this review work as a guide tool for method development. The general principles (instrumental and methodological) of the different on-line couplings of supercritical fluid extraction with chromatographic techniques are described. Advantages and shortcomings of supercritical fluid extraction as hyphenated technique are discussed. Besides, an update of the most recent applications (from 2005 up to now) of the mentioned couplings is also presented in this review.
Directory of Open Access Journals (Sweden)
Lingkang Zhou
2017-05-01
Full Text Available In this paper, power distribution between the inner and outer machines of a co-axial dual-mechanical-port flux-switching permanent magnet (CADMP-FSPM machine is investigated for fuel-based extended range electric vehicle (ER-EV. Firstly, the topology and operation principle of the CADMP-FSPM machine are introduced, which consist of an inner FSPM machine used for high-speed, an outer FSPM machine for low-speed, and a magnetic isolation ring between them. Then, the magnetic field coupling of the inner and outer FSPM machines is analyzed with more attention paid to the optimization of the isolation ring thickness. Thirdly, the power-dimension (PD equations of the inner and outer FSPM machines are derived, respectively, and thereafter, the PD equation of the whole CADMP-FSPM machine can be given. Finally, the PD equations are validated by finite element analysis, which supplies the guidance on the design of this type of machines.
Cerebrospinal Fluid Mechanics and Its Coupling to Cerebrovascular Dynamics
Linninger, Andreas A.; Tangen, Kevin; Hsu, Chih-Yang; Frim, David
2016-01-01
Cerebrospinal fluid (CSF) is not stagnant but displays fascinating oscillatory flow patterns inside the ventricular system and reversing fluid exchange between the cranial vault and spinal compartment. This review provides an overview of the current knowledge of pulsatile CSF motion. Observations contradicting classical views about its bulk production and clearance are highlighted. A clinical account of diseases of abnormal CSF flow dynamics, including hydrocephalus, syringomyelia, Chiari malformation type 1, and pseudotumor cerebri, is also given. We survey medical imaging modalities used to observe intracranial dynamics in vivo. Additionally, we assess the state of the art in predictive models of CSF dynamics. The discussion addresses open questions regarding CSF dynamics as they relate to the understanding and management of diseases.
Coupled discrete element modeling of fluid injection into dense granular media
Zhang, Fengshou; Damjanac, Branko; Huang, Haiying
2013-06-01
The coupled displacement process of fluid injection into a dense granular medium is investigated numerically using a discrete element method (DEM) code PFC2DÂ® coupled with a pore network fluid flow scheme. How a dense granular medium behaves in response to fluid injection is a subject of fundamental and applied research interests to better understand subsurface processes such as fluid or gas migration and formation of intrusive features as well as engineering applications such as hydraulic fracturing and geological storage in unconsolidated formations. The numerical analysis is performed with DEM executing the mechanical calculation and the network model solving the Hagen-Poiseuille equation between the pore spaces enclosed by chains of particles and contacts. Hydromechanical coupling is realized by data exchanging at predetermined time steps. The numerical results show that increase in the injection rate and the invading fluid viscosity and decrease in the modulus and permeability of the medium result in fluid flow behaviors displaying a transition from infiltration-governed to infiltration-limited and the granular medium responses evolving from that of a rigid porous medium to localized failure leading to the development of preferential paths. The transition in the fluid flow and granular medium behaviors is governed by the ratio between the characteristic times associated with fluid injection and hydromechanical coupling. The peak pressures at large injection rates when fluid leakoff is limited compare well with those from the injection experiments in triaxial cells in the literature. The numerical analysis also reveals intriguing tip kinematics field for the growth of a fluid channel, which may shed light on the occurrence of the apical inverted-conical features in sandstone and magma intrusion in unconsolidated formations.
Emergent long-range couplings in arrays of fluid cells
Energy Technology Data Exchange (ETDEWEB)
Abraham, Douglas Bruce [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-08-07
We present a system exhibiting extraordinarily long-range cooperative effects, on a length scale far exceeding the bulk correlation length. We give a theoretical explanation of these phenomena based on the mesoscopic picture of phase coexistence in finite systems, which is confirmedly Monte Carlo (MC) simulation studies. Our work demonstrates that such action-at-a-distance can occur in classical systems involving simple or complex fluids, such as colloid-polymer mixtures, or ferromagnets.
Sega, Marcello; Sbragaglia, Mauro; Kantorovich, Sofia Sergeevna; Ivanov, Alexey Olegovich
2013-01-01
Complex fluid-fluid interfaces featuring mesoscale structures with adsorbed particles are key components of newly designed materials which are continuously enriching the field of soft matter. Simulation tools which are able to cope with the different scales characterizing these systems are fundamental requirements for efficient theoretical investigations. In this paper we present a novel simulation method, based on the approach of Ahlrichs and D\\"unweg [Ahlrichs and D\\"unweg, Int. J. Mod. Phy...
Yeh, S. I.; Huang, Y. C.; Cheng, C. H.; Cheng, C. M.; Yang, J. T.
2016-07-01
In this study, we investigated a fluidic system that adheres to new concepts of energy production. To improve efficiency, cost, and ease of manufacture, a millimetrically scaled device that employs a droplet-based co-axial fluidic system was devised to complete alkali-catalyzed transesterification for biodiesel production. The large surface-to-volume ratio of the droplet-based system, and the internal circulation induced inside the moving droplets, significantly enhanced the reaction rate of immiscible liquids used here â€“ soybean oil and methanol. This device also decreased the molar ratio between methanol and oil to near the stoichiometric coefficients of a balanced chemical equation, which enhanced the total biodiesel volume produced, and decreased the costs of purification and recovery of excess methanol. In this work, the droplet-based co-axial fluidic system performed better than other methods of continuous-flow production. We achieved an efficiency that is much greater than that of reported systems. This study demonstrated the high potential of droplet-based fluidic chips for energy production. The small energy consumption and low cost of the highly purified biodiesel transesterification system described conforms to the requirements of distributed energy (inexpensive production on a moderate scale) in the world.
A strongly coupled anisotropic fluid from dilaton driven holography
Jain, Sachin; Kundu, Nilay; Sen, Kallol; Sinha, Aninda; Trivedi, Sandip(Department of Theoretical Physics, Tata Institute of Fundamental Research, Colaba, Mumbai, 400005, India)
2015-01-01
We consider a system consisting of $5$ dimensional gravity with a negative cosmological constant coupled to a massless scalar, the dilaton. We construct a black brane solution which arises when the dilaton satisfies linearly varying boundary conditions in the asymptotically $AdS_5$ region. The geometry of this black brane breaks rotational symmetry while preserving translational invariance and corresponds to an anisotropic phase of the system. Close to extremality, where the anisotropy is big...
Coupling two-phase fluid flow with two-phase darcy flow in anisotropic porous media
Chen, J.
2014-06-03
This paper reports a numerical study of coupling two-phase fluid flow in a free fluid region with two-phase Darcy flow in a homogeneous and anisotropic porous medium region. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the anisotropic porous medium region. A Robin-Robin domain decomposition method is used for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Obtained results have shown the anisotropic properties effect on the velocity and pressure of the two-phase flow. 2014 Jie Chen et al.
Institute of Scientific and Technical Information of China (English)
H. P. RANI; G. J. REDDY; C. N. KIM
2013-01-01
The unsteady natural convective couple stress fluid flow over a semi-infinite vertical cylinder is analyzed for the homogeneous first-order chemical reaction effect. The couple stress fluid flow model introduces the length dependent effect based on the material constant and dynamic viscosity. Also, it introduces the biharmonic operator in the Navier-Stokes equations, which is absent in the case of Newtonian fluids. The solution to the time-dependent non-linear and coupled governing equations is carried out with an unconditionally stable Crank-Nicolson type of numerical schemes. Numerical results for the transient flow variables, the average wall shear stress, the Nusselt number, and the Sherwood number are shown graphically for both generative and destructive reactions. The time to reach the temporal maximum increases as the reaction constant K increases. The average values of the wall shear stress and the heat transfer rate decrease as K increases, while increase with the increase in the Sherwood number.
A Tightly Coupled Particle-Fluid Model for DNA-Laden Flows in Complex Microscale Geometries
Energy Technology Data Exchange (ETDEWEB)
Trebotich, D; Miller, G H; Colella, P; Graves, D T; Martin, D F; Schwartz, P O
2004-11-18
We present a stable and convergent method for the computation of flows of DNA-laden fluids in microchannels with complex geometry. The numerical strategy combines a ball-rod model representation for polymers tightly coupled with a projection method for incompressible viscous flow. We use Cartesian grid embedded boundary methods to discretize the fluid equations in the presence of complex domain boundaries. A sample calculation is presented showing flow through a packed array microchannel in 2D.
Shearing fluid-filled granular media: A coupled discrete element - continuous approach
Goren, L.; Aharonov, E.; Sparks, D.; Toussaint, R.; Marder, E.
2012-04-01
Fluid-filled granular layers are abundant in the Earth's shallow crust as saturated soils and poorly consolidated hillslope material, and as fluid-filled fault gouge layers. When such grains-fluid systems are subjected to excitation by the passage of seismic waves, tectonic loading, or gravitational loading they exhibit a highly non-trivial dynamical behavior that may lead to instabilities in the form of soil liquefaction, debris flow mobilization, and earthquakes. In order to study the basic coupled mechanics of fluid-filled granular media and the dynamical processes that are responsible for the emergence of instabilities we develop a model that couples granular dynamics (DEM) algorithm with a continuous Eulerian grid-based solver. The two components of the model represent the two phases (grains and fluid) in two different scales. Each grain is represented by a single element in the granular dynamics component, where grains interact by elastic collisions and frictional sliding. The compressible pore fluid is represented on a coarser Darcy scale grid that is super-imposed over the grains layer. The pore space geometry set by the evolving granular packing is used to define smooth porosity and permeability fields, and the individual grain velocities are interpolated to define a smooth field of a solid-fraction velocity. The porosity, permeability, and solid velocity fields are used in the continuous fluid grid-based solver to find pore fluid velocity and pressure. Pore fluid pressure gradients are interpolated back from the fluid grid to individual grains, where they enter the grains force balance equation as seepage forces. Boundary conditions are specified separately for the two phases. For the pore fluid we test two end-member drainage conditions: completely drained system (with infinite boundary permeability) and completely undrained system (with zero boundary permeability). For the grains, two-dimensional time dependent stress and velocity conditions are
Numerical aspects of modelling of coupled chemical reactions and fluid flow in sedimentary basins
Energy Technology Data Exchange (ETDEWEB)
Holstad, Astrid
1998-01-01
Simulation of coupled chemical reactions and fluid flow in porous sedimentary basins, through long time periods, is a numerical challenge. In most models available today the equations representing such a physical problem are solved as PDEs (Partial Differential Equation) where efficient time-stepping with controlled error is very difficult. The DAE (Differential Algebraic Equation) system approach is used where robust adaptive time-stepping algorithms are available in solvers. In this report mathematical and numerical models are derived for coupled chemical reactions and fluid flow. The models have several interesting properties which are discussed. The performance of code is tested. 20 refs., 6 figs., 2 tabs.
On the coupling of fluid dynamics and electromagnetism at the top of the earth's core
Benton, E. R.
1985-01-01
A kinematic approach to short-term geomagnetism has recently been based upon pre-Maxwell frozen-flux electromagnetism. A complete dynamic theory requires coupling fluid dynamics to electromagnetism. A geophysically plausible simplifying assumption for the vertical vorticity balance, namely that the vertical Lorentz torque is negligible, is introduced and its consequences are developed. The simplified coupled magnetohydrodynamic system is shown to conserve a variety of magnetic and vorticity flux integrals. These provide constraints on eligible models for the geomagnetic main field, its secular variation, and the horizontal fluid motions at the top of the core, and so permit a number of tests of the underlying assumptions.
On the coupling of fluid dynamics and electromagnetism at the top of the earth's core
Benton, E. R.
1985-01-01
A kinematic approach to short-term geomagnetism has recently been based upon pre-Maxwell frozen-flux electromagnetism. A complete dynamic theory requires coupling fluid dynamics to electromagnetism. A geophysically plausible simplifying assumption for the vertical vorticity balance, namely that the vertical Lorentz torque is negligible, is introduced and its consequences are developed. The simplified coupled magnetohydrodynamic system is shown to conserve a variety of magnetic and vorticity flux integrals. These provide constraints on eligible models for the geomagnetic main field, its secular variation, and the horizontal fluid motions at the top of the core, and so permit a number of tests of the underlying assumptions.
Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane
Energy Technology Data Exchange (ETDEWEB)
Elliott, Stephen J.; Ni, Guangjian [Institute of Sound and Vibration Research, University of Southampton, Southampton (United Kingdom)
2015-12-31
The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a â€œcoupling massâ€ effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.
Two-way coupled fluid structure interaction simulation of a propeller turbine
Energy Technology Data Exchange (ETDEWEB)
Schmucker, H [Voith Hydro GmbH and Co. KG, Germany Alexanderstrasse 11, 89522 Heidenheim (Germany); Flemming, F; Coulson, S, E-mail: Hannes.Schmucker@voith.co [Voith Hydro Inc. York, PA, 760 East Berlin Road, York, PA, 17408 (United States)
2010-08-15
During the operation of a hydro turbine the fluid mechanical pressure loading on the turbine blades provides the driving torque on the turbine shaft. This fluid loading results in a structural load on the component which in turn causes the turbine blade to deflect. Classically, these mechanical stresses and deflections are calculated by means of finite element analysis (FEA) which applies the pressure distribution on the blade surface calculated by computational fluid dynamics (CFD) as a major boundary condition. Such an approach can be seen as a oneway coupled simulation of the fluid structure interaction (FSI) problem. In this analysis the reverse influence of the deformation on the fluid is generally neglected. Especially in axial machines the blade deformation can result in a significant impact on the turbine performance. The present paper analyzes this influence by means of fully two-way coupled FSI simulations of a propeller turbine utilizing two different approaches. The configuration has been simulated by coupling the two commercial solvers ANSYS CFX for the fluid mechanical simulation with ANSYS Classic for the structure mechanical simulation. A detailed comparison of the results for various blade stiffness by means of changing Young's Modulus are presented. The influence of the blade deformation on the runner discharge and performance will be discussed and shows for the configuration investigated no significant influence under normal structural conditions. This study also highlights that a two-way coupled fluid structure interaction simulation of a real engineering configuration is still a challenging task for today's commercially available simulation tools.
Preparation of Silica-Alumina Hollow Spheres with a Single Surface Hole by Co-axial Microchannelâ˜†
Institute of Scientific and Technical Information of China (English)
Jinyuan Wang; Yujun Wang; Guangsheng Luo
2014-01-01
Si/Al composite hollow spheres with a surface hole were prepared with the co-axial microchannel in a one-step method. It is easy to use the technique for size control and continuous operation. At Si/Al ratio between 4 and 5, a hole forms on the surface, due to the fast gelation process and high viscosity of the sol. Scanning electron micros-copy, nitrogen adsorptionâ€“desorption isotherms, and mercury intrusion method are used to characterize the samples. The hole size is 40â€“150Î¼m and the particle size is 450â€“600Î¼m. The size can be adjusted by the flow rate of the oil phase.
Multiscale Simulation Framework for Coupled Fluid Flow and Mechanical Deformation
Energy Technology Data Exchange (ETDEWEB)
Tchelepi, Hamdi
2014-11-14
A multiscale linear-solver framework for the pressure equation associated with flow in highly heterogeneous porous formations was developed. The multiscale based approach is cast in a general algebraic form, which facilitates integration of the new scalable linear solver in existing flow simulators. The Algebraic Multiscale Solver (AMS) is employed as a preconditioner within a multi-stage strategy. The formulations investigated include the standard MultiScale Finite-Element (MSFE) andMultiScale Finite-Volume (MSFV) methods. The local-stage solvers include incomplete factorization and the so-called Correction Functions (CF) associated with the MSFV approach. Extensive testing of AMS, as an iterative linear solver, indicate excellent convergence rates and computational scalability. AMS compares favorably with advanced Algebraic MultiGrid (AMG) solvers for highly detailed three-dimensional heterogeneous models. Moreover, AMS is expected to be especially beneficial in solving time-dependent problems of coupled multiphase flow and transport in large-scale subsurface formations.
Directory of Open Access Journals (Sweden)
Wei Hua
2015-12-01
Full Text Available In this paper, a co-axial dual-mechanical ports flux-switching permanent magnet (CADMP-FSPM machine for hybrid electric vehicles (HEVs is proposed and investigated, which is comprised of two conventional co-axial FSPM machines, namely one high-speed inner rotor machine and one low-speed outer rotor machine and a non-magnetic ring sandwiched in between. Firstly, the topology and operation principle of the CADMP-FSPM machine are introduced; secondly, the control system of the proposed electronically-controlled continuously-variable transmission (E-CVT system is given; thirdly, the key design specifications of the CADMP-FSPM machine are determined based on a conventional dual-mechanical ports (DMP machine with a wound inner rotor. Fourthly, the performances of the CADMP-FSPM machine and the normal DMP machine under the same overall volume are compared, and the results indicate that the CADMP-FSPM machine has advantages over the conventional DMP machine in the elimination of brushes and slip rings, improved thermal dissipation conditions for the inner rotor, direct-driven operation, more flexible modes, lower cogging torque and torque ripple, lower total harmonic distortion (THD values of phase PM flux linkage and phase electro-motive force (EMF, higher torque output capability and is suitable for the E-CVT systems. Finally, the pros and cons of the CADMP-FSPM machine are highlighted. This paper lays a theoretical foundation for further research on CADMP-FSPM machines used for HEVs.
Energy Technology Data Exchange (ETDEWEB)
Lornage, D.
2001-12-15
Shaft lines of turbo-machineries have to stand increasing reliability, efficiency and safety requirements. A precise modeling of the rotating parts with all possible coupling has become necessary. In this context, this work aims to develop a global modeling of rotating wheel/shaft system inside a surrounding fluid in order to foresee its dynamical behaviour. The use and advantage of Eulerian, Lagrangian and mixed (arbitrary Lagrangian Eulerian - ALE) formulations is recalled first. A bibliographic synthesis of the classical techniques used in structure mechanics and of coupling techniques for rotating machines is presented. The coupling technique retained is presented. It uses fluid and structure models independently developed and validated. The structure domain is discretized by the finite-element method. The fluid domain is discretized by the finite-difference method taking into consideration the hypotheses linked with thin films. A modal base projection combined with a mesh at the fluid-structure interface allows an efficient, adaptable and evolutive coupling. Finally, the method is applied to 3 test-cases. The first two ones comprise a shaft/disc system coupled to a fluid sheet between the disc and the casing and to an hydrodynamic bearing. Both cases allow a first validation of the coupling method. The third case aims to study a structure closer to a real system made of a shaft and a wheel coupled to a fluid sheet between a flange and a casing. These three applications allow to show the trends linked with the fluid effects and the coupling between the flexible sub-parts of the structure. (J.S.)
Fluid-particle flow modelling and validation using two-way-coupled mesoscale SPH-DEM
Robinson, Martin; Ramaioli, Marco
2013-01-01
We present a meshless simulation method for multiphase fluid-particle flows coupling Smoothed Particle Hydrodynamics (SPH) and the Discrete Element Method (DEM). Rather than fully resolving the interstitial fluid, which is often infeasible, the unresolved fluid model is based on the locally averaged Navier Stokes equations, which are coupled with a DEM model for the solid phase. In contrast to similar mesh-based Discrete Particle Methods (DPMs), this is a purely particle-based method and enjoys the flexibility that comes from the lack of a prescribed mesh. It is suitable for problems such as free surface flow or flow around complex, moving and/or intermeshed geometries. It can be used for both one and two-way coupling and is applicable to both dilute and dense particle flows. A comprehensive validation procedure for fluid-particle simulations is presented and applied to the SPH-DEM method, using simulations of single and multiple particle sedimentation in a 3D fluid column and comparison with analytical model...
Meso-scale coupling of FEM/DEM for fluid-particle interactions,
Srivastava, S.; Yazdchi, K.; Luding, S.
2014-01-01
A new method for two-way fluidâ€“particle coupling on an unstructured mesoscopically coarse mesh is presented. In this approach, we combine a (higher order) finite-element method (FEM) on the moving mesh for the fluid with a soft sphere discrete-element method for the particles. The novel feature of t
Study on Fluid-Lining-Rock Coupling Interaction of Diversion Tunnel under Seismic Load
Directory of Open Access Journals (Sweden)
Jian Deng
2015-01-01
Full Text Available Fluid-lining-rock coupling interaction of diversion tunnel under seismic load is a critical problem in seismic research which should be solved urgently. Based on the explicit finite element method for dynamic analysis of single-phase fluid and solid medium and combining with the boundary conditions of coupling interface, a dynamic explicit finite element solving format of diversion tunnel considering fluid-lining coupling interaction is established. In light of the basic theory of dynamic contact force method and applying the nonlinear hyperbolic constitutive model of contact surface, a dynamic explicit finite element time-domain integral equation of combined bearing of lining and surrounding rocks, which takes the bond-slip behavior of the contact surface into account, is put forward. Meanwhile, considering the dynamic interaction process of inner water and lining, lining and surrounding rocks, an explicit finite element numerical simulation analysis method of fluid-lining-rock coupling interaction of diversion tunnel under seismic load is presented. The calculation results of case study reasonably reflect the seismic response characteristics of diversion tunnel, and an effective analysis method is provided for the aseismic design of hydraulic tunnel.
A minimal coupled fluid-discrete element model for bedload transport
Maurin, Raphael; Chareyre, Bruno; Frey, Philippe
2016-01-01
A minimal Lagragian two-phase model to study turbulent bedload transport focusing on the granular phase is presented, and validated with experiments. The model intends to describe bedload transport of massive particles in fully rough flows at relatively low Shields numbers, for which no suspension occurs. A discrete element method for the granular phase is coupled with a one dimensional volume-averaged two-phase momentum equation for the fluid phase. The coupling between the discrete granular phase and the continuous fluid phase is discussed, and a consistent averaging formulation adapted to bedload transport is introduced. An original simple discrete random walk model is proposed to account for the fluid velocity fluctuations. The model is compared with experiments considering both classical sediment transport rate as a function of the Shields number, and depth profiles of solid velocity, volume fraction, and transport rate density, from existing bedload transport experiments in inclined flume. The results s...
Institute of Scientific and Technical Information of China (English)
Cai-Wan Chang-Jian; Her-Terng Yau
2007-01-01
This study performs a dynamic analysis of a rotor supported by two squeeze couple stress fluid film journal bearings with nonlinear suspension. The numerical results show that the stability of the system varies with the non-dimensional speed ratios and the dimensionless parameter l*. It is found that the system is more stable with higher dimensionless parameter l*.Thus it can conclude that the rotor-bearing system lubricated with the couple stress fluid is more stable than that with the conventional Newtonian fluid. The modeling results thus obtained by using the method proposed in this paper can be used to predict the stability of the rotor-bearing system and the undesirable behavior of the rotor and bearing center can be avoided.
Institute of Scientific and Technical Information of China (English)
æ—
2007-01-01
This paper, with a finite element method, studies the interaction of a coupled incompressible fluid-rigid structure system with a free surface subjected to external wave excitations. With this fully coupled model, the rigid structure is taken as "fictitious" fluid with zero strain rate. Both fluid and structure are described by velocity and pressure. The whole domain, including fluid region and structure region, is modeled by the incompressible Navier-Stokes equations which are discretized with fixed Eulerian mesh. However, to keep the structure's rigid body shape and behavior, a rigid body constraint is enforced on the "fictitious" fluid domain by use of the Distributed Lagrange Multiplier/Fictitious Domain (DLM/FD) method which is originally introduced to solve particulate flow problems by Glowinski et al. For the verification of the model presented herein, a 2D numerical wave tank is established to simulate small amplitude wave propagations, and then numerical results are compared with analytical solutions. Finally, a 2D example of fluid-structure interaction under wave dynamic forces provides convincing evidences for the method excellent solution quality and fidelity.
A Coupled Fluid-Structure Interaction Analysis of Solid Rocket Motor with Flexible Inhibitors
Yang, H. Q.; West, Jeff
2014-01-01
A capability to couple NASA production CFD code, Loci/CHEM, with CFDRC's structural finite element code, CoBi, has been developed. This paper summarizes the efforts in applying the installed coupling software to demonstrate/investigate fluid-structure interaction (FSI) between pressure wave and flexible inhibitor inside reusable solid rocket motor (RSRM). First a unified governing equation for both fluid and structure is presented, then an Eulerian-Lagrangian framework is described to satisfy the interfacial continuity requirements. The features of fluid solver, Loci/CHEM and structural solver, CoBi, are discussed before the coupling methodology of the solvers is described. The simulation uses production level CFD LES turbulence model with a grid resolution of 80 million cells. The flexible inhibitor is modeled with full 3D shell elements. Verifications against analytical solutions of structural model under steady uniform pressure condition and under dynamic condition of modal analysis show excellent agreements in terms of displacement distribution and eigen modal frequencies. The preliminary coupled result shows that due to acoustic coupling, the dynamics of one of the more flexible inhibitors shift from its first modal frequency to the first acoustic frequency of the solid rocket motor.
Coupling LAMMPS with Lattice Boltzmann fluid solver: theory, implementation, and applications
Tan, Jifu; Sinno, Talid; Diamond, Scott
2016-11-01
Studying of fluid flow coupled with solid has many applications in biological and engineering problems, e.g., blood cell transport, particulate flow, drug delivery. We present a partitioned approach to solve the coupled Multiphysics problem. The fluid motion is solved by the Lattice Boltzmann method, while the solid displacement and deformation is simulated by Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The coupling is achieved through the immersed boundary method so that the expensive remeshing step is eliminated. The code can model both rigid and deformable solids. The code also shows very good scaling results. It was validated with classic problems such as migration of rigid particles, ellipsoid particle's orbit in shear flow. Examples of the applications in blood flow, drug delivery, platelet adhesion and rupture are also given in the paper. NIH.
Klein, Andreas; Gerlach, Gerald
1998-09-01
This paper deals with the simulation of the fluid-structure interaction phenomena in micropumps. The proposed solution approach is based on external coupling of two different solvers, which are considered here as `black boxes'. Therefore, no specific intervention is necessary into the program code, and solvers can be exchanged arbitrarily. For the realization of the external iteration loop, two algorithms are considered: the relaxation-based Gauss-Seidel method and the computationally more extensive Newton method. It is demonstrated in terms of a simplified test case, that for rather weak coupling, the Gauss-Seidel method is sufficient. However, by simply changing the considered fluid from air to water, the two physical domains become strongly coupled, and the Gauss-Seidel method fails to converge in this case. The Newton iteration scheme must be used instead.
Pathogen control in complex fluids with water-coupled excimer lamps at 282 and 308 nm.
Coogan, John J
2005-01-01
Water-coupled excimer lamp systems have been developed to inactivate microorganisms within complex, low-optical quality, fluids. Monochromatic lamps were selected to minimize UV-B and UV-C absorption within the carrier fluids while maximizing deposition within specific chemical targets. Fundamentals, system scaling and power supply design are discussed. This work used two large-surface area excimer lamps as intense sources of near monochromatic radiation at 308 and 282 nm. Data are presented for two distinct fluid systems: flow-through processing of large-volume metalworking fluids used in heavy industry and batch irradiation of human blood plasma and platelet suspensions used in transfusion medicine. In the first, a 200-600 L/min reactor is used to control bacterial concentrations within metalworking fluids used in large-scale metal machining processes. Control is defined as the maintenance of 10(3) to 10(4) CFU/mL in fluids that without treatment would have concentrations over 10(7) CFU/mL. The second is a batch process for viral inactivation in undiluted blood bank products. Samples of fresh frozen plasma and platelet suspensions were spiked with high titers of porcine parvovirus (PPV) and irradiated at 308 and 282 nm. Although both wavelengths were effective at reducing PPV levels, 308 nm light resulted in both higher rates of viral inactivation (greater than 6 log units) and lower rates of fluid degradation.
Directory of Open Access Journals (Sweden)
P.Selvakumar
2014-03-01
Full Text Available An evacuated tube solar collector using therminol D-12 as heat transfer fluid coupled with parabolic trough is studied in this paper. An experimental set-up was constructed to study the performance of evacuated tube collector with therminol D-12 as heat transfer fluid. The parabolic trough is coupled with evacuated tube collector for better performance. In the traditional solar collectors water is used as heat transfer fluid. The problems in using water as heat transfer fluid are addressed in detail in this paper. The temperature characteristics of heat transfer fluid and water in the storage tank and the heating efficiency are determined under various conditions. The efficiency of therminol based evacuated tube collector coupled with parabolic trough is 40% more than that of water based evacuated tube collector coupled with parabolic trough. This study projects the potential of therminol based evacuated tube solar collector coupled with parabolic trough in the instant hot water generation.
Full-Eulerian fluid-structure coupling simulation of hyperelastic channel flow
Nagano, Naohiro; Sugiyama, Kazuyasu; Takeuchi, Shintaro; Satoshi, II; Takagi, Shu; Matsumoto, Yoichiro
2010-11-01
A full-Eulerian simulation for coupling a Newtonian fluid and hyperelastic material is conducted. The system involves an interaction problem between the fluid and hyperelastic walls and is driven by pressure difference, mimicking a blood flow in a blood vessel. A single set of the governing equations for the fluid and solid is employed, and a volume-of-fluid idea is employed to describe a multi-component geometry. The solid stress is defined in Eulerian frame by using a left Cauchy-Green deformation tensor, and the temporal change in the solid deformation is described by updating the tensor. The method employs a uniform fixed grid system for both fluid and solid and it does not require any mesh generation or reconstruction, aiming at facilitating the practical bio-mechanical fluid-structure analysis based on a medical image. The validity of the simulation results is established through comparison with a theoretical prediction. As an application of the present method, pulsating flows are simulated to demonstrate a nonlinear behavior of the flow rate on the pulsating amplitude, and an effect of employing an anisotropic hyperelastic material is discussed.
Coupled Fluid-Structure Interaction Analysis of Solid Rocket Motor with Flexible Inhibitors
Yang, H. Q.; West, Jeff; Harris, Robert E.
2014-01-01
Flexible inhibitors are generally used in solid rocket motors (SRMs) as a means to control the burning of propellant. Vortices generated by the flow of propellant around the flexible inhibitors have been identified as a driving source of instabilities that can lead to thrust oscillations in launch vehicles. Potential coupling between the SRM thrust oscillations and structural vibration modes is an important risk factor in launch vehicle design. As a means to predict and better understand these phenomena, a multidisciplinary simulation capability that couples the NASA production CFD code, Loci/CHEM, with CFDRC's structural finite element code, CoBi, has been developed. This capability is crucial to the development of NASA's new space launch system (SLS). This paper summarizes the efforts in applying the coupled software to demonstrate and investigate fluid-structure interaction (FSI) phenomena between pressure waves and flexible inhibitors inside reusable solid rocket motors (RSRMs). The features of the fluid and structural solvers are described in detail, and the coupling methodology and interfacial continuity requirements are then presented in a general Eulerian-Lagrangian framework. The simulations presented herein utilize production level CFD with hybrid RANS/LES turbulence modeling and grid resolution in excess of 80 million cells. The fluid domain in the SRM is discretized using a general mixed polyhedral unstructured mesh, while full 3D shell elements are utilized in the structural domain for the flexible inhibitors. Verifications against analytical solutions for a structural model under a steady uniform pressure condition and under dynamic modal analysis show excellent agreement in terms of displacement distribution and eigenmode frequencies. The preliminary coupled results indicate that due to acoustic coupling, the dynamics of one of the more flexible inhibitors shift from its first modal frequency to the first acoustic frequency of the solid rocket motor
Effect of hall currents on thermal instability of dusty couple stress fluid
Directory of Open Access Journals (Sweden)
Aggarwal Amrish Kumar
2016-09-01
Full Text Available In this paper, effect of Hall currents on the thermal instability of couple-stress fluid permeated with dust particles has been considered. Following the linearized stability theory and normal mode analysis, the dispersion relation is obtained. For the case of stationary convection, dust particles and Hall currents are found to have destabilizing effect while couple stresses have stabilizing effect on the system. Magnetic field induced by Hall currents has stabilizing/destabilizing effect under certain conditions. It is found that due to the presence of Hall currents (hence magnetic field, oscillatory modes are produced which were non-existent in their absence.
Coupled Outdoor and Indoor Airflow Prediction for Buildings Using Computational Fluid Dynamics (CFD
Directory of Open Access Journals (Sweden)
Deo Prasad
2013-05-01
Full Text Available The objective of this study is to investigate the accuracy of Computational Fluid Dynamics (CFD for simultaneously predicting the outdoor and indoor airflows of single-cell and multi-storey buildings. Empirical models and two existing wind tunnel experimental data are used for validation. This study found that coupled CFD simulations provide sufficiently accurate airflow predictions and, in cases of buildings with complex faÃ§ade treatments, accurately accounts for changes in ventilation performance, which may be impossible using empirical models. This study concludes that coupled CFD simulations can generally be used to predict ventilation performance in small and large buildings.
Fully implicit, coupled procedures in computational fluid dynamics an engineer's resource book
Mazhar, Zeka
2016-01-01
This book introduces a new generation of superfast algorithms for the treatment of the notoriously difficult velocity-pressure coupling problem in incompressible fluid flow solutions. It provides all the necessary details for the understanding and implementation of the procedures. The derivation and construction of the fully-implicit, block-coupled, incomplete decomposition mechanism are given in a systematic, but easy fashion. Worked-out solutions are included, with comparisons and discussions. A complete program code is included for faster implementation of the algorithm. A brief literature review of the development of the classical solution procedures is included as well. .
Coupled DEM-CFD Investigation of Granular Transport in a Fluid Channel
Zhao, T.; Dai, F.; Xu, N. W.
2015-09-01
This paper presents three dimensional numerical investigations of granular transport in fluids, analysed by the Discrete Element Method (DEM) coupled with Computational Fluid Mechanics (CFD). By employing this model, the relevance of flow velocity and granular depositional morphology has been clarified. The larger the flow velocity is, the further distance the grains can be transported to. In this process, the segregation of solid grains has been clearly identified. This research reveals that coarse grains normally accumulate near the grain source region, while the fine grains can be transported to the flow front. Regardless of the different flow velocities used in these simulations, the intensity of grains segregation remains almost unchanged. The results obtained from the DEM-CFD coupled simulations can reasonably explain the grain transport process occurred in natural environments, such as river scouring, evolution of river/ocean floor, deserts and submarine landslides.
Second law analysis for hydromagnetic couple stress fluid flow through a porous channel
Directory of Open Access Journals (Sweden)
S.O. Kareem
2016-06-01
Full Text Available In this work, the combined effects of magnetic field and ohmic heating on the entropy generation rate in the flow of couple stress fluid through a porous channel are investigated. The equations governing the fluid flow are formulated, non-dimensionalised and solved using a rapidly convergent semi-analytical Adomian decomposition method (ADM. The result of the computation shows a significant dependence of fluidâ€™s thermophysical parameters on Jouleâ€™s dissipation as well as decline in the rate of change of fluid momentum due to the interplay between Lorentz and viscous forces. Moreover, the rate of entropy generation in the flow system drops as the magnitude of the magnetic field increases.
A Coupled Far-Field Formulation for Time-Periodic Numerical Problems in Fluid Dynamics
Indian Academy of Sciences (India)
Edmund Chadwick; Rabea El-Mazuzi
2012-11-01
Consider uniform flow past an oscillating body generating a time-periodic motion in an exterior domain, modelled by a numerical fluid dynamics solver in the near field around the body. A far-field formulation, based on the Oseen equations, is presented for coupling onto this domain thereby enabling the whole space to be modelled. In particular, examples for formulations by boundary elements and infinite elements are described.
Improved dynamics and gravitational collapse of tachyon field coupled with a barotropic fluid
Marto, Joao; Moniz, Paulo Vargas
2013-01-01
We consider a spherically symmetric gravitational collapse with a tachyon field coupled with a barotropic fluid, as matter source. The tachyonic potential is assumed to be of an inverse square form. By employing the holonomy correction imported from loop quantum gravity, we study the dynamics of the collapse within a semiclassical description. We find that the classical black hole and naked singularities, appearing in the corresponding standard general relativistic collapse, are avoided by quantum gravity induced effects.
Mixed Convection Flow of Couple Stress Fluid in a Vertical Channel with Radiation and Soret Effects
Directory of Open Access Journals (Sweden)
Kaladhar Kolla
2016-01-01
Full Text Available The radiation and thermal diffusion effects on mixed convection flow of couple stress fluid through a channel are investigated. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformations. The resulting equations are then solved using the Spectral Quasi-linearization Method (QLM. The results, which are discussed with the aid of the dimensionless parameters entering the problem, are seen to depend sensitively on the parameters.
Explicit Analytical Solutions of Coupled Fluid Flow Transfer Equation in Heterogeneous Porous Media
Institute of Scientific and Technical Information of China (English)
å¼ å¨œ; è”¡ç¿è´¤
2002-01-01
Explicit analytical solutions are presented for the coupled fluid flow transfer equation in heterogeneous porous media. These analytical solutions are useful for their description of actual flow fields and as benchmark solutions to check the rapidly developing numerical calculations and to study various computational methods such as the discrete approximations of the governing equations and grid generation methods. In addition, some novel mathematical methods are used in the analyses.
Miyauchi, Minoru; Miao, Jianjun; Simmons, Trevor J.; Lee, Jong-Won; Doherty, Thomas V.; Dordick, Jonathan S.; Linhardt, Robert J.
2010-01-01
A core-sheath of multi-walled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds nm to several Âµm were prepared by co-axial electrospinning from a non-valatile, non-flammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose disolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to completely remove the IL and dried to form a core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity due to a conductive pathway of bundleled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt% MWNT loading. PMID:20690644
Valenti, Giovanni; Boni, Alessandro; Melchionna, Michele; Cargnello, Matteo; Nasi, Lucia; Bertoni, Giovanni; Gorte, Raymond J.; Marcaccio, Massimo; Rapino, Stefania; Bonchio, Marcella; Fornasiero, Paolo; Prato, Maurizio; Paolucci, Francesco
2016-12-01
Considering the depletion of fossil-fuel reserves and their negative environmental impact, new energy schemes must point towards alternative ecological processes. Efficient hydrogen evolution from water is one promising route towards a renewable energy economy and sustainable development. Here we show a tridimensional electrocatalytic interface, featuring a hierarchical, co-axial arrangement of a palladium/titanium dioxide layer on functionalized multi-walled carbon nanotubes. The resulting morphology leads to a merging of the conductive nanocarbon core with the active inorganic phase. A mechanistic synergy is envisioned by a cascade of catalytic events promoting water dissociation, hydride formation and hydrogen evolution. The nanohybrid exhibits a performance exceeding that of state-of-the-art electrocatalysts (turnover frequency of 15000 H2 per hour at 50 mV overpotential). The Tafel slope of ~130 mV per decade points to a rate-determining step comprised of water dissociation and formation of hydride. Comparative activities of the isolated components or their physical mixtures demonstrate that the good performance evolves from the synergistic hierarchical structure.
Coupled computational fluid-thermal investigation of hypersonic flow over a quilted dome surface
Ostoich, Christopher; Bodony, Daniel; Geubelle, Philippe
2009-11-01
The hypersonic environment is characterized by the high temperatures that are generated in the fluid at a vehicle surface. In the effort to enable the operation of lightweight, reusable hypersonic vehicles, flexible, thin thermal protection panels have been considered to mitigate thermal loads. High surface temperatures create through-the-thickness thermal gradients which cause the panels to bow, resulting in changes to the external flow field and leading to a fully coupled fluid-thermal-structural problem. Certain aspects of the fluid-thermal (no structural) coupling were examined in a 1980s NASA Langley experiment of a Mach 5.74 laminar boundary past an array of spherical domes. We reexamine this case computationally using a high-fidelity Navier-Stokes solver coupled with a thermal solver to investigate the effects on the flow and resulting heat load on the structure due to the bowed panels. Specifically the surface temperature, surface heat flux, and downstream boundary developments are reported, and compared with experiment.
Coupled thermal-fluid-mechanics analysis of twin roll casting of A7075 aluminum alloy
Lee, Yun-Soo; Kim, Hyoung-Wook; Cho, Jae-Hyung; Chun, Se-Hwan
2017-09-01
Better understanding of temperature distribution and roll separation force during twin roll casting of aluminum alloys is critical to successfully fabricate good quality of aluminum strips. Therefore, the simulation techniques are widely applied to understand the twin roll casting process in a comprehensive way and to reduce the experimental time and cost of trial and error. However, most of the conventional approaches are considered thermally coupled flow, or thermally coupled mechanical behaviors. In this study, a fully coupled thermal-fluid-mechanical analysis of twin roll casting of A7075 aluminum strips was carried out using the finite element method. Temperature profile, liquid fraction and metal flow of aluminum strips with different thickness were predicted. Roll separation force and roll temperatures were experimentally obtained from a pilot-scale twin roll caster, and those results were compared with model predictions. Coupling the fluid of the liquid melt to the thermal and mechanical modeling reasonably predicted roll temperature distribution and roll separation force during twin roll casting.
Directory of Open Access Journals (Sweden)
Jinbao Lin
2014-01-01
Full Text Available Carbon-fiber reinforced polymer material impeller is designed for the centrifugal pump to deliver corrosive, toxic, and abrasive media in the chemical and pharmaceutical industries. The pressure-velocity coupling fields in the pump are obtained from the CFD simulation. The stress distribution of the impeller couple caused by the flow water pressure and rotation centrifugal force of the blade is analyzed using one-way fluid-solid coupling method. Results show that the strength of the impeller can meet the requirement of the centrifugal pumps, and the largest stress occurred around the blades root on a pressure side of blade surface. Due to the existence of stress concentration at the blades root, the fatigue limit of the impeller would be reduced greatly. In the further structure optimal design, the blade root should be strengthened.
Hassan, Ehab; Morrison, P J; Horton, W
2016-01-01
Progress in understanding the coupling between plasma instabilities in the equatorial electrojet based on a unified fluid model is reported. A deeper understanding of the linear and nonlinear evolution and the coupling of the gradient-drift and Farley-Buneman instabilities is achieved by studying the e?ect of di?erent combinations of the density-gradient scale-lengths (Ln) and cross-?eld (E?B) drifts on the plasma turbulence. Mechanisms and channels of energy transfer are illucidated for these multiscale instabilities. Energy for the uni?ed model is examined, including the injected, conservative redistribution (between ?elds and scales), and ultimate dissipation. Various physical mechanisms involved in the energetics are categorized as sources, sinks, nonlinear transfer, and coupling to show that the system satisfies the fundamental law of energy Oonservation. The physics of the nonlinear transfer terms is studied to identify their roles in producing energy cascades { the transference of energy from the domin...
Luce, J.S.; Smith, L.P.
1960-11-22
A method and apparatus are given for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons will diffuse to the more positive arc from the negative arc, and positive ions will diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantage that ions which return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. Those discharges are useful in confining an ionized plasma between the discharges, and have the advantage of preventing impurities from the walls of the enclosure from entering ihe plasma area because of the arc barrier set up bv the cylindrical outer arc.
Directory of Open Access Journals (Sweden)
Friedrich-Karl Benra
2011-01-01
Full Text Available The interaction between fluid and structure occurs in a wide range of engineering problems. The solution for such problems is based on the relations of continuum mechanics and is mostly solved with numerical methods. It is a computational challenge to solve such problems because of the complex geometries, intricate physics of fluids, and complicated fluid-structure interactions. The way in which the interaction between fluid and solid is described gives the largest opportunity for reducing the computational effort. One possibility for reducing the computational effort of fluid-structure simulations is the use of one-way coupled simulations. In this paper, different problems are investigated with one-way and two-way coupled methods. After an explanation of the solution strategy for both models, a closer look at the differences between these methods will be provided, and it will be shown under what conditions a one-way coupling solution gives plausible results.
Vibration analysis of hydropower house based on fluid-structure coupling numerical method
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Shu-he WEI
2010-03-01
Full Text Available By using the shear stress transport (SST model to predict the effect of random flow motion in a fluid zone, and using the Newmark method to solve the oscillation equations in a solid zone, a coupling model of the powerhouse and its tube water was developed. The effects of fluid-structure interaction are considered through the kinematic and dynamic conditions applied to the fluid-structure interfaces (FSI. Numerical simulation of turbulent flow through the whole flow passage of the powerhouse and concrete structure vibration analysis in the time domain were carried out with the model. Considering the effect of coupling the turbulence and the powerhouse structure, the time history response of both turbulent flows through the whole flow passage and powerhouse structure vibration were generated. Concrete structure vibration analysis shows that the displacement, velocity, and acceleration of the dynamo floor respond dramatically to pressure fluctuations in the flow passage. Furthermore, the spectrum analysis suggests that pressure fluctuation originating from the static and dynamic disturbances of hydraulic turbine blades in the flow passage is one of the most important vibration sources.
A minimal coupled fluid-discrete element model for bedload transport
Maurin, R.; Chauchat, J.; Chareyre, B.; Frey, P.
2015-11-01
A minimal Lagrangian two-phase model to study turbulent bedload transport focusing on the granular phase is presented and validated with experiments. The model intends to describe bedload transport of massive particles in fully rough flows at relatively low Shields numbers, for which no suspension occurs. A discrete element method for the granular phase is coupled with a one dimensional volume-averaged two-phase momentum equation for the fluid phase. The coupling between the discrete granular phase and the continuous fluid phase is discussed, and a consistent averaging formulation adapted to bedload transport is introduced. An original simple discrete random walk model is proposed to account for the fluid velocity fluctuations. The model is compared with experiments considering both classical sediment transport rate as a function of the Shields number, and depth profiles of solid velocity, volume fraction, and transport rate density, from existing bedload transport experiments in inclined flume. The results successfully reproduce the classical 3/2 power law, and more importantly describe well the depth profiles of the granular phase, showing that the model is able to reproduce the particle scale mechanisms. From a sensitivity analysis, it is shown that the fluctuation model allows to reproduce a realistic critical Shields number, and that the influence of the granular parameters on the macroscopic results is weak. Nevertheless, the analysis of the corresponding depth profiles reveals an evolution of the depth structure of the granular phase with varying restitution and friction coefficients, which denotes the non-trivial underlying physical mechanisms.
Couple-Stress Fluid Improves Dynamic Response of Gear-Pair System Supported by Journal Bearings
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Cai-Wan Chang-Jian
2012-01-01
Full Text Available A systematic analysis of the dynamic behavior of a gear-bearing system with nonlinear suspension, couple-stress fluid flow effect, nonlinear oil-film force, and nonlinear gear mesh force is performed in the present study. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless rotational speed ratio as a control parameter. The onset of chaotic motion is identified from the phase diagrams, power spectra, PoincarÃ© maps, Lyapunov exponents and fractal dimension of the gear-bearing system. The numerical results reveal that the system exhibits a diverse range of periodic, subharmonic, quasiperiodic, and chaotic behaviors. The couple-stress fluid would be a useful lubricating fluid to suppress nonlinear dynamic responses and improve the steady of the systems. The results presented in this study provide some useful insights into the design and development of a gear-bearing system for rotating machinery that operates in highly rotational speed and highly nonlinear regimes.
Strongly Coupled Fluid-Body Dynamics in the Immersed Boundary Projection Method
Wang, Chengjie; Eldredge, Jeff D.
2014-11-01
A computational algorithm is developed to simulate dynamically coupled interaction between fluid and rigid bodies. The basic computational framework is built upon a multi-domain immersed boundary method library, whirl, developed in previous work. In this library, the Navier-Stokes equations for incompressible flow are solved on a uniform Cartesian grid by the vorticity-based immersed boundary projection method of Colonius and Taira. A solver for the dynamics of rigid-body systems is also included. The fluid and rigid-body solvers are strongly coupled with an iterative approach based on the block Gauss-Seidel method. Interfacial force, with its intimate connection with the Lagrange multipliers used in the fluid solver, is used as the primary iteration variable. Relaxation, developed from a stability analysis of the iterative scheme, is used to achieve convergence in only 2-4 iterations per time step. Several two- and three-dimensional numerical tests are conducted to validate and demonstrate the method, including flapping of flexible wings, self-excited oscillations of a system of linked plates and three-dimensional propulsion of flexible fluked tail. This work has been supported by AFOSR, under Award FA9550-11-1-0098.
Energy Technology Data Exchange (ETDEWEB)
Andrade, JosÃƒÂƒÃ‚Â© E; Rudnicki, John W
2012-12-14
In this project, a predictive multiscale framework will be developed to simulate the strong coupling between solid deformations and fluid diffusion in porous rocks. We intend to improve macroscale modeling by incorporating fundamental physical modeling at the microscale in a computationally efficient way. This is an essential step toward further developments in multiphysics modeling, linking hydraulic, thermal, chemical, and geomechanical processes. This research will focus on areas where severe deformations are observed, such as deformation bands, where classical phenomenology breaks down. Multiscale geometric complexities and key geomechanical and hydraulic attributes of deformation bands (e.g., grain sliding and crushing, and pore collapse, causing interstitial fluid expulsion under saturated conditions), can significantly affect the constitutive response of the skeleton and the intrinsic permeability. Discrete mechanics (DEM) and the lattice Boltzmann method (LBM) will be used to probe the microstructure---under the current state---to extract the evolution of macroscopic constitutive parameters and the permeability tensor. These evolving macroscopic constitutive parameters are then directly used in continuum scale predictions using the finite element method (FEM) accounting for the coupled solid deformation and fluid diffusion. A particularly valuable aspect of this research is the thorough quantitative verification and validation program at different scales. The multiscale homogenization framework will be validated using X-ray computed tomography and 3D digital image correlation in situ at the Advanced Photon Source in Argonne National Laboratories. Also, the hierarchical computations at the specimen level will be validated using the aforementioned techniques in samples of sandstone undergoing deformation bands.
A discontinuous finite element approach to cracking in coupled poro-elastic fluid flow models
Wilson, C. R.; Spiegelman, M. W.; Evans, O.; Ulven, O. I.; Sun, W.
2016-12-01
Reaction-driven cracking is a coupled process whereby fluid-induced reactions drive large volume changes in the host rock which produce stresses leading to crack propagation and failure. This in turn generates new surface area and fluid-flow pathways for subsequent reaction in a potentially self-sustaining system. This mechanism has has been proposed for the pervasive serpentinization and carbonation of peridotite, as well as applications to mineral carbon sequestration and hydrocarbon extraction. The key computational issue in this problem is implementing algorithms that adequately model the formation of discrete fractures. Here we present models using a discontinuous finite element method for modeling fracture formation (Radovitsky et al., 2011). Cracks are introduced along facets of the mesh by the relaxation of penalty parameters once a failure criterion is met. It is fully described in the weak form of the equations, requiring no modification of the underlying mesh structure and allowing fluid properties to be easily adjusted along cracked facets. To develop and test the method, we start by implementing the algorithm for the simplified Biot equations for poro-elasticity using the finite element model assembler TerraFERMA. We consider hydro-fracking around a borehole (Grassl et al., 2015), where elevated fluid pressure in the poro-elastic solid causes it to fail radially in tension. We investigate the effects of varying the Biot coefficient and adjusting the fluid transport properties in the vicinity of the crack and compare our results to related dual-graph models (Ulven & Sun, submitted). We discuss issues arising from this method, including the formation of null spaces and appropriate preconditioning and solution strategies. Initial results suggest that this method provides a promising way to incorporate cracking into our reactive fluid flow models and future work aims to integrate the mechanical and chemical aspects of this process.
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Rio Melvin Aro.T
2015-05-01
Full Text Available Flutter is an unstable oscillation which can lead to destruction. Flutter can occur on fixed surfaces, such as blades, wing or the stabilizer. By self-excited aeroelastic instability, flutter can lead to mechanical or structural failure of aircraft engine blades. The modern engines have been designed with increased pressure ratio and reduced weight in order to improve aerodynamic efficiency, resulting in severe aeroelastic problems. Particularly flutter in axial compressors with transonic flow can be characterized by a number of aerodynamic nonlinear effects such as shock boundary layer interaction, rotating stall, and tip vortex instability. Rotating blades operating under high centrifugal forces may also encounter structural nonlinearities due to friction damping and large deformations. In the future work a standard axial flow compressor blade will be taken for analysis, both Subsonic and Transonic range are taken for analysis. Fluid and Structure are two different domains which will be coupled by full system coupling technique to predict the fluttering effect on the compressor blade. ANSYS is a commercial simulation tool, which will be deployed in this work to perform FSI (Fluid Structure Interaction and FSI coupled Modal to predict the flutter in the compressor blades
Generalized asymptotic expansions for coupled wavenumbers in fluid-filled cylindrical shells
Kunte, M. V.; Sarkar, Abhijit; Sonti, Venkata R.
2010-12-01
Analytical expressions are found for the coupled wavenumbers in an infinite fluid-filled cylindrical shell using the asymptotic methods. These expressions are valid for any general circumferential order ( n). The shallow shell theory (which is more accurate at higher frequencies) is used to model the cylinder. Initially, the in vacuo shell is dealt with and asymptotic expressions are derived for the shell wavenumbers in the high- and the low-frequency regimes. Next, the fluid-filled shell is considered. Defining a relevant fluid-loading parameter Î¼, we find solutions for the limiting cases of small and large Î¼. Wherever relevant, a frequency scaling parameter along with some ingenuity is used to arrive at an elegant asymptotic expression. In all cases, Poisson's ratio Î½ is used as an expansion variable. The asymptotic results are compared with numerical solutions of the dispersion equation and the dispersion relation obtained by using the more general Donnell-Mushtari shell theory ( in vacuo and fluid-filled). A good match is obtained. Hence, the contribution of this work lies in the extension of the existing literature to include arbitrary circumferential orders ( n).
Development of a Fast Fluid-Structure Coupling Technique for Wind Turbine Computations
DEFF Research Database (Denmark)
Sessarego, Matias; Ramos GarcÃa, NÃ©stor; Shen, Wen Zhong
2015-01-01
Fluid-structure interaction simulations are routinely used in the wind energy industry to evaluate the aerodynamic and structural dynamic performance of wind turbines. Most aero-elastic codes in modern times implement a blade element momentum technique to model the rotor aerodynamics and a modal......, multi-body, or finite-element approach to model the turbine structural dynamics. The present paper describes a novel fluid-structure coupling technique which combines a threedimensional viscous-inviscid solver for horizontal-axis wind-turbine aerodynamics, called MIRAS, and the structural dynamics model...... used in the aero-elastic code FLEX5. The new code, MIRASFLEX, in general shows good agreement with the standard aero-elastic codes FLEX5 and FAST for various test cases. The structural model in MIRAS-FLEX acts to reduce the aerodynamic load computed by MIRAS, particularly near the tip and at high wind...
A fully-coupled fluid-structure interaction simulation of cerebral aneurysms
Bazilevs, Y.; Hsu, M.-C.; Zhang, Y.; Wang, W.; Liang, X.; Kvamsdal, T.; Brekken, R.; Isaksen, J. G.
2009-10-01
This paper presents a computational vascular fluid-structure interaction (FSI) methodology and its application to patient-specific aneurysm models of the middle cerebral artery bifurcation. A fully coupled fluid-structural simulation approach is reviewed, and main aspects of mesh generation in support of patient-specific vascular FSI analyses are presented. Quantities of hemodynamic interest such as wall shear stress and wall tension are studied to examine the relevance of FSI modeling as compared to the rigid arterial wall assumption. We demonstrate the importance of including the flexible wall modeling in vascular blood flow simulations by performing a comparison study that involves four patient-specific models of cerebral aneurysms varying in shape and size.
Parallelization of a coupled immersed boundary and lattice Boltzmann method for fluid and heat flow
Kasparek, Andrzej; Åapka, Piotr
2017-07-01
The paper presents first approach to the GPU-based parallelization of the coupled Immersed Boundary and Lattice Boltzmann Method. The proposed numerical simulator deals with fluid and heat flow in a domains with complex internal boundaries using Cartesian grid. The solution algorithm was parallelized with the aid of the CUDA architecture. Several heat and fluid flow problems, i.e., heated lid-driven flow and laminar natural convection in square domains without internal obstacles and isothermal flow past stationary cylinder were investigated. Satisfactory accelerations of the solution times were obtained for problems without internal boundaries. For test case with internal boundaries decrease in the parallel computing efficiency was observed as a results of numerical handling of the internal boundaries.
Song Haiyan; Wang Fang; Zhang Jianguo; Zhang Yinong; Yang Shugang
2017-01-01
It is important to study the properties and mechanics of egg drop impacts in order to reduce egg loss during processing and logistics and to provide a basis for the protective packaging of egg products. In this paper, we present the results of our study of the effects of the structural parameters on the mechanical properties of an egg using a finite element model of the egg. Based on Fluid-Solid coupling theory, a finite element model of an egg was constructed using ADINA, a finite element ca...
Fluid-structure coupling in the guide vanes cascade of a pump-turbine scale model
Energy Technology Data Exchange (ETDEWEB)
Roth, S; Hasmatuchi, V; Botero, F; Farhat, M; Avellan, F, E-mail: steven.roth@epfl.c [Laboratory for Hydraulic Machines, Ecole Polytechnique Federale de Lausanne Av. de Cour 33bis, Lausanne, 1007 (Switzerland)
2010-08-15
The present study concerns fluid-structure coupling phenomena occurring in a guide vane cascade of a pump-turbine scale model placed in the EPFL PF3 test rig. An advanced instrument set is used to monitor both vibrating structures and the surrounding flow. The paper highlights the interaction between vibrating guide vanes and the flow behavior. The pressure fluctuations in the stay vanes region are found to be strongly influenced by the amplitude of the vibrating guide vanes. Moreover, the flow induces different hydrodynamic damping on the vibrating guide vanes depending on the operating point of the pump-turbine.
Efficient simulations of fluid flow coupled with poroelastic deformations in pleated filters
Calo, Victor M.
2015-04-27
Pleated filters are broadly used for various applications. In certain cases, especially in solid-liquid separation case, the filtering media may get deflected and that may change the overall performance characteristics of the filter. From the modeling point of view, this is a challenging multiphysics problem, namely the interaction of the fluid with a so-called poroelastic structure. This work focuses on the development of an algorithm for the simulation of the Fluid Porous Structure Interaction (FPSI) problem in the case of pleated filtering media. The first part of the work is concerned with the development of a robust and accurate numerical method for solving the Stokes-Brinkman system of equations on quadrilateral grids. The mathematical model describes a free fluid flow coupled with a flow in porous media in a domain that contains the filtering media. To discretize the complex computational domain we use quadrilateral boundary fitted grids which resolve porous-fluid interfaces. The Stokes-Brinkman system of equations is discretized here using a sophisticated finite volume method, namely multi-point flux approximation (MPFA) O-method. MPFA is widely used, e.g., in solving scalar elliptic equations with full tensor and highly varying coefficients and/or solving on heterogeneous non-orthogonalgrids. Up to the authorsâ€™ knowledge, there was no investigation of MPFA discretization for Stokes-Brinkman problems, and this study aims to fill this gap. Some numerical experiments are presented in order to demonstrate the robustness of the proposed numerical algorithm[1]. The second part of this study focuses on the coupling of the flow model with the deflection of the filtering media. For the consideration of the FPSI problem in 3D, the classical Biot system describes coupled flow and deformations in a porous body due to difference in the upstream and downstream pressures. Solving the Biot system of equations is complicated and requires a significant amount of
Institute of Scientific and Technical Information of China (English)
ç¨‹è¿œæ–¹; æŽä»¤ä¸œ; å´”é’
2013-01-01
As the oil or gas exploration and development activities in deep and ultra-deep waters become more and more, encountering gas hydrate bearing sediments (HBS) is almost inevitable. The variation in temperature and pressure can destabilize gas hydrate in nearby formation around the borehole, which may reduce the strength of the formation and result in wellbore instability. A non-isothermal, transient, two-phase, and fluid-solid coupling mathematical model is proposed to simulate the complex stability performance of a wellbore drilled in HBS. In the model, the phase transition of hydrate dissociation, the heat exchange between drilling fluid and formation, the change of mechanical and petrophysical properties, the gas-water two-phase seepage, and its interaction with rock deformation are considered. A finite element simulator is developed, and the impact of drilling mud on wellbore instability in HBS is simulated. Results indicate that the re-duction in pressure and the increase in temperature of the drilling fluid can accelerate hydrate decomposition and lead to mechanical properties getting worse tremendously. The cohesion decreases by 25% when the hydrate totally dissociates in HBS. This easily causes the wellbore instability accordingly. In the first two hours after the formation is drilled, the regions of hydrate dissociation and wellbore instability extend quickly. Then, with the soaking time of drilling fluid increasing, the regions enlarge little. Choosing the low temperature drilling fluid and increasing the drilling mud pressure appropriately can benefit the wellbore stability of HBS. The established model turns out to be an eï¬ƒcient tool in numerical studies of the hydrate dissociation behavior and wellbore stability of HBS.
Institute of Scientific and Technical Information of China (English)
å¾ä¼šé™; èµµä¹¦éœž; é«˜é£ž; å¼ é’°å¦‚; æŽé›ªæ˜¥; çŽ‹å‹å¹´
2015-01-01
A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to in-vestigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the cir-cuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determi-native role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase (decrease) at the E to H (H to E) mode transition, indicating an improved (worsened) inductive power coupling efficiency.
Xu, Hui-Jing; Zhao, Shu-Xia; Fei, Gao; Yu-Ru, Zhang; Xue-Chun, Li; You-Nian, Wang
2015-11-01
A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to investigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determinative role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase (decrease) at the E to H (H to E) mode transition, indicating an improved (worsened) inductive power coupling efficiency. Project supported by the National Natural Science Foundation of China (Grant Nos. 11175034, 11205025, 11305023, and 11075029).
Institute of Scientific and Technical Information of China (English)
è–›å¼º; æ¢å†°; åˆ˜æ™“ä¸½; æŽå®è‰³
2003-01-01
The process of contaminant transport is a problem of multicomponent and multiphase flow in unsaturated zone. Under the presupposition that gas existence affects water transport , a coupled mathematical model of contaminant transport in unsaturated zone has been established based on fluid-solid interaction mechanics theory. The asymptotical solutions to the nonlinear coupling mathematical model were accomplished by the perturbation and integral transformation method. The distribution law of pore pressure,pore water velocity and contaminant concentration in unsaturated zone has been presented under the conditions of with coupling and without coupling gas phase. An example problem was used to provide a quantitative verification and validation of the model. The asymptotical solution was compared with Faust model solution. The comparison results show reasonable agreement between asymptotical solution and Faust solution, and the gas effect and media deformation has a large impact on the contaminant transport. The theoretical basis is provided for forecasting contaminant transport and the determination of the relationship among pressure-saturation-permeability in laboratory.
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Song Haiyan
2017-01-01
Full Text Available It is important to study the properties and mechanics of egg drop impacts in order to reduce egg loss during processing and logistics and to provide a basis for the protective packaging of egg products. In this paper, we present the results of our study of the effects of the structural parameters on the mechanical properties of an egg using a finite element model of the egg. Based on Fluid-Solid coupling theory, a finite element model of an egg was constructed using ADINA, a finite element calculation and analysis software package. To simplify the model, the internal fluid of the egg was considered to be a homogeneous substance. The egg drop impact was simulated by the coupling solution, and the feasibility of the model was verified by comparison with the experimental results of a drop test. In summary, the modeling scheme was shown to be feasible and the simulation results provide a theoretical basis for the optimum design of egg packaging and egg processing equipment.
Fluctuations of coupled fluid and solid membranes with application to red blood cells
Auth, Thorsten; Safran, S. A.; Gov, Nir S.
2007-11-01
The fluctuation spectra and the intermembrane interaction of two membranes at a fixed average distance are investigated. Each membrane can either be a fluid or a solid membrane, and in isolation, its fluctuations are described by a bare or a wave-vector-dependent bending modulus, respectively. The membranes interact via their excluded-volume interaction; the average distance is maintained by an external, homogeneous pressure. For strong coupling, the fluctuations can be described by a single, effective membrane that combines the elastic properties. For weak coupling, the fluctuations of the individual, noninteracting membranes are recovered. The case of a composite membrane consisting of one fluid and one solid membrane can serve as a microscopic model for the plasma membrane and cytoskeleton of the red blood cell. We find that, despite the complex microstructure of bilayers and cytoskeletons in a real cell, the fluctuations with wavelengths Î»â‰³400nm are well described by the fluctuations of a single, polymerized membrane (provided that there are no inhomogeneities of the microstructure). The model is applied to the fluctuation data of discocytes (â€œnormalâ€ red blood cells), a stomatocyte, and an echinocyte. The elastic parameters of the membrane and an effective temperature that quantifies active, metabolically driven fluctuations are extracted from the experiments.
Radiation fluid stars in the non-minimally coupled Y(R)F{sup 2} gravity
Energy Technology Data Exchange (ETDEWEB)
Sert, Oezcan [Pamukkale University, Department of Mathematics, Faculty of Arts and Sciences, Denizli (Turkey)
2017-02-15
We propose a non-minimally coupled gravity model in Y(R)F{sup 2} form to describe the radiation fluid stars which have the radiative equation of state between the energy density Ï and the pressure p given by Ï = 3p. Here F{sup 2} is the Maxwell invariant and Y(R) is a function of the Ricci scalar R. We give the gravitational and electromagnetic field equations in differential form notation taking the infinitesimal variations of the model. We look for electrically charged star solutions to the field equations under the constraint eliminating complexity of the higher order terms in the field equations. We determine the non-minimally coupled function Y(R) and the corresponding model which admits new exact solutions in the interior of the star and the Reissner-Nordstrom solution at the exterior region. Using the vanishing pressure condition at the boundary together with the continuity conditions of the metric functions and the electric charge, we find the mass-radius ratio, charge-radius ratio, and the gravitational surface redshift depending on the parameter of the model for the radiation fluid star. We derive general restrictions for the ratios and redshift of the charged compact stars. We obtain a slightly smaller upper mass-radius ratio limit than the Buchdahl bound 4/9 and a smaller upper redshift limit than the bound of the standard general relativistic stars. (orig.)
Hassan, Ehab; Hatch, D. R.; Morrison, P. J.; Horton, W.
2016-09-01
Progress in understanding the coupling between plasma instabilities in the equatorial electrojet based on a unified fluid model is reported. Simulations with parameters set to various ionospheric background conditions revealed properties of the gradient-drift and Farley-Buneman instabilities. Notably, sharper density gradients increase linear growth rates at all scales, whereas variations in cross-field E Ã— B drift velocity only affect small-scale instabilities. A formalism defining turbulent fluctuation energy for the system is introduced, and the turbulence is analyzed within this framework. This exercise serves as a useful verification test of the numerical simulations and also elucidates the physics underlying the ionospheric turbulence. Various physical mechanisms involved in the energetics are categorized as sources, sinks, nonlinear transfer, and cross-field coupling. The physics of the nonlinear transfer terms is studied to identify their roles in producing energy cascades, which explain the generation of small-scale structures that are stable in the linear regime. The theory of two-step energy cascading to generate the 3 m plasma irregularities in the equatorial electrojet is verified for the first time in the fluid regime. In addition, the nonlinearity of the system allows the possibility of an inverse energy cascade, potentially responsible for generating large-scale plasma structures at the top of the electrojet as found in different rocket and radar observations.
Mesoscale dynamic coupling of finite- and discrete-element methods for fluid-particle interactions.
Srivastava, S; Yazdchi, K; Luding, S
2014-08-06
A new method for two-way fluid-particle coupling on an unstructured mesoscopically coarse mesh is presented. In this approach, we combine a (higher order) finite-element method (FEM) on the moving mesh for the fluid with a soft sphere discrete-element method for the particles. The novel feature of the proposed scheme is that the FEM mesh is a dynamic Delaunay triangulation based on the positions of the moving particles. Thus, the mesh can be multi-purpose: it provides (i) a framework for the discretization of the Navier-Stokes equations, (ii) a simple tool for detecting contacts between moving particles, (iii) a basis for coarse-graining or upscaling, and (iv) coupling with other physical fields (temperature, electromagnetic, etc.). This approach is suitable for a wide range of dilute and dense particulate flows, because the mesh resolution adapts with particle density in a given region. Two-way momentum exchange is implemented using semi-empirical drag laws akin to other popular approaches; for example, the discrete particle method, where a finite-volume solver on a coarser, fixed grid is used. We validate the methodology with several basic test cases, including single- and double-particle settling with analytical and empirical expectations, and flow through ordered and random porous media, when compared against finely resolved FEM simulations of flow through fixed arrays of particles.
Cooling Systems Design in Hot Stamping Tools by a Thermal-Fluid-Mechanical Coupled Approach
Directory of Open Access Journals (Sweden)
Tao Lin
2014-06-01
Full Text Available Hot stamping tools with cooling systems are the key facilities for hot stamping process of Ultrahigh strength steels (UHSS in automotive industry. Hot stamping tools have significant influence on the final microstructure and properties of the hot stamped parts. In serials production, the tools should be rapidly cooled by cooling water. Hence, design of hot stamping tools with cooling systems is important not only for workpieces of good quality but also for the tools with good cooling performance and long life. In this paper, a new multifield simulation method was proposed for the design of hot stamping tools with cooling system. The deformation of the tools was also analyzed by this method. Based on MpCCI (Mesh-based parallel Code Coupling Interface, thermal-fluid simulation and thermal-fluid-mechanical coupled simulation were performed. Subsequently, the geometrical parameters of the cooling system are investigated for the design. The results show that, both the distance between the ducts and the distance between the ducts and the tools loaded contour have significant influence on the quenching effect. And better quenching effect can be achieved with the shorter distance from the tool surface and with smaller distance between ducts. It is also shown that, thermal expansion is the main reason for deformation of the hot forming tools, which causes the distortion of the cooling ducts, and the stress concentration at corner of the ducts.
Lo, Wei-Cheng; Yeh, Chao-Lung; Lee, Jhe-Wei
2015-09-01
A central issue in the theoretical treatment of a multiphase system is the proper mathematical description of momentum transfer across fluid-solid and fluid-fluid interfaces. Although recent studies have advanced our knowledge on modeling the coupling behavior between a porous framework and the fluids permeating it, the effect of viscous resistance caused by two-fluid flow on elastic wave behavior in unsaturated porous media still remains elusive. In the present study, the theoretical model developed for describing immiscible two-phase fluid flows in a deformable porous medium related to harmonic wave perturbation is generalized to account for viscous cross coupling due to relative velocity between two adjacent fluids. The corresponding dispersion relations whose coefficients feature all elasticity, inertial-drag, and viscous-drag parameters are then precisely formulated, in a physical context characterizing three compressional waves and one shear wave. To evaluate quantitatively this as-yet unknown effect, numerical calculations are conducted to solve the dispersion relations for Columbia fine sandy loam bearing an oil-water mixture as a function of water saturation and excitation frequency. Our results show that the phase speed and attenuation coefficient of the P3 wave which has the smallest speed is strongly sensitive to the presence of viscous cross coupling, as expected since this wave is attributed primarily to the out-of-phase motion of the two pore fluids. Viscous cross coupling also exerts an impact on the attenuation coefficient of the shear wave and the P1 wave whose speed is greatest, which exhibits two opposite trends at different ranges of low and high water contents. Relative differences in these wave attributes are principally independent of excitation frequency. A sensitivity analysis is carried out to assess how changes in viscous cross coupling affect these differences, revealing that some of them become more significant as viscous cross
Yoshihara, Lena; Roth, Christian J; Wall, Wolfgang A
2017-04-01
In this article, a novel approach is presented for combining standard fluid-structure interaction with additional volumetric constraints to model fluid flow into and from homogenised solid domains. The proposed algorithm is particularly interesting for investigations in the field of respiratory mechanics as it enables the mutual coupling of airflow in the conducting part and local tissue deformation in the respiratory part of the lung by means of a volume constraint. In combination with a classical monolithic fluid-structure interaction approach, a comprehensive model of the human lung can be established that will be useful to gain new insights into respiratory mechanics in health and disease. To illustrate the validity and versatility of the novel approach, three numerical examples including a patient-specific lung model are presented. The proposed algorithm proves its capability of computing clinically relevant airflow distribution and tissue strain data at a level of detail that is not yet achievable, neither with current imaging techniques nor with existing computational models. Copyright Â© 2016 John Wiley & Sons, Ltd. Copyright Â© 2016 John Wiley & Sons, Ltd.
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Shiqi Zhou
2013-10-01
Full Text Available Monte Carlo simulations in the canonical ensemble are performed for fluid with potential consisting of a square-well plus a square-barrier to obtain thermodynamic properties such as pressure, excess energy, constant volume excess heat capacity, and excess chemical potential, and structural property such as radial distribution function. The simulations cover a wide density range for the fluid phase, several temperatures, and different combinations of the parameters defining the potential. These simulation data have been used to test performances of a coupling parameter series expansion (CPSE recently proposed by one of the authors [S. Zhou, Phys. Rev. E 74, 031119 (2006], and a traditional 2nd-order high temperature series expansion (HTSE based on a macroscopic compressibility approximation (MAC used with confidence since its introduction in 1967. It is found that (i the MCA-based 2nd-order HTSE unexpectedly and depressingly fails for most situations investigated, and the present simulation results can serve well as strict criteria for testing liquid state theories. (ii The CPSE perturbation scheme is shown to be capable of predicting very accurately most of the thermodynamic properties simulated, but the most appropriate level of truncating the CPSE differs and depends on the range of the potential to be calculated; in particular, the shorter the potential range is, the higher the most appropriate truncating level can be, and along with rising of the potential range the performance of the CPSE perturbation scheme will decrease at higher truncating level. (iii The CPSE perturbation scheme can calculate satisfactorily bulk fluid rdf, and such calculations can be done for all fluid states of the whole phase diagram. (iv The CPSE is a convergent series at higher temperatures, but show attribute of asymptotic series at lower temperatures, and as a result, the surest asymptotic value occurs at lower-order truncation.
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Yonghui Xie
2014-01-01
Full Text Available A three-dimensional fluid-thermal-structural coupled analysis for a radial inflow micro gas turbine is conducted. First, a fluid-thermal coupled analysis of the flow and temperature fields of the nozzle passage and the blade passage is performed by using computational fluid dynamics (CFD. The flow and heat transfer characteristics of different sections are analyzed in detail. The thermal load and the aerodynamic load are then obtained from the temperature field and the pressure distribution. The stress distributions of the blade are finally studied by using computational solid mechanics (CSM considering three cases of loads: thermal load, aerodynamics load combined with centrifugal load, and all the three types of loads. The detailed parameters of the flow, temperature, and the stress are obtained and analyzed. The numerical results obtained provide a useful knowledge base for further exploration of radial gas turbine design.
Fluid flow and heat transfer in Joule-Thomson coolers coupled with infrared detectors
Du, Bingyan; Jia, Weimin
2011-08-01
Joule-Thomson coolers have been widely used in infrared detectors with respect to compact, light and low cost. For self-regulating Joule-Thomson cooler, its performance is required to be improved with the development of higher mass and larger diameter of focal plane infrared detectors. Self-regulating Joule-Thomson coolers use a limited supply of high pressure gas to support the cooling of infrared detectors. In order to develop Joule-Thomson coolers with a given volume of stored gas, it is important to study on fluid flow and heat transfer of Joule-Thomson coolers coupled with infrared detectors, especially the starting time of Joule-Thomson coolers. A serial of experiments of Joule-Thomson coolers coupled with 128Ã—128 focal plane infrared detectors have been carried out. The exchanger of coolers are made of a d=0.5mm capillary finned with a copper wire. The coolers are self-regulated by bellows and the diameters are about 8mm. Nitrogen is used as working gas. The effect of pressure of working gas has been studied. The relation between starting time and pressure of working gas is proved to fit exponential decay. Error analysis has also been carried. It is crucial to study the performance of Joule-Thomson coolers coupled with infrared detectors. Deeper research on Joule-Thomson coolers will be carried on to improve the Joule-Thomson coolers for infrared detectors.
Mathematical model for blood flow through a bifurcated artery using couple stress fluid.
Srinivasacharya, D; Madhava Rao, G
2016-08-01
In this article, the blood flow through a bifurcated artery with mild stenosis is investigated taking blood as couple stress fluid. The artery configuring bifurcation is assumed to be symmetric about the axis of the artery and straight cylinders of finite length. The governing equations are non-dimensionalized and coordinate transformation is used to convert the irregular boundary to a regular boundary. The resulting system of equations is solved numerically using the finite difference method. The variation of shear stress, flow rate and impedance near the apex with pertinent parameters are studied graphically. It has been noticed that shear stress, flow rate and impedance have been changing suddenly with all the parameters on both sides of the apex. This occurs because of the backflow of the streaming blood at the onset of the lateral junction and secondary flow near the apex in the daughter artery.
Influence of asperities on fluid and thermal flow in a fracture: a coupled Lattice Boltzmann study
Neuville, AmÃ©lie; Toussaint, Renaud
2013-01-01
The characteristics of the hydro-thermal flow which occurs when a cold fluid is injected into a hot fractured bedrock depend on the morphology of the fracture. We consider a sharp triangular asperity, invariant in one direction, perturbing an otherwise flat fracture. We investigate its influence on the macroscopic hydraulic transmissivity and heat transfer efficiency, at fixed low Reynolds number. In this study, numerical simulations are done with a coupled lattice Boltzmann method that solves both the complete Navier-Stokes and advection-diffusion equations in three dimensions. The results are compared with those obtained under lubrication approximations which rely on many hypotheses and neglect the three-dimensional (3D) effects. The lubrication results are obtained by analytically solving the Stokes equation and a two-dimensional (integrated over the thickness) advection-diffusion equation. We use a lattice Boltzmann method with a double distribution (for mass and energy transport) on hypercubic and cubic ...
Numerical Simulation of CO2 Flooding of Coalbed Methane Considering the Fluid-Solid Coupling Effect.
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Jianjun Liu
Full Text Available CO2 flooding of coalbed methane (CO2-ECBM not only stores CO2 underground and reduces greenhouse gas emissions but also enhances the gas production ratio. This coupled process involves multi-phase fluid flow and coal-rock deformation, as well as processes such as competitive gas adsorption and diffusion from the coal matrix into fractures. A dual-porosity medium that consists of a matrix and fractures was built to simulate the flooding process, and a mathematical model was used to consider the competitive adsorption, diffusion and seepage processes and the interaction between flow and deformation. Due to the effects of the initial pressure and the differences in pressure variation during the production process, permeability changes caused by matrix shrinkage were spatially variable in the reservoir. The maximum value of permeability appeared near the production well, and the degree of rebound decreased with increasing distance from the production well.
Institute of Scientific and Technical Information of China (English)
LIU Xiang-Mei; SONG Yuan-Hong; WANG You-Nian
2009-01-01
A self-consistent fluid model, which incorporates density and flux balances of electrons, ions, neutrals and nanopar ticles, electron energy balance, and Poiaaon 's equation, is employed to investigate the capacitively coupled silane discharge modulated by dual-frequency electric sources. In this discharge process, nanoparticles are formed by a successive chemical reactions of anion with silane. The density distributions of the precursors in the dust particle formation are put forward, and the charging, transport and growth of nanoparticles are simulated. In this work, we focus our main attention on the influences of the high-frequency and low-frequency voltage on nanoparticle densities, nanoparticle charge distributions in both the bulk plasma and sheath region.
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Sahin Ahmed
2014-12-01
Full Text Available This study focuses analytically on the oscillatory hydromagnetic flow of a viscous, incompressible, electrically-conducting, non-Newtonian fluid in an inclined, rotating channel with non-conducting walls, incorporating couple stress effects. The model is then non-dimensionalized with appropriate variables and shown to be controlled by the inverse Ekman number (K2Â =Â 1/Ek, the hydromagnetic body force parameter (M, channel inclination (Î±, Grashof number (Gr, Prandtl number (Pr, oscillation frequency (Ï‰ and time variable (Ï‰T. Analytical solutions are derived using complex variables. Excellent agreement is obtained between both previous and present work. The influence of the governing parameters on the primary velocity, secondary velocity, temperature (Î¸, primary and secondary flow discharges per unit depth in the channel, and frictional shear stresses due to primary and secondary flow, is studied graphically and using tables. Applications of the study arise in the simulation of the manufacture of electrically-conducting polymeric liquids and hydromagnetic energy systems exploiting rheological working fluids.
Non-Gaussianities in Dissipative EFT of Inflation Coupled to a Fluid
Turiaci, Gustavo Joaquin
2013-01-01
We studied models of inflation with a preferred clock specifying the end of inflation and giving the curvature perturbations, coupled with another non-equivalent clock that at late times defines the same frame and do not contribute to the density perturbations. This can happen in the framework of dissipative EFT of inflation where the additional degrees of freedom include a fluid developing sound waves propagating with sound speed $c_{sr}$. The fluid defines a preferred frame comoving with it. The paradigmatic example of this is the warm inflation scenario. We studied the dynamics of this systems during inflation and the three-point function. We saw that in the strong dissipation regime the nonlinear parameter induced by the new terms is $|f_{\\rm NL}| \\sim 1/c_{sr}^2$, not enhanced by the dissipation parameter which enters the two-point function. We checked that the squeezed limit of the three-point function still satisfies the consistency condition with corrections of order $\\mathcal{O}(k_L^2/k_S^2)$. We com...
Song, Zhongchang; Zhang, Yu; Wei, Chong; Wang, Xianyan
2016-01-01
Through numerically solving the appropriate wave equations, propagation of biosonar signals in a Chinese river dolphin (baiji) was studied. The interfacial waves along the rostrum-tissue interfaces, including both compressional (longitudinal) and shear (transverse) waves in the solid rostrum through fluid-solid coupling were examined. The baiji's rostrum was found to effect acoustic beam formation not only as an interfacial wave generator but also as a sound reflector. The wave propagation patterns in the solid rostrum were found to significantly change the wave movement through the bone. Vibrations in the rostrum, expressed in solid displacement, initially increased but eventually decreased from posterior to anterior sides, indicating a complex physical process. Furthermore, the comparisons among seven cases, including the combination of (1) the rostrum, melon, and air sacs; (2) rostrum-air sacs; (3) rostrum-melon; (4) only rostrum; (5) air sacs-melon; (6) only air sacs; and (7) only melon revealed that the cases including the rostrum were better able to approach the complete system by inducing rostrum-tissue interfacial waves and reducing the differences in main beam angle and -3 dB beam width. The interfacial waves in the rostrum were considered complementary with reflection to determine the obbligato role of the rostrum in the baiji's biosonar emission. The far-field beams formed from complete fluid-solid models and non-fluid-solid models were compared to reveal the effects brought by the consideration of shear waves of the solid structures of the baiji. The results may provide useful information for further understanding the role of the rostrum in this odontocete species.
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Bertolotto, D.
2011-11-15
The current doctoral research is focused on the development and validation of a coupled computational tool, to combine the advantages of computational fluid dynamics (CFD) in analyzing complex flow fields and of state-of-the-art system codes employed for nuclear power plant (NPP) simulations. Such a tool can considerably enhance the analysis of NPP transient behavior, e.g. in the case of pressurized water reactor (PWR) accident scenarios such as Main Steam Line Break (MSLB) and boron dilution, in which strong coolant flow asymmetries and multi-dimensional mixing effects strongly influence the reactivity of the reactor core, as described in Chap. 1. To start with, a literature review on code coupling is presented in Chap. 2, together with the corresponding ongoing projects in the international community. Special reference is made to the framework in which this research has been carried out, i.e. the Paul Scherrer Institute's (PSI) project STARS (Steady-state and Transient Analysis Research for the Swiss reactors). In particular, the codes chosen for the coupling, i.e. the CFD code ANSYS CFX V11.0 and the system code US-NRC TRACE V5.0, are part of the STARS codes system. Their main features are also described in Chap. 2. The development of the coupled tool, named CFX/TRACE from the names of the two constitutive codes, has proven to be a complex and broad-based task, and therefore constraints had to be put on the target requirements, while keeping in mind a certain modularity to allow future extensions to be made with minimal efforts. After careful consideration, the coupling was defined to be on-line, parallel and with non-overlapping domains connected by an interface, which was developed through the Parallel Virtual Machines (PVM) software, as described in Chap. 3. Moreover, two numerical coupling schemes were implemented and tested: a sequential explicit scheme and a sequential semi-implicit scheme. Finally, it was decided that the coupling would be single
Coupled thermal-fluid analysis with flowpath-cavity interaction in a gas turbine engine
Fitzpatrick, John Nathan
This study seeks to improve the understanding of inlet conditions of a large rotor-stator cavity in a turbofan engine, often referred to as the drive cone cavity (DCC). The inlet flow is better understood through a higher fidelity computational fluid dynamics (CFD) modeling of the inlet to the cavity, and a coupled finite element (FE) thermal to CFD fluid analysis of the cavity in order to accurately predict engine component temperatures. Accurately predicting temperature distribution in the cavity is important because temperatures directly affect the material properties including Young's modulus, yield strength, fatigue strength, creep properties. All of these properties directly affect the life of critical engine components. In addition, temperatures cause thermal expansion which changes clearances and in turn affects engine efficiency. The DCC is fed from the last stage of the high pressure compressor. One of its primary functions is to purge the air over the rotor wall to prevent it from overheating. Aero-thermal conditions within the DCC cavity are particularly challenging to predict due to the complex air flow and high heat transfer in the rotating component. Thus, in order to accurately predict metal temperatures a two-way coupled CFD-FE analysis is needed. Historically, when the cavity airflow is modeled for engine design purposes, the inlet condition has been over-simplified for the CFD analysis which impacts the results, particularly in the region around the compressor disc rim. The inlet is typically simplified by circumferentially averaging the velocity field at the inlet to the cavity which removes the effect of pressure wakes from the upstream rotor blades. The way in which these non-axisymmetric flow characteristics affect metal temperatures is not well understood. In addition, a constant air temperature scaled from a previous analysis is used as the simplified cavity inlet air temperature. Therefore, the objectives of this study are: (a) model the
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Qingdong Zeng
2015-10-01
Full Text Available Fluid-solid coupling is ubiquitous in the process of fluid flow underground and has a significant influence on the development of oil and gas reservoirs. To investigate these phenomena, the coupled mathematical model of solid deformation and fluid flow in fractured porous media is established. In this study, the discrete fracture model (DFM is applied to capture fluid flow in the fractured porous media, which represents fractures explicitly and avoids calculating shape factor for cross flow. In addition, the extended finite element method (XFEM is applied to capture solid deformation due to the discontinuity caused by fractures. More importantly, this model captures the change of fractures aperture during the simulation, and then adjusts fluid flow in the fractures. The final linear equation set is derived and solved for a 2D plane strain problem. Results show that the combination of discrete fracture model and extended finite element method is suited for simulating coupled deformation and fluid flow in fractured porous media.
Conjugate transfer of heat and mass in unsteady flow of a micropolar fluid with wall couple stress
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Asma Khalid
2015-12-01
Full Text Available This is an attempt to investigate the unsteady flow of a micropolar fluid with free convection caused due to temperature and concentration differences. Micropolar fluid is taken over a vertical plate oscillating in its own plane. Wall couple stress is engaged at the bounding plate together with isothermal temperature and constant mass diffusion. Problem is modelled in terms of coupled partial differential equations together with some physical conditions and then written in non-dimensional form. Exact solutions are determined using the Laplace transform method. For convenience, they are expressed in simplified form using exponential functions and complementary error functions. Using computational software MATHCAD, analytical results of velocity, temperature, microrotation and concentration are plotted in graphs and discussed for various embedded parameters. Results of skin friction, wall couple stress, rate of heat transfer (Nusselt number and rate of mass transfer (Sherwood number are also evaluated. Present results of micropolar fluid are graphically compared with published results of Newtonian fluid. It is found that micropolar fluid velocity is smaller than Newtonian fluid.
Fakhrabadi, Mir Masoud Seyyed; Rastgoo, Abbas; Ahmadian, Mohammad Taghi
2013-01-01
The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.
Institute of Scientific and Technical Information of China (English)
Liu Jian-jun
2003-01-01
During the development of low permeability reservoirs. the interaction between fluid flow and rock-mass deformation is obvious. On the basis of fluid mechanics in porous media and elasto-plastic theory. the author presents an equivalent continuum model to simulate fluid flow in fractured low-permeability oil reservoir coupled with geo-stress. The model not only reflects the porosity change of matrix, but also the permeability change due to the opening and closing of fracture. By analyzing of simulation results, the changes in porosity and permeability and their effect on oil development are studied.
Mirabolghasemi, M.; Prodanovic, M.
2012-12-01
The problem of fine particle infiltration is seen in fields from subsurface transport, to drug delivery to industrial slurry flows. Sediment filtration and pathogen retention are well-known subsurface engineering problems that have been extensively studied through different macroscopic, microscopic and experimental modeling techniques Due to heterogeneity, standard constitutive relationships and models yield poor predictions for flow (e.g. permeability) and rock properties (e.g. elastic moduli) of the invaded (damaged) porous media. This severely reduces our ability to, for instance, predict retention, pressure build-up, newly formed flow pathways or porous medium mechanical behavior. We chose a coupled computational fluid dynamics (CFD) - discrete element modeling (DEM) approach to simulate the particulate flow through porous media represented by sphere packings. In order to minimize the uncertainty involved in estimating the flow properties of porous media on Darcy scale and address the dynamic nature of filtration process, this microscopic approach is adapted as a robust method that can incorporate particle interaction physics as well as the heterogeneity of the porous medium.. The coupled simulation was done in open-source packages which has both CFD (openFOAM) and DEM components (LIGGGHTS). We ran several sensitivity analyses over different parameters such as particle/grain size ratio, fluid viscosity, flow rate and sphere packing porosity in order to investigate their effects on the depth of invasion and damaged porous medium permeability. The response of the system to the variation of different parameters is reflected through different clogging mechanism; for instance, bridging is the dominant mechanism of pore-throat clogging when larger particles penetrate into the packing, whereas, in case of fine particles which are much smaller than porous medium grains (1/20 in diameter), this mechanism is not very effective due to the frequent formation and
Analysis of Thick-Walled Cylinder Temperature Field based on the Thermal-Fluid-Solid Coupling
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Yonghai Wu
2013-04-01
Full Text Available The barrel is a special thick-walled cylinder. It is significance to study the temperature distribution of thick-walled cylinder under liquid-cooled state to weapon launch safety and effectiveness. Taking a naval gun barrel as research objective, a unified thermal-fluid-solid coupling model is put forward including barrel solid wall, the cooling water and the water jacket solid wall. The unsteady coupled temperature field of the barrel is calculated at the time of single and continuous firing and some influencing factors such as cooling water flow velocity, barrel wall thickness and so on, are analyzed to the barrel temperature field. The results show that the water cooling effect of the barrel outer is closely related to the wall thickness and the cooling water flow velocity. When the barrel wall thickness is small, increasing the flow velocity increase heat dissipation and reduce barrel wall temperature obviously. When the barrel wall thickness is large, the water cooling effect depends on the total cooling time and small correlation with the velocity of cooling water flow.
Fluid-structure coupling for wind turbine blade analysis using OpenFOAM
Dose, Bastian; Herraez, Ivan; Peinke, Joachim
2015-11-01
Modern wind turbine rotor blades are designed increasingly large and flexible. This structural flexibility represents a problem for the field of Computational Fluid Dynamics (CFD), which is used for accurate load calculations and detailed investigations of rotor aerodynamics. As the blade geometries within CFD simulations are considered stiff, the effect of blade deformation caused by aerodynamic loads cannot be captured by the common CFD approach. Coupling the flow solver with a structural solver can overcome this restriction and enables the investigation of flexible wind turbine blades. For this purpose, a new Finite Element (FE) solver was implemented into the open source CFD code OpenFOAM. Using a beam element formulation based on the Geometrically Exact Beam Theory (GEBT), the structural model can capture geometric non-linearities such as large deformations. Coupled with CFD solvers of the OpenFOAM package, the new framework represents a powerful tool for aerodynamic investigations. In this work, we investigated the aerodynamic performance of a state of the art wind turbine. For different wind speeds, aerodynamic key parameters are evaluated and compared for both, rigid and flexible blade geometries. The present work is funded within the framework of the joint project Smart Blades (0325601D) by the German Federal Ministry for Economic Affairs and Energy (BMWi) under decision of the German Federal Parliament.
STABILITY ANALYSIS OF THREE LOBE HYDRODYNAMIC JOURNAL BEARING: COUPLE STRESS FLUID EFFECTS
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N.P.Mehta
2010-10-01
Full Text Available The effects of couple stress fluid, when added to a Newtonian base, are studied by deriving a generalized form of the Reynolds equation. A couple stress parameter â€˜lâ€™ has been used to indicate the length of the long chain molecule being added. Finite element method has been used to solve the generalized Reynolds equation for each lobe to obtain the respective pressure distributions. Stable equilibrium conditions in terms of eccentricity ratios and the attitude angles have been obtained for the vertical load condition. The journal has been perturbed from this equilibrium condition to give the stiffness and the damping coefficients. It has been observed that slight variation of the coupe stress parameter â€˜lâ€™ has great influence on the dynamic characteristics, i.e. the stiffness and the dampingcoefficients. The threshold speed and the critical mass of the journal, obtained as a solution to the linearized equations of motion, are used to demonstrate the increased stability of the journal bearing system.
Numerical simulation on fault water-inrush based on fluid-solid coupling theory
Institute of Scientific and Technical Information of China (English)
HUANG Han-fu; MAO Xian-biao; YAO Bang-hua; PU Hai
2012-01-01
About 75ï¼… water-inrush accidents in China are caused by geological structure such as faults,therefore,it is necessary to investigate the water-inrush mechanism of faults to provide references for the mining activity above confined water.In this paper,based on the fluid-solid coupling theory,we built the stress-seepage coupling model for rock,then we combined with an example of water-inrush caused by fault,studied the water-inrush mechanism by using the numerical software COMSOL Mutiphysics,analyzed the change rule of shear stress,vertical stress,plastic area and water pressure for stope with a fault,and estimated the water-inrush risk at the different distances between working faces and the fault.The numerical simulation results indicate that:(1) the water-inrush risk will grow as the decrease of the distance between working face and the fault;(2) the failure mode of the rock in floor with fault is shear failure; (3) the rock between water-containing fault and working face failure is the reason for water-inrush.
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M PomarÃ¨de
2016-09-01
Full Text Available Numerical simulation of Vortex-Induced-Vibrations (VIV of a rigid circular elastically-mounted cylinder submitted to a fluid cross-flow has been extensively studied over the past decades, both experimentally and numerically, because of its theoretical and practical interest for understanding Flow-Induced-Vibrations (FIV problems. In this context, the present article aims to expose a numerical study based on fully-coupled fluid-solid computations compared to previously published work [34], [36]. The computational procedure relies on a partitioned method ensuring the coupling between fluid and structure solvers. The fluid solver involves a moving mesh formulation for simulation of the fluid structure interface motion. Energy exchanges between fluid and solid models are ensured through convenient numerical schemes. The present study is devoted to a low Reynolds number configuration. Cylinder motion magnitude, hydrodynamic forces, oscillation frequency and fluid vortex shedding modes are investigated and the â€œlock-inâ€ phenomenon is reproduced numerically. These numerical results are proposed for code validation purposes before investigating larger industrial applications such as configurations involving tube arrays under cross-flows [4].
Multi-fluid simulations of the coupled solar wind-magnetosphere-ionsphere system
Lyon, J.
2011-12-01
This paper will review recent work done with the multi-fluid version of the Lyon-Fedder-Mobarry (MF-LFM) global MHD simulation code. We will concentrate on O+ outflow from the ionosphere and its importance for magnetosphere-ionosphere (MI) coupling and also the importance of ionospheric conditions in determining the outflow. While the predominant method of coupling between the magnetosphere and ionosphere is electrodynamic, it has become apparent the mass flows from the ionosphere into the magnetosphere can have profound effects on both systems. The earliest models to attempt to incorporate this effect used very crude clouds of plasma near the Earth. The earliest MF-LFM results showed that depending on the details of the outflow - where, how much, how fast - very different magnetospheric responses could be found. Two approaches to causally driven models for the outflow have been developed for use in global simulations, the Polar Wind Outflow Model (PWOM), started at the Univ. of Michigan, and the model used by Bill Lotko and co-workers at Dartmouth. We will give a quick review of this model which is based on the empirical relation between outflow fluence and Poynting flux discovered by Strangeway. An additional factor used in this model is the precipitating flux of electrons, which is presumed to correlate with the scale height of the upwelling ions. parameters such as outflow speed and density are constrained by the total fluence. The effects of the outflow depend on the speed. Slower outflow tends to land in the inner magnetosphere increasing the strength of the ring current. Higher speed flow out in the tail. Using this model, simulations have shown that solar wind dynamic pressure has a profound effect on the amount of fluence. The most striking result has been the simulation of magnetospheric sawtooth events. We will discuss future directions for this research, emphasizing the need for better physical models for the outflow process and its coupling to the
Zheng, Liang; May, Dave; Gerya, Taras; Bostock, Michael
2016-08-01
Shear deformation, accompanied with fluid activity inside the subduction interface, is related to many tectonic energy-releasing events, including regular and slow earthquakes. We have numerically examined the fluid-rock interactions inside a deforming subduction interface using state-of-the-art 2-D hydromechanical numerical models, which incorporate the rock fracturing behavior as a plastic rheology which is dependent on the pore fluid pressure. Our modeling results suggest that two typical dynamical regimes of the deforming subduction interface exist, namely, a "coupled" and a "decoupled" regime. In the coupled regime the subduction interface is subdivided into multiple rigid blocks, each separated by a narrow shear zone inclined at an angle of 15-20Â° with respect to the slab surface. In contrast, in the decoupled regime the subduction interface is divided into two distinct layers moving relative to each other along a pervasive slab surface-parallel shear zone. Through a systematic parameter study, we observe that the tensile strength (cohesion) of the material within the subduction interface dictates the resulting style of deformation within the interface: high cohesion (~60 MPa) results in the coupled regime, while low cohesion (~10 MPa) leads to the decoupled regime. We also demonstrate that the lithostatic pressure and inflow/outflow fluid fluxes (i.e., fluid-fluxed boundary condition) influence the location and orientation of faults. Predictions from our numerical models are supported by experimental laboratory studies, geological data, and geophysical observations from modern subduction settings.
Xiang, G.L.; Vire, A.; Pavlidis, D.; Pain, C.
2015-01-01
A three-dimensional fracture model developed in the context of the combined finite-discrete element method is incorporated into a two-way fluid-solid coupling model. The fracture model is capable of simulating the whole fracturing process. It includes pre-peak hardening deformation, post-peak strain
Ehrhardt, Matthias
2012-01-01
This second volume contains both, the mathematical analysis of the coupling between fluid flow and porous media flow and state-of-the art numerical techniques, like tailor-made finite element and finite volume methods. Readers will come across articles devoted to concrete applications of these models in the field of energy, biology and environmental research.
Kim, Seunghee
2015-08-19
Water acidification follows CO2 injection and leads to reactive fluid transport through pores and rock fractures, with potential implications to reservoirs and wells in CO2 geologic storage and enhanced oil recovery. Kinetic rate laws for dissolution reactions in calcite and anorthite are combined with Navier-Stokes law and advection-diffusion transport to perform geometry-coupled numerical simulations in order to study the evolution of chemical reactions, species concentration and fracture morphology. Results are summarized as a function of two dimensionless parameters: the DamkÃ¶hler number Da which is the ratio between advection and reaction times, and the transverse Peclet number Pe defined as the ratio between the time for diffusion across the fracture and the time for advection along the fracture. Reactant species are readily consumed near the inlet in a carbonate reservoir when the flow velocity is low (low transverse Peclet number and Da>10-1). At high flow velocities, diffusion fails to homogenize the concentration field across the fracture (high transverse Peclet number Pe>10-1). When the reaction rate is low as in anorthite reservoirs (Da<10-1) reactant species are more readily transported towards the outlet. At a given Peclet number, a lower DamkÃ¶hler number causes the flow channel to experience a more uniform aperture enlargement along the length of the fracture. When the length-to-aperture ratio is sufficiently large, say l/d>30, the system response resembles the solution for 1-D reactive fluid transport. A decreased length-to-aperture ratio slows the diffusive transport of reactant species to the mineral fracture surface, and analyses of fracture networks must take into consideration both the length and slenderness of individual fractures in addition to Pe and Da numbers.
Energy Technology Data Exchange (ETDEWEB)
Mendes, Albert C.R., E-mail: albert@fisica.ufjf.br [Departamento de FÃsica, Universidade Federal de Juiz de Fora, 36036-330, Juiz de Fora - MG (Brazil); Takakura, Flavio I., E-mail: takakura@fisica.ufjf.br [Departamento de FÃsica, Universidade Federal de Juiz de Fora, 36036-330, Juiz de Fora - MG (Brazil); Abreu, Everton M.C., E-mail: evertonabreu@ufrrj.br [Grupo de FÃsica TeÃ³rica e MatemÃ¡tica FÃsica, Departamento de FÃsica, Universidade Federal Rural do Rio de Janeiro, 23890-971, SeropÃ©dica - RJ (Brazil); Departamento de FÃsica, Universidade Federal de Juiz de Fora, 36036-330, Juiz de Fora - MG (Brazil); Neto, Jorge Ananias, E-mail: jorge@fisica.ufjf.br [Departamento de FÃsica, Universidade Federal de Juiz de Fora, 36036-330, Juiz de Fora - MG (Brazil)
2017-05-15
In this work we have obtained a higher-derivative Lagrangian for a charged fluid coupled with the electromagnetic fluid and the Diracâ€™s constraints analysis was discussed. A set of first-class constraints fixed by noncovariant gauge condition were obtained. The path integral formalism was used to obtain the partition function for the corresponding higher-derivative Hamiltonian and the Faddeevâ€“Popov ansatz was used to construct an effective Lagrangian. Through the partition function, a Stefanâ€“Boltzmann type law was obtained. - Highlights: â€¢ Higher-derivative Lagrangian for a charged fluid. â€¢ Electromagnetic coupling and Diracâ€™s constraint analysis. â€¢ Partition function through path integral formalism. â€¢ Stefanâ€“Boltzmann-kind law through the partition function.
Directory of Open Access Journals (Sweden)
M.B. Riaz
2016-12-01
Full Text Available The aim of this article was to analyze the rotational flow of an Oldroyd-B fluid with fractional derivatives, induced by an infinite circular cylinder that applies a constant couple to the fluid. Such kind of problem in the settings of fractional derivatives has not been found in the literature. The solutions are based on an important remark regarding the governing equation for the non-trivial shear stress. The solutions that have been obtained satisfy all imposed initial and boundary conditions and can easily be reduced to the similar solutions corresponding to ordinary Oldroyd-B, fractional/ordinary Maxwell, fractional/ordinary second-grade, and Newtonian fluids performing the same motion. The obtained results are expressed in terms of Newtonian and non-Newtonian contributions. Finally, the influence of fractional parameters on the velocity, shear stress and a comparison between generalized and ordinary fluids is graphically underlined.
Behlert, R.; Schrag, G.; Wachutka, G.
2017-06-01
We studied the fluid transport by a bionically inspired micro-flapper fabricated in piezoelectric thin-film technology. The undulatory, wave-like motion of the proposed design is supposed to generate vortex chains in the surrounding fluid resulting in a directed jet stream and, hence, enhanced mass convection and heat transport inside the fluid. Fully-coupled finite element (FE) simulations have been carried out to investigate the fluid transport induced by such an excitation in order to assess the efficiency of the concept. The results show that there is a significant higher net flow for undulation compared to the simple, resonant-like up-and-down motion of the flap, which corroborates the feasibility of the concept.
Institute of Scientific and Technical Information of China (English)
çŸ³ä¸‡å‡¯; åˆ˜æ•¬; é¾šå»ºæ˜¥
2014-01-01
ä»¥åŒè½´å¯¹è½¬è¡Œæ˜Ÿé½¿è½®ä¼ åŠ¨ç³»ç»Ÿä¸ºç ”ç©¶å¯¹è±¡ï¼ŒåŸºäºŽé½¿è½®ç³»ç»ŸåŠ¨åŠ›å¦å’ŒLagrangeæ–¹ç¨‹ï¼Œé‡‡ç”¨é›†ä¸å‚æ•°æ³•å»ºç«‹äº†åŒè½´å¯¹è½¬ç³»ç»Ÿçš„è€¦åˆåŠ¨åŠ›å¦æ¨¡åž‹ï¼Œæ¨¡åž‹ä¸è€ƒè™‘äº†è½®ç³»çš„æ”¯æ’‘åˆšåº¦ã€å¼¹æ€§è€¦åˆå’ŒåŠŸçŽ‡æµå‘ã€‚åœ¨å„ä¸ªé½¿è½®å‰¯çš„åå¿ƒè¯¯å·®ã€é½¿é¢‘è¯¯å·®å’Œæ—¶å˜å•®åˆåˆšåº¦å…±åŒä½œç”¨ä¸‹ï¼Œç”¨æ•°å€¼åˆ†æžæ–¹æ³•å¾—åˆ°äº†åŒè½´å¯¹è½¬ç³»ç»Ÿçš„ä½ç§»å“åº”å’Œé€Ÿåº¦å“åº”ç‰æ—¶åŸŸåŠ¨æ€ç‰¹æ€§ï¼Œå¹¶å¯¹æ¯”äº†å®šè½´è½®ç³»ä¸Žå·®åŠ¨è½®ç³»çš„è½½è·åˆ†é…ï¼Œä¸ºåŒè½´å¯¹è½¬ä¼ åŠ¨ç³»ç»Ÿçš„åŠ¨æ€æ€§èƒ½ä¼˜åŒ–ä¸ŽæŒ¯åŠ¨å™ªå£°ç ”ç©¶æä¾›äº†ä¾æ®ã€‚%Based on the gear system dynamics and Lagrange equation,a coupled dynamic model of a co-axial counter-rotating epicyclic transmission (CCET)system was built with the lumped-parameter method,and the support stiffness,elastic coupling and power flow of the gear train were considered in the model.Under the action of gear pairs'run-out error,meshing-frequency error and time-varying mesh stiffness together,the time-domain dynamic characteristics including the displacement response and speed response of the CCET system were achieved with the numerical analysis method,and the load distributions were compared between an ordinary gear train and a differential gear train.The results provided a basis for dynamic performance optimization and noise and vibration study of a CCET.
Han, Chang-Liang; Ren, Jing-Jie; Wang, Yan-Qing; Dong, Wen-Ping; Bi, Ming-Shu
2016-12-01
Submerged combustion vaporizer (SCV) has been widely employed in Liquefied Natural Gas (LNG) receiving terminals as the main peaking-shaving facility. In the current work, numerical simulation was carried out to study the intrinsic fluid flow and heat transfer characteristics inside the SCV. After the verification of the numerical model and method with the experimental data, detailed results about flow field and temperature field were presented to have an understanding of the principle of shell-side heat transfer enhancement. The distributions of local LNG temperature, wall temperature, water bath temperature and heat transfer coefficient along the tube length were also revealed. Moreover, the influences of main operating parameters such as flue gas temperature, inlet LNG velocity, inlet LNG pressure, static water height and flue gas flux on the system performance were systematically investigated. Finally, based on current simulation results, two empirical correlations were proposed to predict the coupled heat transfer performance of SCV. The simulated results could provide some insight into the design and optimization of SCV.
Directory of Open Access Journals (Sweden)
Marianne Schmid Daners
Full Text Available The objective of this work is to quantify age-related differences in the characteristics and coupling of cerebral arterial inflow and cerebrospinal fluid (CSF dynamics. To this end, 3T phase-contrast magnetic resonance imaging blood and CSF flow data of eleven young (24 Â± 3 years and eleven elderly subjects (70 Â± 5 years with a comparable sex-ratio were acquired. Flow waveforms and their frequency composition, transfer functions from blood to CSF flows and cross-correlations were analyzed. The magnitudes of the frequency components of CSF flow in the aqueduct differ significantly between the two age groups, as do the frequency components of the cervical spinal CSF and the arterial flows. The males' aqueductal CSF stroke volumes and average flow rates are significantly higher than those of the females. Transfer functions and cross-correlations between arterial blood and CSF flow reveal significant age-dependence of phase-shift between these, as do the waveforms of arterial blood, as well as cervical-spinal and aqueductal CSF flows. These findings accentuate the need for age- and sex-matched control groups for the evaluation of cerebral pathologies such as hydrocephalus.
Institute of Scientific and Technical Information of China (English)
MeenakshiGaur; VikasPruthi; RamasarePrasad; BenM.J.Pereira
2000-01-01
Aim: The elemental composition of the epididymal luminal fluid (ELF) in adult goat (Capra indica) was investigated. Methods: ELF was collected by micropuncture from twelve sites along the epididymal duct. The elemental contents was analyzed with inductively coupled plasma (ICP) emission spectroscopy, a microanalytical technique that can simultaneously measure many elements in minute volumes of sample. The Na and K concentrations were determined by flame photometry. Results: ICP spectroscopy showed the presence of copper, calcium, nickel, iron, magnesium, chromium, titanium and zinc in ELF, with fluctuating levels at different sites along the length of the epididymis.Cadmium, cobalt, lead and manganese were not found. The Na+/K+ ratio was seen to be higher at the initial segments of the epididymis and lower at the distal. Conclusion: It is proposed that the observed characteristic distribution of elements in ELF may have far reaching implications in sperm maturation and storage known to occur in the epididymis. (Asian J Androl 2000 Dec;2:288-292)
Lorentz invariant noncommutative algebra for cosmological models coupled to a perfect fluid
Energy Technology Data Exchange (ETDEWEB)
Abreu, Everton M.C.; Marcial, Mateus V.; Mendes, Albert C.R.; Oliveira, Wilson [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil); Universidade Federal de Juiz de Fora, MG (Brazil)
2013-07-01
Full text: In current theoretical physics there is a relevant number of theoretical investigations that lead to believe that at the first moments of our Universe, the geometry was not commutative and the dominating physics at that time was ruled by the laws of noncommutative (NC) geometry. Therefore, the idea is that the physics of the early moments can be constructed based on these concepts. The first published work using the idea of a NC spacetime were carried out by Snyder who believed that NC principles could make the quantum field theory infinities disappear. However, it did not occur and Snyder's ideas were put to sleep for a long time. The main modern motivations that rekindle the investigation about NC field theories came from string theory and quantum gravity. In the context of quantum mechanics for example, R. Banerjee discussed how NC structures appear in planar quantum mechanics providing a useful way for obtaining them. The analysis was based on the NC algebra used in planar quantum mechanics that was originated from 't Hooft's analysis on dissipation and quantization. In this work we carry out a NC algebra analysis of the Friedmann-Robert-Walker model, coupled to a perfect fluid and in the presence of a cosmological constant. The classical field equations are modified, by the introduction of a shift operator, in order to introduce noncommutativity in these models. (author)
Seydoux-Guillaume, Anne-Magali; Montel, Jean-Marc; de Parseval, Philippe; Bingen, Bernard; Janots, Emilie
2010-05-01
The LREE orthophosphate monazite is a common accessory mineral, important as a U-Th-Pb geochronometer in both metamorphic and magmatic rocks. In order to correctly interpret measured ages, it is essential to properly understand mechanisms that control them. Few studies have shown that coupled dissolution-crystallisation in the presence of a fluid phase is a mechanism incomparably more efficient that solid state diffusion to reset isotopic signature within monazite grains. It is known that dissolution-precipitation is efficiency enhanced by the presence of defects within crystals. Because of its high actinide contents (U and Th), monazite receives intense self-irradiation doses. In contrast to zircon (a silicate), monazite (a phosphate) is less sensitive to irradiation. Natural amorphous monazite has never been reported and the only proof that monazite lattice was destroyed by irradiation is shown by the presence of lattice distortion (strained lattice); this is because defect healing is more efficient than amorphization. The present study focuses on large (cm) single monazite crystals from five distinct localities in Norway, Madagascar, Srilanka, Zwaziland and Morefield. They have different chemical compositions, especially with regard to U, Th and Pb contents, and have ages ranging from ca. 500 to 1000 Ma. Nevertheless, all of them share the same petrographic features. Optical microscope and SEM images reveal variably intense fracturation. BSE imaging in the SEM indicates that monazite is composed of multiple phases: an unaltered monazite (Mnz1) + an altered monazite (Mnz2) associated with Th-rich phase (Thorium silicate or Thorium oxide) +/- Xenotime, depending on the initial composition of Mnz1. Analogous textures were already described by Seydoux-Guillaume et al. (2007) and Hetherington and Harlov (2008;). The alteration textures are always associated with radial cracks emanating from the high radioactive phase (Th-rich phase). The question addressed in the
On in-situ visualization for strongly coupled partitioned fluid-structure interaction
Fernandes, O.; Blom, D.S.; Frey, S.; Van Zuijlen, A.H.; Bijl, H.; Ertl, T.
2015-01-01
We present an integrated in-situ visualization approach for partitioned multi-physics simulation of fluid-structure interaction. The simulation itself is treated as a black box and only the information at the fluid-structure interface is considered, and communicated between the fluid and solid solve
Khan, Ikram Ullah; Serra, Christophe A; Anton, Nicolas; Vandamme, Thierry
2013-01-30
Microchannels based microfluidic systems are able to obtain monodispersed microparticles but are limited by cost, time and channel clogging. We succeeded in on the fly encapsulation of high ketoprofen contents in acrylate-based copolymer microbeads by environment friendly UV induced free radical polymerization in off-the-shelf co-axial microfluidic device. FTIR shows complete polymerization of acrylate monomers and interaction between carboxylic group of ketoprofen and ester group of monomers. DSC and XRD confirm amorphous nature of drug in microbeads. Different comonomer content formulations show limited drug release at low pH, a helpful properties to avoid gastric irritating effect of ketoprofen associated with conventional dosage forms. At pH 6.8 microbeads release higher content of drug by a non-Fickian diffusion mechanism. Their drug release rate depends upon the weight content of ethyl acrylate in the formulation as well as their size, increasing by increasing the former and decreasing the later.
Mendes, Albert C R; Abreu, Everton M C; Neto, Jorge Ananias
2016-01-01
In this work we have obtained a higher-derivative Lagrangian for a charged fluid coupled with the electromagnetic fluid and the Dirac's constraints analysis was discussed. A set of first-class constraints fixed by noncovariant gauge condition was obtained. The path integral formalism was used to obtain the partition function for the corresponding higher-derivative Hamiltonian and the Faddeev-Popov ansatz was used to construct an effective Lagrangian. Through the partition function, a Stefan-Boltzmann type law was obtained.
HÃ¼lÃ¼r, Gizem; Hoppmann, Christiane A; Rauers, Antje; Schade, Hannah; Ram, Nilam; Gerstorf, Denis
2016-08-01
Correctly identifying other's emotional states is a central cognitive component of empathy. We examined the role of fluid cognitive performance for empathic accuracy for happiness in the daily lives of 86 older couples (mean relationship length = 45 years; mean age = 75 years) on up to 42 occasions over 7 consecutive days. Men performing better on the Digit Symbol test were more accurate in identifying ups and downs of their partner's happiness. A similar association was not found for women. We discuss the potential role of fluid cognitive performance and other individual, partner, and situation characteristics for empathic accuracy. (PsycINFO Database Record
Su, Delong; Pu, Shengli; Mao, Lianmin; Wang, Zhaofang; Qian, Kai
2016-12-16
A kind of photonic crystal magnetic field sensor is proposed and investigated numerically. The shoulder-coupled resonant cavity is introduced in the photonic crystal, which is infiltrated with magnetic fluid. Through monitoring the shift of resonant wavelength, the magnetic field sensing is realized. According to the designed infiltration schemes, both the magnetic field sensitivity and full width at half maximum increase with the number of infiltrated air holes. The figure of merit of the structure is defined to evaluate the sensing performance comprehensively. The best structure corresponding to the optimal infiltration scheme with eight air holes infiltrated with magnetic fluid is obtained.
Energy Technology Data Exchange (ETDEWEB)
Pallone, Matthew J.; Meaney, Paul M.; Paulsen, Keith D. [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755 (United States)
2012-06-15
Purpose: Microwave tomographic image quality can be improved significantly with prior knowledge of the breast surface geometry. The authors have developed a novel laser scanning system capable of accurately recovering surface renderings of breast-shaped phantoms immersed within a cylindrical tank of coupling fluid which resides completely external to the tank (and the aqueous environment) and overcomes the challenges associated with the optical distortions caused by refraction from the air, tank wall, and liquid bath interfaces. Methods: The scanner utilizes two laser line generators and a small CCD camera mounted concentrically on a rotating gantry about the microwave imaging tank. Various calibration methods were considered for optimizing the accuracy of the scanner in the presence of the optical distortions including traditional ray tracing and image registration approaches. In this paper, the authors describe the construction and operation of the laser scanner, compare the efficacy of several calibration methods-including analytical ray tracing and piecewise linear, polynomial, locally weighted mean, and thin-plate-spline (TPS) image registrations-and report outcomes from preliminary phantom experiments. Results: The results show that errors in calibrating camera angles and position prevented analytical ray tracing from achieving submillimeter accuracy in the surface renderings obtained from our scanner configuration. Conversely, calibration by image registration reliably attained mean surface errors of less than 0.5 mm depending on the geometric complexity of the object scanned. While each of the image registration approaches outperformed the ray tracing strategy, the authors found global polynomial methods produced the best compromise between average surface error and scanner robustness. Conclusions: The laser scanning system provides a fast and accurate method of three dimensional surface capture in the aqueous environment commonly found in microwave breast
Strongly coupled interaction between a ridge of fluid and an inviscid airflow
Paterson, C.
2015-07-01
Â© 2015 AIP Publishing LLC. The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.
Strongly coupled interaction between a ridge of fluid and an inviscid airflow
Paterson, C.; Wilson, S. K.; Duffy, B. R.
2015-07-01
The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.
Institute of Scientific and Technical Information of China (English)
Yi-rang Yuan
2007-01-01
For a coupled system of multiplayer dynamics of fluids in porous media,the characteristic finite element domain decomposition procedures applicable to parallel arithmetic are put forward.Techniques such as calculus of variations,domain decomposition,characteristic method,negative norm estimate,energy method and the theory of prior estimates are adopted.Optimal order estimates in L2 norm are derived for the error in the approximate solution.
Indian Academy of Sciences (India)
T Hayat; Maryam Iqbal; Humaira Yasmin; Fuad E Alsaadi; Huijun Gao
2015-07-01
A mathematical model is developed to analyse the peristaltic flow of couple-stress fluid in an inclined asymmetric channel with convective conditions. Soret and Dufour and Hall effects are taken into account. Analysis has been carried out in a wave frame of reference. Expressions for velocity, pressure gradient, temperature and concentration are constructed. Pumping and trapping phenomena are examined. Impact of sundry parameters on the velocity, temperature and concentration is discussed.
Energy Technology Data Exchange (ETDEWEB)
Hayat, Tasawar [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; King Saud Univ., Riyadh (Saudi Arabia). Dept. of Physics; Iqbal, Zahid [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; Qasim, Muhammad [COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan). Dept. of Mathematics; Aldossary, Omar M. [King Saud Univ., Riyadh (Saudi Arabia). Dept. of Physics
2012-05-15
This investigation reports the boundary layer flow and heat transfer characteristics in a couple stress fluid flow over a continuos moving surface with a parallel free stream. The effects of heat generation in the presence of convective boundary conditions are also investigated. Series solutions for the velocity and temperature distributions are obtained by the homotopy analysis method (HAM). Convergence of obtained series solutions are analyzed. The results are obtained and discussed through graphs for physical parameters of interest. (orig.)
Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Co-Axial Supersonic Free-Jet Experiment
Baurle, R. A.; Edwards, J. R.
2009-01-01
Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The baseline value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was noted when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid simulation results showed the same trends as the baseline Reynolds-averaged predictions. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions are suggested as a remedy to this dilemma. Comparisons between resolved second-order turbulence statistics and their modeled Reynolds-averaged counterparts were also performed.
Xiao, D.; Yang, P.; Fang, F.; Xiang, J.; Pain, C. C.; Navon, I. M.; Chen, M.
2017-02-01
This work presents the first application of a non-intrusive reduced order method to model solid interacting with compressible fluid flows to simulate crack initiation and propagation. In the high fidelity model, the coupling process is achieved by introducing a source term into the momentum equation, which represents the effects of forces of the solid on the fluid. A combined single and smeared crack model with the Mohr-Coulomb failure criterion is used to simulate crack initiation and propagation. The non-intrusive reduced order method is then applied to compressible fluid and fractured solid coupled modelling where the computational cost involved in the full high fidelity simulation is high. The non-intrusive reduced order model (NIROM) developed here is constructed through proper orthogonal decomposition (POD) and a radial basis function (RBF) multi-dimensional interpolation method. The performance of the NIROM for solid interacting with compressible fluid flows, in the presence of fracture models, is illustrated by two complex test cases: an immersed wall in a fluid and a blasting test case. The numerical simulation results show that the NIROM is capable of capturing the details of compressible fluids and fractured solids while the CPU time is reduced by several orders of magnitude. In addition, the issue of whether or not to subtract the mean from the snapshots before applying POD is discussed in this paper. It is shown that solutions of the NIROM, without mean subtracted before constructing the POD basis, captured more details than the NIROM with mean subtracted from snapshots.
Energy Technology Data Exchange (ETDEWEB)
Yang, Tae-Ho; Hong, Jin-Tae; Ahn, Sung-Ho; Joung, Chang-Young; Heo, Sung-Ho; Jang, Seo-Yun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2015-10-15
1-way fluid-structure coupled analysis is used to estimate the dynamic characteristic of the fuel test rig. the motion at the bottom of the test rig is confirmed. The maximum deformation of the test rig is 0.11 mm. The structural integrity of the test rig is performed by using the comparison with the Von-mises stress of the analysis and yield stress of the material. It is evaluated that the motion at the bottom of the test rig is able to cause other structural problem. Using the 2-way fluid-structural coupled analysis, the structural integrity of the test rig will be performed in further paper. The cooling water with specific flow rate was flowed in the nuclear fuel test rig. The structural integrity of the test rig was affected by the vibration. The fluid-induced vibration test had to be performed to obtain the amplitude of the vibration on the structure. Various test systems was developed. Flow-induced vibration and pressure drop experimental tester was developed in Korea Atomic Energy Research Institute. The vibration test with high fluid flow rate was difficult by the tester. To generate the nuclear fuel test environment, coolant flow simulation system was developed. The scaled nuclear fuel test was able to be performed by the simulation system. The mock-up model of the test rig was used in the simulation system. The mock-up model in the simulation system was manufactured with scaled down full model. In this paper, the fluid induced vibration characteristic of the full model in the nuclear fuel test is studied. The hydraulic pressure on the velocity of the fluid was calculated. The static structure analysis was performed by using the pressure. The structural integrity was assessed using the results of the analysis.
Zeighampour, Hamid; Tadi Beni, Y.
2014-07-01
This work investigated vibrations and instability of double-walled carbon nanotube (DWCNT) conveying fluid by a modified couple stress theory. For this purpose, Donnell's shell model was developed and, using the modified couple stress theory, the equations of motion and corresponding classical and non-classical boundary conditions of DWCNT were obtained through Hamilton's principle. Then, DWCNT with simple-simple and clamped-clamped supports were investigated. The effect of the van der Waals (vdW) forces was considered between the two walls, and the DWCNT surroundings were modeled as a visco-Pasternak foundation. The governing equations of motion and corresponding boundary conditions were discretized through differential quadrature method (DQM), and the vibration problem was solved by using the boundary conditions. The results show that the effects of fluid velocity, stiffness and damping of the visco-Pasternak foundation, nanotube length, and size parameter in the modified couple stress theory are stronger than in the classical theory. Finally, the effect of vdW forces and presence of fluid in the DWCNT examined on the natural frequencies of DWCNT.
Institute of Scientific and Technical Information of China (English)
åˆ˜æ•¬; çŸ³ä¸‡å‡¯; é‚¹å“èˆª
2013-01-01
ä»¥åŒè½´å¯¹è½¬è¡Œæ˜Ÿé½¿è½®ä¼ åŠ¨ç³»ç»Ÿä¸ºç ”ç©¶å¯¹è±¡,ä¸ºæç¤ºå…¶å›ºæœ‰ç‰¹æ€§,åŸºäºŽé½¿è½®ç³»ç»ŸåŠ¨åŠ›å¦å’ŒLagrangeæ–¹ç¨‹å»ºç«‹äº†åŒè½´å¯¹è½¬ç³»ç»Ÿçš„å¹³ç§»-è€¦åˆåŠ¨åŠ›å¦æ¨¡åž‹.æ ¹æ®åŒè½´å¯¹è½¬ç³»ç»Ÿçš„ç›¸å…³å‚æ•°è¿›è¡Œç‰¹å¾å€¼é—®é¢˜çš„æ±‚è§£,å¾—åˆ°ç³»ç»Ÿçš„å›ºæœ‰é¢‘çŽ‡ä¸ŽæŒ¯åž‹çŸ¢é‡.åˆ†æžç»“æžœè¡¨æ˜Žç³»ç»Ÿå˜åœ¨3ç§ä¸åŒçš„æŒ¯åŠ¨æ¨¡å¼:å®šè½´è½®ç³»æŒ¯åŠ¨æ¨¡å¼ã€å·®åŠ¨è½®ç³»æŒ¯åŠ¨æ¨¡å¼å’Œè€¦åˆæŒ¯åŠ¨æ¨¡å¼.åŒæ—¶è®¨è®ºäº†éšç€å·®åŠ¨è½®ç³»è¡Œæ˜Ÿè½®ä¸ªæ•°çš„å¢žåŠ ,ç³»ç»Ÿå›ºæœ‰é¢‘çŽ‡çš„é‡æ ¹æ•°ä¸Žå·®åŠ¨è½®ç³»è¡Œæ˜Ÿè½®ä¸ªæ•°çš„å…³ç³».æœ€åŽåˆ†æžäº†è€¦åˆåˆšåº¦å¯¹ç³»ç»ŸæŒ¯åŠ¨ç‰¹æ€§çš„å½±å“.%Based on the method of gear system dynamics and Lagrange equation,a translational-rottional coupling dynamic model of the Co-axial Counter-rotting Epicyclic Transmissions (CCET) is built to analyze the natural frequencies.The system natural frequency and vibration vector can be obtined by solving the eigenvalue according to the relevant parameters of the CCET,and the analysis result shows that there are three different vibration modes:ordinary gear train vibration mode,differential gear train vibration mode and coupling vibration mode.With the increase of the planetary gear of differential gear train,the relationship between the double root and the number of the planetary gear of differential gear train is received.The impact of coupling stiffness to natural characteristics of the system is analyzed.
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. Â© 2012 Cambridge University Press.
Energy Technology Data Exchange (ETDEWEB)
Mutoh, Takashi; Kumazawa, Ryuhei; Seki, Tetsuo; Simpo, Fujio; Nomura, Goro; Ido, Tsuyoshi; Watari, Tetsuo [National Inst. for Fusion Science, Toki, Gifu (Japan); Norterdaeme, J.M.
1998-06-01
Steady state ICRF heating technologies have been developed to heat plasma for more than 30 minutes in the LHD. Steady state operation tests of high voltage up to 40 kV{sub OP} for more than 30 minutes were carried out on the RF vacuum feedthroughs and the co-axial transmission line in the test set. Four types of ceramic feedthroughs each having a diameter of 240 mm were tested. The cone-type alumina ceramic and the cylinder-type silicon nitride composite-ceramic feedthroughs produced good performances of 40 kV/30 minutes and 50 kV/10 seconds. The others had vacuum leaks when subjected to a long pulse duration. The temperature of the cone-type alumina ceramic feedthrough was measured during the ICRF operations. By using gas-cooling techniques, the temperature increase of the ceramic was substantially reduced and saturated within 20 minutes. Without gas-cooling, the temperature increased linearly and did not saturated. So, this approach could not be used for steady state. The RF dissipation on the ceramic was calculated using the finite element computer code (ANSYS). It was found that damaged feedthroughs had local high heat spots, which could result in vacuum leaks. A water-cooled co-axial transmission line of 240 mm diameter was designed and tested. The specially designed connector components and Teflon insulator disks were tested. During the test, the insulation gases of nitrogen, sulfur hexafluoride and carbon dioxide were used to compare the capability of insulation for steady state. For the duration of a 10-second pulse, these gases performed well up to 60 kV{sub OP}. However, for steady state operation, carbon dioxide gas could not withstand voltages above 40 kV{sub OP}. The connector components of the transmission line performed without problems below 50 kV{sub OP} and 1 kA{sub OP} for a 30-minute operation. The performance of the feedthroughs and transmission line exceeded the specifications for steady state heating in the LHD. (J.P.N.)
Wave turbulence in a two-layer fluid: coupling between free surface and interface waves
Issenmann, Bruno; Falcon, Eric
2016-01-01
We experimentally study gravity-capillary wave turbulence on the interface between two immiscible fluids of close density with free upper surface. We locally measure the wave height at the interface between both fluids by means of a highly sensitive laser Doppler vibrometer. We show that the inertial range of the capillary wave turbulence regime is significantly extended when the upper fluid depth is increased: The crossover frequency between the gravity and capillary wave turbulence regimes is found to decrease whereas the dissipative cut-off frequency of the spectrum is found to increase. We explain most of these observations by the progressive decoupling between waves propagating at the interface and the ones at the free surface, using the full dispersion relation of gravity-capillary waves in a two-layer fluid of finite depths.s.
Treatment of coupled fluid-structure interaction problems by a mixed variational principle
Felippa, Carlos A.; Ohayon, Roger
1989-01-01
A general three-field variational principle is obtained for the motion of an acoustic fluid enclosed in a rigid or flexible container by the method of canonical decomposition applied to a modified form of the wave equation in the displacement potential. The general principle is specialized to a mixed two-field principle that contains the fluid displacement potential and pressure as independent fields. Semidiscrete finite-element equations of motion based on this principle are displayed.
Liu, Yu; Yu, Xiping
2016-09-01
A coupled phase-field and volume-of-fluid method is developed to study the sensitive behavior of water waves during breaking. The THINC model is employed to solve the volume-of-fluid function over the entire domain covered by a relatively coarse grid while the phase-field model based on Allen-Cahn equation is applied over the fine grid. A special algorithm that takes into account the sharpness of the diffuse-interface is introduced to correlate the order parameter obtained on the fine grid and the volume-of-fluid function obtained on the coarse grid. The coupled model is then applied to the study of water waves generated by moving pressures on the free surface. The deformation process of the wave crest during the initial stage of breaking is discussed in details. It is shown that there is a significant variation of the free nappe developed at the front side of the wave crest as the wave steepness differs. It is of a plunging type at large wave steepness while of a spilling type at small wave steepness. The numerical results also indicate that breaking occurs later and the duration of breaking is shorter for waves of smaller steepness and vice versa. Neglecting the capillary effect leads to wave breaking with a sharper nappe and a more dynamic plunging process. The surface tension also has an effect to prevent the formation of a free nappe at the front side of the wave crest in some cases.
Cowen, J. P.; Lin, H.; Jungbluth, S.; Hsieh, C.; Rappe, M.; Glazer, B. T.; Matzinger, M.; Becker, K.; Fisher, A. T.; Amend, J. P.; Johnson, H. P.
2011-12-01
In 1997, a simple 'BioColumn' sampler was coupled to the CORK observatory at borehole 1026B to sample fluid chemistry, biomass and microbial community diversity (16S rRNA). The results demonstrated that the 65oC fluids from the 3.5 My old sediment-buried ocean basement support a diverse Bacteria and Archaea community (Cowen et al. 2003, Science 299, 120-123). The large bore of the overpressured CORK body provided high unassisted flow rates through the BioColumn, but possessed the disadvantage of the unknown extent to which the basement fluids were altered by the chemically and biologically (e.g., biofilm community) reactive surface of CORK's steel pipe. Subsequently, new generations of CORKs have incorporated less reactive materials in the CORK body, the use of stainless steel or inert PVDF (Teflon-like) 0.5" ID fluid delivery lines (FDL) running continuously from basement depths to accessible ports at the seafloor, and multiple FDLs from distinct depth horizons within basement. Simultaneously, we have developed increasingly capable fluid sensor and sampling systems for both real-time (Mobile Pumping and Sampling System-MPSS) and long-term autonomous applications (GeoMICROBE sleds). Both incorporate strong efficient pumps to overcome the drag inherent in the 0.5" or smaller bore FDL, multiple sensors (e.g., flow rate, temperature, O2, pH and redox-voltametry chemistry), versatile multi-port large volume fluid collection and/or in situ filtration systems, integrating computer controller/software and non-contaminating (inert) plumbing. These combined developments now provide unparalleled opportunities for access to large volumes of pristine basement samples for geochemical and microbial ecology studies. The MPSS and GeoMICROBE will be described. The multi-year results of organic geochemical and microbial community studies from recent studies at CORK observatories (boreholes 1301A, 1362A 1362B) on the Juan de Fuca Ridge flank will be summarized.
Prajapati, Ramprasad
2016-07-01
The Rayleigh-Taylor (R-T) instability is recently investigated is strongly coupled plasma looking to its importance in dense stellar systems and Inertial Confinement Fusion [1-3]. In the present work, the effect of quantum corrections are studied on Rayleigh-Taylor (R-T) instability and internal wave propagation in a strongly coupled, magnetized, viscoelastic fluid. The modified generalized hydrodynamic model is used to derive the analytical dispersion relation. The internal wave mode and dispersion relation are modified due to the presence of quantum corrections and viscoelastic effects. We observe that strong coupling effects and quantum corrections significantly modifies the dispersion characteristics. The dispersion relation is also discussed in weakly coupled (hydrodynamic) and strongly coupled (kinetic) limits. The explicit expression of R-T instability criterion is derived which is influenced by shear velocity and quantum corrections. Numerical calculations are performed in astrophysical and experimental relevance and it is examined that both the shear and quantum effects suppresses the growth rate of R-T instability. The possible application of the work is discussed in Inertial Confinement Fusion (ICF) to discuss the suppression of R-T instability under considered situation. References: [1] R. P. Prajapati, Phys. Plasmas 23, 022106 (2016). [2] K. Avinash and A. Sen, Phys. Plasmas 22, 083707 (2015). [3] A. Das and P. Kaw, Phys. Plasmas 21 (2014) 062102.
Weyl spin-orbit-coupling-induced interactions in uniform and trapped atomic quantum fluids
Gupta, Reena; Singh, G. S.; Bosse, JÃ¼rgen
2013-11-01
We establish through analytical and numerical studies of thermodynamic quantities for noninteracting atomic gases that the isotropic three-dimensional spin-orbit coupling, the Weyl coupling, induces interaction which counters â€œeffectiveâ€ attraction (repulsion) of the exchange symmetry present in zero-coupling Bose (Fermi) gas. The exact analytical expressions for the grand potential and hence for several thermodynamic quantities have been obtained for this purpose in both uniform and trapped cases. It is enunciated that many interesting features of spin-orbit-coupled systems revealed theoretically can be understood in terms of coupling-induced modifications in statistical interparticle potential. The temperature dependence of the chemical potential, specific heat, and isothermal compressibility for a uniform Bose gas is found to have signature of the incipient Bose-Einstein condensation in the very weak coupling regime although the system does not really go in the Bose-condensed phase. The transition temperature in the harmonically trapped case decreases with an increase of coupling strength consistent with the weakening of the statistical attractive interaction. Anomalous behavior of some thermodynamic quantities, partly akin to that in dimensions less than two, appears for uniform fermions as soon as the Fermi level goes down the Dirac point on increasing the coupling strength. It is suggested that the fluctuation-dissipation theorem can be utilized to verify anomalous behaviors from studies of long-wavelength fluctuations in bunching and antibunching effects.
Zhang, X; Aravindan, V; Kumar, P Suresh; Liu, H; Sundaramurthy, J; Ramakrishna, S; Madhavi, S
2013-07-07
We report the formation and extraordinary Li-storage properties of TiO2 hollow nanofibers by co-axial electrospinning in both the half-cell and full-cell configurations. Li-insertion properties are first evaluated as anodes in the half-cell configuration (Li/TiO2 hollow nanofibers) and we found that reversible insertion of ~0.45 moles is feasible at a current density of 100 mA g(-1). The half-cell displayed a good cyclability and retained 84% of its initial reversible capacity after 300 galvanostatic cycles. The full-cell is fabricated with a commercially available olivine phase LiFePO4 cathode under optimized mass loading. The LiFePO4/TiO2 hollow nanofiber cell delivered a reversible capacity of 103 mA h g(-1) at a current density of 100 mA g(-1) with an operating potential of ~1.4 V. Excellent cyclability is noted for the full-cell configuration, irrespective of the applied current densities, and it retained 88% of reversible capacity after 300 cycles in ambient conditions at a current density of 100 mA g(-1).
Pang, Xiaomin; Dai, Wei; Wang, Xiaotao; Vanapalli, S.; Luo, Ercang
2016-09-01
Improving the performance of the pulse tube cooler is one of the important objectives of the current studies. Besides the phase shifters and regenerators, heat exchangers also play an important role in determining the system efficiency and cooling capacity. A series of experiments on a 10 W @ 77 K class co-axial type pulse tube cooler with different cold heat exchanger geometries are presented in this paper. The cold heat exchangers are made from a copper block with radial slots, cut through using electrical discharge machining. Different slot widths varying from 0.12 mm to 0.4 mm and different slot numbers varying from around 20-60 are investigated, while the length of cold heat exchangers are kept the same. The cold heat exchanger geometry is classified into three groups, namely, constant heat transfer area, constant porosity and constant slot width. The study reveals that a large channel width of 0.4 mm (about ten times the thermal penetration depth of helium gas at 77 K, 100 Hz and 3.5 MPa) shows poor performance, the other results show complicated interaction effects between slot width and slot number. These systematic comparison experiments provide a useful reference for selecting a cold heat exchanger geometry in a practical cooler.
Energy Technology Data Exchange (ETDEWEB)
Santos, Erick S.R.; Ferreira, Francisco H. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Torres, Marcos P.C. [SMARTTECH Oleo e Gas, Rio de Janeiro, RJ (Brazil)
2008-07-01
In this work a modified logical coupling among a porous reservoir fluid flow and a mechanical simulator is presented, intending to evaluate the influence of the mechanical behavior in the pressure field development within the reservoir rock and vice-versa. The resembled integrated solution arrives from the logical interaction between two robust commercial software, namely: IMEX: a black-oil porous media fluid flow simulator based on a finite difference numerical method and employed in the activities of several oil field assets at PETROBRAS S.A.; and Abaqus, a solid mechanics finite element simulator intended for continuous media and also capable of modeling nonlinearities of different natures, including contact discontinuities for instance. (author)
Directory of Open Access Journals (Sweden)
M Soltani
Full Text Available Modeling of interstitial fluid flow involves processes such as fluid diffusion, convective transport in extracellular matrix, and extravasation from blood vessels. To date, majority of microvascular flow modeling has been done at different levels and scales mostly on simple tumor shapes with their capillaries. However, with our proposed numerical model, more complex and realistic tumor shapes and capillary networks can be studied. Both blood flow through a capillary network, which is induced by a solid tumor, and fluid flow in tumor's surrounding tissue are formulated. First, governing equations of angiogenesis are implemented to specify the different domains for the network and interstitium. Then, governing equations for flow modeling are introduced for different domains. The conservation laws for mass and momentum (including continuity equation, Darcy's law for tissue, and simplified Navier-Stokes equation for blood flow through capillaries are used for simulating interstitial and intravascular flows and Starling's law is used for closing this system of equations and coupling the intravascular and extravascular flows. This is the first study of flow modeling in solid tumors to naturalistically couple intravascular and extravascular flow through a network. This network is generated by sprouting angiogenesis and consisting of one parent vessel connected to the network while taking into account the non-continuous behavior of blood, adaptability of capillary diameter to hemodynamics and metabolic stimuli, non-Newtonian blood flow, and phase separation of blood flow in capillary bifurcation. The incorporation of the outlined components beyond the previous models provides a more realistic prediction of interstitial fluid flow pattern in solid tumors and surrounding tissues. Results predict higher interstitial pressure, almost two times, for realistic model compared to the simplified model.
Freymark, Jessica; Sippel, Judith; Scheck-Wenderoth, Magdalena; BÃ¤r, Kristian; Stiller, Manfred; Fritsche, Johann-Gerhard; Kracht, Matthias
2017-04-01
Numerical models that predict and help to understand subsurface hydrothermal conditions are key to reduce the risk of drilling non-productive geothermal wells. Such simulations of coupled fluid and heat transport need a reliable 3D structural model. Therefore, we use an integrated approach of data-based 3D structural, gravity, conductive thermal and thermo-hydraulic coupled modelling. The Upper Rhine Graben (URG) is known for its large potential for deep geothermal energy that is already used in e.g. Soultz-sous-ForÃªts. In the frame of the EU-funded project "IMAGE" (Integrated Methods for Advanced Geothermal Exploration, grant agreement no. 608553), we assess the dominant processes and effective physical properties that control the deep thermal field of the URG. Therefore, we have built a lithospheric-scale 3D structural model of the URG by integrating existing data-based 3D models, deep seismic reflection and refraction profiles, as well as receiver function data. 3D gravity modelling was used to assess the internal configuration of the upper crystalline crust in addition to deep seismic lines. The resulting gravity-constrained 3D structural model was then used as base to calculate the 3D conductive thermal field. An analysis of deviations between measured and calculated temperatures revealed that heat transport connected to fluid circulation is probably relevant at depths above 2500 m. To test this hypotheses smaller-scale and higher resolution models for coupled fluid and heat transport were simulated. We present the results from this combined workflow considering 3D gravity and 3D thermal modelling.
Eegunjobi, A. S.; Makinde, O. D.
Numerical analysis of the intrinsic irreversibility of a mixed convection hydromagnetic flow of an electrically conducting couple stress fluid through upright channel filled with a saturated porous medium and radiative heat transfer was carried out. The thermodynamics first and second laws were employed to examine the problem. We obtained the dimensionless nonlinear differential equations and solves numerically with shooting procedure joined with a fourth order Runge-Kutta-Fehlberg integration scheme. The temperature and velocity obtained, used to analyse the entropy generation rate together with some various physical parameters of the flow. Our results are presented graphically and talk over.
Energy Technology Data Exchange (ETDEWEB)
Nadeem, Sohail; Akram, Safia [Quaid-i-Azam University, Department of Mathematics, Islamabad (Pakistan)
2011-01-15
The present paper investigates the peristaltic transport of a couple stress fluid in an asymmetric channel with the effect of the induced magnetic field. The exact solutions of momentum and the magnetic field equations have been calculated under the assumptions of long wave length and low but finite Reynolds number. The expression for pressure rise has been computed numerically using mathematics software Mathematica. The graphical results have been presented to discuss the physical behavior of various physical parameters of interest. Finally, the trapping phenomena have been discussed for various physical parameters. (orig.)
HÃ¶lder continuity of Keller-Segel equations of porous medium type coupled to fluid equations
Chung, Yun-Sung; Hwang, Sukjung; Kang, Kyungkeun; Kim, Jaewoo
2017-08-01
We consider a coupled system consisting of a degenerate porous medium type of Keller-Segel system and Stokes system modeling the motion of swimming bacteria living in fluid and consuming oxygen. We establish the global existence of weak solutions and HÃ¶lder continuous solutions in dimension three, under the assumption that the power of degeneracy is above a certain number depending on given parameter values. To show HÃ¶lder continuity of weak solutions, we consider a single degenerate porous medium equation with lower order terms, and via a unified method of proof expanded to generalized porous medium equations, we obtain HÃ¶lder regularity, which is of independent interest.
Institute of Scientific and Technical Information of China (English)
YUAN; Yirang
2006-01-01
For the three-dimensional coupled system of multilayer dynamics of fluids in porous media, the second-order upwind finite difference fractional steps schemes applicable to parallel arithmetic are put forward. Some techniques, such as calculus of variations, energy method,multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estimates in l2 norm are derived to determine the error in the second-order approximate solution. These methods have already been applied to the numerical simulation of migration-accumulation of oil resources.
Institute of Scientific and Technical Information of China (English)
Yirang YUAN
2006-01-01
For nonlinear coupled system of multilayer dynamics of fluids in porous media, the second order and first order upwind finite difference fractional steps schemes applicable to parallel arithmetic are put forward, and two-dimensional and three-dimensional schemes are used to form a complete set. Some techniques, such as calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates, are adopted. Optimal order estimates in L2 norm are derived to determine the error in the second order approximate solution.This method has already been applied to the numerical simulation of migration-accumulation of oil resources.
Directory of Open Access Journals (Sweden)
Victor M. GarcÃa-Chocano
2011-12-01
Full Text Available Transmission of ultrasonic waves through a slit between two water immersed brass plates is studied for sub-wavelength plate thicknesses and slit apertures. Extraordinary high absorption is observed at discrete frequencies corresponding to resonant excitation of Rayleigh waves on the both sides of the channel. The coupling of the Rayleigh waves occurs through the fluid and the corresponding contribution to the dispersion has been theoretically derived and also experimentally confirmed. Symmetric and anti-symmetric modes are predicted but only the symmetric mode resonances have been observed. It follows from the dispersion equation that the coupled Rayleigh waves cannot be excited in a channel with apertures less than the critical one. The calculated critical aperture is in a good agreement with the measured acoustic spectra. These findings could be applied to design a broadband absorptive metamaterial.
Energy Technology Data Exchange (ETDEWEB)
Lin, Jaw-Ren; Hung, Chi-Ren; Lu, Rong-Fang [Nanya Institute of Technology, Jhongli, Taiwan (China). Dept. of Mechanical Engineering; Chu, Li-Ming [I-Shou Univ., Kaohsiung, Taiwan (China). Dept. of Mechanical and Automation Engineering
2011-08-15
According to the experimental work of C. Barus in Am. J. Sci. 45, 87 (1893), the dependency of liquid viscosity on pressure is exponential. Therefore, we extend the study of squeeze film problems of long partial journal bearings for Stokes non-Newtonian couple stress fluids by considering the pressure-dependent viscosity in the present paper. Through a small perturbation technique, we derive a first-order closed-form solution for the film pressure, the load capacity, and the response time of partial-bearing squeeze films. It is also found that the non-Newtonian couple-stress partial bearings with pressure-dependent viscosity provide better squeeze-film characteristics than those of the bearing with constant-viscosity situation. (orig.)
Lin, Jaw-Ren; Chu, Li-Ming; Hung, Chi-Ren; Lu, Rong-Fang
2011-09-01
According to the experimental work of C. Barus in Am. J. Sci. 45, 87 (1893) [1], the dependency of liquid viscosity on pressure is exponential. Therefore, we extend the study of squeeze film problems of long partial journal bearings for Stokes non-Newtonian couple stress fluids by considering the pressure-dependent viscosity in the present paper. Through a small perturbation technique, we derive a first-order closed-form solution for the film pressure, the load capacity, and the response time of partial-bearing squeeze films. It is also found that the non-Newtonian couple-stress partial bearings with pressure-dependent viscosity provide better squeeze-film characteristics than those of the bearing with constant-viscosity situation.
Neusser, Jochen
2015-01-01
We present a numerical scheme for immiscible two-phase flows with one compressible and one incompressible phase. Special emphasis lies in the discussion of the coupling strategy for compressible and incompressible Euler equations to simulate inviscid liquid-vapour flows. To reduce the computational effort further, we also introduce two approximate coupling strategies. The resulting schemes are compared numerically to a fully compressible scheme and show good agreement with these standard algorithm at lower numerical costs.
Coupling ground penetrating radar and fluid flow modeling for oilfield monitoring applications
Miorali, M.; Zhou, F.; Slob, E.C.; Arts, R.J.
2011-01-01
The recent introduction of smart well technology allows for new geophysical monitoring opportunities. Smart wells, which allow zonal production control, combined with monitoring techniques capable of capturing the arrival of undesired fluids, have the potential to significantly increase the oil reco
2017-04-03
and Computational Fluid Dynamics Models for Seakeeping Analysis Awardee: University of Hawaii, Honolulu, Hawaii Technical Contact: Kwok Fai...the coast to provide important information for seakeeping analysis . However, such endeavors involve appreciable numerical errors and complex near...nonlinear and dispersive theories, present-day computational models based on Boussinesq-type equations are being applied over vast regions from deep to
Coupling ground penetrating radar and fluid flow modeling for oilfield monitoring applications
Miorali, M.; Zhou, F.; Slob, E.C.; Arts, R.
2011-01-01
The recent introduction of smart well technology allows for new geophysical monitoring opportunities. Smart wells, which allow zonal production control, combined with monitoring techniques capable of capturing the arrival of undesired fluids, have the potential to significantly increase the oil reco
Coupled fluid-flow and magnetic-field simulation of the Riga dynamo experiment
KenjereÅ¡, S.; HanjaliÄ‡, K.; Renaudier, S.; Stefani, F.; Gerbeth, G.; Gailitis, A.
2006-01-01
Magnetic fields of planets, stars, and galaxies result from self-excitation in moving electroconducting fluids, also known as the dynamo effect. This phenomenon was recently experimentally confirmed in the Riga dynamo experiment [ A. Gailitis et al., Phys. Rev. Lett. 84, 4365 (2000) ; A. Gailitis et
Trimmed simulation of a transport aircraft using fluid-structure coupling
Michler, A.K.; Dwight, R.P.; Heinrich, R.
2009-01-01
The accurate prediction of the aerodynamic coefficients under cruise conditions is of major importance for assessing the aircraftâ€™s fuel consumption. To this end, fluid dynamics, structural mechanics and flight mechanics have to be considered: on the one hand, the structure elastically deforms under
2010-02-28
modes, see the inset of Fig. 6. The area normalized noise spectra are shown in Fig. 7. Using a simple harmonic oscillator analogy a peak frequency and a...single nanoparticles in fluid. Nature Lett., 446:1066â€“1069, 2007. [42] M. R. Paul and J. E. Solomon. Nanodevices for Life Sciences, volume 4, chapter The
Fluid and structure coupling analysis of the interaction between aqueous humor and iris.
Wang, Wenjia; Qian, Xiuqing; Song, Hongfang; Zhang, Mindi; Liu, Zhicheng
2016-12-28
Glaucoma is the primary cause of irreversible blindness worldwide associated with high intraocular pressure (IOP). Elevated intraocular pressure will affect the normal aqueous humor outflow, resulting in deformation of iris. However, the deformation ability of iris is closely related to its material properties. Meanwhile, the passive deformation of the iris aggravates the pupillary block and angle closure. The nature of the interaction mechanism of iris deformation and aqueous humor fluid flow has not been fully understood and has been somewhat a controversial issue. The purpose here was to study the effect of IOP, localization, and temperature on the flow of the aqueous humor and the deformation of iris interacted by aqueous humor fluid flow. Based on mechanisms of aqueous physiology and fluid dynamics, 3D model of anterior chamber (AC) was constructed with the human anatomical parameters as a reference. A 3D idealized standard geometry of anterior segment of human eye was performed. Enlarge the size of the idealization geometry model 5 times to create a simulation device by using 3D printing technology. In this paper, particle image velocimetry technology is applied to measure the characteristic of fluid outflow in different inlet velocity based on the device. Numerically calculations were made by using ANSYS 14.0 Finite Element Analysis. Compare of the velocity distributions to confirm the validity of the model. The fluid structure interaction (FSI) analysis was carried out in the valid geometry model to study the aqueous flow and iris change. In this paper, the validity of the model is verified through computation and comparison. The results indicated that changes of gravity direction of model significantly affected the fluid dynamics parameters and the temperature distribution in anterior chamber. Increased pressure and the vertical position increase the velocity of the aqueous humor fluid flow, with the value increased of 0.015 and 0.035Â mm/s. The results
Coriolis effect on thermal convection in a couple-stress fluid-saturated rotating rigid porous layer
Energy Technology Data Exchange (ETDEWEB)
Shivakumara, I.S.; Devaraju, N. [Bangalore University, UGC-Centre for Advanced studies in Fluid Mechanics, Department of Mathematics, Bangalore (India); Sureshkumar, S. [Siddaganga Institute of Technology, Department of Mathematics, Tumkur (India)
2011-04-15
Both linear and weakly nonlinear stability analyses are performed to study thermal convection in a rotating couple-stress fluid-saturated rigid porous layer. In the case of linear stability analysis, conditions for the occurrence of possible bifurcations are obtained. It is shown that Hopf bifurcation is possible due to Coriolis force, and it occurs at a lower value of the Rayleigh number at which the simple bifurcation occurs. In contrast to the nonrotating case, it is found that the couple-stress parameter plays a dual role in deciding the stability characteristics of the system, depending on the strength of rotation. Nonlinear stability analysis is carried out by constructing a set of coupled nonlinear ordinary differential equations using truncated representation of Fourier series. Sub-critical finite amplitude steady motions occur depending on the choice of physical parameters but at higher rotation rates oscillatory convection is found to be the preferred mode of instability. Besides, the stability of steady bifurcating equilibrium solution is discussed using modified perturbation theory. Heat transfer is calculated in terms of Nusselt number. Also, the transient behavior of the Nusselt number is investigated by solving the nonlinear differential equations numerically using the Runge-Kutta-Gill method. It is noted that increase in the value of Taylor number and the couple-stress parameter is to dampen the oscillations of Nusselt number and thereby to decrease the heat transfer. (orig.)
Larson, John Philip
Smart material electro-hydraulic actuators (EHAs) utilize fluid rectification via one-way check valves to amplify the small, high-frequency vibrations of certain smart materials into large motions of a hydraulic cylinder. Although the concept has been demonstrated in previously, the operating frequency of smart material EHA systems has been limited to a small fraction of the available bandwidth of the driver materials. The focus of this work is to characterize and model the mechanical performance of a magnetostrictive EHA considering key system components: rectification valves, smart material driver, and fluid-system components, leading to an improved actuator design relative to prior work. The one-way valves were modeled using 3-D finite element analysis, and their behavior was characterized experimentally by static and dynamic experimental measurement. Taking into account the effect of the fluid and mechanical conditions applied to the valves within the pump, the dynamic response of the valve was quantified and applied to determine rectification bandwidth of different valve configurations. A novel miniature reed valve, designed for a frequency response above 10~kHz, was fabricated and tested within a magnetostrictive EHA. The nonlinear response of the magnetostrictive driver, including saturation and hysteresis effects, was modeled using the Jiles-Atherton approach to calculate the magnetization and the resulting magnetostriction based on the applied field calculated within the rod from Maxwell's equations. The dynamic pressure response of the fluid system components (pumping chamber, hydraulic cylinder, and connecting passages) was measured over a range of input frequencies. For the magnetostrictive EHA tested, the peak performance frequency was found to be limited by the fluid resonances within the system. A lumped-parameter modeling approach was applied to model the overall behavior of a magnetostrictive EHA, incorporating models for the reed valve response
Kaladhar, K.; Srinivasacharya, D.
2016-12-01
The chemical reaction, Soret and Dufour effects on steady flow of a couple stress fluid between two rotating disks are studied. The lower disc is rotating with angular velocity Î©1 where as the upper disc is rotating with Î©2. The density variation in centrifugal and Coriolis force terms are taken into consideration by invoking a linear density-temperature relation and Boussinesq approximation to account the buoyancy effects. The non-linear governing partial differential equations are transformed into system of ordinary differential equations by using the similarity transformations. Homotopy Analysis Method (HAM) has been used to solve the resulting equations. Graphical illustrations of the dimensionless velocity, concentration and temperature profiles are presented at different values of the emerging parameter of the present study. It has been found that as an increase in couple stresses leads to the decrease in velocity, temperature and increase in concentration of the fluid. Flow velocities, temperature and concentration profiles are decreases with an increase in reaction parameter.
Energy Technology Data Exchange (ETDEWEB)
Rutqvist, J.
2010-06-01
This paper presents recent advancement in and applications of TOUGH-FLAC, a simulator for multiphase fluid flow and geomechanics. The TOUGH-FLAC simulator links the TOUGH family multiphase fluid and heat transport codes with the commercial FLAC{sup 3D} geomechanical simulator. The most significant new TOUGH-FLAC development in the past few years is a revised architecture, enabling a more rigorous and tight coupling procedure with improved computational efficiency. The applications presented in this paper are related to modeling of crustal deformations caused by deep underground fluid movements and pressure changes as a result of both industrial activities (the In Salah CO{sub 2} Storage Project and the Geysers Geothermal Field) and natural events (the 1960s Matsushiro Earthquake Swarm). Finally, the paper provides some perspectives on the future of TOUGH-FLAC in light of its applicability to practical problems and the need for high-performance computing capabilities for field-scale problems, such as industrial-scale CO{sub 2} storage and enhanced geothermal systems. It is concluded that despite some limitations to fully adapting a commercial code such as FLAC{sup 3D} for some specialized research and computational needs, TOUGH-FLAC is likely to remain a pragmatic simulation approach, with an increasing number of users in both academia and industry.
Rutqvist, Jonny
2011-06-01
This paper presents recent advancement in and applications of TOUGH-FLAC, a simulator for multiphase fluid flow and geomechanics. The TOUGH-FLAC simulator links the TOUGH family multiphase fluid and heat transport codes with the commercial FLAC 3D geomechanical simulator. The most significant new TOUGH-FLAC development in the past few years is a revised architecture, enabling a more rigorous and tight coupling procedure with improved computational efficiency. The applications presented in this paper are related to modeling of crustal deformations caused by deep underground fluid movements and pressure changes as a result of both industrial activities (the In Salah CO 2 Storage Project and the Geysers Geothermal Field) and natural events (the 1960s Matsushiro Earthquake Swarm). Finally, the paper provides some perspectives on the future of TOUGH-FLAC in light of its applicability to practical problems and the need for high-performance computing capabilities for field-scale problems, such as industrial-scale CO 2 storage and enhanced geothermal systems. It is concluded that despite some limitations to fully adapting a commercial code such as FLAC 3D for some specialized research and computational needs, TOUGH-FLAC is likely to remain a pragmatic simulation approach, with an increasing number of users in both academia and industry.
Zeinoddini, M.; Matin Nikoo, H.; Ahmadpour, F.
2013-08-01
This study focuses on non-linear seismic response of concrete gravity quay-wall structures subjected to near-fault ground motions, a subject which seems not to have received much attention in the literature. A two-dimensional coupled fluid-structure-soil finite element modelling is employed to obtain the quay-wall response. The seawater medium is represented by acoustic type, potential based fluid elements. The elasto-plastic behavior of the soil medium is idealized using Drucker-Prager yield criterion based on associated flow rule assumption. Four nodded plane strain elements are used to model the concrete wall, foundation, subsoil, backfill and seabed zones. Fluid Structure Interface (FSI) elements are considered between the seawater interfaces with the quay-wall and the seabed. Frictional contact elements are employed between the wall and soil interfaces. The numerical model is validated using field measurements available for permanent drifts in a quay-wall damaged during Kobe earthquake. Reasonable agreements are obtained between the model predictions and the field measurements. Non-linear seismic analyses of the selected quay-wall subjected to both near-fault and far-fault ground motions are performed. An incremental dynamic analysis approach (IDA) is used. In general, at least for models examined in the current study, the gravity quay-walls are found to be more vulnerable to near-field, in comparison with the corresponding far-field, earthquakes.
Protein Simulations in Fluids: Coupling the OPEP Coarse-Grained Force Field with Hydrodynamics.
Sterpone, Fabio; Derreumaux, Philippe; Melchionna, Simone
2015-04-14
A novel simulation framework that integrates the OPEP coarse-grained (CG) model for proteins with the Lattice Boltzmann (LB) methodology to account for the fluid solvent at mesoscale level is presented. OPEP is a very efficient, water-free and electrostatic-free force field that reproduces at quasi-atomistic detail processes like peptide folding, structural rearrangements, and aggregation dynamics. The LB method is based on the kinetic description of the solvent in order to solve the fluid mechanics under a wide range of conditions, with the further advantage of being highly scalable on parallel architectures. The capabilities of the approach are presented, and it is shown that the strategy is effective in exploring the role of hydrodynamics on protein relaxation and peptide aggregation. The end result is a strategy for modeling systems of thousands of proteins, such as in the case of dense protein suspensions. The future perspectives of the multiscale approach are also discussed.
Energy Technology Data Exchange (ETDEWEB)
Lee, Jung Eui; Yeo, Tae Jung; Oh, Kyu Hwan; Yoon, Jong Kyu [School of Materials Science and Engineering, Seoul Nat`l Univ., Seoul (Korea, Republic of); Han, Heung Nam [Oxford Center for Advanced Materials and Composites, Department of Materials, Univ. of Oxford (United Kingdom)
1997-12-31
A mathematical model for a coupled analysis of fluid flow, heat transfer and deformation behavior in the continuously cast beam blank has been developed. The fluid flow, heat transfer and solidification in the mold region were analyzed with 3-dimensional finite difference method (FDM) based on control volume method. A body fitted coordinate system was introduced for the complex geometry of the beam blank. The effects of turbulence and natural convection of molten steel were taken into account in determining the fluid flow in the strand. The thermo-elasto-plastic deformation behavior in the cast strand and the formation of air gap between the solidifying shell and the mold were analyzed by the finite element method (FEM) using the 2-dimensional slice temperature profile calculated by the FDM. The heat flow between the strand and the mold was evaluated by the coupled analysis between the fluid flow-heat transfer analysis and the thermo-elasto-plastic stress analysis. In order to determine the solid fraction in the mushy zone, the microsegregation of solute element was assessed. The effects of fluid flow on the heat transfer, the solidification of steel and the distribution of shell thickness during the casting of the beam blank were simulated. The deformation behavior of the solidifying shell and the possibility of cracking of the strand were also investigated. The recirculating flows were developed in the regions of the web and the flange tip. The impinging of the inlet flow from the nozzle retarded the growing of solidifying shell in the regions of the fillet and the flange. The air gap between the strand and the mold was formed near the region of the corner of the flange tip. At the initial stage of casting, the probability of the surface cracking was high in the regions of the fillet and the flange tip. After the middle stage of casting, the internal cracking was predicted in the regions of the flange tip, and between the fillet and the flange tip. (author) 38
Modeling of Complex Coupled Fluid-Structure Interaction Systems in Arbitrary Water Depth
2009-01-01
deterministic and stochastic environmental conditions from deep water to the surf zone. Physics- specific numerical models included in the framework...applicability of the computational framework to shallow water and the surf zone. APPROACH The approach to achieve the short term objectives is to...examples including: a pure CFD model with a backward facing step, a prescribed moving cylinder in a bounded domain, and a fluid-object interaction
Ye, Jiamin; Wang, Haigang; Yang, Wuqiang
2016-07-01
Electrical capacitance tomography (ECT) is based on capacitance measurements from electrode pairs mounted outside of a pipe or vessel. The structure of ECT sensors is vital to image quality. In this paper, issues with the number of electrodes and the electrode covering ratio for complex liquid-solids flows in a rotating device are investigated based on a new coupling simulation model. The number of electrodes is increased from 4 to 32 while the electrode covering ratio is changed from 0.1 to 0.9. Using the coupling simulation method, real permittivity distributions and the corresponding capacitance data at 0, 0.5, 1, 2, 3, 5, and 8â€‰s with a rotation speed of 96 rotations per minute (rpm) are collected. Linear back projection (LBP) and Landweber iteration algorithms are used for image reconstruction. The quality of reconstructed images is evaluated by correlation coefficient compared with the real permittivity distributions obtained from the coupling simulation. The sensitivity for each sensor is analyzed and compared with the correlation coefficient. The capacitance data with a range of signal-to-noise ratios (SNRs) of 45, 50, 55 and 60 dB are generated to evaluate the effect of data noise on the performance of ECT sensors. Furthermore, the SNRs of experimental data are analyzed for a stationary pipe with permittivity distribution. Based on the coupling simulation, 16-electrode ECT sensors are recommended to achieve good image quality.
Schiller, N K; Franz, T; Weerasekara, N S; Zilla, P; Reddy, B D
2010-12-01
Vascular anastomoses constitute a main factor in poor graft performance due to mismatches in distensibility between the host artery and the graft. This work aims at computational fluid-structure investigations of proximal and distal anastomoses of vein grafts and synthetic grafts. Finite element and finite volume models were developed and coupled with a user-defined algorithm. Emphasis was placed on the simplicity of the coupling algorithm. An artery and vein graft showed a larger dilation mismatch than an artery and synthetic graft. The vein graft distended nearly twice as much as the artery while the synthetic graft displayed only approximately half the arterial dilation. For the vein graft, luminal mismatching was aggravated by development of an anastomotic pseudo-stenosis. While this study focused on end-to-end anastomoses as a vehicle for developing the coupling algorithm, it may serve as useful point of departure for further investigations such as other anastomotic configurations, refined modelling of sutures and fully transient behaviour.
Energy Technology Data Exchange (ETDEWEB)
Sigrist, J.F
2004-11-15
The present work deals with the numerical simulation of a coupled fluid/structure problem with fluid free surface. A generic coupled fluid/structure system is defined, on which a linear problem (modal analysis) and a non-linear problem (temporal analysis) are stated. In the linear case, a strong coupled method is used. It is based on a finite element approach of the structure problem and a finite or a boundary element approach of the fluid problem. The coupled problem is formulated in terms of pressure and displacement, leading to a non-symmetric problem which is solved with an appropriate algorithm. In the non-linear case, the structure problem is described with non-linear equations of motion, whereas the fluid problem is modeled with the Stokes equations. The numerical resolution of the coupled problem is based on a weak coupling procedure. The fluid problem is solved with a finite volume technique, using a moving mesh technique to adjust the structure motion, a VOF method for the description of the free surface and the PISO algorithm for the time integration. The structure problem is solved with a finite element technique, using an explicit/implicit time integration algorithm. A procedure is developed in order to handle the coupling in space (fluid forces and structure displacement exchanges between fluid and structure mesh, fluid re-meshing) and in time (staggered explicit algorithm, dynamic filtering of numerical oscillations). The non linear coupled problem is solved using a CFD code, whose use for FSI problem is validated with a benchmark presented in this work. A comparison is proposed between numerical results and analytical solution for two elementary fluid problems. The validation process can be applied for any CFD numerical code. A numerical study is then proposed on the generic coupled case in order to describe the fluid/structure interaction phenomenon (added mass, displaced mass, mode coupling, influence of structural non-linearity). An industrial
Coupled Hydromechanical Model of Two-Phase Fluid Flow in Deformable Porous Media
Directory of Open Access Journals (Sweden)
You-Seong Kim
2013-01-01
Full Text Available A model of solid-water-air coupling in triphasic mixtures is compared with solid-water coupling in biphasic mixtures with an application to partially saturated porous media. Based on thermodynamics, the mathematical framework governing the behavior of a partially saturated soil is derived using balance equations, and the numerical implementation and drainage tests of a soil column are carried out to validate the obtained formulations. The role of the air phase in the hydro-mechanical behavior of triphasic mixtures can be analyzed from the interactions among multiple phases for the constitutive behavior of a solid skeleton, and the triphasic mixture model can be applied in geotechnical engineering problems, such as CO2 sequestration and air storage in aquifers.
Cell-fluid Interaction: Coupling Between the Deformation of an Adherent Leukocyte and the Shear Flow
Institute of Scientific and Technical Information of China (English)
æ—
2005-01-01
1 IntroductionLeukocyte adhesion is a natural physiopathological phenomenon and the balance between the hemodynamic forces and adhesion forces (molecular bonds) plays a key role. According to hemodynamic theories, blood flow induces the change of the shape and the spatial arrangement of leukocytes. These changes may in turn induce the redistribution of blood flow around the cell. Therefore there exist interaction of the adherent leukocyte with blood flow, which is called as the coupling between the hemodyna...
AlfvÃ©n wave coupled with flow-driven fluid instability in interpenetrating plasmas
Energy Technology Data Exchange (ETDEWEB)
Vranjes, J. [Instituto de Astrofisica de Canarias, 38205 La Laguna, Tenerife, Spain and Departamento de Astrofisica, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain)
2015-05-15
The AlfvÃ©n wave is analyzed in case of one quasineutral plasma propagating with some constant speed v{sub 0} through another static quasineutral plasma. A dispersion equation is derived describing the AlfvÃ©n wave coupled with the flow driven mode Ï‰=kv{sub 0} and solutions are discussed analytically and numerically. The usual solutions for two oppositely propagating AlfvÃ©n waves are substantially modified due to the flowing plasma. More profound is modification of the solution propagating in the negative direction with respect to the magnetic field and the plasma flow. For a large enough flow speed (exceeding the AlfvÃ©n speed in the static plasma), this negative solution may become non-propagating, with frequency equal to zero. In this case, it represents a spatial variation of the electromagnetic field. For greater flow speed it becomes a forward mode, and it may merge with the positive one. This merging of the two modes represents the starting point for a flow-driven instability, with two complex-conjugate solutions. The AlfvÃ©n wave in interpenetrating plasmas is thus modified and coupled with the flow-driven mode and this coupled mode is shown to be growing when the flow speed is large enough. The energy for the instability is macroscopic kinetic energy of the flowing plasma. The dynamics of plasma particles caused by such a coupled wave still remains similar to the ordinary AlfvÃ©n wave. This means that well-known stochastic heating by the AlfvÃ©n wave may work, and this should additionally support the potential role of the AlfvÃ©n wave in the coronal heating.
Coupled fluid-dynamical and structural analysis of a mono-axial mems accelerometer
Directory of Open Access Journals (Sweden)
A Cammarata
2016-09-01
Full Text Available This study is aimed to numerically investigate the elastodynamics of a mono-axial MEMS accelerometer. The vibrating part of the device is dipped into a fluid micro-channel and made of a proof mass connected to the frame by two flexible legs. The adopted mathematical model lies on a linearized motion equations system, where the mass matrix is obtained by means of both lumped and distributed approach. The stiffness matrix is otherwise derived through FEA, in which the proof mass and the compliant legs are modeled as rigid and flexible bodies, respectively. The squeezed-film damping effect is evaluated by a fluid-dynamical FE model based on a modified Reynolds formulation. The ensuing analyses are carried-out for three pressure levels of the narrow gas film surrounding the device, by applying the logarithmic decrement method for evaluating the damping ratio. Numerical results, in terms of acceleration, frequency range and noise disturbance, are successfully compared to analytical and experimental ones previously published in literature. Our model characterizes the accelerometer dynamics in space, allowing, in addition, to assess translational motion errors along directions apart the working one.
Protein simulations in fluids: coupling the OPEP coarse-grained force field with hydrodynamics
Sterpone, Fabio; Derreumaux, Philippe; Melchionna, Simone
2017-01-01
A novel simulation framework that integrates the OPEP coarse-grained (CG) model for proteins with the Lattice Boltzmann (LB) methodology to account for the fluid solvent at mesoscale level, is presented. OPEP is a very efficient, water-free and electrostatic-free force field that reproduces at quasi-atomistic detail processes like peptide folding, structural rearrangements and aggregation dynamics. The LB method is based on the kinetic description of the solvent in order to solve the fluid mechanics under a wide range of conditions, with the further advantage of being highly scalable on parallel architectures. The capabilities of the approach are presented and it is shown that the strategy is effective in exploring the role of hydrodynamics on protein relaxation and peptide aggregation. The end result is a strategy for modelling systems made up to thousands of proteins, such as in the case of dense protein suspensions. The future perspectives of the multi-scale approach are also discussed. PMID:26574390
Measurements of coupled fluid and sediment motion over mobile sand dunes in a laboratory flume
Institute of Scientific and Technical Information of China (English)
Daniel G.WREN; Roger A.KUHNLE
2008-01-01
The relationship between turbulent fluid motions and sediment particle motions over mobile sand dunes was investigated by using a laser Doppler velocimeter and an acoustic backscatter system in laboratory experiments performed at the USDA-ARS-National Sedimentation Laboratory.Profiles of acoustic backscatter from particles and at-a-point turbulence data were collected while translating both measurement devices downstream at the speed of mobile dune bedforms.The resulting data set was used to examine the frequency (recurrence frequency) at which the fluctuating backscatter and fluid velocity signals exceeded magnitude thresholds based on the standard deviation (Ïƒ) of the local velocity and the magnitude the acoustic signal resulting from backscatter from suspended particles.The slope of the downstream and vertical velocity recurrence frequencies generally indicated a gradually increasing recurrence time with increasing elevation.The recurrence frequency for acoustic backscatter data was not strongly variable with elevation.The closest correspondence between the recurrence frequencies of sediment backscatter and vertical velocities at the 1Ïƒ magnitude threshold was in a region defined by X/Lï¼œ0.4 and 3ï¼œ6 cm.The downstream velocity was most closely related to backscatter in a small region at 0.4ï¼œX/Lï¼œ0.8 and less than 3-4 cm from the bed.
Fluid-structure interaction in the left ventricle of the human heart coupled with mitral valve
Meschini, Valentina; de Tullio, Marco Donato; Querzoli, Giorgio; Verzicco, Roberto
2016-11-01
In this paper Direct Numerical Simulations (DNS), implemented using a fully fluid-structure interaction model for the left ventricle, the mitral valve and the flowing blood, and laboratory experiments are performed in order to cross validate the results. Moreover a parameter affecting the flow dynamics is the presence of a mitral valve. We model two cases, one with a natural mitral valve and another with a prosthetic mechanical one. Our aim is to understand their different effects on the flow inside the left ventricle in order to better investigate the process of valve replacement. We simulate two situations, one of a healthy left ventricle and another of a failing one. While in the first case the flow reaches the apex of the left ventricle and washout the stagnant fluid with both mechanical and natural valve, in the second case the disturbance generated by the mechanical leaflets destabilizes the mitral jet, thus further decreasing its capability to penetrate the ventricular region and originating heart attack or cardiac pathologies in general.
Fluid-Plasma-Combustion Coupling Effects on the Ignition of a Fuel Jet
Massa, Luca; Freund, Jonathan
2016-11-01
We analyze the effect of plasma-combustion coupling on the ignition and flame supported by a DBD interacting with a jet of H2 in a air cross-flow. We propose that plasma-combustion coupling is due to the strong temperature-dependence of specific collisional energy loss as predicted by the Boltzmann equation, and that e- transport can be modeled by assuming a form for the E-field pulse in microstreamers. We introduce a two-way coupling based on the Boltzmann equation and the charged species conservation. The addition of this mechanism to a hydrogen combustion scheme leads to an improvement of the ignition prediction and of the understanding of the effect of the plasma on the flow. The key points of the analysis are 1) explanation of the mechanism for the two-stage ignition and quenching observed experimentally, 2) explanation of the existence of a power threshold above which the plasma is beneficial to the ignition probability, 3) understanding of the increase in power absorbed by the plasma in burning conditions and the reduction in power absorbed with an increase in the cross velocity, 4) explanation of the non-symmetric emissions and the increase in luminescence at the rotovibrational H2O band. The model is validated in part against air-H2 flow experiments. This material is based in part upon work supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002374.
Yoon, Jeoung Seok; Zang, Arno; Zimmermann, GÃ¼nter; Stephansson, Ove
2016-04-01
Operation of fluid injection into and withdrawal from the subsurface for various purposes has been known to induce earthquakes. Such operations include hydraulic fracturing for shale gas extraction, hydraulic stimulation for Enhanced Geothermal System development and waste water disposal. Among these, several damaging earthquakes have been reported in the USA in particular in the areas of high-rate massive amount of wastewater injection [1] mostly with natural fault systems. Oil and gas production have been known to induce earthquake where pore fluid pressure decreases in some cases by several tens of Mega Pascal. One recent seismic event occurred in November 2013 near Azle, Texas where a series of earthquakes began along a mapped ancient fault system [2]. It was studied that a combination of brine production and waste water injection near the fault generated subsurface pressures sufficient to induced earthquakes on near-critically stressed faults. This numerical study aims at investigating the occurrence mechanisms of such earthquakes induced by fluid injection [3] and withdrawal by using hydro-geomechanical coupled dynamic simulator (Itasca's Particle Flow Code 2D). Generic models are setup to investigate the sensitivity of several parameters which include fault orientation, frictional properties, distance from the injection well to the fault, amount of fluid withdrawal around the injection well, to the response of the fault systems and the activation magnitude. Fault slip movement over time in relation to the diffusion of pore pressure is analyzed in detail. Moreover, correlations between the spatial distribution of pore pressure change and the locations of induced seismic events and fault slip rate are investigated. References [1] Keranen KM, Weingarten M, Albers GA, Bekins BA, Ge S, 2014. Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection, Science 345, 448, DOI: 10.1126/science.1255802. [2] Hornbach MJ, DeShon HR
Glass transition in driven granular fluids: A mode-coupling approach
Kranz, W. T.; Sperl, M.; Zippelius, A.
2013-02-01
We consider the stationary state of a fluid comprised of inelastic hard spheres or disks under the influence of a random, momentum-conserving external force. Starting from the microscopic description of the dynamics, we derive a nonlinear equation of motion for the coherent scattering function in two and three space dimensions. A glass transition is observed for all coefficients of restitution, É›, at a critical packing fraction Ï†c(É›) below random close packing. The divergence of timescales at the glass transition implies a dependence on compression rate upon further increase of the densityâ€”similar to the cooling-rate dependence of a thermal glass. The critical dynamics for coherent motion as well as tagged particle dynamics is analyzed and shown to be nonuniversal with exponents depending on space dimension and degree of dissipation.
Spence, R.; Streeton, R.J.W.
1956-04-17
The fluid contactor apparatus comprises a cylindrical column mounted co- axially and adapted to rotate within a cylindrical vessel, for the purpose of extracting a solute from am aqueous solution by means of an organic solvent. The column is particularly designed to control the vortex pattern so as to reduce the height of the vortices while, at the same time, the width of the annular radius in the radial direction between the vessel and column is less than half the radius of the column. A plurality of thin annular fins are spaced apart along the rotor approximately twice the radial dimension of the column such that two contrarotating substantially circular vortices are contained within each pair of fins as the column is rotated.
Directory of Open Access Journals (Sweden)
Amelia eGreig
2015-01-01
Full Text Available Computational fluid dynamics (CFD simulations of a radio-frequency (13.56 MHz electro-thermal capacitively coupled plasma (CCP micro-thruster have been performed using the commercial CFD-ACE+ package. Standard operating conditions of a 10 W, 1.5 Torr argon discharge were used to compare with previously obtained experimental results for validation. Results show that the driving force behind plasma production within the thruster is ion-induced secondary electrons ejected from the surface of the discharge tube, accelerated through the sheath to electron temperatures up to 33.5 eV. The secondary electron coefficient was varied to determine the effect on the discharge, with results showing that full breakdown of the discharge did not occur for coefficients coefficients less than or equal to 0.01.
Hundertmark-ZauÅ¡kovÃ¡, A.; LukÃ¡ÄovÃ¡-MedviÄovÃ¡, M.; NeÄasovÃ¡, Å . (Å Ã¡rka)
2016-01-01
We study the existence of weak solution for unsteady fluid-structure interaction problem for shear-thickening flow. The time dependent domain has at one part a flexible elastic wall. The evolution of fluid domain is governed by the generalized string equation with action of the fluid forces. The power-law viscosity model is applied to describe shear-dependent non-Newtonian fluids.
Bao, J.; Zhou, T.; Huang, M.; Hou, Z.; Perkins, W. A.; Harding, S.; Hammond, G. E.; Ren, H.; Thorne, P. D.; Suffield, S. R.; Zachara, J. M.
2016-12-01
Hyporheic exchange between river water and groundwater is an important mechanism for biogeochemical processes, such as carbon and nitrogen cycling, and biodegradation of organic contaminants, in the subsurface interaction zone. The relationship between river flow conditions and hyporheic exchanges therefore is of great interests to hydrologists, biogeochemists, and ecologists. However, quantifying relative influences of hydrostatic and hydrodynamic drivers on hyporheic exchanges is very challenging in large rivers due to accessibility and spatial coverage of measurements, and computational tools available for numerical experiments. In this study, we aim to demonstrate that a high resolution computational fluid dynamics (CFD) model that couples surface and subsurface flow and transport can be used to simulate hyporheic exchanges and the residence time of river water in the hypothetic zone. Base on the assumption that the hyporheic exchange does not affect the surface water flow condition due to its small magnitude compared to the velocity of river water, we developed a one way coupled surface and subsurface water flow model in a commercial CFD software STAR-CCM+, that connects the Reynolds-averaged Navier-Stokes (RANS) equation solver with a realizable two-layer turbulence model, a two-layer all y+ wall treatment, and the volume of fluid (VOF) method for tracking the free water-air interface as well as porous media flow in the subsurface domain. The model is applied to a 7-km long section of the Columbia River and validated against measurements from the acoustic Doppler current profiler (ADCP) in the surface water and hyporheic fluxes derived from a set of temperature profilers installed across the riverbed. The validated model is then employed to systematically investigate how hyporheic exchanges influenced by 1) riverbed properties such as the permeability and thickness of the alluvial layer; 2) surface water hydrodynamics due to channel geomorphological settings
Two-dimensional coupled fluid and electrodynamic calculations for a MHD DCW channel with slag layers
Liu, B. L.
1982-01-01
A fully coupled, two dimensional numerical method of modeling linear, coal-fired MHD generators is developed for the case of a plasma flow bounded by a slag layer on the channel walls. The governing partial differential equations for the plasma flow, slag layer and electrodynamics are presented and their coupling discussed. An iterative, numerical procedure employing non-uniform computational meshes and appropriate tridiagonal matrix solution schemes for the equations is presented. The method permits the investigation of the mutual plasma flow-slag layer development for prescribed wall temperatures, electrode geometry, slag properties and channel loading. In particular, the slag layer-plasma interface properties which require prior specification in an uncoupled analysis comprise part of the solution in the present approach. Results are presented for a short diagonally connected generator channel and include contour plots of the electric potential and current stream function as well as transverse and axial profiles of pertinent plasma properties. The results indicate that a thin electrode slag layer can be maintained in the presence of reasonable current density levels.
Luke, Jensen; Lebit, Hermann; Paterson, Scott; Miller, Robert; Vernon, Ron
2017-04-01
The Cascades crystalline core forms part of the Cretaceous magmatic belt of western North America and exposes a crustal section composed of primarily tonalitic plutons that intruded siliciclastic metasediments of an arc-derived accretional system, and local meta-basalt/chert sequences. This study is the first attempt to correlate the well understood intrusive and P-T-t history of the metasedimentary and plutonic terrane with the kinematics and tectonic boundary conditions by rigorous analysis of structures documented in the Tonga Formation exposed at the western edge of the core. The Tonga Formation comprises pelite-psammite metasediments, which increase from greenschist ( 300-350Â° C) to amphibolite grade ( 500-600Â° C) from south to north. This metamorphic gradient is inverted relative to a major westward verging and downward facing fold system that dominates the internal architecture of the formation and implies that the initial regional metamorphic signature was established prior to the early fold generation. Subsequent co-axial fold superposition is seen as a consequence of the persistent accretional west-vergent thrusting in the foreland of the magmatic arc. The central section of the Cascades Range, exposed in western Washington, forms part of the Cretaceous accretional/magmatic arc extending over 4,000 km along western North America from Baja California to British Columbia (Fig. 1a) (e.g. Misch, 1966; Brown, 1987; Tabor et al., 1989). Two models exist for the evolution of the Cascades crystalline core with one invoking magmatic loading (e.g. Brown and Walker, 1993) as the major cause for rapid loading, consequent regional metamorphism and vertical uplift (Evans and Berti, 1986). Conversely, other workers favor a model that suggests loading as a consequence of tectonic, thrust-related thickening, followed by rapid exhumation of the exposed crustal section of 10 to 40 km paleodepth (e.g. Matzel, 2004; Patterson et al., 2004; Stowell et al., 2007). In this
Institute of Scientific and Technical Information of China (English)
AL-SAIF A.S.J.; ZHU Zheng-you
2005-01-01
The problem of two-dimensional steady flow of an incompressible second-order viscoelastic fluid coupled with heat transfer between parallel plates was considered.A viscous dissipation function was included in the energy equation.When the elastic property of the fluid is weaker, the zeroth-order and first-order approximate governing equations were obtained by means of the perturbation method.To understand the behavior of flow near the tube wall, the half-domain was divided into two sub-domains, in which one is a thin layer near the wall called the inner domain and the remainder is called the outer domain.The governing equations in the inner domain and in the outer domain were discretized respectively by using the Differential Quadrature Method (DQM).The matching conditions at the interface between the inner and outer domains were presented.An iterative method for solving these discretized equations was given in this paper.The numerical results obtained agree with existing results.
Directory of Open Access Journals (Sweden)
Lin Wei
2015-01-01
Full Text Available Heat recovery unit (HRU is a heat exchange device in drying process. In HRU, room air is preheated by waste hot air and then transported to drying oven to remove moisture, which helps to save both energy and time. The main purpose of this paper is to build a heat transfer model of HRU and study its characteristics. A numerical method based on fluid-solid coupling was used to calculate the heat transfer between tube and fluids, and the actual structure was simplified to improve computation efficiency. The results were validated by theoretical calculation and experiments. Effects of Reynolds number (Re on outlet temperature, Nusselt number, and pressure drop were investigated. It was found that the thermal resistance of shell side is large, by reducing which the total heat transfer coefficient can be improved. The difference between finned tube and smooth tube is in the shell side. Larger Re of shell side leads to good heat transfer performance but also larger pressure drop which increases the flow resistance.
Long-range interactions and phase defects in chains of fluid-coupled oscillators
Brumley, Douglas R; Kotar, Jurij; Goldstein, Raymond E; Cicuta, Pietro; Polin, Marco
2016-01-01
Eukaryotic cilia and flagella are chemo-mechanical oscillators capable of generating long-range coordinated motions known as metachronal waves. Pair synchronization is a fundamental requirement for these collective dynamics, but it is generally not sufficient for collective phase-locking, chiefly due to the effect of long-range interactions. Here we explore experimentally and numerically a minimal model for a ciliated surface; hydrodynamically coupled oscillators rotating above a no-slip plane. Increasing their distance from the wall profoundly effects the global dynamics, due to variations in hydrodynamic interaction range. The array undergoes a transition from a traveling wave to either a steady chevron pattern or one punctuated by periodic phase defects. Within the transition between these regimes the system displays behavior reminiscent of chimera states.
Institute of Scientific and Technical Information of China (English)
PANI P. K.; BHATTACHARYYA S. K.
2009-01-01
The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin's theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-b method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.
The fluidâ€“solid coupling analysis of screw conveyor in drilling fluid centrifuge based on ANSYS
Directory of Open Access Journals (Sweden)
Hongbin Liu
2015-09-01
Full Text Available In the centrifugal separations of drilling fluid, screw conveyor is a critical component to push and separate the sediment. The work performance and structural parameters of conveyor are immediately related to the production capability, the working life and the separating effect of the centrifuge. The existing researches always use the theoretical calculation of the approximate loads to analyze the strength of conveyor, and it cannot reflect the stress situations accurately. In order to ensure the precise mastery of the working performance, this article obtained pressure distribution under working conditions from CFX evaluation and gained equivalent stress and deformation under several load conditions by using the ANSYS Workbench platform to check the strength of conveyor. The results showed that the influence of centrifugal hydraulic pressure was less than that of centrifugal force on the strength and deformation of conveyor. Besides, the maximum equivalent stress occurred at the inside of the feed opening, while the maximum deformation occurred at the conveyor blade edge of taper extremity. Furthermore, whether considered the feed opening or not, the computing model had a great influence on the analysis results, and the simplified loads had a great influence on the deformation analysis results. The methods and results from this article can provide reference for the design and the improvement of screw conveyor.
GCFR Coupled Neutronic and Thermal-Fluid-Dynamics Analyses for a Core Containing Minor Actinides
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Diego Castelliti
2009-01-01
Full Text Available Problems about future energy availability, climate changes, and air quality seem to play an important role in energy production. While current reactor generations provide a guaranteed and economical energy production, new nuclear power plant generation would increase the ways and purposes in which nuclear energy can be used. To explore these new technological applications, several governments, industries, and research communities decided to contribute to the next reactor generation, called â€œGeneration IV.â€ Among the six Gen-IV reactor designs, the Gas Cooled Fast Reactor (GCFR uses a direct-cycle helium turbine for electricity generation and for a CO2-free thermochemical production of hydrogen. Additionally, the use of a fast spectrum allows actinides transmutation, minimizing the production of long-lived radioactive waste in an integrated fuel cycle. This paper presents an analysis of GCFR fuel cycle optimization and of a thermal-hydraulic of a GCFR-prototype under steady-state and transient conditions. The fuel cycle optimization was performed to assess the capability of the GCFR to transmute MAs, while the thermal-hydraulic analysis was performed to investigate the reactor and the safety systems behavior during a LOFA. Preliminary results show that limited quantities of MA are not affecting significantly the thermal-fluid-dynamics behavior of a GCFR core.
Markowich, Peter
2010-06-01
We study the system ct + u Â· âˆ‡c = âˆ‡c -nf(c) nt + u Â· âˆ‡n = âˆ‡n m - âˆ‡ Â· (nÃ—(c) âˆ‡c) ut + uÂ·âˆ‡u + âˆ‡P - Î·âˆ‡u + nâˆ‡Ï†/ = 0 âˆ‡Â·u = 0. arising in the modelling of the motion of swimming bacteria under the effect of diffusion, oxygen-taxis and transport through an incompressible fluid. The novelty with respect to previous papers in the literature lies in the presence of nonlinear porous-medium-like diffusion in the equation for the density n of the bacteria, motivated by a finite size effect. We prove that, under the constraint m Îµ (3/2, 2] for the adiabatic exponent, such system features global in time solutions in two space dimensions for large data. Moreover, in the case m = 2 we prove that solutions converge to constant states in the large-time limit. The proofs rely on standard energy methods and on a basic entropy estimate which cannot be achieved in the case m = 1. The case m = 2 is very special as we can provide a Lyapounov functional. We generalize our results to the three-dimensional case and obtain a smaller range of exponents m Îµ (m*, 2] with m* > 3/2, due to the use of classical Sobolev inequalities.
Coupled fluid/structure analyses of the MEGAPIE spallation source target during transients
Energy Technology Data Exchange (ETDEWEB)
Smith, B.L. [Thermal-Hydraulics Laboratory, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)]. E-mail: brian.smith@psi.ch; Leung, W. [Spallation Neutron Source Division, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Zucchini, A. [UTS Tecnologie Fisiche Avanzate, Sezione Metodologie e Diagnostiche, ENEA, Bologna (Italy)
2007-09-15
The paper describes some R and D activities undertaken in support of the design and safe operation of MEGAPIE (MEGAwatt PIlot Experiment) spallation source target, which is scheduled to be irradiated by a proton beam in the SINQ facility at the Paul Scherrer Institute in 2006. The target material is lead bismuth eutectic (LBE), which also acts as the primary coolant. As a consequence of the spallation reactions, about 600 kW of heat would be deposited in the target during operation, and considerable R and D effort is being expended to demonstrate continuing coolability and structural integrity under a variety of operational and abnormal conditions. The paper gives three examples of transient analyses carried out as part of the safety assessment of the target: (1) a beamline trip and recovery; (2) failure of the primary electro-magnetic pump (EMP); (3) failure of the secondary EMP (used to cool the base of the target). The study involves the simultaneous application of a system-analysis code, in our case a version of RELAP5, a computational fluid dynamics (CFD) tool (CFX-4), and a structural analysis code (ABAQUS). The RELAP5 code is used to provide transient boundary conditions for a localized conjugate heat transfer analysis of the lower target region, undertaken using CFD, and includes the feed-back effects arising from the secondary cooling and control systems. A conjugate heat transfer problem is then solved using CFD, which provides time-dependent thermal and flow data within the LBE, together with the thermal and mechanical loads to the target structures. Finally, an in-house interface program is employed to transfer mesh geometry, model topology and (time-dependent) thermal/mechanical data to enable stress analysis of the principal lower-target structural components to be performed. It is demonstrated that none of the transients considered result in critical stress conditions occurring in the target components, but that further operation is not recommended
Alfven wave coupled with flow-driven fluid instability in interpenetrating plasmas
Vranjes, J
2015-01-01
The Alfven wave is analyzed in case of one quasineutral plasma propagating with some constant speed $v_0$ through another static quasineutral plasma. A dispersion equation is derived describing the Alfven wave coupled with the flow driven mode $\\omega= k v_0$ and solutions are discussed analytically and numerically. The usual solutions for two oppositely propagating Alfv\\'en waves are substantially modified due to the flowing plasma. More profound is modification of the solution propagating in the negative direction with respect to the magnetic field and the plasma flow. For a large enough flow speed (exceeding the Alfven speed in the static plasma), this negative solution may become non-propagating, with frequency equal to zero. In this case it represents a spatial variation of the electromagnetic field. For greater flow speed it becomes a forward mode, and it may merge with the positive one. This merging of the two modes represents the starting point for a flow-driven instability, with two complex-conjugate...
Jing, Dalei; Bhushan, Bharat
2015-09-15
Fluid drag of micro/nano fluidic systems has inspired wide scientific interest. Surface charge and boundary slip at the solid-liquid interface are believed to affect fluid drag. This review summarizes the recent studies on the coupling of surface charge and slip, and their combined effect on fluid drag at micro/nano scale. The effect of pH on surface charge of borosilicate glass and silica surfaces in deionized (DI) water and saline solution is discussed using a method based on colloidal probe atomic force microscopy (AFM). The boundary slip of various oil-solid interfaces are discussed for samples with different degrees of oleophobicity prepared by nanoparticle-binder system. By changing the pH of solution or applying an electric field, effect of surface charge on slip of a smooth hydrophobic octadecyltrichlorosilane (OTS) in DI water and saline solution is studied. A theoretical model incorporating the coupling relationship between surface charge and slip is used to discuss the combined effect of surface charge-induced electric double layer (EDL) and slip on fluid drag of pressure-driven flow in a one-dimensional parallel-plates microchannel. A theoretical method is used to reduce the fluid drag. The studies show that the increasing magnitude of surface charge density leads to a decrease in slip length. The surface charge results in a larger fluid drag, and the coupling of surface charge and slip can further increase the fluid drag. Surface charge-induced EDLs with asymmetric zeta potentials can effectively reduce the fluid drag.
Coupled fluid/structure analyses of the MEGAPIE spallation source target during transients
Energy Technology Data Exchange (ETDEWEB)
Smith, Brian L. [Thermal-Hydraulics Laboratory, Nuclear Energy and Safety Dept., Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Waihung Leung [Spallation Neutron Source Division, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Alberto Zucchini [UTS Tecnologie Fisiche Avanzate, Sezione Metodologie e Diagnostiche, ENEA, Bologna (Italy)
2005-07-01
Full text of publication follows: In the ADS (Accelerator Driven System) concept, neutrons generated from spallation reactions are used to initiate and maintain a continuous chain reaction in a sub-critical nuclear core. In some ADS designs, the spallation neutrons are generated from the proton bombardment of liquid lead bismuth eutectic (LBE). In this arrangement, the LBE acts both as the target material and the means by which heat is removed from the spallation region. A pilot facility at the Paul Scherrer Institute in Switzerland, supported by an international partnership, aims to demonstrate the feasibility of the LBE target concept. Efforts are coordinated under the project title MEGAPIE, and groups from Belgium, France, Germany, Italy, Japan, South Korea, Switzerland and the USA are involved in the design, manufacture and safety assessment of the target. As a consequence of the spallation reactions, about 700 kW of heat is deposited in the target, and considerable effort is being expended to ensure continuing coolability and structural integrity under a variety of operational and abnormal conditions. It is not possible to fully verify the cooling principle by means of mock-up experiments, because of the difficulty in reproducing the volumetric heating at the appropriate power density (at maximum, 1 GW/m{sup 3} for a beam power of 1 MW). Consequently, heavy reliance is placed on detailed, numerical analyses. This requires the simultaneous application of a system-analysis capability, in our case RELAP5, a Computational Fluid Dynamics (CFD) tool, in our case CFX-4, and a structural analysis code (ABAQUS). The paper gives three examples of transient analyses carried out as part of the safety assessment of the target: (1) a beamline trip; (2) failure of the primary electro-magnetic pump (EMP); and (3) failure of the secondary EMP. Beamline trips are expected to occur frequently as a consequence of accelerator problems and/or beam instabilities during the
Energy Technology Data Exchange (ETDEWEB)
Soria, JosÃ©, E-mail: jose.soria@probien.gob.ar [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET â€“ UNCo), 1400 Buenos Aires St., 8300 NeuquÃ©n (Argentina); Gauthier, Daniel; Flamant, Gilles [Processes, Materials and Solar Energy Laboratory (PROMES-CNRS, UPR 8521), 7 Four Solaire Street, Odeillo, 66120 Font-Romeu (France); Rodriguez, Rosa [Chemical Engineering Institute, National University of San Juan, 1109 Libertador (O) Avenue, 5400 San Juan (Argentina); Mazza, GermÃ¡n [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET â€“ UNCo), 1400 Buenos Aires St., 8300 NeuquÃ©n (Argentina)
2015-09-15
Highlights: â€¢ A CFD two-scale model is formulated to simulate heavy metal vaporization from waste incineration in fluidized beds. â€¢ MSW particle is modelled with the macroscopic particle model. â€¢ Influence of bed dynamics on HM vaporization is included. â€¢ CFD predicted results agree well with experimental data reported in literature. â€¢ This approach may be helpful for fluidized bed reactor modelling purposes. - Abstract: Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073 K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator.
Energy Technology Data Exchange (ETDEWEB)
Hu, Xiexiaomen; Tutuncu, Azra; Eustes, Alfred; Augustine, Chad
2017-05-01
Enhanced Geothermal Systems (EGS) could potentially use technological advancements in coupled implementation of horizontal drilling and multistage hydraulic fracturing techniques in tight oil and shale gas reservoirs along with improvements in reservoir simulation techniques to design and create EGS reservoirs. In this study, a commercial hydraulic fracture simulation package, Mangrove by Schlumberger, was used in an EGS model with largely distributed pre-existing natural fractures to model fracture propagation during the creation of a complex fracture network. The main goal of this study is to investigate optimum treatment parameters in creating multiple large, planar fractures to hydraulically connect a horizontal injection well and a horizontal production well that are 10,000 ft. deep and spaced 500 ft. apart from each other. A matrix of simulations for this study was carried out to determine the influence of reservoir and treatment parameters on preventing (or aiding) the creation of large planar fractures. The reservoir parameters investigated during the matrix simulations include the in-situ stress state and properties of the natural fracture set such as the primary and secondary fracture orientation, average fracture length, and average fracture spacing. The treatment parameters investigated during the simulations were fluid viscosity, proppant concentration, pump rate, and pump volume. A final simulation with optimized design parameters was performed. The optimized design simulation indicated that high fluid viscosity, high proppant concentration, large pump volume and pump rate tend to minimize the complexity of the created fracture network. Additionally, a reservoir with 'friendly' formation characteristics such as large stress anisotropy, natural fractures set parallel to the maximum horizontal principal stress (SHmax), and large natural fracture spacing also promote the creation of large planar fractures while minimizing fracture complexity.
Tutolo, Benjamin M.; Luhmann, Andrew J.; Kong, Xiang-Zhao; Saar, Martin O.; Seyfried, William E.
2015-07-01
To investigate CO2 Capture, Utilization, and Storage (CCUS) in sandstones, we performed three 150 Â°C flow-through experiments on K-feldspar-rich cores from the Eau Claire formation. By characterizing fluid and solid samples from these experiments using a suite of analytical techniques, we explored the coupled evolution of fluid chemistry, mineral reaction rates, and hydrogeochemical properties during CO2 sequestration in feldspar-rich sandstone. Overall, our results confirm predictions that the heightened acidity resulting from supercritical CO2 injection into feldspar-rich sandstone will dissolve primary feldspars and precipitate secondary aluminum minerals. A core through which CO2-rich deionized water was recycled for 52 days decreased in bulk permeability, exhibited generally low porosity associated with high surface area in post-experiment core sub-samples, and produced an Al hydroxide secondary mineral, such as boehmite. However, two samples subjected to âˆ¼3 day single-pass experiments run with CO2-rich, 0.94 mol/kg NaCl brines decreased in bulk permeability, showed generally elevated porosity associated with elevated surface area in post-experiment core sub-samples, and produced a phase with kaolinite-like stoichiometry. CO2-induced metal mobilization during the experiments was relatively minor and likely related to Ca mineral dissolution. Based on the relatively rapid approach to equilibrium, the relatively slow near-equilibrium reaction rates, and the minor magnitudes of permeability changes in these experiments, we conclude that CCUS systems with projected lifetimes of several decades are geochemically feasible in the feldspar-rich sandstone end-member examined here. Additionally, the observation that K-feldspar dissolution rates calculated from our whole-rock experiments are in good agreement with literature parameterizations suggests that the latter can be utilized to model CCUS in K-feldspar-rich sandstone. Finally, by performing a number of reactive
Siebenaller, Luc; Vanderhaeghe, Olivier; Jessell, Mark; Boiron, Marie-Christine; Hibsch, Christian
2016-11-01
The presence of external fluids in metamorphic rocks has been shown to have a profound impact on rock rheology as high fluid pressure processes promote embrittlement and favor ductile deformation by recrystallization. Moreover, it has been proposed that brittle deformation guides fluid circulation and that intracrystalline deformation is responsible for fluid redistribution at the grain scale. Nevertheless, the amount of fluid present in the metamorphic ductile crust is debated and the nature of the interaction between fluids and recrystallization processes are not clearly identified. The aim of this study is to document the spatial distribution of fluid inclusions relative to microstructures in quartz grains and aggregates from veins sampled in amphibolite facies metamorphic rocks, exposed in the island of Naxos in the center of the Attic-Cycladic Metamorphic Complex in Greece. The veins, ranging from discordant structures with sharp contacts to totally transposed structures into the metamorphic foliation, display a large variety of microstructures and fluid evidences interpreted as recording exhumation processes through the ductile/brittle transition: (i) remnants of primary quartz grains contain abundant CO2-H2O fluid inclusions, decrepitated for the most part, distributed in clusters and in fluid inclusion trails, (ii) fluid inclusions with a similar composition are less abundant in recrystallized zones and in subgrains but are concentrated along grain boundaries indicating that grain boundary migration is responsible for redistribution of CO2-H2O fluids, (iii) subgrains of the last generation are almost devoid of fluid inclusions and are characterized by thick grain boundaries with abundant metamorphic fluids locally forming a continuous film. CO2-H2O fluid inclusions aligned in parallel, regularly spaced intragranular trails, locally rooted into grain boundaries, are interpreted as reflecting the spatial redistribution of these fluids in quartz slip planes
Directory of Open Access Journals (Sweden)
Kempka Thomas
2015-04-01
Full Text Available We assessed the synergetic benefits of simultaneous formation fluid extraction during CO2 injection for reservoir pressure management by coupled hydro-mechanical simulations at the prospective Vedsted storage site located in northern Denmark. Effectiveness of reservoir pressure management was investigated by simulation of CO2 storage without any fluid extraction as well as with 66% and 100% equivalent volume formation fluid extraction from four wells positioned for geothermal heat recovery. Simulation results demonstrate that a total pressure reduction of up to about 1.1 MPa can be achieved at the injection well. Furthermore, the areal pressure perturbation in the storage reservoir can be significantly decreased compared to the simulation scenario without any formation fluid extraction. Following a stress regime analysis, two stress regimes were considered in the coupled hydro-mechanical simulations indicating that the maximum ground surface uplift is about 0.24Â m in the absence of any reservoir pressure management. However, a ground uplift mitigation of up to 37.3% (from 0.24Â m to 0.15Â m can be achieved at the injection well by 100% equivalent volume formation fluid extraction. Well-based adaptation of fluid extraction rates can support achieving zero displacements at the proposed formation fluid extraction wells located close to urban infrastructure. Since shear and tensile failure do not occur under both stress regimes for all investigated scenarios, it is concluded that a safe operation of CO2 injection with simultaneous formation fluid extraction for geothermal heat recovery can be implemented at the Vedsted site.
Sun, Qiang; Wu, Guo Xiong
2013-03-01
A mathematical model and a numerical solution procedure are developed to simulate flow field through a 3D permeable vessel with multibranches embedded in a solid tumour. The model is based on Poisseuille's law for the description of the flow through the vessels, Darcy's law for the fluid field inside the tumour interstitium, and Starling's law for the flux transmitted across the vascular walls. The solution procedure is based on a coupled method, in which the finite difference method is used for the flow in the vessels and the boundary element method is used for the flow in the tumour. When vessels meet each other at a junction, the pressure continuity and mass conservation are imposed at the junction. Three typical representative structures within the tumour vasculature, symmetrical dichotomous branching, asymmetrical bifurcation with uneven radius of daughter vessels and trifurcation, are investigated in detail as case studies. These results have demonstrated the features of tumour flow environment by the pressure distributions and flow velocity field.
LÃ¸vholt, Finn; NorÃ¨n-Cosgriff, Karin; Madshus, Christian; Ellingsen, StÃ¥le Engvik
2017-05-01
Aircraft, supersonic flights, blasts, and explosions emit sound with substantial energy below 100 Hz. When the low frequency sound is transmitted inside a building, it generates vibration and rattling that may lead to annoyance. Our understanding of these low frequency phenomena is presently limited. In this paper, we attempt to improve our computational capabilities related to the low frequency sound transmission. For this purpose, a finite element methodology that incorporates a two-way coupled fluid-structure interaction, has been developed. Results from a broad experimental investigation of low frequency sound transmission are compared with the numerical finite element simulations. Plain walls, and walls with windows are studied. Close agreement between the simulations and the laboratory measurement data is obtained in the frequency range investigated (10-100 Hz). It was found that structural connections were of large importance for modeling the vibration and sound transmission. The windows control the low frequency transmission from 15 to 30 Hz, whereas the walls control the sound transmission from 30 to 100 Hz. Mitigation of vibrations and rattling induced by low frequency sound therefore needs to consider both wall and window construction.
Chaplin, Vernon H.; Bellan, Paul M.
2015-12-01
A time-dependent two-fluid model has been developed to understand axial variations in the plasma parameters in a very high density (peak neâ‰³ 5 Ã—1019 m-3 ) argon inductively coupled discharge in a long 1.1 cm radius tube. The model equations are written in 1D with radial losses to the tube walls accounted for by the inclusion of effective particle and energy sink terms. The ambipolar diffusion equation and electron energy equation are solved to find the electron density ne(z ,t ) and temperature Te(z ,t ) , and the populations of the neutral argon 4s metastable, 4s resonant, and 4p excited state manifolds are calculated to determine the stepwise ionization rate and calculate radiative energy losses. The model has been validated through comparisons with Langmuir probe ion saturation current measurements; close agreement between the simulated and measured axial plasma density profiles and the initial density rise rate at each location was obtained at pA r=30 -60 mTorr . We present detailed results from calculations at 60 mTorr, including the time-dependent electron temperature, excited state populations, and energy budget within and downstream of the radiofrequency antenna.
Zubkov, V. S.
2012-07-06
We present a mathematical model describing the spatial distribution of tear film osmolarity across the ocular surface of a human eye during one blink cycle, incorporating detailed fluid and solute dynamics. Based on the lubrication approximation, our model comprises three coupled equations tracking the depth of the aqueous layer of the tear film, the concentration of the polar lipid, and the concentration of physiological salts contained in the aqueous layer. Diffusive boundary layers in the salt concentration occur at the thinnest regions of the tear film, the black lines. Thus, despite large Peclet numbers, diffusion ameliorates osmolarity around the black lines, but nonetheless is insufficient to eliminate the build-up of solute in these regions. More generally, a heterogeneous distribution of solute concentration is predicted across the ocular surface, indicating that measurements of lower meniscus osmolarity are not globally representative, especially in the presence of dry eye. Vertical saccadic eyelid motion can reduce osmolarity at the lower black line, raising the prospect that select eyeball motions more generally can assist in alleviating tear film hyperosmolarity. Finally, our results indicate that measured evaporative rates will induce excessive hyperosmolarity at the black lines, even for the healthy eye. This suggests that further evaporative retardation at the black lines, for instance due to the cellular glycocalyx at the ocular surface or increasing concentrations of mucus, will be important for controlling hyperosmolarity as the black line thins. Â© 2012 Society for Mathematical Biology.
Directory of Open Access Journals (Sweden)
Jian Zhou
2016-09-01
Full Text Available Hydraulic fracturing is a useful tool for enhancing rock mass permeability for shale gas development, enhanced geothermal systems, and geological carbon sequestration by the high-pressure injection of a fracturing fluid into tight reservoir rocks. Although significant advances have been made in hydraulic fracturing theory, experiments, and numerical modeling, when it comes to the complexity of geological conditions knowledge is still limited. Mechanisms of fluid injection-induced fracture initiation and propagation should be better understood to take full advantage of hydraulic fracturing. This paper presents the development and application of discrete particle modeling based on two-dimensional particle flow code (PFC2D. Firstly, it is shown that the modeled value of the breakdown pressure for the hydraulic fracturing process is approximately equal to analytically calculated values under varied in situ stress conditions. Furthermore, a series of simulations for hydraulic fracturing in competent rock was performed to examine the influence of the in situ stress ratio, fluid injection rate, and fluid viscosity on the borehole pressure history, the geometry of hydraulic fractures, and the pore-pressure field, respectively. It was found that the hydraulic fractures in an isotropic medium always propagate parallel to the orientation of the maximum principal stress. When a high fluid injection rate is used, higher breakdown pressure is needed for fracture propagation and complex geometries of fractures can develop. When a low viscosity fluid is used, fluid can more easily penetrate from the borehole into the surrounding rock, which causes a reduction of the effective stress and leads to a lower breakdown pressure. Moreover, the geometry of the fractures is not particularly sensitive to the fluid viscosity in the approximate isotropic model.
Institute of Scientific and Technical Information of China (English)
J. V. R. REDDY; D. SRIKANTH; S. K. MURTHY
2014-01-01
This paper explores the mathematical model for couple stress fluid flow through an annular region. The above model is used for studying the blood flow be-tween the clogged (stenotic) artery and the catheter. The asymmetric nature of the stenosis is considered. The closed form expressions for the physiological parameters such as impedance and shear stress at the wall are obtained. The effects of various geomet-ric parameters and the parameters arising out of the fluid considered are discussed by considering the slip velocity and tapering angle. The study of the above model is very significant as it has direct applications in the treatment of cardiovascular diseases.
Lu, C.; Deng, S.; Podgorney, R. K.; Huang, H.
2011-12-01
Reliable reservoir performance predictions of enhanced geothermal reservoir systems require accurate and robust modeling for the coupled thermal-hydrological-mechanical processes. Conventionally, in order to reduce computational cost, these types of problems are solved using operator splitting method, usually by sequentially coupling a subsurface flow and heat transport simulator with a solid mechanics simulator via input files. However, such operator splitting approaches are applicable only to loosely coupled problems and usually converge slowly. As in most enhanced geothermal systems (EGS), fluid flow, heat transport, and rock deformation are typically strongly nonlinearly coupled, an alternative is to solve the system of nonlinear partial differential equations that govern the system simultaneously using a fully coupled solution procedure for fluid flow, heat transport, and solid mechanics. This procedure solves for all solution variables (fluid pressure, temperature and rock displacement fields) simultaneously, which leads to one large nonlinear algebraic system that needs to be solved by a strongly convergent nonlinear solver. Development over the past 10 years in the area of physics-based conditioning, strongly convergent nonlinear solvers (such as Jacobian Free Newton methods) and efficient linear solvers (such as GMRES, AMG), makes such an approach competitive. In this presentation, we will introduce a continuum-scaled parallel physics-based, fully coupled, modeling tool for predicting the dynamics of fracture initiation and propagation, fluid flow, rock deformation, and heat transport in a single integrated code named FALCON (Fracturing And Liquid-steam CONvection). FALCON is built upon a parallel computing framework developed at Idaho National Laboratory (INL) for solving coupled systems of nonlinear equations with finite element method with unstructured and adaptively refined/coarsened grids. Currently, FALCON contains poro- and thermal- elastic models
Ortega, Jesus D.; Christian, Joshua M.; Yellowhair, Julius E.; Ho, Clifford K.
2015-09-01
Traditional tubular receivers used in concentrating solar power are formed using tubes connected to manifolds to form panels; which in turn are arranged in cylindrical or rectangular shapes. Previous and current tubular receivers, such as the ones used in Solar One, Solar Two, and most recently the Ivanpah solar plants, have used a black paint coating to increase the solar absorptance of the receiver. However, these coatings degrade over time and must be reapplied, increasing the receiver maintenance cost. This paper presents the thermal efficiency evaluation of novel receiver tubular panels that have a higher effective solar absorptance due to a light-trapping effect created by arranging the tubes in each panel into unique geometric configurations. Similarly, the impact of the incidence angle on the effective solar absorptance and thermal efficiency is evaluated. The overarching goal of this work is to achieve effective solar absorptances of ~90% and thermal efficiencies above 85% without using an absorptance coating. Several panel geometries were initially proposed and were down-selected based on structural analyses considering the thermal and pressure loading requirements of molten salt and supercritical carbon-dioxide receivers. The effective solar absorptance of the chosen tube geometries and panel configurations were evaluated using the ray-tracing modeling capabilities of SolTrace. The thermal efficiency was then evaluated by coupling computational fluid dynamics with the ray-tracing results using ANSYS Fluent. Compared to the base case analysis (flat tubular panel), the novel tubular panels have shown an increase in effective solar absorptance and thermal efficiency by several percentage points.
Energy Technology Data Exchange (ETDEWEB)
Peniguel, C. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches; Rupp, I. [Simulog, 78 (France)
1997-12-31
Thermal aspects take place in several industrial applications in which Electricite de France (EdF) is concerned. In most cases, several physical phenomena like conduction, radiation and convection are involved in thermal transfers. The aim of this paper is to present a numerical tool adapted to industrial configurations and which uses the coupling between fluid convection (resolved with ESTET in finite-volumes or with N3S in finite-elements) and radiant heat transfers between walls (resolved with SYRTHES using a radiosity method). SYRTHES manages the different thermal exchanges that can occur between fluid and solid domains thanks to an explicit iterative method. An extension of SYRTHES has been developed which allows to take into account simultaneously several fluid codes using `message passing` computer tools like Parallel Virtual Machine (PVM) and the code coupling software CALCIUM developed by the Direction of Studies and Researches (DER) of EdF. Various examples illustrate the interest of such a numerical tool. (J.S.) 12 refs.
Mithraratne, K; Ho, H; Hunter, P J; Fernandez, J W
2012-10-01
A coupled computational model of the foot consisting of a three-dimensional soft tissue continuum and a one-dimensional (1D) transient blood flow network is presented in this article. The primary aim of the model is to investigate the blood flow in major arteries of the pathologic foot where the soft tissue stiffening occurs. It has been reported in the literature that there could be up to about five-fold increase in the mechanical stiffness of the plantar soft tissues in pathologic (e.g. diabetic) feet compared with healthy ones. The increased stiffness results in higher tissue hydrostatic pressure within the plantar area of the foot when loaded. The hydrostatic pressure acts on the external surface of blood vessels and tend to reduce the flow cross-section area and hence the blood supply. The soft tissue continuum model of the foot was modelled as a tricubic Hermite finite element mesh representing all the muscles, skin and fat of the foot and treated as incompressible with transversely isotropic properties. The details of the mechanical model of soft tissue are presented in the companion paper, Part 1. The deformed state of the soft tissue continuum because of the applied ground reaction force at three foot positions (heel-strike, midstance and toe-off) was obtained by solving the Cauchy equations based on the theory of finite elasticity using the Galerkin finite element method. The geometry of the main arterial network in the foot was represented using a 1D Hermite cubic finite element mesh. The flow model consists of 1D Navier-Stokes equations and a nonlinear constitutive equation to describe vessel radius-transmural pressure relation. The latter was defined as the difference between the fluid and soft tissue hydrostatic pressure. Transient flow governing equations were numerically solved using the two-step Lax-Wendroff finite difference method. The geometry of both the soft tissue continuum and arterial network is anatomically-based and was developed using
Institute of Scientific and Technical Information of China (English)
çŽ‹è¿›å»·; å¼ æ¥šæ±‰; é‡‘å³°
2004-01-01
Wave reflection and refraction in layered media is a topic closely related to seismology, acoustics, geophysics and earthquake engineering. Analytical solutions for wave reflection and refraction coefficients in multi-layered media subjected to P wave incidence from the elastic half-space are derived in terms of displacement potentials. The system is composed of ideal fluid, porous medium, and underlying elastic solid. By numerical examples, the effects of porous medium and the incident wave angle on the dynamic pressures of ideal fluid are analyzed. The results show that the existence of the porous medium, especially in the partially saturated case, may significantly affect the dynamic pressures of the overlying fluid.
Energy Technology Data Exchange (ETDEWEB)
Muller, J. [IRSID, Institut de Recherches Siderurgie, 57 - Maizieres-les-Metz (France)
1996-12-31
Radiant heat transfer is the main solution retained in many iron and steel metallurgy installations (re-heating and annealing furnaces etc..). Today, it has become important to dispose of performing radiant heat transfer models in heat transfer and fluid mechanics simulation softwares, and well adapted to multidimensional industrial problems. This work presents the discrete ordinate radiant heat transfer model developed at the IRSID (the French institute of research in iron and steel metallurgy) and coupled with the PHOENICS heat transfer-fluid mechanics software. Three modeling approaches are presented concerning the radiative properties of gases (H{sub 2}O-CO{sub 2}). A ``weighted grey gases sum`` model gives satisfactory results for several 1-D validation cases. (J.S.) 20 refs.
Atwood, Christopher A.
1993-01-01
The June 1992 to May 1993 grant NCC-2-677 provided for the continued demonstration of Computational Fluid Dynamics (CFD) as applied to the Stratospheric Observatory for Infrared Astronomy (SOFIA). While earlier grant years allowed validation of CFD through comparison against experiments, this year a new design proposal was evaluated. The new configuration would place the cavity aft of the wing, as opposed to the earlier baseline which was located immediately aft of the cockpit. This aft cavity placement allows for simplified structural and aircraft modification requirements, thus lowering the program cost of this national astronomy resource. Three appendices concerning this subject are presented.
Coupling Analysis of Fluid-Structure Interaction and Flow Erosion of Gas-Solid Flow in Elbow Pipe
Hongjun Zhu; Hongnan Zhao; Qian Pan; Xue Li
2014-01-01
A numerical simulation has been conducted to investigate flow erosion and pipe deformation of elbow in gas-solid two-phase flow. The motion of the continuous fluid phase is captured based on calculating three-dimensional Reynolds-averaged-Navier-Stokes (RANS) equations, while the kinematics and trajectory of the discrete particles are evaluated by discrete phase model (DPM), and a fluid-structure interaction (FSI) computational model is adopted to calculate the pipe deformation. The effects o...
Dutrow, B. L.; Henry, D.; Gable, C. W.; Heydari, E.; Travis, B. J.
2016-12-01
Hydrothermal, metamorphic and metasomatic rocks develop through a complex set of coupled thermal, chemical and mechanical processes that contain non-linear feedbacks. The integrated outcome results in a mineral assemblage with a specific texture that records the rates, magnitude and duration of the controlling processes. However, it is often difficult to extract this coupled information from the rock record due to the competing and time-integrated nature of the final product. A particularly problematic case arises when advective metasomatism accompanies thermal energy transport. Advective transport of reactive components by thermally driven flowing fluids can dramatically alter the original bulk rock chemistry. In some instances, these chemical transformations are slow but in others, these alterations can occur over short time scales (yrs). To facilitate investigations of coupled, complex systems and to constrain the rates, duration and relative importance of governing processes during a thermal event, high-resolution 3-D time dependent computational modeling is used. An example of the integrated effects of thermal and chemical transport is found in subsurface Louisiana. Here, an 11m alkali igneous dike intruded Late Jurassic sandy limestones transforming these into new mineral assemblages rich in alkali, alkaline earth elements and F; hydrogrossular, diopside, pectolite (pct), apophyllite, fluorite, and feldspars. Increased temperatures (Ts) and significant mass transport of components from the dike into the host rocks are required. A series of coupled heat and mass transport calculations constrain the rates and duration of the thermal pulse and provide insights into the time-scale of mass transport within this system. For example, calculations incorporating silica transport indicate that at the pct zone (1.5m), thermal conditions remained above 150oC for 2.8 yrs assuming anisotropic permeability (K) and 4.2 yrs (layered K) reaching Tmax at 0.36 (aniso) or 0.53 yr
Hurdelbrink, Keith R.; Anderson, Jacob P.; Siddique, Zahed; Altan, M. Cengiz
2016-03-01
Bismaleimide (BMI) resin with quartz (AQ581) fiber reinforcement is a composite material frequently used in aerospace applications, such as engine cowlings and radomes. Various composite components used in aircrafts are exposed to different types of hydraulic fluids, which may lead to anomalous absorption behavior over the service life of the composite. Accurate predictive models for absorption of liquid penetrants are particularly important as the composite components are often exposed to long-term degradation due to absorbed moisture, hydraulic fluids, or similar liquid penetrants. Microstructural features such as fiber volume fraction and void fraction can have a significant effect on the absorption behavior of fiber-reinforced composites. In this paper, hydraulic fluid absorption characteristics of quartz/BMI laminates fabricated from prepregs preconditioned at different relative humidity and subsequently cured at different pressures are presented. The composite samples are immersed into hydraulic fluid at room temperature, and were not subjected to any prior degradation. To generate process-induced microvoids, prepregs were conditioned in an environmental chamber at 2% or 99% relative humidity at room temperature for a period of 24 hours prior to laminate fabrication. To alter the fiber volume fraction, the laminates were fabricated at cure pressures of 68.9 kPa (10 psi) or 482.6 kPa (70 psi) via a hot-press. The laminates are shown to have different levels of microvoids and fiber volume fractions, which were observed to affect the absorption dynamics considerably and exhibited clear non-Fickian behavior. A one-dimensional hindered diffusion model (HDM) was shown to be successful in predicting the hydraulic fluid absorption. Model prediction indicates that as the fabrication pressure increased from 68.9 kPa to 482.6 kPa, the maximum fluid content (Mâˆž) decreased from 8.0% wt. to 1.0% wt. The degree of non-Fickian behavior, measured by hindrance coefficient (Î
DEFF Research Database (Denmark)
Tang, Tian; Roenby, Johan; Hededal, Ole
by formulating the strong interactions between soil skeleton and the pore fluid via a coupled set of partial differential equations. A single bounding surface soil model capable of simulating the accumulations of pore pressures, strains, dilatancy, and strain â€žsofteningâ€Ÿ, is then adopted for quantifying...... the cyclic soil constitutive relations. To deal with the high non-linearity in the equations, the finite volume (FV) method is proposed for the numerical simulation. The corresponding discretization strategies and solution algorithms, including the conventional segregated method and the more recent block...
CSIR Research Space (South Africa)
Suliman, Ridhwaan
2012-07-01
Full Text Available stress measure which relates forces in the deformed configuration with areas in the undeformed configuration), body force, density and acceleration, respectively and Xj are the coordinates of a point on the solid body in the undeformed configuration... and Navier-Stokes equations: ?vi ?xi = 0 (11) ? ?vi ?t + ?(vj ? v ? j ) ?vi?xj + ?p ?xi ? ??ij ?xj ? ?fi = 0 (12) where ?, vi, p, ?ij and fi are the fluid density, fluid velocity, pressure, stress and body forces respectively, xi are the fixed...
Meijer, P. M.; Passchier, J. D. P.; W. J. Goedheer,; Bezemer, J.; van Sark, Wgjhm
1994-01-01
The results of a two-dimensional fluid model for argon rf discharges in a closed cylindrical vacuum chamber are compared with experimental data from an amorphous silicon deposition reactor. Good agreement is obtained for the relation between the dc autobias voltage and the dissipated power in the fr
W. J. Goedheer,; Meijer, P. M.; Bezemer, J.; Passchier, J. D. P.; van Sark, Wgjhm
1995-01-01
The results of a 2-D fluid model for argon radiofrequency (RF) discharges in a closed cylindrical vacuum chamber are compared with experimental data from an amorphous silicon deposition reactor operated in argon. Good agreement is obtained for the relation between the DC autobias voltage and the dis
Glor, FP; Westenberg, JJM; Vierendeels, J; Danilouchkine, M; Verdonck, P
2002-01-01
Magnetic resonance imaging (MRI) can be used in vivo in combination with computational fluid dynamics (CFD) to derive velocity profiles in space and time and accordingly, pressure drop and wall shear stress distribution in natural or artificial vessel segments. These hemodynamic data are difficult o
Institute of Scientific and Technical Information of China (English)
çŽ‹æ™“äº®; å•é›ªé›„; é™ˆä¸½
2011-01-01
The stratosphere airships need a larger volume for the purpose of obtaining the buoyancy. Because of the inflated large membrane structure, the fluid-structure coupled characteristics are very important. Based on the Computational Fluid Dynamica ( CFD) software FLUENT and Computation Struccure Dynamics ( CSD) software ABAQUS, a fluid-structure coupled computational meihod is proposed. To verify the validity of this method, the comparison between experimental and computational results of inflated sphere and NACA65A006 wing are done. It will be seen that from the comparison of results that this method is valid for the analysis of aero-elastic characteristics of aerostats. Thus, an efficient analysis tool is proposed for the study of fluid-structure coupled characteristics of stratosphere airship. The structure response of a certain stratosphere airship is analyzed under the condition of gust, and some conclusions are obtained.%å¹³æµå±‚é£žè‰‡ä¸ºäº†åœ¨å¹³æµå±‚çŽ¯å¢ƒä¸‹èŽ·å¾—è¶³å¤Ÿçš„æµ®åŠ›,è¦æ±‚å…¶ä½“ç§¯åºžå¤§,ç”±äºŽè·¨åº¦è¾ƒå¤§çš„å……æ°”æŸ”æ€§æ°”å›Šç»“æž„å®¹æ˜“å‘ç”Ÿå˜å½¢,ä½¿å¾—æµå›ºè€¦åˆç‰¹æ€§éžå¸¸æ˜¾è‘—.é’ˆå¯¹è¯¥ç±»é£žè¡Œå™¨çš„æµå›ºè€¦åˆæ–¹æ³•çš„ç ”ç©¶æ˜¯å¯¹å…¶æµå›ºè€¦åˆç‰¹æ€§åˆ†æžçš„é¦–è¦æ¡ä»¶.æœ¬æ–‡åŸºäºŽæµä½“åŠ¨åŠ›å¦è®¡ç®—è½¯ä»¶FLUENTå’Œç»“æž„åŠ¨åŠ›å¦åˆ†æžè½¯ä»¶ABAQUS,å½¢æˆäº†åˆ†æžå¹³æµå±‚é£žè‰‡è¿™ç±»å¤§åž‹æŸ”æ€§å……æ°”ç»“æž„æµå›ºè€¦åˆç‰¹æ€§çš„éžçº¿æ€§åŠ¨æ€æµä½“-ç»“æž„äº¤é”™ç§¯åˆ†è€¦åˆæ³•.é€šè¿‡å……æ°”çš„åœ†çƒè–„è†œçš„è§£æžè§£å’ŒNACA65A006æœºç¿¼é¢¤æŒ¯ç‰¹æ€§çš„å®žéªŒç»“æžœä¸Žè®¡ç®—ç»“æžœçš„æ¯”è¾ƒå¯¹è¯¥æ–¹æ³•çš„æœ‰æ•ˆæ€§è¿›è¡Œäº†åˆ†æž.è¿™ä¸ºå¹³æµå±‚é£žè‰‡æµå›ºè€¦åˆé—®é¢˜çš„ç ”ç©¶æä¾›äº†ä¸€ç§æœ‰æ•ˆçš„åˆ†æžå·¥å…·,å¹¶å¯¹æŸå¹³æµå±‚é£žè‰‡çš„çªé£Žå¹²æ‰°å“åº”ç‰¹æ€§è¿›è¡Œäº†åˆ†æž,å¾—å‡ºå…¶æµå›ºè€¦åˆç‰¹æ€§çš„å˜åŒ–è§„å¾‹.
Li, Minghua; Hikihara, Takashi
2008-01-01
The redox (Reduction-Oxidation) flow battery is one of the most promising rechargeable batteries due to its ability to average loads and output of power sources. The transient characteristics are well known as the remarkable feature of the battery. Then it can also compensate for a sudden voltage drop. The dynamics are governed by the chemical reactions, fluid flow, and electrical circuit of its structure. This causes the difficulty of the analysis at transient state. This paper discusses the...
Institute of Scientific and Technical Information of China (English)
çŽ‹å€©; å‘¨è‹±æ“; çŽ‹åˆš; è’‹å®ä¼Ÿ; åˆ˜çŽ‰çŸ³
2012-01-01
A fluid-solid-chemistry coupling model is built considering fluid flow and ion transmission induced by shale-drilling fluid system electrochemical potential osmosis, nonlinearity of flow and solute diffusion in shale-drilling fluid system, and solid deformation resulted from fluid flow and ion transmission. The model is used to compute the time-varying pore pressure, stress and damage index in formations around the wellbore of a well. The result shows that the pore pressure and stress are lower without consideration of the diffusion potential induced by ion selective character of shale membrane. The linear model overestimates the pore pressure and stress fields around the sidewall. The damage index reveals that collapse first occurs in formations near the wellbore, the caving pressure increases and changes obviously with time, the fracture pressure reduces but doesn't change significantly with time, and the drilling fluid density window narrows down with time.%è€ƒè™‘æ³¥é¡µå²©-é’»äº•æ¶²ä½“ç³»ç”µåŒ–åŠ¿æ¸—é€äº§ç”Ÿçš„æµä½“æµåŠ¨å’Œç¦»åè¿ç§»ã€æ³¥é¡µå²©-é’»äº•æ¶²ä½“ç³»ä¸æµä½“æµåŠ¨å’Œæº¶è´¨æ‰©æ•£è¿‡ç¨‹çš„éžçº¿æ€§ã€æµä½“æµåŠ¨å’Œç¦»åè¿ç§»å¯¹å›ºä½“å˜å½¢çš„å½±å“,å»ºç«‹æ³¥é¡µå²©äº•å£ç¨³å®šæµ-å›º-åŒ–è€¦åˆæ¨¡åž‹.åº”ç”¨å»ºç«‹çš„æ¨¡åž‹è®¡ç®—å®žä¾‹äº•äº•çœ¼å‘¨å›´åœ°å±‚éšæ—¶é—´å˜åŒ–çš„å”éš™åŽ‹åŠ›ã€åº”åŠ›ä»¥åŠç ´åæŒ‡æ•°.ç»“æžœè¡¨æ˜Ž,è‹¥ä¸è€ƒè™‘æ³¥é¡µå²©è†œç¦»åé€‰æ‹©æ€§å½¢æˆçš„æ‰©æ•£ç”µåŠ¿,è®¡ç®—çš„å”éš™åŽ‹åŠ›å’Œåº”åŠ›åå°,è€Œçº¿æ€§æ¨¡åž‹è¿‡é«˜åœ°é¢„æµ‹äº†äº•å£å‘¨å›´çš„å”éš™åŽ‹åŠ›åœºå’Œåº”åŠ›åœº.æ ¹æ®ç ´åæŒ‡æ•°å¯ä»¥çœ‹å‡º,åå¡Œç ´åé¦–å…ˆå‘ç”Ÿåœ¨äº•å£é™„è¿‘åœ°å±‚,åå¡ŒåŽ‹åŠ›éšæ—¶é—´å»¶é•¿å¢žå¤§ä¸”å˜åŒ–è¾ƒæ˜Žæ˜¾,ç ´è£‚åŽ‹åŠ›éšæ—¶é—´å»¶é•¿å‡å°ä½†å˜åŒ–ä¸æ˜¾è‘—,é’»äº•æ¶²å¯†åº¦çª—å£éšæ—¶é—´å˜çª„.
Well-Posed Stokes/Brinkman and Stokes/Darcy Problems for Coupled Fluid-Porous Viscous Flows
Angot, Philippe
2010-09-01
We present a well-posed model for the Stokes/Brinkman problem with a family of jump embedded boundary conditions (J.E.B.C.) on an immersed interface with weak regularity assumptions. It is issued from a general framework recently proposed for fictitious domain problems. Our model is based on algebraic transmission conditions combining the stress and velocity jumps on the interface Î£ separating the fluid and porous domains. These conditions, well chosen to get the coercivity of the operator, are sufficiently general to get the usual immersed boundary conditions on Î£ when fictitious domain methods are concerned: Stefan-like, Robin (Fourier), Neumann or Dirichletâ€¦ Moreover, the general framework allows to prove the global solvability of some models with physically relevant stress or velocity jump boundary conditions for the momentum transport at a fluid-porous interface. The Stokes/Brinkman problem with Ochoa-Tapia & Whitaker (1995) interface conditions and the Stokes/Darcy problem with Beavers & Joseph (1967) conditions are both proved to be well-posed by an asymptotic analysis. Up to our knowledge, only the Stokes/Darcy problem with Saffman (1971) approximate interface conditions was known to be well-posed.
Qu, Shuping; Du, Zhenxia; Zhang, Yun
2015-03-01
Determination of free fatty acids (FFAs) in food products is of enormous interest mainly because they are related to the quality and authenticity of the oils. In this study, supercritical fluid chromatography (SFC), followed by an electrospray ionisation triple-quadrupole mass spectrometry (ESI-MS), is shown to provide a novel method for the separation and detection of FFAs in edible oils without any pretreatment. Eight FFAs were separated on a HSS C18 SB column with gradient elution within 3 min. Effects of different columns, modifiers and column temperature changes were evaluated. The results indicated the feasibility of this method for the high-throughput determination of individual FFAs with satisfactory correlation coefficients (R(2)>0.994) and good reproducibility of RSDoil were successfully distinguished into several categories, showing a potential application for the determination of oil quality or authenticity.
Directory of Open Access Journals (Sweden)
S. Saha
2016-04-01
Full Text Available Combustion instability in solid propellant rocket motor is numerically simulated by implementing propellant response function with quasi steady homogeneous one dimensional formulation. The convolution integral of propellant response with pressure history is implemented through a user defined function in commercial computational fluid dynamics software. The methodology is validated against literature reported motor test and other simulation results. Computed amplitude of pressure fluctuations compare closely with the literarture data. The growth rate of pressure oscillations of a cylindrical grain solid rocket motor is determined for different response functions at the fundamental longitudinal frequency. It is observed that for response function more than a critical value, the motor exhibits exponential growth rate of pressure oscillations.
Tong, Z.; Zhang, Y.; Zhang, Z.; Hua, H.
2007-01-01
A direct-BEM/Fem method was proposed to analyze the vibration and acoustic radiation characteristics of a submerged structure. Model parameters of the structure and the fluid-structure interaction due to surrounding water were analyzed by using FEM and direct BEM. Vibration velocity of the outer hull surface and underwater sound pressure were computed through modal superposition technique. The direct-BEM/FEM method was first validated by analyzing a submerged cylindrical shell, then was used to analyze the vibro-acoustic behavior of a submarine stern structure. The results have demonstrated the direct-BEM/FEM method is more effective than FEM in computing the underwater sound radiation of the stern structure.
Centrella, Stephen; Austrheim, HÃ¥kon; Putnis, Andrew
2015-11-01
The Precambrian granulite facies rocks of LindÃ¥s Nappe, Bergen Arcs, Caledonides of W. Norway are partially hydrated at amphibolite and eclogite facies conditions. The LindÃ¥s Nappe outcrops over an area of ca. 1000 km2 where relict granulite facies lenses make up only ca. 10%. At Hillandsvatnet, garnetite displays sharp hydration fronts across which the granulite facies assemblage composed of garnet (55%) and clinopyroxene (45%) is replaced by an amphibolite facies mineralogy defined by chlorite, epidote and amphibole. The major element bulk composition does not change significantly across the hydration front, apart from the volatile components (loss on ignition, LOI) that increases from 0.17 wt.% in the granulite to 2.43 wt.% in the amphibolite. However the replacements of garnet and of clinopyroxene are pseudomorphic so that the grain shapes of the garnet and clinopyroxene are preserved even when they are completely replaced. The textural evolution during the replacement of garnet by pargasite, epidote and chlorite and of pyroxene by hornblende and quartz in our rock sample conforms to that expected by a coupled dissolution-precipitation mechanism. SEM and electron microprobe analysis coupled with the software XMapTools V 1.06.1 were used to quantify the local mass transfer required during the replacement processes. The element losses and gains in replacing the garnet are approximately balanced by the opposite gains and losses associated with the replacement of clinopyroxene. The coupling between dissolution and precipitation on both the grain and whole rock spatial scale preserves the volume of the rock throughout the hydration process. However, the hydration involves reduction of rock density and mass balance calculations, together with volume preservation (isovolumetric reaction) require a significant loss of the mass of the rock to the fluid phase. This suggests a mechanism for coupling between the local stress generated by hydration reactions and mass
Institute of Scientific and Technical Information of China (English)
CHEN Lu-wang; QIN Yuan; GUI He-rong; ZHANG Shi-lei
2012-01-01
To study the behavior of overlying strata and the likelihood of water inrush and quicksand with different mining sequences under an unconsolidated alluvium aquifer,a numerical model based on the fluid-solid coupling theory was constructed by FLAC3D.Simulation results revealed that the mining sequences had a significant influence on the seepage,displacement and failure characteristics of the overlying strata.In this kind of geological and hydrogeological conditions,the workface close to the outcrop of coal seam easily suffers from water inrush and quicksand during mining.In the simulation resuits,the plastic zone,vertical displacement and pore water pressure in the overlying strata of the workface decrease more or less using the upward mining sequence than using the downward mining sequence.Therefore,the application of the upward mining sequence in the process of mining is preferential to prevent water inrush and quicksand.
DEFF Research Database (Denmark)
Tang, Tian; Roenby, Johan; Hededal, Ole
by formulating the strong interactions between soil skeleton and the pore fluid via a coupled set of partial differential equations. A single bounding surface soil model capable of simulating the accumulations of pore pressures, strains, dilatancy, and strain â€žsofteningâ€Ÿ, is then adopted for quantifying...... the cyclic soil constitutive relations. To deal with the high non-linearity in the equations, the finite volume (FV) method is proposed for the numerical simulation. The corresponding discretization strategies and solution algorithms, including the conventional segregated method and the more recent block...... matrix solver, are discussed as well. Overall, investigations in this paper provide a methodology for developing a numerical code simulating liquefaction and cyclic mobility. In future work this will be implemented in practice with the aid of the open source CFD toolbox, OpenFOAM....
Dharodi, Vikram; Patel, Bhavesh; Kaw, Predhiman
2015-01-01
The strongly coupled dusty plasma has often been modelled by the Generalized Hydrodynamic (GHD) model used for representing visco-elastic fluid systems. The incompressible limit of the model which supports transverse shear wave mode is studied in detail. In particular dipole structures are observed to emit transverse shear waves in both the limits of sub and super - luminar propagation, where the structures move slower and faster than the phase velocity of the shear waves, respectively. In the sub - luminar limit the dipole gets engulfed within the shear waves emitted by itself, which then backreacts on it and ultimately the identity of the structure is lost. However, in the super - luminar limit the emission appears like a wake from the tail region of the dipole. The dipole, however, keeps propagating forward with little damping but minimal distortion in its form. A Poynting like conservation law with radiative, convective and dissipative terms being responsible for the evolution of W , which is similar to `...
Institute of Scientific and Technical Information of China (English)
YUAN Yirang
2005-01-01
For coupled system of multilayer dynamics of fluids in porous media,the characteristic alternating-direction finite element methods for nonrectangular regions applicable to parallel arithmetic are put forward and two-dimensional and three-dimensional schemes are used to form a complete set. Some techniques,such as calculus of variations,isoparametric transformation,patch approximation,operator-splitting,characteristic method,negative norm estimate,energy method,the theory of prior estimates and techniques are used.For the nonrectangular regions case,optimal order estimates in L2norm are derived for the error in the approximation solution.Thus the well-known theoretical problem has been thoroughly and completely solved.These methods have been successfully used in multilayer oil resources migration-accumulation numerical simulation.
Energy Technology Data Exchange (ETDEWEB)
Neubauer, M. [Muons, Inc.; Dudas, A. [Muons, Inc.; Rimmer, Robert A. [JLAB; Guo, Jiquan [JLAB; Williams, R. Scott [JLAB
2013-12-01
A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.
Ema, S. A.; Hossen, M. R.; Mamun, A. A.
2016-04-01
The nonlinear propagation of ion-acoustic (IA) waves in a strongly coupled plasma system containing Maxwellian electrons and nonthermal ions has been theoretically and numerically investigated. The well-known reductive perturbation technique is used to derive both the Burgers and Korteweg-de Vries (KdV) equations. Their shock and solitary wave solutions have also been numerically analyzed in understanding localized electrostatic disturbances. It has been observed that the basic features (viz. polarity, amplitude, width, etc.) of IA waves are significantly modified by the effect of polarization force and other plasma parameters (e.g., the electron-to-ion number density ratio and ion-to-electron temperature ratio). This is a unique finding among all theoretical investigations made before, whose probable implications are discussed in this investigation. The implications of the results obtained from this investigation may be useful in understanding the wave propagation in both space and laboratory plasmas.
Garven, G.; Dumoulin, J. A.; Bradley, D. A.; Young, L. E.; Kelley, K. D.; Leach, D. L.
2002-12-01
Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in submarine basins where other mechanisms for driving pore fluid flow such as topography, compaction and crustal deformation are too weak or too slow to have a significant effect on disturbing conductive heat flow. Fault zones appear to play a crucial role in focusing fluid migration in basins, as inferred in ancient rocks by many examples of hydrothermal deposits of sediment-hosted ores worldwide. Many rift-hosted deposits of lead, zinc, and barite ore appear to have formed at or near the seafloor by focused venting of hot basinal fluids and modified seawater, although the geophysical nature of these systems is not so well known. For example, the upper Kuna Formation, a finely laminated, black, organic-rich siliceous mudstone and shale in the Western Brooks Range of northwest Alaska, is host to the largest resources of zinc yet discovered in the Earth's crust, containing ore reserves in excess of 175 Mt averaging about 16% Zn and 5% Pb. Although situated today in a highly-deformed series of structural allocthonous plates thrusted during the Jurassic to Cretaceous Brookian Orogeny, the stratiform ores are thought to have formed much earlier in the anoxic, mud-rich Carboniferous-age Kuna Basin when adjacent carbonate platforms were drowned by rifting and tectonic subsidence. Fluid inclusion studies of ore-stage sphalerite and gangue minerals indicate sub-seafloor mineralization temperatures less than 200oC and most likely between 120 to 150 oC, during a period of sediment diagenesis and extensional faulting. We have constructed fully-coupled numerical models of heat and fluid flow to test hydrologic theories for free convection, submarine venting and subsequent ore formation, as constrained by paleoheat flow and petrologic observations. A finite element grid was designed and adapted for a cross section of the Kuna Basin, geologically restored to latest Mississippian time
Schallhorn, Paul; Roth, Jacob; Marsell, Brandon; Kirk, Daniel; Gutierrez, Hector; Saenz-Otero, Alvar; Dorney, Daniel; Moder, Jeffrey
2013-01-01
Accurate prediction of coupled fluid slosh and launch vehicle or spacecraft dynamics (e.g., nutation/precessional movement about various axes, attitude changes, ect.) requires Computational Fluid Dynamics (CFD) models calibrated with low-gravity, long duration slosh data. Recently completed investigations of reduced gravity slosh behavior have demonstrated the limitations of utilizing parabolic flights on specialized aircraft with respect to the specific objectives of the experiments. Although valuable data was collected, the benefits of longer duration low-gravity environments were clearly established. The proposed research provides the first data set from long duration tests in zero gravity that can be directly used to benchmark CFD models, including the interaction between the sloshing fluid and the tank/vehicle dynamics. To explore the coupling of liquid slosh with the motion of an unconstrained tank in microgravity, NASA's Kennedy Space Center, Launch Services Program has teamed up with the Florida Institute of Technology (FIT), Massachusetts Institute of Technology (MIT) and the NASA Game Changing Development Program (GCD) to perform a series of slosh dynamics experiments on the International Space Station using the SPHERES platform. The Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) testbed provides a unique, free-floating instrumented platform on ISS that can be utilized in a manner that would solve many of the limitations of the current knowledge related to propellant slosh dynamics on launch vehicle and spacecraft fuel tanks. The six degree of freedom (6-DOF) motion of the SPHERES free-flyer is controlled by an array of cold-flow C02 thrusters, supplied from a built-in liquid C02 tank. These SPHERES can independently navigate and re-orient themselves within the ISS. The intent of this project is to design an externally mounted tank to be driven inside the ISS by a set of two SPHERES devices (Figure 1). The tank geometry
Tsai, Wen-Chyan; Rizvi, Syed S H
2017-06-01
A new technique of liposomal microencapsulation, consisting of supercritical fluid extraction followed by rapid expansion of the supercritical solution and vacuum-driven cargo loading, was successfully developed. It is a continuous flow-through process without usage of any toxic organic solvent. For use as a coating material, the solubility of soy phospholipids in supercritical carbon dioxide was first determined using a dynamic equilibrium system and the data was correlated with the Chrastil model with good agreement. Liposomes were made with D-(+)-glucose as a cargo and their properties were characterized as functions of expansion pressure, temperature, and cargo loading rates. The highest encapsulation efficiency attained was 31.7% at the middle expansion pressure of 12.41MPa, highest expansion temperature of 90Â°C, and lowest cargo loading rate of 0.25mL/s. The large unilamellar vesicles and multivesicular vesicles were observed to be a majority of the liposomes produced using this eco-friendly process. Copyright Â© 2017 Elsevier Ltd. All rights reserved.
Cho, Yunju; Choi, Man-Ho; Kim, Byungjoo; Kim, Sunghwan
2016-04-29
An experimental setup for the speciation of compounds by hydrogen/deuterium exchange (HDX) with atmospheric pressure ionization while performing chromatographic separation is presented. The proposed experimental setup combines the high performance supercritical fluid chromatography (SFC) system that can be readily used as an inlet for mass spectrometry (MS) and atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI) HDX. This combination overcomes the limitation of an approach using conventional liquid chromatography (LC) by minimizing the amount of deuterium solvents used for separation. In the SFC separation, supercritical CO2 was used as a major component of the mobile phase, and methanol was used as a minor co-solvent. By using deuterated methanol (CH3OD), AP HDX was achieved during SFC separation. To prove the concept, thirty one nitrogen- and/or oxygen-containing standard compounds were analyzed by SFC-AP HDX MS. The compounds were successfully speciated from the obtained SFC-MS spectra. The exchange ions were observed with as low as 1% of CH3OD in the mobile phase, and separation could be performed within approximately 20min using approximately 0.24 mL of CH3OD. The results showed that SFC separation and APPI/APCI HDX could be successfully performed using the suggested method.
Bazilevs, Y.; Moutsanidis, G.; Bueno, J.; Kamran, K.; Kamensky, D.; Hillman, M. C.; Gomez, H.; Chen, J. S.
2017-07-01
In this two-part paper we begin the development of a new class of methods for modeling fluid-structure interaction (FSI) phenomena for air blast. We aim to develop accurate, robust, and practical computational methodology, which is capable of modeling the dynamics of air blast coupled with the structure response, where the latter involves large, inelastic deformations and disintegration into fragments. An immersed approach is adopted, which leads to an a-priori monolithic FSI formulation with intrinsic contact detection between solid objects, and without formal restrictions on the solid motions. In Part I of this paper, the core air-blast FSI methodology suitable for a variety of discretizations is presented and tested using standard finite elements. Part II of this paper focuses on a particular instantiation of the proposed framework, which couples isogeometric analysis (IGA) based on non-uniform rational B-splines and a reproducing-kernel particle method (RKPM), which is a meshfree technique. The combination of IGA and RKPM is felt to be particularly attractive for the problem class of interest due to the higher-order accuracy and smoothness of both discretizations, and relative simplicity of RKPM in handling fragmentation scenarios. A collection of mostly 2D numerical examples is presented in each of the parts to illustrate the good performance of the proposed air-blast FSI framework.
Bazilevs, Y.; Moutsanidis, G.; Bueno, J.; Kamran, K.; Kamensky, D.; Hillman, M. C.; Gomez, H.; Chen, J. S.
2017-03-01
In this two-part paper we begin the development of a new class of methods for modeling fluid-structure interaction (FSI) phenomena for air blast. We aim to develop accurate, robust, and practical computational methodology, which is capable of modeling the dynamics of air blast coupled with the structure response, where the latter involves large, inelastic deformations and disintegration into fragments. An immersed approach is adopted, which leads to an a-priori monolithic FSI formulation with intrinsic contact detection between solid objects, and without formal restrictions on the solid motions. In Part I of this paper, the core air-blast FSI methodology suitable for a variety of discretizations is presented and tested using standard finite elements. Part II of this paper focuses on a particular instantiation of the proposed framework, which couples isogeometric analysis (IGA) based on non-uniform rational B-splines and a reproducing-kernel particle method (RKPM), which is a meshfree technique. The combination of IGA and RKPM is felt to be particularly attractive for the problem class of interest due to the higher-order accuracy and smoothness of both discretizations, and relative simplicity of RKPM in handling fragmentation scenarios. A collection of mostly 2D numerical examples is presented in each of the parts to illustrate the good performance of the proposed air-blast FSI framework.
Dong, Chuanfei
This dissertation presents numerical simulation results of the solar wind interaction with the Martian upper atmosphere by using three comprehensive 3-D models: the Mars Global Ionosphere Thermosphere Model (M-GITM), the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS), and the BATS-R-US Mars multi-fluid MHD (MF-MHD) model. The coupled framework has the potential to provide improved predictions for ion escape rates for comparison with future data to be returned by the MAVEN mission (2014-2016) and thereby improve our understanding of present day escape processes. Estimates of ion escape rates over Mars history must start from properly validated models that can be extrapolated into the past. This thesis aims to build a model library for the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, which will thus enhance the science return from the MAVEN mission. In this thesis, we aim to address the following four main scientific questions by adopting the one-way coupled framework developed here: (1) What are the Martian ion escape rates at the current epoch and ancient times? (2) What controls the ion escape processes at the current epoch? How are the ion escape variations connected to the solar cycle, crustal field orientation and seasonal variations? (3) How do the variable 3-D cold neutral thermosphere and hot oxygen corona affect the solar wind-Mars interaction? (4) How does the Martian atmosphere respond to extreme variations (e.g., ICMEs) in the solar wind and its interplanetary environment? These questions are closely related to the primary scientific goals of NASA's MAVEN mission and European Space Agency's Mars Express (MEX) mission. We reasonably answer all these four questions at the end of this thesis by employing the one-way coupled framework and comparing the simulation results with both MEX and MAVEN observational data.
Energy Technology Data Exchange (ETDEWEB)
Fakcharoenphol, Perapon [Colorado School of Mines, Golden, CO (United States); Xiong, Yi [Colorado School of Mines, Golden, CO (United States); Hu, Litang [Colorado School of Mines, Golden, CO (United States); Winterfeld, Philip H. [Colorado School of Mines, Golden, CO (United States); Xu, Tianfu [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wu, Yu-Shu [Colorado School of Mines, Golden, CO (United States)
2013-05-01
TOUGH2-EGS is a numerical simulation program coupling geomechanics and chemical reactions for fluid and heat flows in porous media and fractured reservoirs of enhanced geothermal systems. The simulator includes the fully-coupled geomechanical (THM) module, the fully-coupled geochemical (THC) module, and the sequentially coupled reactive geochemistry (THMC) module. The fully-coupled flow-geomechanics model is developed from the linear elastic theory for the thermo-poro-elastic system and is formulated with the mean normal stress as well as pore pressure and temperature. The chemical reaction is sequentially coupled after solution of flow equations, which provides the flow velocity and phase saturation for the solute transport calculation at each time step. In addition, reservoir rock properties, such as porosity and permeability, are subjected to change due to rock deformation and chemical reactions. The relationships between rock properties and geomechanical and chemical effects from poro-elasticity theories and empirical correlations are incorporated into the simulator. This report provides the user with detailed information on both mathematical models and instructions for using TOUGH2-EGS for THM, THC or THMC simulations. The mathematical models include the fluid and heat flow equations, geomechanical equation, reactive geochemistry equations, and discretization methods. Although TOUGH2-EGS has the capability for simulating fluid and heat flows coupled with both geomechanical and chemical effects, it is up to the users to select the specific coupling process, such as THM, THC, or THMC in a simulation. There are several example problems illustrating the applications of this program. These example problems are described in details and their input data are presented. The results demonstrate that this program can be used for field-scale geothermal reservoir simulation with fluid and heat flow, geomechanical effect, and chemical reaction in porous and fractured media.
Simard, Isabelle; Luck, David; Mottron, Laurent; Zeffiro, Thomas A; SouliÃ¨res, Isabelle
2015-01-01
Different test types lead to different intelligence estimates in autism, as illustrated by the fact that autistic individuals obtain higher scores on the Raven's Progressive Matrices (RSPM) test than they do on the Wechsler IQ, in contrast to relatively similar performance on both tests in non-autistic individuals. However, the cerebral processes underlying these differences are not well understood. This study investigated whether activity in the fluid "reasoning" network, which includes frontal, parietal, temporal and occipital regions, is differently modulated by task complexity in autistic and non-autistic individuals during the RSPM. In this purpose, we used fMRI to study autistic and non-autistic participants solving the 60 RSPM problems focussing on regions and networks involved in reasoning complexity. As complexity increased, activity in the left superior occipital gyrus and the left middle occipital gyrus increased for autistic participants, whereas non-autistic participants showed increased activity in the left middle frontal gyrus and bilateral precuneus. Using psychophysiological interaction analyses (PPI), we then verified in which regions did functional connectivity increase as a function of reasoning complexity. PPI analyses revealed greater connectivity in autistic, compared to non-autistic participants, between the left inferior occipital gyrus and areas in the left superior frontal gyrus, right superior parietal lobe, right middle occipital gyrus and right inferior temporal gyrus. We also observed generally less modulation of the reasoning network as complexity increased in autistic participants. These results suggest that autistic individuals, when confronted with increasing task complexity, rely mainly on visuospatial processes when solving more complex matrices. In addition to the now well-established enhanced activity observed in visual areas in a range of tasks, these results suggest that the enhanced reliance on visual perception has a
Directory of Open Access Journals (Sweden)
Isabelle Simard
2015-01-01
Full Text Available Different test types lead to different intelligence estimates in autism, as illustrated by the fact that autistic individuals obtain higher scores on the Raven's Progressive Matrices (RSPM test than they do on the Wechsler IQ, in contrast to relatively similar performance on both tests in non-autistic individuals. However, the cerebral processes underlying these differences are not well understood. This study investigated whether activity in the fluid â€œreasoningâ€ network, which includes frontal, parietal, temporal and occipital regions, is differently modulated by task complexity in autistic and non-autistic individuals during the RSPM. In this purpose, we used fMRI to study autistic and non-autistic participants solving the 60 RSPM problems focussing on regions and networks involved in reasoning complexity. As complexity increased, activity in the left superior occipital gyrus and the left middle occipital gyrus increased for autistic participants, whereas non-autistic participants showed increased activity in the left middle frontal gyrus and bilateral precuneus. Using psychophysiological interaction analyses (PPI, we then verified in which regions did functional connectivity increase as a function of reasoning complexity. PPI analyses revealed greater connectivity in autistic, compared to non-autistic participants, between the left inferior occipital gyrus and areas in the left superior frontal gyrus, right superior parietal lobe, right middle occipital gyrus and right inferior temporal gyrus. We also observed generally less modulation of the reasoning network as complexity increased in autistic participants. These results suggest that autistic individuals, when confronted with increasing task complexity, rely mainly on visuospatial processes when solving more complex matrices. In addition to the now well-established enhanced activity observed in visual areas in a range of tasks, these results suggest that the enhanced reliance on visual
Kopach, Olga; Vats, Juliana; Netsyk, Olga; Voitenko, Nana; Irving, Andrew; Fedirko, Nataliya
2012-04-15
Cannabinoid receptors (CBRs) belong to the G protein-coupled receptor superfamily, and activation of CBRs in salivary cells inhibits agonist-stimulated salivation and modifies saliva content. However, the role of different CBR subtypes in acinar cell physiology and in intracellular signalling remains unclear. Here, we uncover functional CB(1)Rs and CB(2)Rs in acinar cells of rat submandibular gland and their essential role in saliva secretion. Pharmacological activation of CB(1)Rs and CB(2)Rs in the submandibular gland suppressed saliva outflow and modified saliva content produced by the submandibular gland in vivo. Using Na(+)-selective microelectrodes to record secretory Na(+) responses in the lumen of acini, we observed a reduction in Na(+) transport following the activation of CBRs, which was counteracted by the selective CB(1)R antagonist AM251. In addition, activation of CB(1)Rs or CB Rs caused inhibition of Na(+)-K(+) 2 -ATPase activity in microsomes derived from the gland tissue as well as in isolated acinar cells. Using a Ca(2+) imaging technique, we showed that activation of CB(1)Rs and CB(2)Rs alters [Ca(2+)](cyt) signalling in acinar cells by distinct pathways, involving Ca(2+) release from the endoplasmic reticulum (ER) and store-operated Ca(2+) entry (SOCE), respectively. Our data demonstrate the expression of CB(1)Rs and CB(2)Rs in acinar cells, and their involvement in the regulation of salivary gland functioning.
Kim, Ho Jun; Lee, Hae June
2016-06-01
The wide applicability of capacitively coupled plasma (CCP) deposition has increased the interest in developing comprehensive numerical models, but CCP imposes a tremendous computational cost when conducting a transient analysis in a three-dimensional (3D) model which reflects the real geometry of reactors. In particular, the detailed flow features of reactive gases induced by 3D geometric effects need to be considered for the precise calculation of radical distribution of reactive species. Thus, an alternative inclusive method for the numerical simulation of CCP deposition is proposed to simulate a two-dimensional (2D) CCP model based on the 3D gas flow results by simulating flow, temperature, and species fields in a 3D space at first without calculating the plasma chemistry. A numerical study of a cylindrical showerhead-electrode CCP reactor was conducted for particular cases of SiH4/NH3/N2/He gas mixture to deposit a hydrogenated silicon nitride (SiN x H y ) film. The proposed methodology produces numerical results for a 300â€‰mm wafer deposition reactor which agree very well with the deposition rate profile measured experimentally along the wafer radius.
Ilton, Eugene S.; Veblen, David R.; Moses, Carl O.; Raeburn, Stuart P.
1997-09-01
Large single crystals of biotite and near-endmember phlogopite were reacted with aqueous solutions bearing 20 Î¼M Cr(VI) and different concentrations of NaCl, LiCl, RbCl, CsCl, NaClO 4, and Na 2SO 4. Solutions were maintained at 25 Â± 0.5Â°C, 1 atm, and pH = 4.00 Â± 0.02. Samples were extracted from the reaction chamber at 1, 3, 5, 10, and 20 h. The edges and basal planes of the reacted micas were analyzed by X-ray photoelectron spectroscopy (XPS) for major elements and Cr. XPS analyses of biotite show trivalent chromium on edge surfaces but no detectable chromium on the basal plane. XPS analyses of near-endmember phlogopites that were reacted in the same experiments as biotite showed no detectable Cr on either the basal plane or edge surfaces. Increasing Na and Li salt concentrations increased the rate of coupled sorption-reduction of chromate at the biotite edge-fluid interface, where the order of effectiveness was NaCl Ëœ NaClO 4 > Na 2SO 4 > LiCl. In contrast, no Cr was detected on mica edges after reaction in RbCl and CsCl solutions. Comparison of equimolar NaCl and LiCl experiments indicate that the active agent is Na and Li, not ionic strength or the anion. Sulfate tends to block the reaction more so than chloride. We conclude that it is the substitution of hydrated cations for interlayer K in biotite that enhances the heterogeneous reduction of chromate at the biotite edge-fluid interface.
Energy Technology Data Exchange (ETDEWEB)
Dharodi, Vikram; Das, Amita, E-mail: amita@ipr.res.in; Patel, Bhavesh; Kaw, Predhiman [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2016-01-15
The strongly coupled dusty plasma has often been modelled by the Generalized Hydrodynamic (GHD) model used for representing visco-elastic fluid systems. The incompressible limit of the model which supports transverse shear wave mode is studied in detail. In particular, dipole structures are observed to emit transverse shear waves in both the limits of sub- and super-luminar propagation, where the structures move slower and faster than the phase velocity of the shear waves, respectively. In the sub-luminar limit the dipole gets engulfed within the shear waves emitted by itself, which then backreacts on it and ultimately the identity of the structure is lost. However, in the super-luminar limit the emission appears like a wake from the tail region of the dipole. The dipole, however, keeps propagating forward with little damping but minimal distortion in its form. A Poynting-like conservation law with radiative, convective, and dissipative terms being responsible for the evolution of W, which is similar to â€œenstrophyâ€ like quantity in normal hydrodynamic fluid systems, has also been constructed for the incompressible GHD equations. The conservation law is shown to be satisfied in all the cases of evolution and collision amidst the nonlinear structures to a great accuracy. It is shown that monopole structures which do not move at all but merely radiate shear waves, the radiative term, and dissipative losses solely contribute to the evolution of W. The dipolar structures, on the other hand, propagate in the medium and hence convection also plays an important role in the evolution of W.
Sibra, A.; Dupays, J.; Murrone, A.; Laurent, F.; Massot, M.
2017-06-01
In this paper, we tackle the issue of the accurate simulation of evaporating and reactive polydisperse sprays strongly coupled to unsteady gaseous flows. In solid propulsion, aluminum particles are included in the propellant to improve the global performances but the distributed combustion of these droplets in the chamber is suspected to be a driving mechanism of hydrodynamic and acoustic instabilities. The faithful prediction of two-phase interactions is a determining step for future solid rocket motor optimization. When looking at saving computational ressources as required for industrial applications, performing reliable simulations of two-phase flow instabilities appears as a challenge for both modeling and scientific computing. The size polydispersity, which conditions the droplet dynamics, is a key parameter that has to be accounted for. For moderately dense sprays, a kinetic approach based on a statistical point of view is particularly appropriate. The spray is described by a number density function and its evolution follows a Williams-Boltzmann transport equation. To solve it, we use Eulerian Multi-Fluid methods, based on a continuous discretization of the size phase space into sections, which offer an accurate treatment of the polydispersion. The objective of this paper is threefold: first to derive a new Two Size Moment Multi-Fluid model that is able to tackle evaporating polydisperse sprays at low cost while accurately describing the main driving mechanisms, second to develop a dedicated evaporation scheme to treat simultaneously mass, moment and energy exchanges with the gas and between the sections. Finally, to design a time splitting operator strategy respecting both reactive two-phase flow physics and cost/accuracy ratio required for industrial computations. Using a research code, we provide 0D validations of the new scheme before assessing the splitting technique's ability on a reference two-phase flow acoustic case. Implemented in the industrial
Jayanthi, Aditya; Coker, Christopher
2016-11-01
In the last decade, CFD simulations have transitioned from the stage where they are used to validate the final designs to the main stream development of products driven by the simulation. However, there are still niche areas of applications liking oiling simulations, where the traditional CFD simulation times are probative to use them in product development and have to rely on experimental methods, which are expensive. In this paper a unique example of Sprocket-Chain simulation will be presented using nanoFluidx a commercial SPH code developed by FluiDyna GmbH and Altair Engineering. The grid less nature of the of SPH method has inherent advantages in the areas of application with complex geometry which pose severe challenge to classical finite volume CFD methods due to complex moving geometries, moving meshes and high resolution requirements leading to long simulation times. The simulations times using nanoFluidx can be reduced from weeks to days allowing the flexibility to run more simulation and can be in used in main stream product development. The example problem under consideration is a classical Multiphysics problem and a sequentially coupled solution of Motion Solve and nanoFluidX will be presented. This abstract is replacing DFD16-2016-000045.
Matsubara, Atsuki; Uchikata, Takato; Shinohara, Masakazu; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi
2012-06-01
Epoxy carotenoids, which are products of carotenoid oxidation, are potential oxidative stress markers. However, it is difficult to profile epoxy carotenoids owing to their small amount and difficulty in their separation from hydroxy carotenoids. In this study, a high-performance analytical system based on supercritical fluid chromatography (SFC) coupled with tandem mass spectrometry (MS/MS) was developed for the simultaneous analysis of carotenoids and epoxy carotenoids. SFC is an effective separation technique for hydrophobic compounds, by which major carotenoids in human serum and their epoxidation products can be analyzed within 20 min. The use of MS/MS increased the sensitivity; the detection limit for each carotenoid was of the sub-fmol order. When the constructed method was applied to biological samples such as human serum and low-density lipoprotein (LDL), the precise detection of the target carotenoids was disturbed by several isomers. However, highly selective detection of epoxy carotenoids was performed by targeting product ions that were generated with a structure-specific neutral loss of 80Da. Furthermore, the sample volume needed for the analysis was only 0.1ml for the serum, indicating the efficiency of this system in performing small-scale analyses. Using the analytical system developed in this study, highly sensitive and selective analysis of epoxy carotenoids could be performed in a short time. These features show the usefulness of this system in application to screening analysis of carotenoid profiles that are easily modified by oxidative stress.
Institute of Scientific and Technical Information of China (English)
Fang Wang; Yan-chun Lou; Rui Chen; Zhao-wei Song; Bao-kuan Li
2015-01-01
The vibrating electrode method was proposed in the electro-slag remelting (ESR) process in this paper, and the effect of vibrating electrode on the solidiifcation structure of ingot was studied. A transient three-dimensional (3D) coupled mathematical model was established to simulate the electromagnetic phenomenon, fluid flow as well as pool shape in the ESR process with the vibrating electrode. The finite element volume method is developed to solve the electromagnetic field using ANSYS mechanical APDL software. Moreover, the electromagnetic force and Joule heating are interpolated as the source term of the momentum and energy equations. The multi-physical fields have been investigated and compared between the traditional electrode and the vibrating electrode in the ESR process. The results show that the drop process of metal droplets with the traditional electrode is scattered randomly. However, the drop process of metal droplets with the vibrating electrode is periodic. The highest temperature of slag layer with the vibrating electrode is higher than that with the traditional electrode, which can increase the melting rate due to the enhanced heat transfer in the vicinity of the electrode tip. The results also show that when the amplitude and frequency of the vibrating electrode increase, the cycle of drop process of metal droplets decreases signiifcantly.
Directory of Open Access Journals (Sweden)
Fang Wang
2015-07-01
Full Text Available The vibrating electrode method was proposed in the electro-slag remelting (ESR process in this paper, and the effect of vibrating electrode on the solidification structure of ingot was studied. A transient three-dimensional (3D coupled mathematical model was established to simulate the electromagnetic phenomenon, fluid flow as well as pool shape in the ESR process with the vibrating electrode. The finite element volume method is developed to solve the electromagnetic field using ANSYS mechanical APDL software. Moreover, the electromagnetic force and Joule heating are interpolated as the source term of the momentum and energy equations. The multi-physical fields have been investigated and compared between the traditional electrode and the vibrating electrode in the ESR process. The results show that the drop process of metal droplets with the traditional electrode is scattered randomly. However, the drop process of metal droplets with the vibrating electrode is periodic. The highest temperature of slag layer with the vibrating electrode is higher than that with the traditional electrode, which can increase the melting rate due to the enhanced heat transfer in the vicinity of the electrode tip. The results also show that when the amplitude and frequency of the vibrating electrode increase, the cycle of drop process of metal droplets decreases significantly.
Wang, Zhifeng; Cui, Zhaojie
2016-12-01
A method using derivatization and supercritical fluid extraction coupled with gas chromatography was developed for the analysis of dimethylarsinate, monomethylarsonate and inorganic arsenic simultaneously in solid matrices. Thioglycolic acid n-butyl ester was used as a novel derivatizing reagent. A systematic discussion was made to investigate the effects of pressure, temperature, flow rate of the supercritical CO2 , extraction time, concentration of the modifier, and microemulsion on extraction efficiency. The application for real environmental samples was also studied. Results showed that thioglycolic acid n-butyl ester was an effective derivatizing reagent that could be applied for arsenic speciation. Using methanol as modifier of the supercritical CO2 can raise the extraction efficiency, which can be further enhanced by adding a microemulsion that contains Triton X-405. The optimum extraction conditions were: 25 MPa, 90Â°C, static extraction for 10 min, dynamic extraction for 25 min with a flow rate of 2.0 mL/min of supercritical CO2 modified by 5% v/v methanol and microemulsion. The detection limits of dimethylarsinate, monomethylarsonate, and inorganic arsenic in solid matrices were 0.12, 0.26, and 1.1 mg/kg, respectively. The optimized method was sensitive, convenient, and reliable for the extraction and analysis of different arsenic species in solid samples.
Del Carmen Salvatierra-Stamp, Vilma; Ceballos-MagaÃ±a, Silvia G; Gonzalez, Jorge; Ibarra-GalvÃ¡n, Valentin; MuÃ±iz-Valencia, Roberto
2015-05-01
An analytical method using supercritical-fluid chromatography coupled with diode-array detection for the determination of seven emerging contaminants-two pharmaceuticals (carbamazepine and glyburide), three endocrine disruptors (17Î±-ethinyl estradiol, bisphenol A, and 17Î²-estradiol), one bactericide (triclosan), and one pesticide (diuron)-was developed and validated. These contaminants were chosen because of their frequency of use and their toxic effects on both humans and the environment. The optimized chromatographic separation on a Viridis BEH 2-EP column achieved baseline resolution for all compounds in less than 10 min. This separation was applied to environmental water samples after sample preparation. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using C18-OH cartridges. The proposed method was validated, finding recoveries higher than 94 % and limits of detection and limits of quantification in the range of 0.10-1.59 Î¼g L(-1) and 0.31-4.83 Î¼g L(-1), respectively. Method validation established the proposed method to be selective, linear, accurate, and precise. Finally, the method was successfully applied to environmental water samples.
Directory of Open Access Journals (Sweden)
Muthuraj R.
2012-01-01
Full Text Available A mathematical model is developed to examine the effect of chemical reaction on MHD mixed convective heat and mass transfer flow of a couple-stress fluid in vertical porous space in the presence of temperature dependent heat source with travelling thermal waves. The dimensionless governing equations are assumed to be made up of two parts: a mean part corresponding to the fully developed mean flow, and a small perturbed part, using amplitude as a small parameter. The analytical solution of perturbed part have been carried out by using the long-wave approximation. The expressions for the zeroth-order and the first order solutions are obtained and the results of the heat and mass transfer characteristics are presented graphically for various values of parameters entering into the problem. It is noted that velocity of the fluid increases with the increase of the couple stress parameter and increasing the chemical reaction parameter leads suppress the velocity of the fluid. Cross velocity decreases with an increase of the phase angle. The increase of the chemical reaction parameter and Schmidt number lead to decrease the fluid concentration. The hydrodynamic case for a non-porous space in the absence of the temperature dependent heat source for Newtonian fluid can be captured as a limiting case of our analysis by taking, and Î±1â†’0, Daâ†’âˆž, aâ†’âˆž.
Energy Technology Data Exchange (ETDEWEB)
Xiong, Yi [Colorado School of Mines, Golden, CO (United States); Fakcharoenphol, Perapon [Colorado School of Mines, Golden, CO (United States); Wang, Shihao [Colorado School of Mines, Golden, CO (United States); Winterfeld, Philip H. [Colorado School of Mines, Golden, CO (United States); Zhang, Keni [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wu, Yu-Shu [Colorado School of Mines, Golden, CO (United States)
2013-12-01
TOUGH2-EGS-MP is a parallel numerical simulation program coupling geomechanics with fluid and heat flow in fractured and porous media, and is applicable for simulation of enhanced geothermal systems (EGS). TOUGH2-EGS-MP is based on the TOUGH2-MP code, the massively parallel version of TOUGH2. In TOUGH2-EGS-MP, the fully-coupled flow-geomechanics model is developed from linear elastic theory for thermo-poro-elastic systems and is formulated in terms of mean normal stress as well as pore pressure and temperature. Reservoir rock properties such as porosity and permeability depend on rock deformation, and the relationships between these two, obtained from poro-elasticity theories and empirical correlations, are incorporated into the simulation. This report provides the user with detailed information on the TOUGH2-EGS-MP mathematical model and instructions for using it for Thermal-Hydrological-Mechanical (THM) simulations. The mathematical model includes the fluid and heat flow equations, geomechanical equation, and discretization of those equations. In addition, the parallel aspects of the code, such as domain partitioning and communication between processors, are also included. Although TOUGH2-EGS-MP has the capability for simulating fluid and heat flows coupled with geomechanical effects, it is up to the user to select the specific coupling process, such as THM or only TH, in a simulation. There are several example problems illustrating applications of this program. These example problems are described in detail and their input data are presented. Their results demonstrate that this program can be used for field-scale geothermal reservoir simulation in porous and fractured media with fluid and heat flow coupled with geomechanical effects.
Sinha, Sumit; Hardy, Richard; Smith, Gregory; Kazemifar, Farzan; Christensen, Kenneth; Best, Jim
2017-04-01
Biofilms are ubiquitously present in fluvial systems, growing on almost all wetted surface and has a significant impact on both water quantity, in terms of ambient flow condition, as well as water quality, biofilms growing in water distribution system leads to unwanted contamination. The local hydraulic conditions have a significant impact on the biofilm lifecycle as in order to sustain their growth biofilms draw essential nutrients either from the flow or from the surface on which they grow. This implies that in convection dominated flow, nutrient transfer from water, would nurture the growth of biofilms. However, at higher flow rates biofilms are subjected to higher stresses which may lead to their detachment. Furthermore, biofilms in ambient flow conditions oscillate and therefore alter the local flow conditions. There is, therefore, a complex feedback between biofilms and flow which have has implications for flow dynamics and water quality issues in riverine ecosystems. The research presented here describes a fluid-structure interaction solver to examine the coupled nature of biofilm oscillations due to the ambient flow and its feedback on the local flow structures. The fluid flow is modelled by the incompressible Navier-Stokes equations and structural deformation of the biofilm is modeled by applying a linear elastic model. The governing equations are numerically solved through Finite Volume methodology based on cell-centered scheme. Simulations are conducted in a laminar regime for a biofilm streamer modelled as moving slender plate. The temporal evolution of the pressure, flow structures are examined in the vicinity of the biofilm. Further investigations examine the impact of changing Reynolds number on the oscillation frequency as well as drag and lift forces experienced by the biofilm. The changing frequency of biofilm oscillation with varying Reynolds number is characterized by the Strouhal number (St). Our investigation reveals that as the flow separates
Lou, Wentao; Zhu, Miaoyong
2014-10-01
A computation fluid dynamics-simultaneous reaction model (CFD-SRM) coupled model has been proposed to describe the desulfurization behavior in a gas-stirred ladle. For the desulfurization thermodynamics, different models were investigated to determine sulfide capacity and oxygen activity. For the desulfurization kinetic, the effect of bubbly plume flow, as well as oxygen absorption and oxidation reactions in slag eyes are considered. The thermodynamic and kinetic modification coefficients are proposed to fit the measured data, respectively. Finally, the effects of slag basicity and gas flow rate on the desulfurization efficiency are investigated. The results show that as the interfacial reactions (Al2O3)-(FeO)-(SiO2)-(MnO)-[S]-[O] simultaneous kinetic equilibrium is adopted to determine the oxygen activity, and the Young's model with the modification coefficient R th of 1.5 is adopted to determine slag sulfide capacity, the predicted sulfur distribution ratio LS agrees well with the measured data. With an increase of the gas blowing time, the predicted desulfurization rate gradually decreased, and when the modification parameter R k is 0.8, the predicted sulfur content changing with time in ladle agrees well with the measured data. If the oxygen absorption and oxidation reactions in slag eyes are not considered in this model, then the sulfur removal rate in the ladle would be overestimated, and this trend would become more obvious with an increase of the gas flow rate and decrease of the slag layer height. With the slag basicity increasing, the total desulfurization ratio increases; however, the total desulfurization ratio changes weakly as the slag basicity exceeds 7. With the increase of the gas flow rate, the desulfurization ratio first increases and then decreases. When the gas flow rate is 200 NL/min, the desulfurization ratio reaches a maximum value in an 80-ton gas-stirred ladle.
Gensterblum, Y.; Krooss, B. M.
2013-12-01
The interaction and the coupling of slip-flow, a fluid dynamic phenomenon, and the cleat volume compressibility which is a poroelastic phenomenon has been investigated on two samples from the Taroom coal measure, Surat Basin, Queensland Australia. Measurements were performed using inert (helium and argon) and sorbing gases (nitrogen, methane and carbon dioxide) at controlled effective stress. We observed the following regular sequence of permeability coefficients for the different gases: Helium >> argon => nitrogen > methane >> CO2 Even after slip-flow correction, different intrinsic permeability coefficients are obtained for the same sample if different gases are used in the tests. The permeability values determined with helium are largest while those measured with CO2 are lowest. Inert gases like helium and argon show higher apparent- and even slip flow-corrected permeability coefficients than sorbing gases like methane or carbon dioxide. This observation is contrary to the prediction that the slip-flow corrected permeability have to be the same for all gases. The cleat volume compressibility cf was evaluated using the 'matchstick approach' [1, 2]. The cleat volume compressibility coefficients cf are almost identical for the two samples taken from the same well. However, for one sample a strong dependence of the cf with the mean pore pressure was observed. This is attributed to a strong slip-flow effect caused by a narrow cleat system as compared to the sister sample. The cleat volume compressibility coefficient cf is almost the same for inert and sorbing gases. We conclude that the occurrence of slip-flow in coals is able to compensate the permeability reduction resulting from increasing effective stress. This should lead to a much higher productivity of coal bed methane reservoirs in the third production phase (pseudo-steady state phase; [3]). This conclusion appears to be also valid for shale gas and tight gas reservoirs, where the gas transport takes place in
Energy Technology Data Exchange (ETDEWEB)
Gul, Banat, E-mail: banatgul@gmail.com [Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan); Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Aman-ur-Rehman, E-mail: amansadiq@gmail.com [Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)
2015-10-15
Fluid model has been applied to perform a comparative study of hydrogen bromide (HBr)/He and HBr/Ar capacitively coupled plasma discharges that are being used for anisotropic etching process. This model has been used to identify the most dominant species in HBr based plasmas. Our simulation results show that the neutral species like H and Br, which are the key player in chemical etching, have bell shape distribution, while ions like HBr{sup +}, Br{sup +}, which play a dominant rule in the physical etching, have double humped distribution and show peaks near electrodes. It was found that the dilution of HBr by Ar and/or He results in an increase in electron density and electron temperature, which results in more ionization and dissociation and hence higher densities of neutral and charged species can be achieved. The ratio of positive ion flux to the neutral flux increases with an increase in additive gas fraction. Compare to HBr/He plasma, the HBr/Ar plasma shows a maximum change in the ion density and flux and hence the etching rate can be considered in the ion-assisted and in the ion-flux etch regime in HBr/Ar discharge. The densities of electron and other dominant species in HBr/Ar plasma are higher than those of HBr/He plasma. The densities and fluxes of the active neutrals and positive ions for etching and subsequently chemical etching versus physical sputtering in HBr/Ar and HBr/He plasmas discharge can be controlled by tuning gas mixture ratio and the desire etching can be achieved.
Energy Technology Data Exchange (ETDEWEB)
C. B. Davis; C. H. Oh; R. B. Barner; D. F. Wilson
2005-06-01
The Department of Energy is investigating the use of high-temperature nuclear reactors to produce hydrogen using either thermochemical cycles or high-temperature electrolysis. Although the hydrogen production processes are in an early stage of development, coupling either of these processes to the hightemperature reactor requires both efficient heat transfer and adequate separation of the facilities to assure that off-normal events in the production facility do not impact the nuclear power plant. An intermediate heat transport loop will be required to separate the operations and safety functions of the nuclear and hydrogen plants. A next generation high-temperature reactor could be envisioned as a single-purpose facility that produces hydrogen or a dual-purpose facility that produces hydrogen and electricity. Early plants, such as the proposed Next Generation Nuclear Plant, may be dual-purpose facilities that demonstrate both hydrogen and efficient electrical generation. Later plants could be single-purpose facilities. At this stage of development, both single- and dual-purpose facilities need to be understood. Seven possible configurations for a system that transfers heat between the nuclear reactor and the hydrogen and/or electrical generation plants were identified. These configurations included both direct and indirect cycles for the production of electricity. Both helium and liquid salts were considered as the working fluid in the intermediate heat transport loop. Methods were developed to perform thermalhydraulic and cycle-efficiency evaluations of the different configurations and coolants. The thermalhydraulic evaluations estimated the sizes of various components in the intermediate heat transport loop for the different configurations. The relative sizes of components provide a relative indication of the capital cost associated with the various configurations. Estimates of the overall cycle efficiency of the various configurations were also determined. The
Hardick, Justin; Won, Helen; Jeng, Kevin; Hsieh, Yu-Hsiang; Gaydos, Charlotte A.; Richard E Rothman; Yang, Samuel
2012-01-01
Spontaneous bacterial peritonitis (SBP) can be a severe complication occurring in patients with cirrhosis and ascites, with associated mortality often as high as 40%. Traditional diagnostics for SBP rely on culture techniques for proper diagnosis, although recent reports suggest that the presence of bacterial DNA in peritoneal fluid in patients with cirrhosis and ascites is an indicator of SBP. A previously published broad-range PCR (16S PCR) coupled with high-resolution melt analysis (HRMA) ...
Institute of Scientific and Technical Information of China (English)
æ¢æ–Œ; æŽæˆŽ; å¼ ä¼Ÿ
2011-01-01
æ ¹æ®Loveå£³ä½“ç†è®ºç ”ç©¶äº†åŸºäºŽåŠŸèƒ½æ¢¯åº¦ææ–™çš„å……æ¶²åœ†æŸ±å£³çš„è€¦åˆæŒ¯åŠ¨ç‰¹æ€§.åˆ©ç”¨æ³¢åŠ¨æ³•,æŽ¨å¯¼å‡ºè€ƒè™‘æ¶²ä½“å½±å“æ—¶FGåœ†æŸ±å£³è€¦åˆç³»ç»Ÿçš„æŒ¯åŠ¨æ–¹ç¨‹.é€šè¿‡å˜æ¢è½´å‘æ³¢æ•°,å¾—åˆ°ä¸åŒè¾¹ç•Œæ¡ä»¶ä¸‹å……æ¶²FGåœ†æŸ±å£³çš„å›ºæœ‰é¢‘çŽ‡.ä¸Žå·²æœ‰æ–‡çŒ®çš„åˆ†æžç»“æžœè¿›è¡Œå¯¹æ¯”,éªŒè¯äº†æ–‡ä¸ç ”ç©¶çš„å‡†ç¡®æ€§.ç ”ç©¶è¡¨æ˜Ž,æ¶²ä½“å¯¹FGåœ†æŸ±å£³çš„å›ºæœ‰é¢‘çŽ‡æœ‰ç€æ˜Žæ˜¾çš„å½±å“,è½´å‘åŠæ³¢æ•°ã€è¾¹ç•Œæ¡ä»¶å’Œå£³ä½“é•¿åº¦ä¸ŽåŠå¾„æ¯”å¯¹å›ºæœ‰é¢‘çŽ‡çš„å½±å“ä¸»è¦è¡¨çŽ°åœ¨å‘¨å‘æ³¢æ•°è¾ƒå°çš„æƒ…å†µä¸‹.%The coupled vibration of fluid-filled cylindrical shell based on functionally graded material (FG) is presented.The study is carried out using Love's thin shell theory.Based on wave propagation method the equation of motion of the coupled system with the fluid effect is derived.By means of conversion switch on axial wave number,the coupled frequency of FG cylindrical shell with various boundary conditions is obtained.Then the frequency of fluid-filled FG cylindrical shell with different boundary conditions is illustrated by examples.The present analysis is validated by comparing results with those in the literature.The results show that the influences of liquids on natural frequencies of fluid-filled FG cylindrical shell are obvious.The effects of axial half wave number,boundary condition and ratio of length to radius on natural frequencies have mainly manifested in the cases of low circumferential wave numbers.
Energy Technology Data Exchange (ETDEWEB)
Butto, C.; Fudym, O.; Joly, J.L.; Platel, V.; Zely, D. [Toulouse-3 Univ., 31 (France); Franchisseur, R.; Grandpeix, J.Y.; Lahellec, A. [Centre National de la Recherche Scientifique (CNRS), 91 - Orsay (France)
1993-12-31
This text presents the interest of TEF (Transfer Evolution Formalism) method in three cases: thermocapillar pumping, Peltier effect thermoelements and electrophoresis cell , that illustrate on the one hand, the easiness of modelizing coupled phenomena thanks to TEF, and on the other hand, the use of coupling analysis in order to understand the running of a device. (TEC). figs., refs.
Institute of Scientific and Technical Information of China (English)
å´”æ¶›; å¼ å«åŽ; å™å¸®æˆ
2013-01-01
ç»“åˆæ—¢æœ‰ç³»ç»ŸåŠ¨åŠ›å¦åˆ†æžæ–¹æ³•å’Œç©ºæ°”åŠ¨åŠ›å¦ç ”ç©¶æ–¹æ³•,ç»™å‡ºåŸºäºŽä»»æ„æ‹‰æ ¼æœ—æ—¥-æ¬§æ‹‰æ³•çš„é«˜é€Ÿåˆ—è½¦ä¸Žæ°”æµè€¦åˆæŒ¯åŠ¨çš„æ•°å€¼åˆ†æžæ–¹æ³•,åŒ…æ‹¬ç¦»çº¿è€¦åˆåˆ†æžæ–¹æ³•å’Œåœ¨çº¿è€¦åˆåˆ†æžæ–¹æ³•,åœ¨çº¿è€¦åˆåˆå¯åˆ†ä¸ºæ˜¾å¼è€¦åˆåˆ†æžæ–¹æ³•å’Œéšå¼è€¦åˆåˆ†æžæ–¹æ³•.ä»‹ç»ä¸åŒè€¦åˆåˆ†æžæ–¹æ³•åœ¨ç«™å°é€šè¿‡ã€é«˜é€Ÿäº¤ä¼šã€ä¾§é£Žç‰è¿è¡Œå®‰å…¨æ€§æ–¹é¢çš„åº”ç”¨,è€ƒè™‘æµå›ºå…³ç³»åŽ,åˆ—è½¦ä¾§é£Žå®‰å…¨æ€§å’Œäº¤ä¼šå®‰å…¨æ€§è¿›ä¸€æ¥é™ä½Ž.æµå›ºè€¦åˆæ•°å€¼åˆ†æžæ–¹æ³•åœ¨å®žä¾‹åº”ç”¨ä¸å¾—åˆ°ç›´æŽ¥æˆ–é—´æŽ¥çš„éªŒè¯,ä¸ºé«˜é€Ÿåˆ—è½¦æµå›ºå…³ç³»ç ”ç©¶æä¾›1ç§æ–¹æ³•å’Œæ€è·¯.%The new numeric analysis methodology based on Arbitrary Lagrangian-Eulerian(ALE) for high-speed train and airflow coupling vibration was presented by integrating the existing Finite Volume Method of Computational Fluid Dynamics and the numerical simulation method of Multi-Body Systems Dynamics.This methodology included off-line coupling and on-line coupling,and the latter included the explicit coupling method and implicit coupling method.The applications of these coupling methods in platform passing,high-speed crossing and side winds were introduced.Safety of train crossing and trains running in side winds was reduced when the coupling relationship of train system and airflow was taken into account.The methodology was verified in applications directly and indirectly.It offers a methodology and a idea for study of fluid-solid coupling relationship of high-speed trains.
Refrigerating fluids; Fluides frigorigenes
Energy Technology Data Exchange (ETDEWEB)
Anon.
1999-03-01
Refrigerating fluids are experiencing a real revolution since few years. CFCs with their destructive effect on the ozone layer are now prohibited while HCFCs will be progressively eliminated and replaced by HFCs. However, HFCs can contribute to the increase of the greenhouse effect. The solutions proposed by thermal engineering professionals consist in the confinement of air-conditioning installations (elimination of recurrent leaks) and in the improvement of installations efficiency. HCFC fluids like the R 22 are still widely used in air-conditioning but they are supposed to be replaced by HFC fluids like the R 134a, the R 407C or the R 410A. This short paper gives a brief presentation of these fluids and of their chemical characteristics. (J.S.)
Energy Technology Data Exchange (ETDEWEB)
McMaster, W.H.; Quinones, D.F.; Landram, C.S.; Norris, D.M.; Gong, E.Y.; Macken, N.A.; Nickell, R.E.
1979-11-01
This report concludes a developmental effort to obtain a two-dimensional or axisymmetric computer code that calculates fluid-structure interaction problems in boiling-water-reactor (BWR) pressure-suppression systems. In this report several verification problems are concluded and applications to the Mark I and Mark II pressure-suppression systems are presented. 31 refs., 47 figs., 11 tabs.
Institute of Scientific and Technical Information of China (English)
å¼ æ°; æ¢æ”¿; éŸ©ä¼ å†›
2014-01-01
ä¸ºç ”ç©¶å¤šå¼¯ç®¡è·¯ç³»ç»Ÿçš„åŠ¨åŠ›å¦ç‰¹æ€§ï¼ŒåŸºäºŽæµå›ºè€¦åˆå’Œæœ‰é™å…ƒåŽŸç†ï¼Œå¯¹å……æ¶²Låž‹ç®¡é“çš„å›ºæœ‰ç‰¹æ€§è¿›è¡Œäº†æ•°å€¼æ¨¡æ‹Ÿï¼Œå¹¶ä¸ŽTMMï¼ˆä¼ é€’çŸ©é˜µæ³•ï¼‰è¿›è¡Œäº†å¯¹æ¯”ï¼Œè¯æ˜Žäº†æ•°å€¼æ¨¡åž‹çš„åˆç†æ€§ã€‚å»ºç«‹äº†æ°´ä¸‹å¤šå¼¯ç®¡è·¯çš„æ•°å€¼æ¨¡åž‹ï¼Œè¿›è¡Œäº†æµå›ºè€¦åˆæ¨¡æ€åˆ†æžï¼Œç ”ç©¶äº†å£åŽšã€ç®¡å¾„å¯¹ç®¡è·¯å›ºæœ‰é¢‘çŽ‡çš„å½±å“è§„å¾‹ã€‚å¹¶å¯¹éžå®šå¸¸æµä¸‹å¤šå¼¯ç®¡è·¯ç³»ç»Ÿçš„åŠ¨åŠ›å“åº”è¿›è¡Œäº†åˆ†æžï¼Œç ”ç©¶äº†å£åŽšå’Œæ³¢åŠ¨é€Ÿåº¦å¯¹ç®¡é“æŒ¯åŠ¨çš„å½±å“è§„å¾‹ã€‚ç ”ç©¶ç»“æžœè¡¨æ˜Žï¼šè€ƒè™‘ç®¡å†…ã€å¤–æµä½“ä¸Žç®¡é“ä¸‰è€…è€¦åˆæ—¶çš„ç®¡é“å›ºæœ‰é¢‘çŽ‡æ¯”åªè€ƒè™‘ç®¡å†…æµä½“ä¸Žç®¡é“äºŒè€…è€¦åˆå’Œä¸è€ƒè™‘è€¦åˆæ—¶å°ï¼Œä½†æµå›ºè€¦åˆä½œç”¨å¯¹ç®¡é“æ¨¡æ€æŒ¯åž‹çš„å½±å“è¾ƒå°ï¼›ç®¡é“çš„å›ºæœ‰é¢‘çŽ‡éšç®¡å¾„å’Œå£åŽšçš„å¢žå¤§è€Œå¢žå¤§ï¼Œæ°”ä½“ä¸Žç®¡é“ä¹‹é—´è€¦åˆä½œç”¨å¯¹ç®¡é“å›ºæœ‰é¢‘çŽ‡çš„å½±å“å°äºŽæ¶²ä½“ï¼›éžå®šå¸¸æµä¸‹ï¼Œå¤šå¼¯ç®¡è·¯çš„æŒ¯åŠ¨å¹…å€¼éšç€å£åŽšçš„å¢žå¤§è€Œå‡å°ï¼Œéšç€æ³¢åŠ¨é€Ÿåº¦çš„å¢žå¤§è€Œå¢žå¤§ã€‚%In order to study the dynamic characteristics of more curved pipe system , according to the fluid-structure coupling and the finite element theory , the inherent characteristics of L-type pile were simulated .The results were compared with that calculated by TMM ( Transfer Matrix Method ) , which proved that the FE model was rationality . The numerical model of underwater more curved pipe was established , the fluid-structure coupling modal analysis was conducted , and the effects of wall thickness and diameter on the natural frequency were studied .The dynamic response of pipe under the unsteady flow was analyzed , the influence of wall thickness and wave speed on the pipe vibration were researched .The results showed that the natural frequency of pipe system drops when considering the three couplings among outer and inter fluid with pipe , compared with the two coupling between inter fluid with pipe and no coupling .The natural frequency of the pipe increases with the increasing of wall thickness
Institute of Scientific and Technical Information of China (English)
éƒ‘å°æ³¢; çŽ‹çŽ²å†›; ç¿å‡¯
2016-01-01
ä¸ºäº†æ·±å…¥ç ”ç©¶æµå›ºè€¦åˆä½œç”¨å¯¹è´¯æµå¼æ°´è½®æœºè½¬è½®åŠ¨åŠ›ç‰¹æ€§åŠå†…éƒ¨æµåœºçš„å½±å“ï¼Œæ–‡ä¸é‡‡ç”¨å•†ä¸šè½¯ä»¶CFXå’ŒANSYS APDLå¯¹è´¯æµå¼æ°´è½®æœºæµä½“åŸŸå’Œå›ºä½“åŸŸè¿›è¡Œè€¦åˆæ±‚è§£ï¼Œåˆ†æžäº†è€¦åˆä½œç”¨å¯¹ç»“æž„åº”åŠ›åŠåº”å˜çš„å½±å“ï¼Œå¹¶å°†è€¦åˆæ•°å€¼è®¡ç®—å¾—åˆ°çš„è½¬è½®å¤–ç‰¹æ€§ä¸Žå®žæµ‹å€¼è¿›è¡Œäº†å¯¹æ¯”ã€‚ç»“æžœè¡¨æ˜Žï¼šè€ƒè™‘è€¦åˆä½œç”¨åŽï¼Œè½¬è½®çš„æ•ˆçŽ‡ã€æ°´å¤´ä¸Žè€¦åˆå‰ç›¸æ¯”éƒ½æœ‰ä¸åŒç¨‹åº¦çš„ä¸‹é™ï¼Œæœ€å¤§å€¼åˆ†åˆ«ä¸º0.6%ã€0.21 mã€‚åŒæ—¶åœ¨é è¿‘å¶ç‰‡å‡ºæ°´è¾¹è½®ç¼˜é™„è¿‘ï¼Œè€¦åˆåŽåŽ‹åŠ›é¢ä¸Žå¸åŠ›é¢åŽ‹åŠ›å·®æœ‰æ‰€ä¸‹é™ï¼Œè¯´æ˜Žè€¦åˆä½œç”¨ä¼šé™ä½Žè½¬è½®çš„æ°´åŠ›æ€§èƒ½ã€‚2ç§è€¦åˆè®¡ç®—æ–¹æ³•æ±‚è§£å¾—åˆ°çš„å¶ç‰‡çš„ç‰æ•ˆåº”åŠ›åˆ†å¸ƒåŸºæœ¬ä¸€è‡´ï¼Œåº”åŠ›é›†ä¸éƒ½å‡ºçŽ°åœ¨è½¬è½®å¶ç‰‡ä¸Žæž¢è½´æ³•å…°è”æŽ¥å¤„ï¼ŒåŒæ—¶åŒå‘è€¦åˆä¸‹æœ€å¤§ç‰æ•ˆåº”åŠ›çš„ä¸»é¢‘ä¸Žå•å‘è€¦åˆç›¸æ¯”æœ‰æ˜Žæ˜¾ä¸‹é™çš„è¶‹åŠ¿ï¼Œç”±äºŽåŒå‘è€¦åˆè€ƒè™‘äº†ç»“æž„åœ¨è¿åŠ¨è¿‡ç¨‹ä¸å‘¨å›´æ°´ä½“ä¸Žç»“æž„çš„ç›¸äº’å½±å“ã€‚è¯¥ç ”ç©¶ä¸ºå®žé™…å·¥ç¨‹ä¸å‡†ç¡®åœ°è¿›è¡Œè½¬è½®çš„æ°´åŠ›æ€§èƒ½é¢„ä¼°å’Œå¶ç‰‡ç»“æž„åœ¨æ°´ä¸çž¬æ€å“åº”è®¡ç®—æä¾›äº†å‚è€ƒã€‚%In order to study the stress, displacement and flow characteristics of flow field of the tubular turbine under the effect of coupling, the flow field and the structural response of the runner blade in the tubular turbine are calculated in one-way and two-way coupling by using the commercial software ANSYS 12.0 CFX and ANSYS APDL. The flow field is based on RANS control equation, two-equation SST-Ï‰turbulence model and runner blade structure of the solid domain using the equations of the motion of elastic structure. The fluid-structure coupling numerical calculation of the tubular turbine under different working conditions is carried out for stress and displacement of the runner blade and the distribution of the pressure field of the runner in this paper. The calculated structural stress, the displacement distribution and the variation trend of the structure are compared. The difference of
... carefully. Removing a sample of the fluid through amniocentesis can provide information about the sex, health, and development of the fetus. Images Amniocentesis Amniotic fluid Polyhydramnios Amniotic fluid References Cunningham FG, ...
Institute of Scientific and Technical Information of China (English)
åˆ˜é«˜æ´; éƒç…§ç«‹; æ–½ä¿æ˜Œ
2016-01-01
The flow and diffusion of miscible fluid in a porous medium with a high PÂ´elcet number (Pe) and large viscosity ratio widely exist in industrial processes, such as oil recovery, geological sequestration of carbon dioxide, and chemical engineering process. When these problems are studied by numerical methods, the key point is to accurately describe the flow dynamics and diffusion process in a porous medium at the same time. As an alternative to conventional numerical methods, the lattice Boltzmann method based on kinetic theory is well suited to pore-scale simulations of miscible fluid flows and molecular diffusion. However, most of the existing lattice Boltzmann models have many diï¬ƒculties (e.g. robustness and numerical stability) in simulating such systems at high Pe and large viscosity ratio. In this paper, in order to overcome the above diï¬ƒculties, we propose a coupled lattice Boltzmann model based on the multiple-relaxation-time model and the lattice kinetic scheme for the fluid flow and diffusion, respectively. It can be shown that the incompressible Navier-Stokes equations and the convection-diffusion equation can be derived from the presented coupled model through the Chapman-Enskog procedure. The proposed model is validated by simulating a concentration gradient driven flow in a porous channel. Numerical results demonstrate that the model is of second-order accuracy in space. We further simulate a flow through two types of artificial porous media. The robustness of the presented model is investigated by measuring the permeability and diffusivity under different relaxation times. It is found that the model is insensitive to relaxation parameters. In addition, the miscible viscous displacement in two parallel plates is simulated to test the numerical stability of the model. It is observed that the results accord well with those reported in previous work, and the model is very stable at high Pe and large viscosity ratio in comparison with the standard
Energy Technology Data Exchange (ETDEWEB)
Shin, Chang Hwan; Seo, Kyong Won; Chun, Tae Hyun; Kim, Kang Seog
2005-03-15
Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too.
Institute of Scientific and Technical Information of China (English)
æž—é•¿äº®; çŽ‹æµ©æ–‡; é™ˆä»è‰¯; å°šæ™“å†¬
2012-01-01
During the process of bird impact on helicopter blades, the relative speed is quite fast and the bird presents the fluid characteristic. So the impact between the bird and helicopter blade is a typical transient fluid-structure coupling dynamics. Firstly, to verify the calculation method and the bird model, the bird impact on aluminum plate test in the literature is analyzed by adopting ALE fluid-solid coupling method. Then numerical simulation of bird impact on the blades is conducted. The numerical simulation results show that the ALE method can accurately simulate and be applied to the process of bird impact on helicopter blade. The detailed analysis to the calculation result such as stress, displacement and impact pressure provides a reference to anti-bird impact on helicopter rotor design.%åœ¨é¸Ÿæ’žç›´å‡æœºæ¡¨å¶è¿‡ç¨‹ä¸,é¸Ÿä½“ä¸Žæ¡¨å¶æ’žå‡»ç›¸å¯¹é€Ÿåº¦å¾ˆå¤§,å‘ˆçŽ°å‡ºæµä½“ç‰¹æ€§,å±žäºŽå…¸åž‹çš„æµå›ºè€¦åˆçž¬æ€å†²å‡»åŠ¨åŠ›å¦é—®é¢˜.é¦–å…ˆé’ˆå¯¹æ–‡çŒ®ä¸çš„é¸Ÿæ’žé“æ¿è¯•éªŒé‡‡ç”¨ALEæµå›ºè€¦åˆæ–¹æ³•è¿›è¡Œäº†åˆ†æž,å¯¹è®¡ç®—æ–¹æ³•ä¸Žé¸Ÿä½“æ¨¡åž‹è¿›è¡Œäº†éªŒè¯.ç„¶åŽè¿›è¡Œäº†æ¡¨å¶é¸Ÿæ’žæ•°å€¼æ¨¡æ‹Ÿ.æ•°å€¼æ¨¡æ‹Ÿç»“æžœè¡¨æ˜ŽALEæ–¹æ³•èƒ½å¤Ÿå‡†ç¡®æ¨¡æ‹Ÿé¸Ÿæ’žè¿‡ç¨‹,é€‚ç”¨äºŽç›´å‡æœºæ¡¨å¶é¸Ÿæ’žåˆ†æž.é€šè¿‡åº”åŠ›ã€ä½ç§»ä»¥åŠæ’žå‡»åŽ‹åŠ›ç‰è®¡ç®—ç»“æžœçš„è¯¦ç»†åˆ†æž,å¯¹ç›´å‡æœºæ—‹ç¿¼æŠ—é¸Ÿæ’žè®¾è®¡å…·æœ‰ä¸€å®šçš„å‚è€ƒä»·å€¼.
Energy Technology Data Exchange (ETDEWEB)
Schunk, P.R.; Sackinger, P.A.; Rao, R.R. [and others
1996-01-01
GOMA is a two- and three-dimensional finite element program which excels in analyses of manufacturing processes, particularly those involving free or moving interfaces. Specifically, the full-Newton-coupled heat, mass, momentum, and pseudo-solid mesh motion algorithm makes GOMA ideally suited for simulating processes in which the bulk fluid transport is closely coupled to the interfacial physics. Examples include, but are not limited to, coating and polymer processing flows, soldering, crystal growth, and solid-network or solution film drying. The code is based on the premise that any boundary can be (1) moving or free, with an apriori unknown position dictated by the distinguishing physics, (2) fixed, according to a global analytical representation, or (3) moving in time and space under user-prescribed kinematics. The goal is to enable the user to predict boundary position or motion simultaneously with the physics of the problem being analyzed and to pursue geometrical design studies and fluid-structure interaction problems. The moving mesh algorithm treats the entire domain as a computational Lagrangian solid that deforms subject to the physical principles which dictate boundary position. As an added benefit, the same Lagrangian solid mechanics can be exploited to solve multi-field problems for which the solid motion and stresses interact with other transport phenomena, either within the same material phase (e.g. shrinking coating) or in neighboring material phases (e.g. flexible blade coating). Thus, analyses of many fluid-structure interaction problems and deformable porous media problems are accessible. This document serves as a user`s guide and reference for GOMA and provides a brief overview of GOMA`s capabilities, theoretical background, and classes of problems for which it is targeted.
Institute of Scientific and Technical Information of China (English)
ZHAO Li-Yun; GUO Bo-Ling; HUANG Hai-Yang
2011-01-01
@@ The explicit solutions to both the Oldroyd-B model with an infinite Weissenberg number and the coupled Navier- Stokes/phase-field system are constructed by the method of separation of variables.It is found that the solutions blow up in finite time.%The explicit solutions to both the Oldroyd-B model with an infinite Weissenberg number and the coupled Navier- Stokes/phase-Beld system are constructed by the method of separation of variables. It is found that the solutions blow up in finite time.
Yuen, Po Ki
2013-05-07
This article presents a simple method for controlling fluid in microfluidic devices without the need for valves or pumps. A fluid conveyance extension is fluidly coupled to the enclosed outlet chamber of a microfluidic device. After a fluid is introduced into the microfluidic device and saturates the fluid conveyance extension, a fluid flow in the microfluidic device is generated by contacting an absorbent microfluidic flow modulator with the fluid conveyance extension to absorb the fluid from the fluid conveyance extension through capillary action. Since the fluid in the microfluidic device is fluidly coupled with the fluid conveyance extension and the fluid conveyance extension is fluidly coupled with the absorbent microfluidic flow modulator, the absorption rate of the absorbent microfluidic flow modulator, which is the rate at which the absorbent microfluidic flow modulator absorbs fluid, matches the fluid flow rate in the microfluidic device. Thus, the fluid flow rate in the microfluidic device is set by the absorption rate of the absorbent microfluidic flow modulator. Sheath flow and fluid switching applications are demonstrated using this simple fluid control method without the need for valves or pumps. Also, the ability to control the fluid flow rate in the microfluidic device is demonstrated using absorbent microfluidic flow modulators with various absorbent characteristics and dimensions.
Institute of Scientific and Technical Information of China (English)
é©¬è‰³è‰³
2011-01-01
We investigate the influential factors on the performance of journal bearings lubricated with couple stress fluids.We analyzed pressure distribution along the circumferential direction for various dynamic parameters,elastic coefficient and couple stress parameters,load-carrying capacity for various elastic coefficient and dynamic parameter,attitude angle and friction coefficient for various eccentricity ratio.The numerical results show that the value of the maximum pressure for a bearing increases with dynamic parameters,and the couple stress effect is more obvious.The bearing load-carrying capacity decreases with the increase of elastic coefficient and increases with the couple stress parameters or dynamic parameters.The couple stress makes the attitude angle increase and the friction coefficient decrease.%ç ”ç©¶äº†åº”åŠ›å¶æµä½“æ¶¦æ»‘æ»‘åŠ¨è½´æ‰¿æ€§èƒ½çš„å½±å“å› ç´ ã€‚åˆ†æžäº†ä¸åŒçš„åŠ¨åŠ›å‚æ•°ã€å¼¹æ€§ç³»æ•°ä¸Žåº”åŠ›å¶å‚æ•°å¯¹è½´æ‰¿ä¸æˆªé¢å‘¨å‘æ²¹è†œåŽ‹åŠ›åˆ†å¸ƒçš„å½±å“,ä¸åŒçš„å¼¹æ€§ç³»æ•°ä¸ŽåŠ¨åŠ›å‚æ•°å¯¹è½´ç“¦æ‰¿è½½åŠ›çš„å½±å“ä»¥åŠæ‰¿è½½åŠ›çš„ä½œç”¨è§’å’Œæ‘©æ“¦ç³»æ•°éšåå¿ƒçŽ‡çš„å˜åŒ–ã€‚ç»“æžœè¡¨æ˜Žï¼šåŠ¨åŠ›å‚æ•°è¶Šå¤§,æœ€å¤§æ²¹è†œåŽ‹åŠ›è¶Šå¤§,åº”åŠ›å¶æ•ˆåº”è¶Šæ˜¾è‘—;å¼¹æ€§ç³»æ•°è¶Šå¤§è½´æ‰¿çš„æ‰¿è½½åŠ›è¶Šå°è€Œåº”åŠ›å¶å‚æ•°ä¸ŽåŠ¨åŠ›å‚æ•°è¶Šå¤§è½´æ‰¿çš„æ‰¿è½½åŠ›è¶Šå¤§;åº”åŠ›å¶å‚æ•°è¶Šå¤§,æ‰¿è½½åŠ›çš„ä½œç”¨è§’å¢žå¤§,æ‘©æ“¦ç³»æ•°å‡å°ã€‚
Fluid Dynamics and Viscosity in Strongly Correlated Fluids
Schaefer, Thomas
2014-01-01
We review the modern view of fluid dynamics as an effective low energy, long wavelength theory of many body systems at finite temperature. We introduce the notion of a nearly perfect fluid, defined by a ratio $\\eta/s$ of shear viscosity to entropy density of order $\\hbar/k_B$ or less. Nearly perfect fluids exhibit hydrodynamic behavior at all distances down to the microscopic length scale of the fluid. We summarize arguments that suggest that there is fundamental limit to fluidity, and review the current experimental situation with regard to measurements of $\\eta/s$ in strongly coupled quantum fluids.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Y.; Lu, T., E-mail: likesurge@sina.com
2016-12-01
Highlights: â€¢ Two characteristic parameters of the temperature fluctuations are used for qualitative analysis. â€¢ A quantitative assessment method for high-cycle thermal fatigue of a T-pipe is proposed. â€¢ The time-dependent curves for the temperature and thermal stress are not always â€œin-phaseâ€. â€¢ Large magnitude of thermal stresses may not mean large number of fatigue cycles. â€¢ The normalized fatigue damage rate and normalized RMS temperature are positively related. - Abstract: With the development of nuclear power and nuclear power safety, high-cycle thermal fatigue of the pipe structures induced by the flow and heat transfer of the fluid in pipes have aroused more and more attentions. Turbulent mixing of hot and cold flows in a T-pipe is a well-recognized source of thermal fatigue in piping system, and thermal fatigue is a significant long-term degradation mechanism. It is not an easy work to evaluate thermal fatigue of a T-pipe under turbulent flow mixing because of the thermal loads acting at fluidâ€“structure interface of the pipe are so complex and changeful. In this paper, a one-way Computational Fluid Dynamics-Finite Element Method (CFD-FEM method) coupling based on the ANSYS Workbench 15.0 software has been developed to calculate transient thermal stresses with the temperature fields of turbulent flow mixing, and thermal fatigue assessment has been carried out with this obtained fluctuating thermal stresses by programming in the software platform of Matlab based on the rainflow counting method. In the thermal analysis, the normalized mean temperatures and the normalized root mean square (RMS) temperatures are obtained and compared with the experiment of the test case from the Vattenfall benchmark facility to verify the accuracy of the CFD calculation and to determine the position which thermal fatigue is most likely to occur in the T-junction. Besides, more insights have been obtained in the coupled CFD-FEM analysis and the thermal fatigue
Institute of Scientific and Technical Information of China (English)
æ¨Šæ´ªæµ·; çŽ‹å®‡; å¼ ä¸½è; æ¨è¡Œ; æ¨å‘åŒ; éå³°
2011-01-01
çž¬æ€åŽ‹åŠ›å†²å‡»è¯±å‘å……æ¶²ç®¡é“ç»“æž„è€¦åˆæŒ¯åŠ¨,å‰§çƒˆçš„æŒ¯åŠ¨å°†å¯¼è‡´ç®¡é“ç»“æž„å¤±æ•ˆ.ç¬”è€…å°†è¿›ä¸€æ¥é˜æ˜Žå¤©ç„¶æ°”çš„çž¬å˜æµåŠ¨è¯±å‘é«˜åŽ‹æ°”äº•å®Œäº•ç®¡æŸ±çš„è€¦åˆæŒ¯åŠ¨è¿‡ç¨‹.æ ¹æ®å……æ¶²ç®¡é“æµå›ºè€¦åˆæŒ¯åŠ¨æ¨¡åž‹,æŽ¨å¯¼äº†é€‚ç”¨äºŽæ°”äº•å®Œäº•ç®¡æŸ±çš„æµå›ºè€¦åˆæŒ¯åŠ¨å››æ–¹ç¨‹æ¨¡åž‹,é‡‡ç”¨ç‰¹å¾çº¿æ³•åŠçº¿æ€§æ’å€¼æ–¹æ³•è¿›è¡Œæ•°å€¼æ±‚è§£.ä»¥çŽ°åœºä¸€å£é«˜åŽ‹æ°”äº•äº•å£é˜€é—¨å¼€å¯è¿‡ç¨‹ä¸çš„çž¬æ€å“åº”ä¸ºä¾‹,ç»“åˆå®Œäº•ç®¡æŸ±ç³»ç»Ÿçš„åˆè¾¹å€¼æ¡ä»¶,åˆ©ç”¨MATLABè¯è¨€ç¼–åˆ¶äº†ç›¸åº”çš„è®¡ç®—æœºç¨‹åº,è®¡ç®—åˆ†æžäº†æµä½“ä¸Žç®¡æŸ±çš„è€¦åˆæŒ¯åŠ¨å“åº”è¿‡ç¨‹.è®¡ç®—ç»“æžœè¡¨æ˜Ž:å¤©ç„¶æ°”çš„çž¬å˜æµåŠ¨é€šè¿‡æ³Šæ¾è€¦åˆæ•ˆåº”è¯±å‘å®Œäº•ç®¡æŸ±è½´å‘å¾€å¤è¿åŠ¨,è½´å‘å¾€å¤è¿åŠ¨å°†åŠ å‰§å®Œäº•ç®¡æŸ±ç»“æž„çš„ç–²åŠ³ç ´åä¸Žç£¨æŸç ´å.è¯¥ç»“æžœå¯¹é¢„é˜²å®Œäº•ç®¡æŸ±å…ˆæœŸå¤±æ•ˆæœ‰å®žé™…å·¥ç¨‹æ„ä¹‰.%Transient pressure fluctuations in a liquid-filled pipe could induce coupled oscillations of pipe structures, even a structural failure if severe.The present paper elaborated the coupled oscillation process of completion string induced by transient flow of natural gas, and a fluid-solid coupled oscillation four-equation model applicable to completion string in gas wells was derived based on the fluid-solid coupled oscillation model for liquid-filled pipes.The model was numerically solved by the characteristic method and linear interpolation.Taking a transient flow caused instantaneously by opening the valve of a high-pressure gas well as an example, a corresponding software, combined with initial and boundary conditions, was programmed with the MATLAB code, which could calculate and analyze the process in response to coupled oscillations derived from fluid and pipe string.The calculation indicated that the transient flow of natural gas could induce an axial reciprocation of completion string by the Poisson coupling effect, which would aggravate the structural damage of completion string via stress fatigue and rubbing abrasion
Energy Technology Data Exchange (ETDEWEB)
Sigrist, J.F. [DCN Propulsion, Service Technique et Scientifique, 44 - La Montagne (France); Broc, D. [CEA Saclay, Lab. d' Etude Mecanique et Sismique, 91 - Gif-sur-Yvette (France)
2007-03-15
A homogenization method is presented and validated in order to perform the dynamic analysis of a nuclear pressure vessel with a 'reduced' numerical model accounting for inertial fluid-structure coupling and describing the geometrical details of the internal structures, periodically embedded within the nuclear reactor. Homogenization techniques have been widely used in nuclear engineering to model confinement effects in reactor cores or tubes bundles. Application of such techniques to reactor internals is investigated in the present paper. The theory bases of the method are first recalled. Adaptation of the homogenization approach to the case of reactor internals is then exposed: it is shown that in such case, confinement effects can be modelled by a suitable modification of classical fluid-structure symmetric formulation. The method is then validated by comparison of 3D and 2D calculations. In the latter, a 'reduced' model with homogenized fluid is used, whereas in the former, a full finite element model of the nuclear pressure vessel with internal structures is elaborated. The homogenization approach is proved to be efficient from the numerical of view point and accurate from the physical point of view. Confinement effects in the industrial case can then be highlighted. (authors)
Lemasson, Elise; Bertin, Sophie; Hennig, Philippe; Lesellier, Eric; West, Caroline
2016-11-11
Impurity profiling of organic products synthesized as possible drug candidates represents a major analytical challenge. Complementary analytical methods are required to ensure that all impurities are detected. Both high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) can be used for this purpose. In this study, we compared ultra-high performance HPLC (UHPLC) and ultra-high performance SFC (UHPSFC) using a large dataset of 140 pharmaceutical compounds. Four previously optimized methods (two on each technique) were selected to ensure fast high-resolution separations. The four methods were evaluated based on response rate, peak capacity, peak shape and capability to detect impurities (UV). The orthogonality between all methods was also assessed. The best UHPLC method and UHPSFC methods provided comparable quality for the 140 compounds included in this study. Moreover, they were found to be highly orthogonal. At last, the potential of the combined use of UHPLC and UHPSFC for impurity profiling is illustrated with practical examples.
Institute of Scientific and Technical Information of China (English)
å¼ æ™“å…‰; çŽ‹é•¿è¾‰; åˆ˜å®‡; ä»»å†›å¦
2011-01-01
In order to accurately predict the thermal and structural behavior of throat inserts in solid rocket-motor environments, a fluid-thermal-structural coupling model was established based on CFD code FLUENT and FEM code ANSYS. Fully coupled fluid-solid analysis was performed first to simulate the heat transfer and material erosion process, using the method of whole-field discretization and solution in FLUENT. Subsequently, the structural analysis was carried out in ANSYS based on the resulting pressure and thermal loading. In such a procedure, two-way coupling was considered between flow and heat transfer while one-way coupling method was employed in structural analysis. Numerical results show that the convective heat transfer coefficient gradually decreases with increase of wall temperature during the motor firing. The wall temperature and erosion rate follow the trend exhibited by the heat flux distribution, and attain peak at upstream of the throat. The stress is most severe in the throat region due to the steep temperature gradient.%ä¸ºäº†å‡†ç¡®é¢„ç¤ºå›ºä½“ç«ç®å‘åŠ¨æœºå–‰è¡¬åœ¨ç‡ƒæ°”çŽ¯å¢ƒä¸çš„çƒ§èš€ä¼ çƒåŠçƒç»“æž„è¡Œä¸º,å»ºç«‹äº†åŸºäºŽFLUENTæµä½“è®¡ç®—è½¯ä»¶å’ŒANSYSç»“æž„åˆ†æžè½¯ä»¶çš„æµåœºåŠçƒç»“æž„è€¦åˆåˆ†æžæ¨¡åž‹.ç”±FLUENTé‡‡ç”¨æ•´åœºç¦»æ•£ã€æ•´åœºæ±‚è§£çš„æ–¹æ³•è¿›è¡Œæµå›ºè€¦åˆçƒ§èš€ä¼ çƒæ¨¡æ‹Ÿ,å¾—åˆ°çš„åŽ‹å¼ºåŠæ¸©åº¦åˆ†å¸ƒå¯¼å…¥ANSYSè¿›è¡Œç»“æž„åˆ†æž,å®žçŽ°äº†æµåœºä¸Žçƒ§èš€ä¼ çƒçš„åŒå‘è€¦åˆä»¥åŠæµåœºã€çƒåˆ°ç»“æž„çš„å•å‘è€¦åˆ.ç®—ä¾‹ç»“æžœè¡¨æ˜Ž,åœ¨å‘åŠ¨æœºå·¥ä½œè¿‡ç¨‹ä¸,å–‰è¡¬å†…å£å¯¹æµæ¢çƒç³»æ•°å› å£æ¸©å‡é«˜è€Œé€æ¸é™ä½Žï¼›å†…å£æ¸©åº¦åŠçƒ§èš€çŽ‡éµå¾ªå†…å£çƒæµå¯†åº¦çš„åˆ†å¸ƒè§„å¾‹,åœ¨å–‰éƒ¨ä¸Šæ¸¸è¾¾åˆ°å³°å€¼ï¼›å–‰éƒ¨åŒºåŸŸå¯¹æµæ¢çƒä¸¥é‡,å›ºç›¸ææ–™æ¸©åº¦æ¢¯åº¦é«˜,æ˜¯åº”åŠ›é›†ä¸åŒº.
Institute of Scientific and Technical Information of China (English)
é‡‘ç‚œæž«; å‘¨å¥
2015-01-01
ä¸ºäº†å°†åªé€‚ç”¨äºŽå›ºä½“çš„ç¦»æ•£é¢—ç²’â€“è¿žç»åœŸä½“è€¦åˆæ–¹æ³•åº”ç”¨è‡³é¥±å’ŒåœŸä½“ï¼Œæž„å»ºæµä½“ä¸Žç¦»æ•£é¢—ç²’â€“è¿žç»åœŸä½“çš„è€¦åˆæ¡†æž¶ï¼Œæ¤æ¡†æž¶è¦æ±‚æµä½“æ–¹ç¨‹å…·æœ‰è¾¹ç•Œç½‘æ ¼ç§»åŠ¨èƒ½åŠ›ï¼Œå¹¶ä¸”æµä½“æ–¹ç¨‹åˆ†åˆ«ä¸Žç¦»æ•£é¢—ç²’å’Œè¿žç»åœŸä½“è€¦åˆæ—¶å…·æœ‰ç»Ÿä¸€çš„å½¢å¼ã€‚ç„¶åŽå»ºç«‹æ–°çš„æµä½“æ–¹ç¨‹ç»„ï¼Œæ¤æµä½“æ–¹ç¨‹ç»„åŸºäºŽä»»æ„æ‹‰æ ¼æœ—æ—¥â€“æ¬§æ‹‰æè¿°ä»¥å®žçŽ°æµä½“è¾¹ç•Œç½‘æ ¼ç§»åŠ¨æŽ§åˆ¶ï¼Œå¹¶ä¸”åœ¨ç¦»æ•£é¢—ç²’å’Œè¿žç»åœŸä½“åŒºåŸŸä»¥ä¸åŒæ–¹å¼æå–çš„æµå›ºè€¦åˆåŠ›å¯ä»¥çº³å…¥ç»Ÿä¸€çš„æµä½“æ–¹ç¨‹è¿›è¡Œè®¡ç®—ã€‚ä¸ºäº†ä¿è¯æµä½“å¾®åˆ†æ–¹ç¨‹æœ‰é™å…ƒç¦»æ•£åŽçš„ç¨³å®šæ€§ï¼ŒåŸºäºŽç‰¹å¾çº¿åˆ†ç¦»æ–¹æ³•å¯¹å»ºç«‹çš„æµä½“æ–¹ç¨‹è¿›è¡Œåˆ†ç¦»åˆ†æ¥ï¼Œç„¶åŽåŸºäºŽæ ‡å‡†ä¼½è¾½é‡‘ç¦»æ•£èŽ·å¾—å…¶æœ‰é™å…ƒæ ¼å¼ã€‚æœ€åŽé€šè¿‡æ¨¡æ‹Ÿå¯æ¶²åŒ–åœºåœ°ä¸åœ°ä¸‹ç®¡çº¿åœ°éœ‡å“åº”çš„ç¦»å¿ƒæœºè¯•éªŒï¼Œè¡¨æ˜Žå¼•å…¥æµä½“æ–¹ç¨‹åŽçš„ç¦»æ•£é¢—ç²’â€“è¿žç»åœŸä½“è€¦åˆæ–¹æ³•å¯ä»¥æœ‰æ•ˆæè¿°ç¦»æ•£é¢—ç²’ä¸Žåœ°ä¸‹ç»“æž„çš„éžè¿žç»åŠ¨åŠ›æŽ¥è§¦ä½œç”¨ï¼ŒåŒæ—¶æœ‰æ•ˆé™ä½Žç¦»æ•£å…ƒçš„æ¨¡æ‹Ÿè§„æ¨¡ï¼Œå¹¶ä¸”å¯ä»¥å…¼é¡¾åœ°ä¸‹ç»“æž„ç§»åŠ¨æ—¶æµä½“çš„è¾¹ç•Œç§»åŠ¨é—®é¢˜ã€‚%For the approach of coupled discrete-continuous solids for solid phase to be extended to saturated soil, a theoretical framework of coupling the fluid with the discrete-continuous solids was established. The unified dynamic equations for the fluid-phase were established based on the ALE(arbitrary Lagrangian Eulerian) description which controlled the moving boundaries and meshes conveniently. The interaction forces between the fluid and the solid derived in the discrete and continuous domains separately were incorporated in these fluid equations in a unified form. The dynamic equations of fluid were split based on the algorithm of splitting the characteristic curves to obtain the proper forms suitable for the application of the standard Galerkin discretization procedure. The proposed method was applied to simulate the underground structure buried in the liquefiable soil under seismic
Institute of Scientific and Technical Information of China (English)
è”¡å®šå›½; å§šè‚²æˆ; å¾ä¸šå½¬; å”é‡‘æƒ
2012-01-01
å£é¢ç©ºæ°”å¯¹æµæ¢çƒåˆ†æžæ˜¯å½±å“çŽ¯æ°§æµ‡æ³¨å¹²å¼å˜åŽ‹å™¨æ¸©åº¦åœºæ•°å€¼æ¨¡æ‹Ÿå‡†ç¡®ä¸Žå¦çš„ä¸»è¦å› ç´ .ä¸ºäº†æ¨¡æ‹Ÿå¯¹æµæ¢çƒè¿‡ç¨‹,æ‘†è„±æ°”é“å‚æ•°å¯¹å˜åŽ‹å™¨æ¸©å‡è®¡ç®—ç»“æžœçš„å½±å“,ä»Žç©ºæ°”è´¨é‡ã€åŠ¨é‡ã€èƒ½é‡å®ˆæ’æ–¹ç¨‹å‡ºå‘,å»ºç«‹å¹²å¼å˜åŽ‹å™¨æµå›ºè€¦åˆåœºæ•°å€¼æ¨¡åž‹,é‡‡ç”¨æœ‰é™å·®åˆ†æ³•å¯¹æ¸©åº¦åœºè¿›è¡Œäº†è®¡ç®—,å¹¶ä¸Žå®žéªŒç»“æžœè¿›è¡Œäº†æ¯”è¾ƒ,æ¨¡æ‹Ÿç»“æžœä¸Žå®žéªŒå»åˆè¾ƒå¥½.è€ƒè™‘ç©ºæ°”æµåœºçš„æµå›ºè€¦åˆæ¨¡åž‹èƒ½å‡†ç¡®åˆ†æžå¹²å¼å˜åŽ‹å™¨å·¥ä½œä¸çš„æ¸©å‡é—®é¢˜,å¯åˆ†æžå˜åŽ‹å™¨å†…éƒ¨æ¸©åº¦åˆ†å¸ƒè§„å¾‹åŠå½±å“æ¸©åº¦åˆ†å¸ƒçš„å› ç´ ,æŒ‡å¯¼å˜åŽ‹å™¨ä¼˜åŒ–è®¾è®¡.%The analyzing of the wall and air convection heat exchange greatly affects accuracy of the numerical simulation of the cast-resin dry type transformer temperature field. In order to get rid of the influence of the air way parameters and simulate the convection heat exchange physics process accurately, the numerical model of the dry type transformer fluid solid coupling field is set up from the continuity, momentum and energy conservation equations. The temperature field is calculated by finite difference method and compared to the experiment. The simulation results fit the experiment well. The temperature rise and its influence factors may be analyzed by the fluid solid coupling model considering the air flow. It provides guidance to the transformer optimal design.
Sigrist, J. F.; Laine, C.; Peseux, B.
2002-12-01
Une prÃ©occupation constante de tout industriel est la maÃ®trise des marges de dimensionnement de ses structures. Le recours aux techniques de calcul scientifique permet en phase de conception dÃ©taillÃ©e un dimensionnement au plus juste des structures, tout en respectant les diffÃ©rentes contraintes de conception (exigences fonctionnelles, conditions d'environnement, aspects rÃ©glementaires). Une meilleure maÃ®trise des marges passe donc par une meilleure connaissance de l'outil de calcul (prÃ©cision intrinsÃ¨que, mise en Å“uvre de techniques de calcul plus ou moins Ã©laborÃ©es) et la prise en compte d'une rÃ©alitÃ© physique plus complexe (avec par exemple un couplage entre diffÃ©rents phÃ©nomÃ¨nes physiques) pour une meilleure reprÃ©sentativitÃ© du calcul. Une dÃ©marche globale de recherche et dÃ©veloppement a Ã©tÃ© mise en place au sein du Service Scientifique et Technique de l'Ã©tablissement DCN de Nantes Indret pour rÃ©pondre Ã ce besoin. Nous prÃ©sentons ici un exemple d'application pour le calcul de structures en prÃ©sence de fluide. Cette Ã©tude numÃ©rique et expÃ©rimentale nous permet de valider conjointement le processus de calcul en bureau d'Ã©tude et les mÃ©thodes de mesure sur site dans le domaine de l'analyse frÃ©quentielle de structures mouillÃ©es.
Institute of Scientific and Technical Information of China (English)
æ›¹çª; æŽè¿›è´¤; å”é‡‘å…°; å†¯å–œå¹³; ä¾¯æ™“
2009-01-01
The Fluid-Structure Interactions (FSI) phenomena in solid rocket motor ignition transient taken much more attention with the first prequalification motor (PQM-1) in the Titan IV Solid Rocket Motor exploded during the first full - scale static test firing. In this paper,research actuality and development trend of FSI which are from three parts-ignition gas flow,grain deformation and experiment are summarized at home and abroad. Combined with our national development conditions,the new approach on studying coupled Fluid-Structure in SRM ignition transient are discussed preliminarily.%éšç€ç¾Žå›½"å¤§åŠ›ç¥ž4"é¦–å‘å…¨å°ºå¯¸é™æ€è¯•éªŒå‘åŠ¨æœºPQM-1çš„å¤±è´¥,å›ºä½“å‘åŠ¨æœºç‚¹ç«çž¬é—´çš„æµå›ºè€¦åˆçŽ°è±¡é€æ¸å¾—åˆ°äº†äººä»¬çš„é‡è§†.æœ¬æ–‡å°†æµå›ºè€¦åˆç ”ç©¶çŽ°çŠ¶åˆ†ä¸ºç‚¹ç«ç‡ƒæ°”æµåŠ¨ã€è¯æŸ±å˜å½¢å’Œå®žéªŒç ”ç©¶ä¸‰ä¸ªæ–¹é¢,ç»¼è¿°äº†å›½å†…å¤–çš„å‘å±•çŽ°çŠ¶ä¸Žè¶‹åŠ¿.ç»“åˆæˆ‘å›½å‘å±•çš„å®žé™…æƒ…å†µ,åˆæ¥æŽ¢è®¨äº†ç ”ç©¶å›ºä½“å‘åŠ¨æœºç‚¹ç«çž¬é—´æµå›ºè€¦åˆçš„æ–°æ–¹æ³• .
Hardick, Justin; Won, Helen; Jeng, Kevin; Hsieh, Yu-Hsiang; Gaydos, Charlotte A; Rothman, Richard E; Yang, Samuel
2012-07-01
Spontaneous bacterial peritonitis (SBP) can be a severe complication occurring in patients with cirrhosis and ascites, with associated mortality often as high as 40%. Traditional diagnostics for SBP rely on culture techniques for proper diagnosis, although recent reports suggest that the presence of bacterial DNA in peritoneal fluid in patients with cirrhosis and ascites is an indicator of SBP. A previously published broad-range PCR (16S PCR) coupled with high-resolution melt analysis (HRMA) was compared with standard culture techniques for diagnosis of SBP in 106 peritoneal fluid samples from patients with suspected SBP. The sensitivity and specificity for 16S PCR for detecting eubacterial DNA compared with those of standard culture techniques were 100% (17/17) and 91.5% (85/89), respectively. Overall, HRMA concordance with species identification was 70.6% (12/17), although the 5 samples that were discordant at the species level were SBP resulting from a polymicrobial infection, and species-level identification for polymicrobial infections is outside the capability of HRMA. Both the broad-range 16S PCR and HRMA analysis provide useful diagnostic adjunctive assays for clinicians in detecting and identifying pathogens responsible for SBP.
Institute of Scientific and Technical Information of China (English)
ä»˜ç£Š; å”å…‹ä¼¦; æ–‡åŽæ–Œ; çŽ‹ç»´æ…§; ä»˜ä¼¶
2012-01-01
ç»“åˆåŒ–å·¥è¡Œä¸šä¸ä½¿ç”¨çš„æŸåž‹å·ç®¡å£³å¼æ¢çƒå™¨çš„ç»“æž„å›¾å’Œå·¥è‰ºå‚æ•°,å¯¹æ¢çƒå™¨çš„ç»“æž„è¿›è¡Œäº†åˆç†çš„ç®€åŒ–,åˆ©ç”¨ANSYSå‚æ•°åŒ–å»ºæ¨¡æ–¹æ³•å»ºç«‹äº†ç®¡å£³å¼æ¢çƒå™¨çš„å‚æ•°åŒ–æ¨¡åž‹ã€‚åœ¨ANSYS FLUENT14.0æ•°å€¼æ¨¡æ‹Ÿè½¯ä»¶ä¸å¯¹æ¢çƒå™¨çš„æµä½“æµåŠ¨ä»¥åŠè€¦åˆä¼ çƒè¿›è¡Œäº†æ•°å€¼æ¨¡æ‹Ÿ,å¾—åˆ°ç®¡ç¨‹å’Œå£³ç¨‹æµä½“çš„æµé€Ÿåˆ†å¸ƒã€åŽ‹é™æƒ…å†µã€æ¸©åº¦åœºå˜åŒ–çš„ç»†èŠ‚ä¿¡æ¯ã€‚è¯¥å·¥ä½œå¯¹äºŽè®¾è®¡ä¼ çƒæ•ˆçŽ‡é«˜ã€æµä½“é˜»åŠ›å°çš„æ¢çƒå™¨è¿›è¡Œäº†æœ‰ç›ŠæŽ¢ç´¢ã€‚%This paper presented a numerical simulation of shell and tube heat exchanger fluid flow and coupled heat transfer.The structure of the heat exchanger currently being used in chemical industry was simplified.A numerical model of a shell and tube heat exchanger was established using ANSYS FLUENT14.0,under which the model was tested.Fluid velocity distribution,pressure drop conditions and temperature changes inside the heat exchanger tube were obtained and analyzed.This research could be beneficial to the design of heat exchanger with high heat transfer efficiencies and low fluid resistance.
Zhang, Yang; ToksÃ¶z, M Nafi
2012-08-01
The seismic response of saturated porous rocks is studied numerically using microtomographic images of three-dimensional digitized Berea sandstones. A stress-strain calculation is employed to compute the velocities and attenuations of rock samples whose sizes are much smaller than the seismic wavelength of interest. To compensate for the contributions of small cracks lost in the imaging process to the total velocity and attenuation, a hybrid method is developed to recover the crack distribution, in which the differential effective medium theory, the Kuster-ToksoÌˆz model, and a modified squirt-flow model are utilized in a two-step Monte Carlo inversion. In the inversion, the velocities of P- and S-waves measured for the dry and water-saturated cases, and the measured attenuation of P-waves for different fluids are used. By using such a hybrid method, both the velocities of saturated porous rocks and the attenuations are predicted accurately when compared to laboratory data. The hybrid method is a practical way to model numerically the seismic properties of saturated porous rocks until very high resolution digital data are available. Cracks lost in the imaging process are critical for accurately predicting velocities and attenuations of saturated porous rocks.
Directory of Open Access Journals (Sweden)
JÃºlio Cezar Flores JOHNER
2016-01-01
Full Text Available Abstract The present work describes setting up a laboratory unit for supercritical fluid extraction. In addition to its construction, a survey of cost was done to compare the cost of the homemade unit with that of commercial units. The equipment was validated using an extraction of annatto seedsâ€™ oil, and the extraction and fractionation of fennel oil were used to validate the two separators; for both systems, the solvent was carbon dioxide. The chemical profiles of annatto and fennel extracts were assessed using thin layer chromatography; the images of the chromatographic plates were processed using the free ImageJ software. The cost survey showed that the homemade equipment has a very low cost (~US$ 16,000 compared to commercial equipment. The extraction curves of annatto were similar to those obtained in the literature (yield of 3.8% oil. The separators were validated, producing both a 2.5% fraction of fennel seed extract rich in essential oils and another extract fraction composed mainly of oleoresins. The ImageJ software proved to be a low-cost tool for obtaining an initial evaluation of the chemical profile of the extracts.
Garven, G.; Raffensperger, J.P.; Dumoulin, J.A.; Bradley, D.A.; Young, L.E.; Kelley, K.D.; Leach, D.L.
2003-01-01
The Red Dog deposit is a giant 175 Mton (16% Zn, 5% Pb), shale-hosted Pb-Zn-Ag-Ba ore district situated in the Carboniferous Kuna Basin, Western Brooks Range, Alaska. These SEDEX-type ores are thought to have formed in calcareous turbidites and black mudstone at elevated sub-seafloor temperatures (120-150??C) within a hydrogeologic framework of submarine convection that was structurally organized by large normal faults. The theory for modeling brine migration and heat transport in the Kuna Basin is discussed with application to evaluating flow patterns and heat transport in faulted rift basins and the effects of buoyancy-driven free convection on reactive flow and ore genesis. Finite element simulations show that hydrothermal fluid was discharged into the Red Dog subbasin during a period of basin-wide crustal heat flow of 150-160 mW/m2. Basinal brines circulated to depths as great as 1-3 km along multiple normal faults flowed laterally through thick clastic aquifers acquiring metals and heat, and then rapidly ascended a single discharge fault zone at rates ??? 5 m/year to mix with seafloor sulfur and precipitate massive sulfide ores. ?? 2003 Elsevier Science B.V. All rights reserved.
Drazin, Philip
1987-01-01
Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)
DEFF Research Database (Denmark)
Hansen, Klaus Marius
2001-01-01
Fluid interaction, interaction by the user with the system that causes few breakdowns, is essential to many user interfaces. We present two concrete software systems that try to support fluid interaction for different work practices. Furthermore, we present specificity, generality, and minimality...... as design goals for fluid interfaces....
Drazin, Philip
1987-01-01
Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)
Micromachined Fluid Inertial Sensors
Directory of Open Access Journals (Sweden)
Shiqiang Liu
2017-02-01
Full Text Available Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri-axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern.
Active colloids in complex fluids
Patteson, Alison E; Arratia, Paulo E
2016-01-01
We review recent work on active colloids or swimmers, such as self-propelled microorganisms, phoretic colloidal particles, and artificial micro-robotic systems, moving in fluid-like environments. These environments can be water-like and Newtonian but can frequently contain macromolecules, flexible polymers, soft cells, or hard particles, which impart complex, nonlinear rheological features to the fluid. While significant progress has been made on understanding how active colloids move and interact in Newtonian fluids, little is known on how active colloids behave in complex and non-Newtonian fluids. An emerging literature is starting to show how fluid rheology can dramatically change the gaits and speeds of individual swimmers. Simultaneously, a moving swimmer induces time dependent, three dimensional fluid flows, that can modify the medium (fluid) rheological properties. This two-way, non-linear coupling at microscopic scales has profound implications at meso- and macro-scales: steady state suspension proper...
Institute of Scientific and Technical Information of China (English)
è‹ä¸œå‡; å¼ åº†æ²³; å™å»ºå†›; æŽæ˜Žæ˜Ÿ
2016-01-01
Based on CFDâƒDEM method, using computational fluid dynamics software OpenFOAM, particle moâƒtion simulation software LIGGGHTS and CFDEM coupling library, a coupled fluidâƒparticle model was developed and applied in the investigation of flow and particle near bed in different hydrodynamic conditions. The simulation results show that the coupled model has a good performance on describing turbulence intensity and the distribution of Reynold stress. For particle motion, this model can also depict well the three typical states of settled, bedload transport and bedloadâƒsuspended load transport. The simulated results of bedload discharge per unit have a good match with experimental data and empirical formula.%åŸºäºŽCFD-DEMæ–¹æ³•ï¼Œé‡‡ç”¨æµä½“è®¡ç®—è½¯ä»¶OpenFOAMã€é¢—ç²’è¿åŠ¨æ¨¡æ‹Ÿè½¯ä»¶LIGGGHTSåŠCFDEMè€¦åˆåº“ï¼Œå»ºç«‹æµä½“â€”é¢—ç²’è¿åŠ¨è€¦åˆæ¨¡åž‹ï¼Œå¹¶åˆ©ç”¨æ¨¡åž‹ç ”ç©¶ä¸åŒæ°´åŠ¨åŠ›æ¡ä»¶ä¸‹è¿‘åºŠé¢æµä½“ä¸Žé¢—ç²’çš„è¿åŠ¨è§„å¾‹ã€‚æ¨¡æ‹Ÿç»“æžœè¡¨æ˜Žï¼Œæ¨¡åž‹èƒ½è¾ƒå¥½æ¨¡æ‹Ÿè¿‘åºŠé¢æ°´æµç´ŠåŠ¨ç‰¹æ€§åŠé›·è¯ºåº”åŠ›åˆ†å¸ƒï¼Œä¹Ÿèƒ½è¾ƒå‡†ç¡®åˆ»ç”»å‡ºé¢—ç²’æœªèµ·åŠ¨ã€æŽ¨ç§»è´¨è¾“æ²™åŠæŽ¨ç§»è´¨å’Œæ‚¬ç§»è´¨å…±åŒè¾“æ²™çš„ä¸‰ç§çŠ¶æ€ï¼Œè®¡ç®—å¾—åˆ°çš„æŽ¨ç§»è´¨å•å®½è¾“æ²™çŽ‡ä¸Žå®žéªŒç»“æžœåŠç»éªŒå…¬å¼å»åˆè¾ƒå¥½ã€‚
Energy Technology Data Exchange (ETDEWEB)
Hueso, C.; Aleman, A.; Colomer, C.; Fabbri, M.; Martin, M.; Saellas, J.
2013-07-01
In this work identifies a possible area of improvement through the creation of a code of coupling between deposition energy codes which calculate neutron (MCNP), and data from heading into fluid dynamics (ANSYS-Fluent) or codes thermomechanical, called MAFACS (Monte Carlo ANSYS Fluent Automatic Coupling Software), being possible to so summarize the process by shortening the needs of computing time, increasing the precision of the results and therefore improving the design of the components.
Keye, Stefan; Togiti, Vamish; Eisfeld, Bernhard; Brodersen, Olaf P.; Rivers, Melissa B.
2013-01-01
The accurate calculation of aerodynamic forces and moments is of significant importance during the design phase of an aircraft. Reynolds-averaged Navier-Stokes (RANS) based Computational Fluid Dynamics (CFD) has been strongly developed over the last two decades regarding robustness, efficiency, and capabilities for aerodynamically complex configurations. Incremental aerodynamic coefficients of different designs can be calculated with an acceptable reliability at the cruise design point of transonic aircraft for non-separated flows. But regarding absolute values as well as increments at off-design significant challenges still exist to compute aerodynamic data and the underlying flow physics with the accuracy required. In addition to drag, pitching moments are difficult to predict because small deviations of the pressure distributions, e.g. due to neglecting wing bending and twisting caused by the aerodynamic loads can result in large discrepancies compared to experimental data. Flow separations that start to develop at off-design conditions, e.g. in corner-flows, at trailing edges, or shock induced, can have a strong impact on the predictions of aerodynamic coefficients too. Based on these challenges faced by the CFD community a working group of the AIAA Applied Aerodynamics Technical Committee initiated in 2001 the CFD Drag Prediction Workshop (DPW) series resulting in five international workshops. The results of the participants and the committee are summarized in more than 120 papers. The latest, fifth workshop took place in June 2012 in conjunction with the 30th AIAA Applied Aerodynamics Conference. The results in this paper will evaluate the influence of static aeroelastic wing deformations onto pressure distributions and overall aerodynamic coefficients based on the NASA finite element structural model and the common grids.
Energy Technology Data Exchange (ETDEWEB)
Khivsara, Sagar [Indian Institute of Science, Bangalor (India)
2015-01-01
Recent studies have evaluated closed-loop supercritical carbon dioxide (s-CO_{2}) Brayton cycles to be a higher energy-density system in comparison to conventional superheated steam Rankine systems. At turbine inlet conditions of 923K and 25 MPa, high thermal efficiency (~50%) can be achieved. Achieving these high efficiencies will make concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. To incorporate a s-CO_{2} Brayton power cycle in a solar power tower system, the development of a solar receiver capable of providing an outlet temperature of 923 K (at 25 MPa) is necessary. To satisfy the temperature requirements of a s-CO_{2} Brayton cycle with recuperation and recompression, it is required to heat s-CO_{2 }by a temperature of ~200 K as it passes through the solar receiver. Our objective was to develop an optical-thermal-fluid model to design and evaluate a tubular receiver that will receive a heat input ~1 MWth from a heliostat field. We also undertook the documentation of design requirements for the development, testing and safe operation of a direct s-CO_{2} solar receiver. The main purpose of this document is to serve as a reference and guideline for design and testing requirements, as well as to address the technical challenges and provide initial parameters for the computational models that will be employed for the development of s-CO_{2} receivers.
Institute of Scientific and Technical Information of China (English)
å¢ç§€æ³‰; é©¬æ–‡æ˜Ÿ; æŽé›ªæ¾; å´å²³è¯—; è®¸æ–‡
2014-01-01
é™çŸ©åž‹æ¶²åŠ›å¶åˆå™¨å§‹ç»ˆå·¥ä½œåœ¨éƒ¨åˆ†å……æ¶²çŠ¶æ€ä¸‹ï¼Œå·¥ä½œè…”å†…éƒ¨çš„å·¥ä½œæ¶²ä½“åšå¤æ‚çš„æ°”-æ¶²ä¸¤ç›¸èžºæ—‹çŽ¯æµè¿åŠ¨ã€‚åœ¨ä¸åŒçš„è½½è·å·¥å†µä¸‹ï¼Œå·¥ä½œæ¶²ä½“æ°”-æ¶²ä¸¤ç›¸çš„å…·ä½“åˆ†å¸ƒå½¢å¼å’ŒçŽ¯æµå½¢æ€å¾ˆå¤§ç¨‹åº¦ä¸Šå†³å®šäº†å¶åˆå™¨çš„é™çŸ©ç‰¹æ€§ã€‚ä¸ºäº†æŽŒæ¡é™çŸ©åž‹å¶åˆå™¨å†…éƒ¨çš„æ°”-æ¶²ä¸¤ç›¸çŽ¯æµç‰¹æ€§ï¼Œè¯¥æ–‡ä»¥YOXD200å¶åˆå™¨ä¸ºåˆ†æžæ¨¡åž‹ï¼Œåœ¨å»ºç«‹å…¨æµé“æ¨¡åž‹çš„åŸºç¡€ä¸Šï¼Œåº”ç”¨æ»‘ç§»ç½‘æ ¼çž¬æ€ç®—æ³•ï¼Œä¸¤ç›¸æµæ¨¡åž‹é‡‡ç”¨æµä½“ä½“ç§¯æ³•VOFï¼ˆvolume of fluidï¼‰æ¨¡åž‹ï¼Œå¯¹3ç§å…¸åž‹å……æ¶²çŽ‡ä¸‹çš„çŽ¯æµå½¢æ€è¿›è¡ŒCFDæ•°å€¼æ¨¡æ‹Ÿåˆ†æžã€‚æ•°å€¼æ¨¡æ‹Ÿç»“æžœå¾ˆå¥½åœ°é¢„æµ‹äº†åœ¨ä¸åŒå……æ¶²çŽ‡ä¸‹ï¼Œéšè½½è·çš„å¢žåŠ ï¼Œå†…éƒ¨æ°”-æ¶²ä¸¤ç›¸æµä½“ç”±å°çŽ¯æµå‘å¤§çŽ¯æµè¿åŠ¨çš„è½¬åŒ–è¿‡ç¨‹ã€‚è¯¥æ–‡ä¸ºå®žçŽ°é™çŸ©åž‹æ¶²åŠ›å¶åˆå™¨è½¬çŸ©è·Œè½å·¥å†µç‚¹çš„é¢„æµ‹åŠè¿‡è½½èƒ½åŠ›çš„ä¼°ç®—æä¾›äº†æ•°å€¼è®¡ç®—çš„æ–¹æ³•å’Œä¾æ®ã€‚%As the hydraulic transmission components, torque limited hydrodynamic coupling regards fluid as the transmission medium, and its gas-liquid two-phase fluid in the chamber works in a complex circulation spiral motion. With the difference of working condition in different filled ratio and speed ratio, gas-liquid two-phase flow presents the different characteristics of combination and distribution law, and it influences the external output performance parameters of the coupling for this reason. Torque limited hydrodynamic couplingâ€™s torque limiting function is mainly through the work of changing gas-liquid two phase flows to split the fluid in the working chamber to the front auxiliary oil chamber while the coupling overloads. It is difficult to establish an accurate mathematical model to describe it due to the complexity of its internal gas-liquid two-phase flow. In engineering it is usually through adjusting the flow channel structure parameters repeatedly in the way of the combination of experience design and performance test to meet certain overload and delay start matching requirements
Sullivan, Scott C; Fansler, Douglas
2014-10-14
A vehicle having multiple isolated fluid circuits configured to be filled through a common fill port includes a first fluid circuit disposed within the vehicle, the first fluid circuit having a first fill port, a second fluid circuit disposed within the vehicle, and a conduit defining a fluid passageway between the first fluid circuit and second fluid circuit, the conduit including a valve. The valve is configured such that the first and second fluid circuits are fluidly coupled via the passageway when the valve is open, and are fluidly isolated when the valve is closed.
Institute of Scientific and Technical Information of China (English)
è¿žä¼šé’; å¤å‘å¦; å†‰ä¼Ÿ; èµµå¯å³°
2015-01-01
Analogue simulation is an important method for researching water burst mechanism of mine and high water-resistance prop-erty of fluid-solid coupling simulation material is the key.For mining face with roof water burst danger in Shigetai Colliery, matching ex-periment of fluid-solid coupling analogue simulation material was made.Applying medium-coarse sand, plaster, calcium carbonate, paraffin and vaseline to stirring evenly with some proportion and simulating actual rock strata ( medium sandstone, sandy mudstone, siltstone, coal-seam, fine sandstone) , permeability ratio of every group specimen was tested and permeability coefficient was calculat-ed.According to classification criterion of permeability parameters, using the permeability coefficient which was smaller than 10-5cm/s as indication value of high water-resistance property, 48 groups experiment was finished.Results showed that with paraffin content in-creasing, specimen's strength rose and flexibility reduced, when paraffin content was larger than 8%, water-resistance property was ex-cellent, on the basis of this, 8%of vaseline mixture could reduce specimen's elastic module and improve deformation ability.Rational mixture of vaseline and paraffin could make fluid-solid coupling material with high water-resistance property.%ç›¸ä¼¼æ¨¡æ‹Ÿå®žéªŒæ˜¯ç ”ç©¶çŸ¿äº•çªæ°´æœºç†çš„ä¸€ç§é‡è¦æ‰‹æ®µï¼Œæµå›ºè€¦åˆç›¸ä¼¼æ¨¡æ‹Ÿææ–™çš„é«˜æŠ—æ°´æ€§èƒ½è‡³å…³é‡è¦ã€‚ä»¥çŸ³åœªå°ç…¤çŸ¿å˜åœ¨é¡¶æ¿çªæ°´æºƒç ‚é£Žé™©çš„å·¥ä½œé¢ä¸ºå¯¹è±¡ï¼Œå¼€å±•äº†æµå›ºè€¦åˆç›¸ä¼¼ææ–™é…æ¯”å®žéªŒå·¥ä½œã€‚é’ˆå¯¹å®žé™…å²©å±‚ï¼ˆä¸ç ‚å²©ã€ç ‚è´¨æ³¥å²©ã€ç²‰ç ‚å²©ã€ç…¤å±‚ã€ç»†ç ‚å²©ï¼‰ï¼Œåˆ©ç”¨ä¸ç²—ç ‚ã€çŸ³è†ã€ç¢³é…¸é’™ã€çŸ³èœ¡å’Œå‡¡å£«æž—æŒ‰ä¸€å®šé…æ¯”å‡åŒ€æ…æ‹ŒåŽ‹åˆ¶æˆè¯•ä»¶ï¼Œå„ç»„è¯•ä»¶ç»è‡ªç„¶å…»æŠ¤åŽæµ‹å®šå…¶æ¸—é€çŽ‡ï¼Œå¹¶è®¡ç®—æ¸—é€ç³»æ•°ï¼ŒåŒæ—¶ç»“åˆçŽ°åœºéš”æ°´å±‚æ¸—é€æ€§å‚æ•°å’Œå²©åœŸæ¸—é€æ€§åˆ†çº§æ ‡å‡†ï¼Œå°†æ¸—é€ç³»æ•°å°äºŽ10ï¼5 cmï¼sä½œä¸ºæŠ—æ°´æ€§è‰¯å¥½çš„åˆ¤åˆ«å‡†åˆ™ï¼Œå…±å®Œæˆ48ç»„å®žéªŒã€‚ç ”ç
Acharya, Ranadip; Bansal, Rohan; Gambone, Justin J.; Das, Suman
2014-12-01
Scanning laser epitaxy (SLE) is a new laser-based additive manufacturing technology under development at the Georgia Institute of Technology. SLE is aimed at the creation of equiaxed, directionally solidified, and single-crystal deposits of nickel-based superalloys through the melting of alloy powders onto superalloy substrates using a fast scanning Nd:YAG laser beam. The fast galvanometer control movement of the laser (0.2 to 2 m/s) and high-resolution raster scanning (20 to 200 Âµm line spacing) enables superior thermal control over the solidification process and allows the production of porosity-free, crack-free deposits of more than 1000 Âµm thickness. Here, we present a combined thermal and fluid flow model of the SLE process applied to alloy CMSX-4 with temperature-dependent thermo-physical properties. With the scanning beam described as a moving line source, the instantaneous melt pool assumes a convex hull shape with distinct leading edge and trailing edge characteristics. Temperature gradients at the leading and trailing edges are of order 2 Ã— 105 and 104 K/m, respectively. Detailed flow analysis provides insights on the flow characteristics of the powder incorporating into the melt pool, showing velocities of order 1 Ã— 10-4 m/s. The Marangoni effect drives this velocity from 10 to 15 times higher depending on the operating parameters. Prediction of the solidification microstructure is based on conditions at the trailing edge of the melt pool. Time tracking of solidification history is incorporated into the model to couple the microstructure prediction model to the thermal-fluid flow model, and to predict the probability of the columnar-to-equiaxed transition. Qualitative agreement is obtained between simulation and experimental result.
Institute of Scientific and Technical Information of China (English)
ä¸ç³; éƒ‘æº; å¼ ç¦æ˜Ÿ
2013-01-01
Upon the analysis of fluid-solid coupling,the forces on the blades and spindle of the building integration wind turbine were discussed.Based on an actual project,the one-way fluid-structure coupling method in the structure analysis software ANSYS Workbench was used to calculate and analyze the static stresses of the blades and spindle under the wind speed of 10 m/s and 50 m/s.The results showed that the maximum static stress of the wind turbine blades occurs at the connection between the blades and spindle under different working conditions,and the maximum static stress increases with the increasing of wind speed.The maximum static stress is far less than the yield limit of material,thus it will not destroy the wind turbine blades and spindle structure.The connection between the blades and spindle has the stress concentration phenomenon,and the thickness of the connection area can be increased to prevent fatigue failure.%ä¸ºäº†é€šè¿‡æµå›ºè€¦åˆåˆ†æž,æŽ¢è®¨é£Žæœºå»ºç‘ä¸€ä½“åŒ–ä¸åž‚ç›´è½´é£ŽåŠ›æœºå¶ç‰‡å’Œä¸»è½´çš„å—åŠ›æƒ…å†µ,ç»“åˆå®žé™…å·¥ç¨‹,åœ¨ç»“æž„åˆ†æžè½¯ä»¶ANSYS Workbench[(11)]ä¸è¿ç”¨å•å‘æµå›ºè€¦åˆçš„æ–¹æ³•åˆ†åˆ«å¯¹é£Žé€Ÿæ˜¯10 m/så’Œ50 m/sæ—¶çš„é£Žæœºå¶ç‰‡å’Œä¸»è½´çš„é™åº”åŠ›è¿›è¡Œäº†è®¡ç®—åˆ†æžå’Œæ¯”è¾ƒ.ç»“æžœè¡¨æ˜Ž:å„ç§å·¥å†µä¸‹,é£ŽåŠ›æœºå¶ç‰‡çš„æœ€å¤§é™åº”åŠ›å‡ºçŽ°åœ¨å¶ç‰‡ä¸Žä¸»è½´è¿žæŽ¥å¤„,é£ŽåŠ›å‘ç”µæœºå¶ç‰‡å’Œä¸»è½´çš„æœ€å¤§é™åº”åŠ›éšç€é£Žé€Ÿçš„å¢žåŠ è€Œå˜å¤§.é™åº”åŠ›æœ€é«˜å€¼è¿œå°äºŽææ–™çš„å±ˆæœæžé™,æ‰€ä»¥é™åº”åŠ›ä¸ä¼šä½¿é£Žæœºå¶ç‰‡å’Œä¸»è½´ç»“æž„äº§ç”Ÿç ´å.å¶ç‰‡ä¸Žä¸»è½´çš„è¿žæŽ¥å¤„éƒ½å‡ºçŽ°äº†åº”åŠ›é›†ä¸çŽ°è±¡,ä¸ºäº†é˜²æ¢ç–²åŠ³ç ´å,å¯ä»¥é€‚å½“åœ°åŠ åŽšå¶ç‰‡å’Œä¸»è½´è¿žæŽ¥å¤„çš„åŽšåº¦.
Institute of Scientific and Technical Information of China (English)
æŽå®; ç©†å¡”é‡Œå¤«â€¢é˜¿èµ«è¿ˆå¾·; å•æ˜Ÿåˆš
2016-01-01
Based on the 3D finite element models of the fluid-film and solid of the friction pair interface for spiral groove me-chanical seal,the fluid-film between the faces of the static and dynamic is simulated ,and the law of the pressure distribution was obtained,the result show that pressure distribution is nonlinear.After that,the pressure was imported into static analysis module as one boundary condition of dynamic ring,then the one-way fluid-solid weak coupling was achieved by automatic iterative of the two steps.,the values indicate that the maximum deformation occurs on the spiral groove in the face of dynamic ring,while the maxi-mum stress occurs on the end of the spiral groove.Further,the effect of the rotational speed of dynamic ring,the pressure differ-ence and the viscosity on the maximum deformation and stress were also studied,the result provide a beneficial reference for the optimization of sealing performance.%åŸºäºŽå»ºç«‹çš„ä¸‰ç»´èžºæ—‹æ§½æœºæ¢°å¯†å°æ‘©æ“¦å‰¯ç•Œé¢çš„æµã€å›ºæœ‰é™å…ƒæ¨¡åž‹ï¼Œæ•°å€¼æ¨¡æ‹Ÿäº†åŠ¨é™çŽ¯ç«¯é¢é—´çš„æµä½“è†œï¼Œå¾—åˆ°æ¶²è†œçš„åŽ‹åŠ›åˆ†å¸ƒè§„å¾‹ï¼Œç»“æžœæ˜¾ç¤ºåŽ‹åŠ›å‘ˆéžçº¿æ€§åˆ†å¸ƒï¼›ç„¶åŽå°†å¾—åˆ°çš„åŽ‹åŠ›å€¼ä½œä¸ºè¾¹ç•Œæ¡ä»¶ä¹‹ä¸€å¯¼å…¥åˆ°åŠ¨çŽ¯ç«¯é¢çš„é™åŠ›å¦åˆ†æžä¸ï¼Œåˆ©ç”¨ä¸¤è€…æŽ¥è§¦é¢é—´çš„è‡ªåŠ¨è¿ä»£è®¡ç®—å®žçŽ°å•å‘å¼±æµå›ºè€¦åˆåˆ†æžï¼Œç»“æžœè¡¨æ˜Žï¼šæœ€å¤§å˜å½¢å‘ç”Ÿåœ¨åŠ¨çŽ¯ç«¯é¢èžºæ—‹æ§½å¤„ï¼Œè€Œæœ€å¤§åº”åŠ›å‘ç”Ÿåœ¨èžºæ—‹æ§½é¡¶ç«¯ï¼›å¹¶è¿›ä¸€æ¥ç ”ç©¶äº†åŠ¨çŽ¯çš„è½¬é€Ÿä»¥åŠä»‹è´¨åŽ‹åŠ›å’Œç²˜åº¦å¯¹æœ€å¤§å˜å½¢å’Œæœ€å¤§åº”åŠ›çš„å½±å“è§„å¾‹ï¼Œä¸ºå¯†å°æ€§èƒ½çš„ä¼˜åŒ–æä¾›äº†æœ‰ç›Šçš„å‚è€ƒã€‚
Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Meng, X.; Combi, M. R.
2013-12-01
The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered a great of interest in recent years. Among the large number of topics in this research area, the investigation of ion escape fluxes has become increasingly important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0~300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100km~5RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model outputs fields into the 3-D BATS-R-US Mars multi-fluid MHD model (100km~20RM) that can better simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres, allowing us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model outputs are used as the inputs for the multi-fluid model and M-GITM is used as input into the AMPS exosphere model. The calculations are carried out for selected cases with different nominal solar wind, solar cycle and crustal field orientation conditions. This work has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN primary mission (2014-2016) and thereby improve our understanding of present day escape processes. Acknowledgments: The work presented here was supported by NASA grants NNH10CC04C, NNX09AL26G, NSF grant ATM-0535811.
Kundu, Pijush K; Dowling, David R
2011-01-01
Fluid mechanics, the study of how fluids behave and interact under various forces and in various applied situations-whether in the liquid or gaseous state or both-is introduced and comprehensively covered in this widely adopted text. Revised and updated by Dr. David Dowling, Fluid Mechanics, 5e is suitable for both a first or second course in fluid mechanics at the graduate or advanced undergraduate level. Along with more than 100 new figures, the text has been reorganized and consolidated to provide a better flow and more cohesion of topics.Changes made to the
Energy Technology Data Exchange (ETDEWEB)
Rawlinson, A.P.; White, J.
1987-06-23
A soluble oil, suitable when diluted with water, for use as a cutting fluid comprises an alkali or alkaline-earth metal alkyl benzene sulphonate, a fatty acid diethanolamide, a mixed alkanolamine borate, a polyisobutenesuccinimide and a major proportion of mineral oil. The soluble oil is relatively stable without the need for a conventional coupling agent and some soluble oil emulsions are bio-static even though conventional biocides are not included.
Institute of Scientific and Technical Information of China (English)
æ½˜èè; é™ˆé•¿å¾; åŸå¼º
2012-01-01
å¡”ç’åŠ¨æ€ç‰¹æ€§åˆ†æžå¯¹é£ŽåŠ›å‘ç”µæœºçš„æŒ¯åŠ¨è®¾è®¡èµ·ç€å…³é”®ä½œç”¨.æ–‡ç« ä»¥1.5 MWé£ŽåŠ›å‘ç”µæœºå¡”ç’ä¸ºç ”ç©¶å¯¹è±¡,å°†å¶ç‰‡æ—‹è½¬å’Œéšæœºé£Žè½½è·ä½œä¸ºè½½è·è¾“å…¥æ¡ä»¶,å»ºç«‹é£ŽåŠ›æœºå¡”ç’å¶ç‰‡æ—‹è½¬è½½è·æ¨¡åž‹ã€æµå›ºè€¦åˆé£Žè½½è·æ¨¡åž‹ã€ç»“æž„åŠ¨åŠ›å¦æ–¹ç¨‹,åˆ†æžè®¡ç®—å¾—åˆ°éšæœºè½½è·ä¸‹å¶ç‰‡æ—‹è½¬å’Œé£Žè½½å…±åŒä½œç”¨æ—¶,é£ŽåŠ›æœºå¡”ç’åŠ¨æ€ç‰¹æ€§è¯„ä¼°æ–¹æ³•.%The dynamic characteristic of wind turbine tower is important for the wind turbine vibration design. A 1.5 MW wind turbine tower is analyzed in this paper. The blade wheel load and wind load are inputted as conditions to establish a wind wheel load model, a tower fluid-structure coupled model and a structural dynamics equation. By the analysis, the feasible method for evaluating the dynamic characteristics of wind turbine tower is gotten under both the wind turbine wind load and the rotation of blade at random load.
DEFF Research Database (Denmark)
Brorsen, Michael
These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University.......These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University....
Global Dynamics of Shaft Lines Rotating in Surrounding Fluids Application to Thin Fluid Films
Directory of Open Access Journals (Sweden)
David Lornage
2004-01-01
a disc and a thin-walled shaft mounted on a hydrodynamic bearing. The second is intended for studying a more realistic structure composed of a shaft and a wheel coupled with a fluid film between the wheel and a casing. These applications make it possible to identify trends related to fluid effects and couplings between the flexible structural parts.
Institute of Scientific and Technical Information of China (English)
å¼ ä»‚; è°·èŠ³
2012-01-01
é‡‡ç”¨å¤šç‰©ç†åœºè€¦åˆæ–¹æ³•,å»ºç«‹äº†ç®¡å£³å¼æ¢çƒå™¨çš„è®¡ç®—æµä½“åŠ›å¦(CFD)çƒæµå›ºè€¦åˆä»¿çœŸåˆ†æžæ¨¡åž‹,å¯¹20ç§ä¸åŒæŠ˜æµæ¿ç»“æž„å‚æ•°çš„ç®¡å£³å¼æ¢çƒå™¨è¿›è¡Œäº†æµåŠ¨ä¸Žä¼ çƒçš„æ•°å€¼æ¨¡æ‹Ÿ.CFDä»¿çœŸè®¡ç®—ç»“æžœæ˜¾ç¤º,æ¢çƒå™¨çš„æŠ˜æµæ¿é—´è·å’ŒæŠ˜æµæ¿ç¼ºå£é«˜åº¦å¯¹æµåŠ¨å’Œä¼ çƒçš„å½±å“ç›¸äº’å…³è”,ä¸èƒ½è¿›è¡Œå•ç›®æ ‡ä¼˜åŒ–è®¾è®¡.ä»¥JFå› åä½œä¸ºæ¢çƒå™¨ç»¼åˆæ€§èƒ½çš„è¯„ä»·å‡†åˆ™,å¯¹ç®¡å£³å¼æ¢çƒå™¨çš„æŠ˜æµæ¿é—´è·å’ŒæŠ˜æµæ¿ç¼ºå£é«˜åº¦è¿›è¡Œäº†ç»“æž„ä¼˜åŒ–è®¾è®¡,æå‡ºåœ¨æ¢çƒå™¨å†…å¾„(d)200 mmã€æ¢çƒç®¡é•¿1140 mmã€å¹¶æµæ¡ä»¶ä¸‹,è¯¥æ¢çƒå™¨çš„æœ€ä½³æŠ˜æµæ¿é—´è·ä¸º80 mm(æŠ˜æµæ¿æ•°ç›®ä¸º10),æœ€ä½³æŠ˜æµæ¿ç¼ºå£é«˜åº¦ä¸º0.3d(å³60 mm).%A thermal-fluid-structure coupling simulation model for shell-and-tube heat exchangers was established based on computational fluid dynamics(CFD) by a multi-physical field coupling method. The flow and heat transfer in 20 different types of shell-and-tube heat exchangers with different baffle structural parameters were simulated by the model. The CFD simulation results showed that the effects of the baffle spacing and baffle gap height on the flow and heat transfer interconnected, which showed that the single-objective optimization could not be achieved. With JF factors as the evaluation criteria of the heat exchanger performances, the baffle spacings and baffle gap heights in the shell-and-tube heat exchangers were optimized. It was put forward that under the conditions of parallel flow, inside diameter of the heat exchanger(d)200 mm and heat exchange tube length 1 140 mm, the baffle space and baffle gap height were 80 mm(the baffle number 10) and 0.3d(60 mm), respectively.
Fluid dynamics of dilatant fluid
DEFF Research Database (Denmark)
Nakanishi, Hiizu; Nagahiro, Shin-ichiro; Mitarai, Namiko
2012-01-01
A dense mixture of granules and liquid often shows a severe shear thickening and is called a dilatant fluid. We construct a fluid dynamics model for the dilatant fluid by introducing a phenomenological state variable for a local state of dispersed particles. With simple assumptions for an equation...... of the state variable, we demonstrate that the model can describe basic features of the dilatant fluid such as the stress-shear rate curve that represents discontinuous severe shear thickening, hysteresis upon changing shear rate, and instantaneous hardening upon external impact. An analysis of the model...... reveals that the shear thickening fluid shows an instability in a shear flow for some regime and exhibits the shear thickening oscillation (i.e., the oscillatory shear flow alternating between the thickened and the relaxed states). The results of numerical simulations are presented for one- and two...
Institute of Scientific and Technical Information of China (English)
åˆ˜å…ˆçŠ; è®¸æ˜Ž
2013-01-01
ã€€ã€€æ²¹äº•å‡ºç ‚æœºåˆ¶çš„ç ”ç©¶æ˜¯æé«˜æ²¹è—äº§èƒ½å’ŒçŸ³æ²¹å¼€é‡‡æˆæœ¬å‡å°çš„å…³é”®è¯¾é¢˜ï¼Œè€Œå¸¸è§„çš„å®è§‚åŠ›å¦ç†è®ºå’Œæ–¹æ³•ä¸èƒ½å…¨é¢åæ˜ æ²¹è—å¼€é‡‡è¿‡ç¨‹ä¸æ²¹äº•å‡ºç ‚çš„å‘ç”Ÿå’Œå‘å±•ã€‚é‰´äºŽç ‚å²©å‚¨å±‚çš„ç‰©ç†æ€§è´¨å’Œå°„å”è¯•éªŒç‰¹å¾ï¼Œä»Žå²©åœŸåŠ›å¦çš„è§’åº¦å»ºç«‹åŸºäºŽæŸ±åæ ‡ç³»çš„ä¸‰ç»´é¢—ç²’æµæ•°å€¼æ¨¡åž‹ï¼Œä¸Žç†è®ºåˆ†æžæˆæžœè¿›è¡Œæ¯”è¾ƒï¼Œä»¥è¯´æ˜Žè¯¥ç»†è§‚æ•°å€¼æ¨¡åž‹å¯è¡Œæ€§ï¼Œæœ‰æ•ˆåœ°æ¨¡æ‹Ÿå‡ºç ‚è¿‡ç¨‹ä¸çš„æ¸—æµåŠæµ-å›ºè€¦åˆæ•ˆåº”ã€‚åœ¨è¯¥åŸºç¡€ä¸Šï¼Œç»¼åˆè€ƒè™‘æµä½“åŽ‹åŠ›æ¢¯åº¦åŠ›å’Œæ‹–æ›³åŠ›ï¼ŒåŸºäºŽ PFC3D æ¨¡åž‹æ¨¡æ‹Ÿæµä½“ä¸åŒè¿åŠ¨æ—¶çš„ç ‚å²©æ€§æ€ã€‚æ•°å€¼åˆ†æžå¾—åˆ°çš„æ¨¡åž‹å®è§‚åº”åŠ›å›¾å½¢è¯´æ˜Žæµä½“è¿åŠ¨å¯¹ç ‚å²©åŠ›å¦ç‰¹æ€§çš„å½±å“ä¸å¯å¿½ç•¥ï¼Œä¸”åœ¨ç›¸åŒæ¡ä»¶ä¸‹ï¼Œæµé‡è¶Šå¤§ï¼Œç ‚å²©çš„å¡‘æ€§åŒºè¶Šå¤§ï¼Œå½¢æˆç ‚å²©ç ´åå‡ºç ‚çš„å‡ çŽ‡ä¹Ÿè¶Šå¤§ã€‚åŒæ—¶ï¼Œä¸åŒå·¥å†µçš„ç ‚å²©é»ç»“åˆ†å¸ƒå’Œé¢—ç²’è½¬åŠ¨å›¾å½¢è¡¨æ˜Žï¼Œç›¸åŒæ¡ä»¶ä¸‹æµé‡è¶Šå¤§ï¼Œé¢—ç²’é—´å¹³è¡Œé»ç»“ç ´åè¶Šå¤šï¼Œé¢—ç²’è½¬åŠ¨è¶Šå¤§ï¼Œå¤±åŽ»é»ç»“çº¦æŸçš„é¢—ç²’ä¹Ÿè¶Šå¤šï¼Œå‡ºç ‚é‡å°±è¶Šå¤§ï¼Œå¯è§ä¸¤ç§ç»†è§‚ç‰¹å¾å›¾å½¢ä¸Žå®è§‚åº”åŠ›å›¾å½¢å˜åŒ–è§„å¾‹ä¸€è‡´ï¼Œè¯¥æ¨¡åž‹å¯ç”¨äºŽæ²¹äº•å‡ºç ‚æœºåˆ¶çš„ç ”ç©¶ï¼Œå¯ä¸ºå‡ºç ‚é‡é¢„æµ‹åŠå‡ºç ‚æŽ§åˆ¶æä¾›æ–°çš„ç ”ç©¶æ€è·¯ã€‚%Research on mechanism of sand production has been the key topic to improve the oil production and reduce the oil extraction cost; however, current investigations are mainly based on rock macromechanical theory and methods; and these achievements cannot comprehensively reflect initiation and propagation of the sand production. Considering physical property of the sand reservoir and real characteristics of the perforation test, 3-Dimensional numerical model based on PFC3D under cylindrical coordinate system from a geomechanics prospective was established to research the fluid-solid coupling effect and the micromechanism of sand production. The comparison with theoretical results shows the feasibility of the forward 3-Dimensional micro numerical
Institute of Scientific and Technical Information of China (English)
å®å°‘æ¦; å²æ²»å®‡; æŽæ™“æ¾
2016-01-01
An equivalent fluid model was employed to characterize the absorption of sound in the sound absorptive material.A vibro-acoustic coupling model was developed for the sound insulation of an sandwich structure filled with sound absorptive material in convected fluids.The performance of sound transmission was analysed by employing the wave method.The analysed influential factors of vibro-acoustic responses include the incident angles and azimuch angles,the velocity and direction of convected flow and the geometrical dimensions of the double panels.The studies show that the insulation of the structure filled with absorptive material instead of air is improved;the larger the thicknesses of the up and low panels and the gap are,the larger the sound transmission loss is;the larger the incident elevation angles and azimuch angles are,the smaller the sound transmission loss is;in the calculation frequency band (0 ~5 000 Hz),the sound transmission loss decreases with the increase of Mach number when the sound is incident in the upstream but increases with the increase of Mach number when the sound is incident in the downstream.%é‡‡ç”¨ç‰æ•ˆæµä½“æ¨¡æ‹Ÿå¸å£°ææ–™ï¼Œå»ºç«‹äº†å¤–éƒ¨æµåœºä½œç”¨ä¸‹å¡«å……å¸å£°ææ–™å¤¹å±‚æ¿ç»“æž„çš„å£°æŒ¯è€¦åˆæ¨¡åž‹ï¼Œåº”ç”¨æ³¢åŠ¨åˆ†æžæ–¹æ³•ç ”ç©¶ç»“æž„ä¸å£°çš„é€å°„ç‰¹æ€§ï¼Œåˆ†æžäº†å…¥å°„å£°æ³¢å…¥å°„è§’å’Œæ–¹ä½è§’ã€æµåœºæµé€Ÿå’Œæµå‘ã€å¤¹å±‚ç»“æž„å‡ ä½•å°ºå¯¸ç‰å‚æ•°å¯¹å¡«å……å¸å£°ææ–™å¤¹å±‚æ¿ç»“æž„å£°æŒ¯è€¦åˆç‰¹æ€§çš„å½±å“ã€‚ä»¿çœŸè®¡ç®—è¡¨æ˜Žå¸å£°ææ–™æé«˜äº†åŒå±‚æ¿ç»“æž„çš„éš”å£°æ€§èƒ½ï¼›éš”å£°æ€§èƒ½éšç€é¢æ¿åŽšåº¦å’Œå¤¹å±‚åŽšåº¦çš„å¢žåŠ è€Œæé«˜ï¼Œéšç€å…¥å°„è§’å’Œæ–¹ä½è§’çš„å¢žå¤§è€Œå‡å°ï¼›åœ¨è®¡ç®—é¢‘æ®µå†…ï¼ˆ0ï½ž5000 Hzï¼‰ï¼Œé€†æµå…¥å°„æ—¶ä¼ å£°æŸå¤±éšç€é©¬èµ«æ•°çš„å¢žå¤§è€Œå‡å°ï¼Œé¡ºæµå…¥å°„æ—¶å´éšç€é©¬èµ«æ•°çš„å¢žå¤§è€Œå¢žå¤§ã€‚
Institute of Scientific and Technical Information of China (English)
å™æ˜Žç¤¼; å´”æµ·è“‰; æ±ªå½¬; é™†çˆ½; å¾æ¢¦æ™¨
2011-01-01
The paper presents a tilt sensor with magnetic fluid, which is dedicated to measure small inclination angles with respect to a horizontal or vertical plane. The operating principle of the sensor is introduced; the formulas of the output voltage and sensitivity are deduced. Based on the finite element software ANSYS, the magnetic circuit coupling field of the sensor is analyzed. Numerical simulation results show that the output voltage of the sensor has a linear relationship with the inclination angle. The factors affecting sensor sensitivity are inspected , which include the exciting signal frequency, peak voltage and magnetic fluid susceptibility. These factors also have linear relationship with the sensor sensitivity. However, when the excitation signal frequency exceeds a certain range, the sensitivity increasing of the sensor is gelling slow down. We suggest that the exciting signal frequency should be less than 1.5 kHz.%æ ¹æ®ä¸€ç§å·®åŠ¨å¼å˜åŽ‹å™¨ç»“æž„çš„ç£æ€§æ¶²ä½“å€¾æ–œè§’ä¼ æ„Ÿå™¨å·¥ä½œåŽŸç†,æŽ¨å¯¼å‡ºä¼ æ„Ÿå™¨è¾“å‡ºç”µåŽ‹ä¸Žçµæ•åº¦å…¬å¼,å¹¶åˆ©ç”¨ANSYSè½¯ä»¶å¯¹è¿™ç§ç»“æž„çš„ä¼ æ„Ÿå™¨è¿›è¡Œç”µç£-ç”µè·¯çš„è€¦åˆåœºåˆ†æž,é€šè¿‡å¯¹æ•°å€¼æ¨¡æ‹Ÿç»“æžœè¿›è¡Œæ·±å…¥åˆ†æžä»¥ä¾¿èƒ½ä¸ºä¼ æ„Ÿå™¨çš„è®¾è®¡æä¾›æŒ‡å¯¼,å¹¶å°†æ¨¡æ‹Ÿç»“æžœä¸Žå·²å…¬å¼€å‘è¡¨çš„å®žéªŒæ•°æ®è¿›è¡Œå¯¹æ¯”.å¾—å‡ºå½“ç£æ€§æ¶²ä½“å€¾æ–œè§’ä¼ æ„Ÿå™¨çš„ç»“æž„å‚æ•°ç¡®å®šåŽ,ä¼ æ„Ÿå™¨çš„è¾“å‡ºç”µåŽ‹ä¸Žè½¬åŠ¨è§’åº¦æˆçº¿æ€§æ£æ¯”å…³ç³»;ä¸”ä¼ æ„Ÿå™¨çš„çµæ•åº¦ä¸Žæ¿€åŠ±ç”µåŽ‹çš„æŒ¯å¹…ã€ç£æ€§æ¶²ä½“ç›¸å¯¹ç£å¯¼çŽ‡åŠæ¿€åŠ±ç”µåŽ‹é¢‘çŽ‡æˆæ£æ¯”,ä½†æ¿€åŠ±ç”µåŽ‹é¢‘çŽ‡è¶…è¿‡ä¸€å®šèŒƒå›´åŽ,ä¼ æ„Ÿå™¨çµæ•åº¦å¢žåŠ å€¼ä¼šé€æ¸å‡å°,å»ºè®®æ¿€åŠ±ç”µåŽ‹é¢‘çŽ‡æœ€å¥½ä¸è¶…è¿‡1.5 kHz.
Bernard, Peter S
2015-01-01
This book presents a focused, readable account of the principal physical and mathematical ideas at the heart of fluid dynamics. Graduate students in engineering, applied math, and physics who are taking their first graduate course in fluids will find this book invaluable in providing the background in physics and mathematics necessary to pursue advanced study. The book includes a detailed derivation of the Navier-Stokes and energy equations, followed by many examples of their use in studying the dynamics of fluid flows. Modern tensor analysis is used to simplify the mathematical derivations, thus allowing a clearer view of the physics. Peter Bernard also covers the motivation behind many fundamental concepts such as Bernoulli's equation and the stream function. Many exercises are designed with a view toward using MATLAB or its equivalent to simplify and extend the analysis of fluid motion including developing flow simulations based on techniques described in the book.
Institute of Scientific and Technical Information of China (English)
æŽé‘«; éç‡•æ°; æŽå›½ä¸€
2015-01-01
æŒ‡å‡ºäº†æ°”æºå¼æ¶²æ¶²æ—‹æµå™¨æ˜¯æ¸¯åŒºå°åž‹åŒ–ã€èˆ¹è½½åŒ–æ´—èˆ±ã€åŽ‹ä»“å«æ²¹åºŸæ°´é¢„å¤„ç†çš„å…³é”®è®¾å¤‡.é‡‡ç”¨æµå›ºè€¦åˆæ•°å€¼æ¨¡æ‹Ÿæ–¹æ³•å†çŽ°åŽ‹ç¼©æœºè¿›æ°”ã€æ²¹æ°´æ—‹æµä¸Žè®¾å¤‡æœ¬ä½“çš„æ•´ä½“æ°”æµ®â€”æ—‹æµâ€”åˆ†ç¦»è€¦åˆè®¡ç®—æ¨¡åž‹ ,å¯¹å…¶æ ¸å¿ƒéƒ¨ä»¶å¾®å”æ—‹æµå¥—ç®¡çš„æž„åž‹ã€å”å¾„ã€å†…å¤–åŽ‹å·®åŠè…”å†…æµåœºåˆ†å¸ƒè¿›è¡Œäº†ä¸‰ç»´æ•°å€¼æ¨¡æ‹Ÿ ,å¾—åˆ°äº†å¾®å”æ—‹æµè…”å†…æ±½ã€æ°´ã€æ²¹ä¸‰ç›¸çš„æµåœºåˆ†å¸ƒ ,åˆç†ç¡®å®šäº†æ³¨æ°”è…”æ°”â€”æ°´å¹³è¡¡åˆ†åŽ‹ã€æº¢æµæ¯”å’Œå¾®å”å”å¾„ ,å¹¶æ¨¡æ‹Ÿäº†åŽ‹ç¼©æœºã€æ½œæ°´æ³µæ£å¸¸å·¥å†µä¸‹è¿›æ°”ã€è¿›æ°´ã€å‡ºæ°´ã€æ²¹æ±¡æº¢æµçš„æµé‡ã€æµé€Ÿæ³¢åŠ¨èŒƒå›´ ,ä¸ºè¯¥è®¾å¤‡çš„ä¸€ä½“åŒ–æž„åž‹è®¾è®¡å’ŒåŠ å·¥é€‰ææä¾›äº†å‚è€ƒæ•°æ®.%Gas-injected liquid-liquid hydro-cyclone is a key device in the miniaturization of the port ,washing tank of the ship and pretreatment of oily wastewater.Adopting the numerical simulation of fluid -solid coupling ,the article reappears the flotation-cyclone separation coupling calculation model for compressor's air inflow ,oil-water cyclone and the apparatus.The article also make a 3-D numerical simulation of micro-porous cyclone drive pipe's configuration ,aperture ,internal and external differential pressure and flow field distribution of chamber ,which is the core block of gas -injected liquid -liquid hydro -cyclone.Through the simulation ,the article gets the field distribution of steam ,water and oil phase flow inside micro-porous cyclone chamber.Meanwhile ,the gas injection cavity ,equilibrium partial pressure of gas water ,overflow ratio and micro-porous aperture are rationally determined by the simulation method.In addition ,it simulates the compressor and submersible pump's water inflow and outflow , air inflow ,discharge and velocity fluctuation of oil overflow under normal condition ,w hich provide reference data for the integrated design of configuration ,selection of materials and processing of the apparatus.
Institute of Scientific and Technical Information of China (English)
å´æ ¹è€€; æ¢æ±Ÿå¹³; æ¨å»ºå›½; æœ±å¾·ä¸°; é™ˆå‡äº®; ç”³å®¶å¹´
2012-01-01
è¿™æ˜¯ä»¥â€œç›†â€â€œå±±â€è€¦åˆç†è®ºæŒ‡å¯¼ç›†åœ°å¼‚å¸¸é«˜åŽ‹ç ”ç©¶çš„é¦–æ¬¡å°è¯•.å¼‚å¸¸é«˜åŽ‹çš„æˆå› å’Œåˆ†å¸ƒç‰¹å¾ä¸»è¦å–å†³äºŽåŒºåŸŸæž„é€ åº”åŠ›åœº,åœ¨æŒ¤åŽ‹åž‹ç›†åœ°ä¸å½¢æˆå¼‚å¸¸é«˜åŽ‹çš„ä¸»æŽ§å› ç´ æ˜¯æŒ¤åŽ‹åº”åŠ›å’Œå¤©ç„¶æ°”(æ²¹æ°”)å……æ³¨,å¼‚å¸¸é«˜åŽ‹å‘ˆå¹³è¡Œé€ å±±å¸¦çš„(å®½)å¸¦çŠ¶æˆ–è¿žç»çš„é¢çŠ¶åˆ†å¸ƒ;æ‹‰å¼ åž‹ç›†åœ°å’Œå‰ªåˆ‡â€”æ‹‰åˆ†ç›†åœ°çš„ä¸»æŽ§å› ç´ æ˜¯çƒä½œç”¨.å¼‚å¸¸é«˜åŽ‹åœ¨æ‹‰å¼ åž‹ç›†åœ°ä¸ä¸ºæ•£ç‚¹çŠ¶æˆ–è¢«åˆ†éš”çš„é¢çŠ¶åˆ†å¸ƒ,åœ¨å‰ªåˆ‡åž‹ç›†åœ°ä¸å‘ˆç‚¹çŠ¶æˆ–æ•£ç‚¹çŠ¶åˆ†å¸ƒ.ä¸åŒç±»åž‹çš„ç›†åœ°å†…æ–è£‚çš„äº§çŠ¶ä¸åŒ,å†³å®šäº†å¼‚å¸¸é«˜åŽ‹æœ‰ä¸åŒçš„ä¼ å¯¼æ–¹å‘,æŒ¤åŽ‹â€”åè½¬æ—¶å¼‚å¸¸é«˜åŽ‹çš„ä¿å˜æˆ–é‡Šæ”¾(æ³„åŽ‹)ä¹Ÿå„å…·ç‰¹ç‚¹.è¿™ä¸ºâ€œç›†â€â€œå±±â€è€¦åˆä»ŽæŒ‡å¯¼ç›†åœ°åŠ¨æ€æ¼”åŒ–çš„ç ”ç©¶å‘å±•å¼•ä¼¸ä¸ºæŒ‡å¯¼å‚¨å±‚å’Œæµä½“åŠ¨æ€æ¼”åŒ–çš„ç ”ç©¶è·¨å‡ºäº†é‡è¦çš„ä¸€æ¥.%The basin-orogeny coupling theory was applied to study the abnormally high pressure in basin for the first time in this paper. The formation and distribution of abnormally high pressure were controlled by regional stress fields. In compressed basins, the key contributing factors for abnormally high pressure were compressive stress and charging of natural gas (or oil-gas), where the abnormally high pressure distributed zonaly or planar-ly. In extended and pull-apart basins, the abnormally high pressure was mainly resulted from thermal activities. In extended basins, the abnormally high pressure distributed in the shape of scattered points or restricted planes, and it distributed pointedly or in the shape of scattered points in sheared basins. The reverse, normal and strike -slip faults had different occurrences, which decided the oblique or vertical conductions of abnormally high pressure. There were different ways for pressure reservation or releasing in compression or reversion. From the dynamic evolution of basin to the dynamic evolution of reservoir and fluid, it was an important step for the application of basin-orogeny coupling theory.
Institute of Scientific and Technical Information of China (English)
ç‰›åç…œ; é™ˆç‘›; æŽå¿—åŒ
2014-01-01
é’¢ç‹æ··å‡åœŸåŸ‹æ¶µä¼˜åŒ–è®¾è®¡æ˜¯å¤šåœºã€å¤šå·¥å†µã€å¤šå˜é‡ã€å¤šçº¦æŸå’Œå¤šç›®æ ‡çš„å¤æ‚çš„ç¦»æ•£å˜é‡ä¼˜åŒ–é—®é¢˜ã€‚ä»¥å—æ°´åŒ—è°ƒä¸œçº¿ç©¿é»„å·¥ç¨‹æ»©åœ°åŸ‹ç®¡ä¸ºä¾‹ï¼Œæå‡ºäº†åŸºäºŽæµå›ºè€¦åˆå’Œæžé™çŠ¶æ€åˆ†æžçš„åŸ‹æ¶µä¼˜åŒ–è®¾è®¡æ–¹æ³•ã€‚ç”¨ä¼˜åŒ–è½¯ä»¶é›†æˆå¤šç›®æ ‡é—ä¼ ç®—æ³•NSGAï¼â…¡ã€å‚æ•°åŒ–æµå›ºè€¦åˆæœ‰é™å…ƒæ¨¡åž‹å’Œæžé™çŠ¶æ€åˆ†æžç¨‹åºï¼Œä»¥åŸ‹æ¶µå£åŽšã€é’¢ç‹ç›´å¾„ã€é’¢ç‹é—´è·ä¸ºè®¾è®¡å˜é‡ï¼Œåœ¨æ»¡è¶³å°ºå¯¸çº¦æŸã€æ‰¿è½½åŠ›æžé™çŠ¶æ€çº¦æŸã€é™è£‚çº¦æŸã€æž„é€ çº¦æŸç‰æ¡ä»¶ä¸‹ï¼Œä»¥é€ ä»·æœ€çœã€è£‚ç¼å®½åº¦æœ€å°ä¸ºç›®æ ‡å‡½æ•°ï¼Œå¾—åˆ°äº†å¤šç›®æ ‡ä¼˜åŒ–é—®é¢˜çš„Paretoæœ€ä¼˜è§£é›†ã€‚æ–‡ç« æå‡ºçš„ä¼˜åŒ–è®¾è®¡æ–¹æ³•å¯ä»¥è‡ªåŠ¨è¿è¡Œï¼Œé¿å…äº†ä¸åŒåœ°è´¨ã€ä¸åŒåŸ‹æ·±çš„é•¿çº¿è·¯åŸ‹æ¶µçš„é‡å¤æ€§æ‰‹å·¥å»ºæ¨¡ï¼Œå¤§å¤§æé«˜äº†è®¾è®¡åˆ†æžæ•ˆçŽ‡ã€‚%The optimized design of the embedded concrete culvert is the complicated discrete variable one which features lots of fields, couples of conditions, many variables, various restrains and multi-objectives.In design of the embedded culverts at Tandi where the south-to-north water diversion project underpasses the Yellow River, for example, the optimized design method for the embedded culvert based on fluid-structure couple and limit state analysis is proposed.By application of the optimization software, the multi-objective ge-netic algorithm NSGA-II, the parameterization fluid-structure finite element model and the limit state analysis program are integrated. With such design variables of the wall thickness of the embedded culvert, reinforcement diameter and reinforcement spacing as well as with the objective function of minimum cost and crack width, the optimum solution set of Pareto of the multiple-objective optimization is derived in condition of satisfying size constrain, bearing capacity limit state restrain, limit crack restrain and structural constrain.The op-timization design method proposed in the paper can automatically run, avoiding the repeat model
Institute of Scientific and Technical Information of China (English)
çŽ‹è¾‰æ˜Š; æ²ˆçŸ¥å½¼; é‚“çœŸ; çŽ‹å®½; è©¹çº¢ç”Ÿ
2015-01-01
ç›®çš„ï¼šå»ºç«‹å…¨é¢ˆæ¤Žç”Ÿç‰©åŠ›å¦æ•°å—ä»¿çœŸç ”ç©¶å¹³å°ã€‚æ–¹æ³•ï¼šå‚è€ƒå¤§é‡è§£å‰–å¦æ•°æ®å’Œäººä½“é¢ˆæ¤Žæ ‡æœ¬çš„å®žéªŒæ•°æ®ï¼Œåº”ç”¨é€†å‘å·¥ç¨‹åŽŸç†å¯¹åºåˆ—èžºæ—‹CT å›¾ç‰‡è¿›è¡Œå¤„ç†ï¼Œåˆ†åˆ«æž„å»ºé¢ˆæ¤Žæ¤Žä½“ã€æ¤ŽåŠ¨è„‰ã€éŸ§å¸¦ã€æ¤Žé—´ç›˜ã€å…³èŠ‚é¢è½¯éª¨å’Œç»ˆæ¿ç‰ç»“æž„æ¨¡åž‹ï¼Œå¹¶ä»Žè§£å‰–å½¢æ€å’Œæ´»åŠ¨åŠŸèƒ½ä¸¤æ–¹é¢éªŒè¯è¯¥æ¨¡åž‹ä¸Žäººä½“ç”Ÿç†çŠ¶æ€çš„ä¸€è‡´æ€§ã€‚ç»“æžœï¼šæž„å»ºäº†äººä½“é¢ˆæ¤Žä¸‰ç»´æœ‰é™å…ƒæ¨¡åž‹ï¼Œè¯¥æ¨¡åž‹æ¤Žä½“è¡¨é¢åº”åŠ›é›†ä¸è§„å¾‹ã€åŒä¾§æ¤ŽåŠ¨è„‰è¡€ç®¡å£æ‰€å—åº”åŠ›ç‰¹ç‚¹ä»¥åŠè¡€æµé€Ÿåº¦â€”æ—¶é—´å˜åŒ–æ›²çº¿ç‰å†…å®¹ä¸Žæ–‡çŒ®æŠ¥é“çš„äººä½“é¢ˆæ¤Žæ ‡æœ¬å®žéªŒç»“æžœè¶‹åŠ¿ä¸€è‡´ï¼Œå¹¶èƒ½åˆç†è§£é‡Šç›¸å¯¹åº”çš„ä¸´åºŠçŽ°è±¡ã€‚ç»“è®ºï¼šæˆåŠŸæž„å»ºäº†äººä½“å…¨é¢ˆæ¤Žä¸‰ç»´æœ‰é™å…ƒæµå›ºè€¦åˆæ¨¡åž‹ï¼Œè¯¥æ¨¡åž‹èƒ½ä¸ºæ·±å…¥äº†è§£äººä½“é¢ˆæ¤ŽåŠå…¶é™„å±žç»“æž„çš„ç”Ÿç‰©åŠ›å¦æœºåˆ¶æä¾›æ–°çš„ç ”ç©¶æ€è·¯ã€‚%Objective: To construct a human cervical spine with bilateral vertebral artery fluid-solid coupling model .Methods: Helical CT images under the principle of reverse engineering and meshed in finite element model ( FEM ) related software were used to establish a human cervical spine with bilateral vertebral artery fluid-solid coupling model . In the process of modeling of vertebral body , vertebral artery ,Â ligament , intervertebral disc , cartilage and endplate large anatomic data and cadaver experiments results were referenced .From the morphology and function the simulation of model with real physiological status was tested .Results: The study showed that the stress concentration on the surface of vertebral body and the blood wall of the bilateral vertebral artery , and the result of the volume flow rate-time curve of bilateral vertebral artery of the model were consistent with the published literatures .This model was well consistent with the clinical phenomenon .Conclusion: The three-dimensional FEM of the human cervical spine established by the introduced method has been effectively verified.The modeling
Institute of Scientific and Technical Information of China (English)
æŽä¿Šå¿; è®¸ç‡•è; åˆ˜å½¦ä¸°
2012-01-01
æŽŒæ¡æ±½è½®å‘ç”µæœºä¸çš„æ¸©åº¦åˆ†å¸ƒå¯¹ç”µæœºå†·å´ç³»ç»Ÿçš„ä¼˜åŒ–è®¾è®¡å’Œå¯é è¿è¡Œéƒ½æ˜¯éžå¸¸å¿…è¦çš„.åœ¨æ°´æ°¢æ°¢å†·å´çš„å¤§åž‹æ±½è½®å‘ç”µæœºä¸,å˜åœ¨ä¸¤ç§å†·å´ä»‹è´¨å’Œä¸¤å¥—å†·å´ç³»ç»Ÿ,å…¶æµä½“æµåŠ¨ä¸Žä¼ çƒè¾ƒå¤æ‚.æ ¹æ®å…¶å†·å´ç³»ç»Ÿå†…æµä½“æµåŠ¨ä¸Žä¼ çƒçš„ç‰¹ç‚¹,å»ºç«‹äº†å®šåæ•´ä¸ªè½´å‘é•¿åº¦èŒƒå›´å†…æµä½“æµåŠ¨ä¸Žä¼ çƒè€¦åˆè®¡ç®—çš„ç‰©ç†æ¨¡åž‹å’Œæ•°å¦æ¨¡åž‹,é‡‡ç”¨æœ‰é™ä½“ç§¯æ³•å¯¹æµä½“åœºå’Œæ¸©åº¦åœºè¿›è¡Œè€¦åˆè®¡ç®—,å¾—åˆ°äº†å®šåæœ¬ä½“ä¸è¯¦ç»†çš„æ¸©åº¦åˆ†å¸ƒæ•°å€¼åŠè¿‡çƒç‚¹çš„ä½ç½®,ç»™å‡ºäº†æµä½“çš„é€Ÿåº¦åˆ†å¸ƒå›¾ä»¥åŠå®šåå„éƒ¨åˆ†çš„æ¸©åº¦åˆ†å¸ƒå›¾.è¯¦ç»†åˆ†æžäº†æ°¢æ°”ã€å†·å´æ°´ã€å®šåé“å¿ƒã€å®šåç»•ç»„ç‰å„éƒ¨åˆ†çš„æ¸©åº¦åˆ†å¸ƒæƒ…å†µ.å°†è€¦åˆåœºè®¡ç®—ç»“æžœä¸ŽçŽ°åœºå®žæµ‹æ•°æ®è¿›è¡Œæ¯”è¾ƒ,è¡¨æ˜Žäº†æ¨¡åž‹å’Œè®¡ç®—æ–¹æ³•çš„æ£ç¡®æ€§.å…¶ç»“è®ºå¯å¯¹æ°´æ°¢æ°¢å†·å´æ±½è½®å‘ç”µæœºçš„å†·å´ç³»ç»Ÿè®¾è®¡ä¸Žå®žé™…è¿è¡Œæä¾›ç†è®ºä¾æ®.%It is necessary to know temperature distribution in turbo-generators for optimal design of cooling system and reliable operation of generators. In turbo-generators cooled by water and hydrogen where the fluid-flow and heat-transfer are complicated, there are two cooling mediums and corresponding systems. Considering the characteristics of fluid-flow and heat-transfer of turbo-generators cooled by water and hydrogen, the three-dimensional (3-D) physical and mathematical models of stator overall axis region for fluid and temperature coupling calculation were established, which were calculated numerically by finite volume method, then the temperature distribution and heat spot in stator noumenon were obtained. Fluit velocity and stator temperature contours were provided. The temperature distribution in hydrogen, cooling water, stator iron and windings is analyzed in detail. Theoretical approach together with experimental results confirms the validity of the proposed model and calculation method. The conclusion provides important method and theory basis for design of cooling
Directory of Open Access Journals (Sweden)
Caimmi R.
2008-01-01
Full Text Available A theory of collisionless fluids is developed in a unified picture, where nonrotating (â„¦f1 = â„¦f2 = â„¦f3 = 0 figures with some given random velocity component distributions, and rotating (â„¦f1 = â„¦f2 = â„¦f3 figures with a different random velocity component distributions, make adjoint configurations to the same system. R fluids are defined as ideal, self-gravitating fluids satisfying the virial theorem assumptions, in presence of systematic rotation around each of the principal axes of inertia. To this aim, mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The figure rotation is defined as the mean angular velocity, weighted on the moment of inertia, with respect to a selected axis. The generalized tensor virial equations (Caimmi and Marmo 2005 are formulated for R fluids and further attention is devoted to axisymmetric configurations where, for selected coordinate axes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and vice versa. A microscopical analysis of systematic and random motions is performed under a few general hypotheses, by reversing the sign of tangential or axial velocity components of an assigned fraction of particles, leaving the distribution function and other parameters unchanged (Meza 2002. The application of the reversion process to tangential velocity components is found to imply the conversion of random motion rotation kinetic energy into systematic motion rotation kinetic energy. The application of the reversion process to axial velocity components is found to imply the conversion of random motion translation kinetic energy into systematic motion translation kinetic energy, and the loss related to a change of reference frame is expressed in terms of systematic motion (imaginary rotation kinetic energy. A number of special situations are investigated in greater
Visual Simulation of Multiple Unmixable Fluids
Institute of Scientific and Technical Information of China (English)
Wen Zheng; Jun-Hai Yong; Jean-Claude Paul
2007-01-01
We present a novel grid-based method for simulating multiple unmixable fluids moving and interacting.Unlike previous methods that can only represent the interface between two fluids (usually between liquid and gas), this method can handle an arbitrary number of fluids through multiple independent level sets coupled with a constrain condition.To capture the fluid surface more accurately, we extend the particle level set method to a multi-fluid version.It shares the advantages of the particle level set method, and has the ability to track the interfaces of multiple fluids.To handle the dynamic behavior of different fluids existing together, we use a multiphase fluid formulation based on a smooth weight function.
Directory of Open Access Journals (Sweden)
Caimmi, R.
2008-06-01
Full Text Available A theory of collisionless fluids is developed in a unified picture, where nonrotating $(widetilde{Omega_1}=widetilde{Omega_2}= widetilde{Omega_3}=0$ figures with some given random velocity component distributions, and rotating $(widetilde{Omega_1} ewidetilde{Omega_2} e widetilde{Omega_3} $ figures with a different random velocity component distributions, make adjoint configurations to the same system. R fluids are defined as ideal, self-gravitating fluids satisfying the virial theorem assumptions, in presence of systematic rotation around each of the principal axes of inertia. To this aim, mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The figure rotation is defined as the mean angular velocity, weighted on the moment of inertia, with respectto a selected axis. The generalized tensor virial equations (Caimmi and Marmo 2005 are formulated for R fluidsand further attention is devoted to axisymmetric configurations where, for selected coordinateaxes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and viceversa. A microscopical analysis of systematic and random motions is performed under a fewgeneral hypotheses, by reversing the sign of tangential or axial velocity components of anassigned fraction of particles, leaving the distribution function and other parametersunchanged (Meza 2002. The application of the reversion process to tangential velocitycomponents is found to imply the conversion of random motion rotation kinetic energy intosystematic motion rotation kinetic energy. The application ofthe reversion process to axial velocity components is found to imply the conversionof random motion translation kinetic energy into systematic motion translation kinetic energy, and theloss related to a change of reference frame is expressed in terms of systematic motion (imaginary rotation kinetic
Coupled transfers; Transferts couples
Energy Technology Data Exchange (ETDEWEB)
Nicolas, X.; Lauriat, G.; Jimenez-Rondan, J. [Universite de Marne-la-Vallee, Lab. d' Etudes des Transferts d' Energie et de Matiere (LETEM), 77 (France); Bouali, H.; Mezrhab, A. [Faculte des Sciences, Dept. de Physique, Lab. de Mecanique et Energetique, Oujda (Morocco); Abid, C. [Ecole Polytechnique Universitaire de Marseille, IUSTI UMR 6595, 13 Marseille (France); Stoian, M.; Rebay, M.; Lachi, M.; Padet, J. [Faculte des Sciences, Lab. de Thermomecanique, UTAP, 51 - Reims (France); Mladin, E.C. [Universitaire Polytechnique Bucarest, Faculte de Genie Mecanique, Bucarest (Romania); Mezrhab, A. [Faculte des Sciences, Lab. de Mecanique et Energetique, Dept. de Physique, Oujda (Morocco); Abid, C.; Papini, F. [Ecole Polytechnique, IUSTI, 13 - Marseille (France); Lorrette, C.; Goyheneche, J.M.; Boechat, C.; Pailler, R. [Laboratoire des Composites ThermoStructuraux, UMR 5801, 33 - Pessac (France); Ben Salah, M.; Askri, F.; Jemni, A.; Ben Nasrallah, S. [Ecole Nationale d' Ingenieurs de Monastir, Lab. d' Etudes des Systemes Thermiques et Energetiques (Tunisia); Grine, A.; Desmons, J.Y.; Harmand, S. [Laboratoire de Mecanique et d' Energetique, 59 - Valenciennes (France); Radenac, E.; Gressier, J.; Millan, P. [ONERA, 31 - Toulouse (France); Giovannini, A. [Institut de Mecanique des Fluides de Toulouse, 31 (France)
2005-07-01
This session about coupled transfers gathers 30 articles dealing with: numerical study of coupled heat transfers inside an alveolar wall; natural convection/radiant heat transfer coupling inside a plugged and ventilated chimney; finite-volume modeling of the convection-conduction coupling in non-stationary regime; numerical study of the natural convection/radiant heat transfer coupling inside a partitioned cavity; modeling of the thermal conductivity of textile reinforced composites: finite element homogenization on a full periodical pattern; application of the control volume method based on non-structured finite elements to the problems of axisymmetrical radiant heat transfers in any geometries; modeling of convective transfers in transient regime on a flat plate; a conservative method for the non-stationary coupling of aero-thermal engineering codes; measurement of coupled heat transfers (forced convection/radiant transfer) inside an horizontal duct; numerical simulation of the combustion of a water-oil emulsion droplet; numerical simulation study of heat and mass transfers inside a reactor for nano-powders synthesis; reduction of a combustion and heat transfer model of a direct injection diesel engine; modeling of heat transfers inside a knocking operated spark ignition engine; heat loss inside an internal combustion engine, thermodynamical and flamelet model, composition effects of CH{sub 4}H{sub 2} mixtures; experimental study and modeling of the evolution of a flame on a solid fuel; heat transfer for laminar subsonic jet of oxygen plasma impacting an obstacle; hydrogen transport through a A-Si:H layer submitted to an hydrogen plasma: temperature effects; thermal modeling of the CO{sub 2} laser welding of a magnesium alloy; radiant heat transfer inside a 3-D environment: application of the finite volume method in association with the CK model; optimization of the infrared baking of two types of powder paints; optimization of the emission power of an infrared
Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; Liu, J.; Macias, B.; Martin, D. S.; Minkoff, L.; Ploutz-Snyder, R.; Ribeiro, L. C.; Sargsyan, A.; Smith, S. M.
2017-01-01
Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid
Florkowski, W.; Maj, R.
The recently introduced approach describing coupled quark and gluon anisotropic fluids is generalized to include explicitly the transitions between quarks and gluons. We study the effects of such processes on the thermalization rate of anisotropic systems. We find that the quark-gluon transitions may enhance the overall thermalization rate in the cases where the initial momentum anisotropies correspond to mixed oblate-prolate or prolate configurations. On the other hand, no effect on the thermalization rate is found in the case of oblate configurations. The observed regularities are connected with the late-time behavior of the analyzed systems which is described either by the exponential decay or the power law.
Florkowski, Wojciech
2013-01-01
The recently introduced approach describing coupled quark and gluon anisotropic fluids is generalized to include explicitly the transitions between quarks and gluons. We study the effects of such processes on the thermalization rate of anisotropic systems. We find that the quark-gluon transitions may enhance the overall thermalization rate in the cases where the initial momentum anisotropies correspond to mixed oblate-prolate or prolate configurations. On the other hand, no effect on the thermalization rate is found in the case of oblate configurations. The observed regularities are connected with the late-time behavior of the analyzed systems which is described either by the exponential decay or the power law.
Institute of Scientific and Technical Information of China (English)
åº·æ°¸å°š; é‚“æ³½; çŽ‹çº¢å²©; åˆ˜æ´ªæž—; è¢æ˜¥æž—; èµµç¾¤
2016-01-01
é¡µå²©åŽ‹è£‚æ”¹é€ è¿‡ç¨‹ä¸æ¸—é€çŽ‡å˜åŒ–å’ŒåŽ‹è£‚ç¼æ‰©å±•çš„æœºç†å¯¹é¡µå²©æ°”å¼€å‘åŽ‹è£‚å·¥ç¨‹è®¾è®¡å…·æœ‰é‡è¦æ„ä¹‰ï¼Œé€šè¿‡é¡µå²©å²©å¿ƒé¦–æ¬¡åŠ è½½ï¼å¸è½½ï¼äºŒæ¬¡åŠ è½½æµï¼å›ºè€¦åˆç‰©ç†æ¨¡æ‹Ÿå®žéªŒå’ŒäºŒæ¬¡åŠ è½½å®žéªŒåŽå²©å¿ƒå¾®ç±³ CT æˆåƒåˆ†æžï¼Œæç¤ºå‡ºä¸¤ä¸ªé‡è¦çŽ°è±¡ï¼šï¼ˆ1ï¼‰é¦–æ¬¡åŠ è½½ï¼å¸è½½ï¼äºŒæ¬¡åŠ è½½è¿‡ç¨‹ï¼Œæœ‰åŠ©äºŽæé«˜å²©å¿ƒçš„æ¸—é€çŽ‡ï¼›ï¼ˆ2ï¼‰åœ¨äºŒæ¬¡åŠ è½½è¿‡ç¨‹ä¸ï¼Œå²©å¿ƒæ¸—é€çŽ‡éšè½´åŽ‹å¢žåŠ å‡ºçŽ°å¢žåŠ æˆ–é™ä½Žä¸åŒçš„çŽ°è±¡ï¼Œåˆ†åˆ«å¯¹åº”åŽ‹è£‚ç¼çš„æœ‰åºåŒ–å’Œæ–¹å‘æ€§æ‰©å±•æˆ–æ— åºåŒ–å’Œå±€éƒ¨ç³œæ£±åŒ–æ‰©å±•ã€‚å®žéªŒèŽ·å¾—çš„è®¤è¯†å¯¹é¡µå²©å‚¨å±‚åŽ‹è£‚æ”¹é€ æœ‰ä¸¤æ¡å¯ç¤ºï¼šï¼ˆ1ï¼‰æ³µå…¥ï¼åœæ³µï¼å†æ³µå…¥å¾ªçŽ¯åŽ‹è£‚æœ‰åŠ©äºŽæ”¹å–„é¡µå²©æ°”å‚¨å±‚çš„æ¸—é€çŽ‡ï¼›ï¼ˆ2ï¼‰å¯¹å¤©ç„¶è£‚ç¼å‘è‚²çš„é¡µå²©å‚¨å±‚ï¼ŒåŽ‹è£‚è§„æ¨¡çš„é’ˆå¯¹æ€§è®¾è®¡ååˆ†å…³é”®ã€‚%The mechanisms of permeability variations and fracture extension are essential for hydraulic fracturing design in shale gas exploitation.Based on fluid-solid coupling physical experiments and Micro-CT imaging analysis,this study reveals two im-portant phenomena:(1)loading-unloading-reloading cycle has an effect on increasing the permeability of shale samples,(2) during the reloading process,the permeability of shale samples show different trends with increasing axial pressure.In the per-meability increasing case with increasing axial pressure,the fractures are produced directionally and orderly.In another case, the fractures are produced disorderly and locally mylonitic.The results show that (1)pumping-intermission-repumping multi-cycles could help modify the stimulation effect of in-site fracturing operations,and (2)hydraulic fracturing volume should be appropriately controlled for naturally fractured shale gas reservoirs.
Institute of Scientific and Technical Information of China (English)
æœ±åˆ©å‡¯; èƒ¡æ•¬å®; å¼ å†›è¾‰; æŽæµ©
2012-01-01
Three groups of models were designed for chemical vessel supplementary water pumps and three-dimensional models were established by using the software Pro/E. CFD software was used to conduct a simulation and a test was per formed of the hydraulic models to acquire an optimum model by comparing the test results with the simulation ones. The link of the CFD with the Static Structural and Modal was established by using the Ansys Workbench to conduct an analysis of the optimum model. On the basis of the three-dimensional steady numerical calculation results of the pump and by making use of the sequence coupling technology, an iterative calculation was performed of the solid and fluid domain to analyze the static stress and vibration mode of the impeller. It has been found that under the action of the hydraulic pressure,the maximal displacement due to the blade deformation occurs at a place nearing the trailing edge of the blade. Due to an action of the balance holes,the equivalent stress of the blade is relatively uniform and small. Under the action of the pressure difference before and after the wheel,the hub has a relatively big e-quivalent stress. Under the design operating condition,the deformation of the hub has a conspicuous influence on the vibration mode.%è®¾è®¡3ç»„åŒ–å®¹è¡¥æ°´æ³µæ¨¡åž‹,è¿ç”¨Pro/Eå»ºç«‹ä¸‰ç»´æ¨¡åž‹,ç”±CFDè½¯ä»¶ä»¿çœŸ,å¹¶å¯¹æ°´åŠ›æ¨¡åž‹è¿›è¡Œè¯•éªŒ,å¯¹æ¯”è¯•éªŒä¸Žä»¿çœŸç»“æžœ,èŽ·å–æœ€ä¼˜æ¨¡åž‹.é€šè¿‡ANSYS Workbenchå»ºç«‹CFDä¸ŽStatic Structural(é™åŠ›å¦)å’ŒModal(æ¨¡æ€)è¿žæŽ¥,å¯¹æœ€ä¼˜æ¨¡åž‹è¿›è¡Œåˆ†æž,ä»¥æ³µä¸‰ç»´å®šå¸¸æ•°å€¼è®¡ç®—ç»“æžœä¸ºåŸºç¡€,åˆ©ç”¨é¡ºåºè€¦åˆæŠ€æœ¯,å¯¹å›ºä½“å’Œæµä½“åŸŸè¿›è¡Œè¿ä»£,åˆ†æžå¶è½®çš„é™æ€åº”åŠ›å’ŒæŒ¯åž‹.ç»“æžœè¡¨æ˜Ž,åœ¨æ°´åŽ‹åŠ›ä½œç”¨ä¸‹å¶ç‰‡å˜å½¢æœ€å¤§ä½ç§»å‘ç”Ÿåœ¨å¶ç‰‡å‡ºæ°´è¾¹é è¿‘å¶ç‰‡è¾¹ç¼˜å¤„,ç”±å¹³è¡¡å”ä½œç”¨,å¶ç‰‡çš„ç‰æ•ˆåº”åŠ›ç›¸å¯¹å‡åŒ€è¾ƒå°,å¶è½®è½®æ¯‚å¤„å› å¶è½®å‰åŽé¢åŽ‹å·®ä½œç”¨,ç‰æ•ˆåº”åŠ›è¾ƒå¤§.è®¾è®¡å·¥å†µä¸‹,å¶è½®è½®æ¯‚å˜å½¢å¯¹æŒ¯åž‹çš„å½±å“æ˜Žæ˜¾.
Institute of Scientific and Technical Information of China (English)
å®‰ä¼Ÿ; ä¸‡å©·å©·
2011-01-01
It will cost a lot of time,manpower and financial resources through experiments to understand the flow characteristics of catalytic converter.With the development of CAE technology, testing effort and the design cycle can be reduced greatly,besides it can provide structural optimization foundation for early product design and development.Based on one type catalytic converter of manifold type, a finite element analytical model is established,through which heat transfer boundary conditions are obtained by analyzing and calculating with method of solid-fluid coupling, the temperature field of the converter is got as well,under which thermal stress analysis is carried out.Thus the thermal-stress distribute status can be got about this type converterAnd optimization and modification for structure where the stress is concentrated and reach maximum are advised to avoid structural damage caused by the stress concentration effectively%é€šè¿‡å®žéªŒæ¥äº†è§£æ§ç®¡å¼å‚¬åŒ–è½¬åŒ–å™¨æµåŠ¨ç‰¹æ€§ã€çƒå˜å½¢çŠ¶å†µ,æ—¢è´¹æ—¶åˆè´¹äº†åŠ›.é€šè¿‡CAEæŠ€æœ¯å¯ä»¥å¤§å¤§å‡å°‘è¯•éªŒå·¥ä½œé‡,ç¼©çŸè®¾è®¡å‘¨æœŸ,ä¸ºäº§å“å‰æœŸè®¾è®¡å¼€å‘æä¾›äº†ç»“æž„ä¼˜åŒ–ä¾æ®.é’ˆå¯¹æŸåž‹å·æ§ç®¡å¼å‚¬åŒ–è½¬åŒ–å™¨å»ºç«‹äº†æœ‰é™å…ƒåˆ†æžæ¨¡åž‹,é‡‡ç”¨æµå›ºè€¦åˆæ–¹æ³•åˆ†æžè®¡ç®—å¾—åˆ°ä¼ çƒåˆ†æžçš„è¾¹ç•Œæ¡ä»¶,å†ç»è¿‡ä¼ çƒåˆ†æžå¾—åˆ°è½¬åŒ–å™¨çš„æ¸©åº¦åœº,å¹¶åœ¨æ¤æ¸©åº¦åœºä¸‹å¯¹å‚¬åŒ–è½¬åŒ–å™¨è¿›è¡Œçƒåº”åŠ›åˆ†æž.å¾—åˆ°äº†è¯¥åž‹å·æ§ç®¡ç»“æž„çƒåº”åŠ›åˆ†å¸ƒçŠ¶å†µ,å¯¹åº”åŠ›é›†ä¸ä¸Žåº”åŠ›æœ€å¤§å¤„ç»“æž„æå‡ºäº†ç›¸åº”çš„ä¼˜åŒ–ä¸Žä¿®æ”¹æ„è§,æœ‰æ•ˆçš„é¿å…äº†å› åº”åŠ›é›†ä¸é€ æˆçš„ç»“æž„ç ´å.
Energy Technology Data Exchange (ETDEWEB)
Moridis, George; Freeman, Craig
2013-09-30
We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas . The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include: coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas
Dipolar fluids under external perturbations
Energy Technology Data Exchange (ETDEWEB)
Klapp, Sabine H L [Stranski-Laboratorium fuer Physikalische und Theoretische Chemie Sekretariat TC7, Technische Universitaet Berlin, Strasse des 17. Juni 124, D-10623 Berlin (Germany)
2005-04-20
We discuss recent developments and present new findings on the structural and phase properties of dipolar model fluids influenced by various external perturbations. We concentrate on systems of spherical particles with permanent (point) dipole moments. Starting from what is known about the three-dimensional systems, particular emphasis is given to dipolar fluids in different confining situations involving both simple and complex (disordered) pore geometries. Further topics concern the effect of quenched positional disorder, the influence of external (electric or magnetic) fields, and the fluid-fluid phase behaviour of various dipolar mixtures. It is demonstrated that due to the translational-orientational coupling and due to the long range of dipolar interactions even simple perturbations such as hard walls can have a profound impact on the systems. (topical review)
PYESSENCE: Generalized Coupled Quintessence Linear Perturbation Python Code
Leithes, Alexander
2016-09-01
PYESSENCE evolves linearly perturbed coupled quintessence models with multiple (cold dark matter) CDM fluid species and multiple DE (dark energy) scalar fields, and can be used to generate quantities such as the growth factor of large scale structure for any coupled quintessence model with an arbitrary number of fields and fluids and arbitrary couplings.
Ruban, Anatoly I
This is the first book in a four-part series designed to give a comprehensive and coherent description of Fluid Dynamics, starting with chapters on classical theory suitable for an introductory undergraduate lecture course, and then progressing through more advanced material up to the level of modern research in the field. The present Part 1 consists of four chapters. Chapter 1 begins with a discussion of Continuum Hypothesis, which is followed by an introduction to macroscopic functions, the velocity vector, pressure, density, and enthalpy. We then analyse the forces acting inside a fluid, and deduce the Navier-Stokes equations for incompressible and compressible fluids in Cartesian and curvilinear coordinates. In Chapter 2 we study the properties of a number of flows that are presented by the so-called exact solutions of the Navier-Stokes equations, including the Couette flow between two parallel plates, Hagen-Poiseuille flow through a pipe, and Karman flow above an infinite rotating disk. Chapter 3 is d...
Topology Optimisation for Coupled Convection Problems
DEFF Research Database (Denmark)
Alexandersen, Joe; Andreasen, Casper Schousboe; Aage, Niels
conduction governs in the solid parts of the design domain and couples to convection-dominated heat transfer to a surrounding fluid. Both loosely coupled and tightly coupled problems are considered. The loosely coupled problems are convection-diffusion problems, based on an advective velocity field from......The work focuses on applying topology optimisation to forced and natural convection problems in fluid dynamics and conjugate (fluid-structure) heat transfer. To the authors' knowledge, topology optimisation has not yet been applied to natural convection flow problems in the published literature...... and the current work is thus seen as contributing new results to the field. In the literature, most works on the topology optimisation of weakly coupled convection-diffusion problems focus on the temperature distribution of the fluid, but a selection of notable exceptions also focusing on the temperature...
Hydromechanical coupling in geologic processes
Neuzil, C.E.
2003-01-01
Earth's porous crust and the fluids within it are intimately linked through their mechanical effects on each other. This paper presents an overview of such "hydromechanical" coupling and examines current understanding of its role in geologic processes. An outline of the theory of hydromechanics and rheological models for geologic deformation is included to place various analytical approaches in proper context and to provide an introduction to this broad topic for nonspecialists. Effects of hydromechanical coupling are ubiquitous in geology, and can be local and short-lived or regional and very long-lived. Phenomena such as deposition and erosion, tectonism, seismicity, earth tides, and barometric loading produce strains that tend to alter fluid pressure. Resulting pressure perturbations can be dramatic, and many so-called "anomalous" pressures appear to have been created in this manner. The effects of fluid pressure on crustal mechanics are also profound. Geologic media deform and fail largely in response to effective stress, or total stress minus fluid pressure. As a result, fluid pressures control compaction, decompaction, and other types of deformation, as well as jointing, shear failure, and shear slippage, including events that generate earthquakes. By controlling deformation and failure, fluid pressures also regulate states of stress in the upper crust. Advances in the last 80 years, including theories of consolidation, transient groundwater flow, and poroelasticity, have been synthesized into a reasonably complete conceptual framework for understanding and describing hydromechanical coupling. Full coupling in two or three dimensions is described using force balance equations for deformation coupled with a mass conservation equation for fluid flow. Fully coupled analyses allow hypothesis testing and conceptual model development. However, rigorous application of full coupling is often difficult because (1) the rheological behavior of geologic media is complex
... Home Visit Global Sites Search Help? Pleural Fluid Analysis Share this page: Was this page helpful? Formal name: Pleural Fluid Analysis Related tests: Pericardial Fluid Analysis , Peritoneal Fluid Analysis , ...
Institute of Scientific and Technical Information of China (English)
ç”°æ ‘åˆš; å¼ çˆ±å†›; ä»»æ–‡æ¸Š; çŽ‹å©·
2015-01-01
According to the site information of an offshore project of wind turbine,the dynamic characteristics and the seismic response of the supporting system of turbine were analyzed by considering the complicated interactions of water,soil,and supporting system. The fluid-structure coupling,the seepage of saturated soil and the pile-soil contact behaviour were simulated using the finite element method. Four working conditions were considered for the analysis of characteristics of natural vibration,i.e. the single-pile supporting with water and without water in consideration,the four-pile supporting with water and without water in consideration. The results from the simulations indicated that water had negligible influence on the lower-order frequencies of the structure, but led to a large reduction on the high-order frequencies. Water reduced the horizontal and the vertical displacements,the peak acceleration and the effective stress of the supporting system. The excess pore water pressure in the foundation soil fluctuated under seismic actions. The calculated structural displacements and effective stresses met the regulation requirements.%ç»“åˆè¿‘æµ·é£Žç”µå•æ¡©åŠå››æ¡©åŸºç¡€æ”¯æ’‘ä½“ç³»å·¥ç¨‹å®žé™…åœºåœ°èµ„æ–™ï¼Œé‡‡ç”¨æœ‰é™å…ƒæ•°å€¼åˆ†æžæ–¹æ³•ï¼Œè€ƒè™‘æ°´â€“åœŸâ€“ç»“æž„åŠ¨åŠ›ç›¸äº’ä½œç”¨ï¼Œå³è€ƒè™‘æµâ€“å›ºè€¦åˆæ•ˆåº”ã€é¥±å’ŒåœŸçš„å¤šå”ä»‹è´¨æ¸—æµå±žæ€§åŠæ¡©â€“åœŸæŽ¥è§¦ç›¸äº’ä½œç”¨ï¼Œåˆ†æžç»“æž„ä½“ç³»åŠ¨åŠ›ç‰¹æ€§åŠåœ°éœ‡ååº”ã€‚åˆ†æžå•æ¡©æœ‰æ°´ä¸Žæ— æ°´åŠå››æ¡©æœ‰æ°´ä¸Žæ— æ°´4ç§å·¥å†µæ”¯æ’‘ä½“ç³»çš„è‡ªæŒ¯ç‰¹æ€§å’Œå•æ¡©æœ‰æ°´ä¸Žæ— æ°´2ç§å·¥å†µæ”¯æ’‘ä½“ç³»çš„åœ°éœ‡ååº”ã€‚ç»“æžœè¡¨æ˜Žï¼šæ°´å±‚å¯¹ç»“æž„ä½Žé˜¶é¢‘çŽ‡å½±å“ä¸å¤§ï¼Œå¯¹é«˜é˜¶é¢‘çŽ‡é™ä½Žå¹…åº¦è¾ƒå¤§ï¼›æ°´å±‚å¯¹ä½“ç³»çš„æ°´å¹³ä½ç§»ã€ç«–å‘æ²‰é™ã€å³°å€¼åŠ é€Ÿåº¦åŠæœ‰æ•ˆåº”åŠ›å‡æœ‰ä¸åŒç¨‹åº¦åœ°å‰Šå‡ï¼›åœ°éœ‡ä½œç”¨ä¸‹åœŸä½“çš„è¶…é™å”éš™æ°´åŽ‹åŠ›å‘ˆçŽ°æ³¢åŠ¨ç‰¹æ€§ï¼›ç»“æž„çš„ä½ç§»åŠåº”åŠ›å“åº”å‡èƒ½æ»¡è¶³è§„èŒƒè¦æ±‚ã€‚è¯æ˜Žè€ƒè™‘å¤šä»‹è´¨è€¦åˆçš„åŠ¨åŠ›æœ‰é™å…ƒåˆ†æžæ–¹æ³•æ˜¯è
Energy Technology Data Exchange (ETDEWEB)
Copps, Kevin D.
2011-12-01
For a CASL grid-to-rod fretting problem, Sandia's Percept software was used in conjunction with the Sierra Mechanics suite to analyze the convergence behavior of the data transfer from a fluid simulation to a solid mechanics simulation. An analytic function, with properties relatively close to numerically computed fluid approximations, was chosen to represent the pressure solution in the fluid domain. The analytic pressure was interpolated on a sequence of grids on the fluid domain, and transferred onto a separate sequence of grids in the solid domain. The error in the resulting pressure in the solid domain was measured with respect to the analytic pressure. The error in pressure approached zero as both the fluid and solids meshes were refined. The convergence of the transfer algorithm was limited by whether the source grid resolution was the same or finer than the target grid resolution. In addition, using a feature coverage analysis, we found gaps in the solid mechanics code verification test suite directly relevant to the prototype CASL GTRF simulations.
Futterer, B.; Egbers, C.; Dahley, N.; Koch, S.; Jehring, L.
2010-01-01
Physical mechanisms of thermally driven rotating fluids are important for a large number of geophysical problems, e.g. to explain the convection of the Earth's liquid outer core. Objective of the 'GeoFlow' experiment is to study stability, pattern formation, and transition to chaos of thermal convection in fluid-filled concentric, co-axially rotating spheres. This experiment is integrated in the Fluid Science Laboratory of the European COLUMBUS module on International Space Station. Fluid dynamics of the experiment was predicted with numerical simulations by means of a spectral code. In the non-rotating case the onset of convection bifurcated into steady fluid flow. Here patterns of convection showed co-existing states with axisymmetric, cubic and pentagonal modes. Transition to chaos was in the form of sudden onset. For the thermal convection in rotating spheres the onset of first instability showed an increase of modes for higher parameter regime. Transition was from steady via periodic to chaotic behaviour. Convection patterns of the experiment are observed with the Wollaston shearing interferometry. Images are in terms of interferograms with fringe patterns corresponding to special convective flows. A first glance at the images showed the classification of sub- and supercritical flow regimes. Aligned with numerical data a shift between experiment and numerical simulation was identified. Identification of convection patterns in interferograms was demonstrated for the example of a supercritical flow.
MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS
Energy Technology Data Exchange (ETDEWEB)
Leishear, R.
2009-09-09
Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels.
DEFF Research Database (Denmark)
Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter
2015-01-01
We study motivations for and outcomes of couples starting up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010, while comparing them to a set of comparable firms and couples. The main motivation for joint entrepreneurship is to create...
Multiscale coupling:challenges and opportunities
Institute of Scientific and Technical Information of China (English)
HE Guowei; XIA Mengfen; KE Fuju; BAI Yilong
2004-01-01
Multiscale coupling is ubiquitous in nature and attracts broad interests of scientists from mathematicians, physicists, machinists, chemists to biologists. However, much less attention has been paid to its intrinsic implication. In this paper, multiscale coupling is introduced by studying two typical examples in classic mechanics: fluid turbulence and solid failure. The nature of multiscale coupling in the two examples lies in their physical diversities and strong coupling over wide-range scales. The theories of dynamical system and statistical mechanics provide fundamental methods for the multiscale coupling problems. The diverse multiscale couplings call for unified approaches and might expedite new concepts, theories and disciplines.
Geochemical modeling of fluid-fluid and fluid-mineral interactions during geological CO2 storage
Zhu, C.; Ji, X.; Lu, P.
2013-12-01
The long time required for effective CO2 storage makes geochemical modeling an indispensable tool for CCUS. One area of geochemical modeling research that is in urgent need is impurities in CO2 streams. Permitting impurities, such as H2S, in CO2 streams can lead to potential capital and energy savings. However, predicting the consequences of co-injection of CO2 and impurities into geological formations requires the understanding of the phase equilibrium and fluid-fluid interactions. To meet this need, we developed a statistical associating fluid theory (SAFT)-based equation of state (EOS) for the H2S-CO2-H2O-NaCl system at 373.15 dew pressures decrease with increasing H2S content, while the mass density increases at low pressures and decreases at high pressures. Furthermore, the EoS can be incorporated into reservoir simulators so that the dynamic development of mixed fluid plumes in the reservoir can be simulated. Accurate modeling of fluid-mineral interactions must confront unresolved uncertainties of silicate dissolution - precipitation reaction kinetics. Most prominent among these uncertainties is the well-known lab-field apparent discrepancy in dissolution rates. Although reactive transport models that simulate the interactions between reservoir rocks and brine, and their attendant effects on porosity and permeability changes, have proliferated, whether these results have acceptable uncertainties are unknown. We have conducted a series of batch experiments at elevated temperatures and numerical simulations of coupled dissolution and precipitation reactions. The results show that taking into account of reaction coupling is able to reduce the gap between the field and lab rates by about two orders of magnitude at elevated temperatures of 200-300 oC. Currently, we are using Si isotopes as a new tool to unravel the coupled reactions in ambient temperature laboratory experiments. These new experimental data, together with coupled reactive mass transport modeling
Supercritical fluid technology
Energy Technology Data Exchange (ETDEWEB)
Penninger, J.M.L.; McHugh, M.A.; Radosz, M.; Krukonis, V.J.
1985-01-01
This book presents the state-of-the-art in the science and technology of supercritical fluid (scf) processing. Current research as described in the book, focuses on developments in equations of state for binary and multicomponent mixtures (including polymer solutions), solubility measurements at near-critical conditions, measurements of critical properties of binary mixtures and their correlation with equations of state. Progress in thermodynamics, coupled with advances in the design and construction of high pressure equipment, has opened up a wide avenue of commercial application (e.g. decaffeination of coffee beans, extractions of flavours and spices, purification of pharmaceutical products, separations of polymeric materials, deodorization and deacidification of vegetable oils, fractionation of fatty acids, coal liquefaction, wood delignitication, etc.)
Thermophysical Properties of Fluids and Fluid Mixtures
Energy Technology Data Exchange (ETDEWEB)
Sengers, Jan V.; Anisimov, Mikhail A.
2004-05-03
The major goal of the project was to study the effect of critical fluctuations on the thermophysical properties and phase behavior of fluids and fluid mixtures. Long-range fluctuations appear because of the presence of critical phase transitions. A global theory of critical fluctuations was developed and applied to represent thermodynamic properties and transport properties of molecular fluids and fluid mixtures. In the second phase of the project, the theory was extended to deal with critical fluctuations in complex fluids such as polymer solutions and electrolyte solutions. The theoretical predictions have been confirmed by computer simulations and by light-scattering experiments. Fluctuations in fluids in nonequilibrium states have also been investigated.
Energy Technology Data Exchange (ETDEWEB)
Le Guen, Y
2006-10-15
CO{sub 2} injection into geological repositories will induce chemical and mechanical instabilities. The study of these instabilities is based on experimental deformation of natural rock samples under stress, in the presence of fluids containing, or not, dissolved CO{sub 2}. Triaxial cells used for the experiments permitted an independent control and measurement of stress, temperature, fluid pressure and composition. Vertical strains were measured during several months, with a resolution of 1.10{sup -12} s{sup -1} on the strain rate. Simultaneously, fluids were analysed in order to quantify fluid-rock interactions. For limestone samples, percolation of CO{sub 2}-rich fluids increases strain rate by a factor 1.7 up to 5; on the other hand, sandstone deformation remained almost the same. Increase in strain rate with limestone samples was explained by injected water acidification by the CO{sub 2} which increases rock solubility and reaction kinetics. On the opposite, small effect of CO{sub 2} on quartz explains the absence of deformation. X-ray observations confirmed the importance of rock composition and structure on the porosity evolution. Numerical simulations of rock elastic properties showed increasing shear stress into the sample. Measured deformation showed an evolution of reservoir rocks mechanical properties. It was interpreted as the consequence of pressure solution mechanisms both at grains contacts and on grain free surfaces. (author)
Fluid-structure interactions models, analysis and finite elements
Richter, Thomas
2017-01-01
This book starts by introducing the fundamental concepts of mathematical continuum mechanics for fluids and solids and their coupling. Special attention is given to the derivation of variational formulations for the subproblems describing fluid- and solid-mechanics as well as the coupled fluid-structure interaction problem. Two monolithic formulations for fluid-structure interactions are described in detail: the well-established ALE formulation and the modern Fully Eulerian formulation, which can effectively deal with problems featuring large deformation and contact. Further, the book provides details on state-of-the-art discretization schemes for fluid- and solid-mechanics and considers the special needs of coupled problems with interface-tracking and interface-capturing techniques. Lastly, advanced topics like goal-oriented error estimation, multigrid solution and gradient-based optimization schemes are discussed in the context of fluid-structure interaction problems.
Institute of Scientific and Technical Information of China (English)
èŒƒå¦å¹³; æŽç§€ç”Ÿ; å¼ å£«è¯š
2001-01-01
As in low permeability reservoir with variable medium the filtration flow and lithophysical properties are quite sensitive to the change of stress field, use of the coupling stress fluid and fluid filtration field may represent actual situation more reasonably. This paper conducted a comprehensive analysis on the coupling mathematics analog theory of fluid filtration and rock stress, also, demonstrating by instances of a multiple facies flow oil reservoir, gas reservoir, and the presence of hydralic fractured fractures. The study shows that the method suggested in this paper could be used to predict the variation of permeability, and storage capability of the rock, its stress and strain, and their influence upon production. Application of the method recommended here promises very well in petroleum engineering.%ä½Žæ¸—é€å˜å½¢ä»‹è´¨æ²¹æ°”è—æµä½“æ¸—æµå’Œå²©çŸ³ç‰©æ€§å¯¹åº”åŠ›åœºçš„å˜åŒ–æ¯”è¾ƒæ•æ„Ÿ,é‡‡ç”¨è€¦åˆåº”åŠ›åœºå’Œæµä½“æ¸—æµåœºèƒ½è¾ƒå¥½åœ°ååº”å®žé™…æƒ…å†µã€‚å¯¹æµä½“æ¸—æµå’Œå²©çŸ³åº”å˜è€¦åˆæ•°å¦æ¨¡æ‹Ÿç†è®ºå’Œå²©çŸ³åŠ›å¦å®žéªŒæ–¹æ³•è¿›è¡Œäº†ç»¼åˆåˆ†æž,ä»¥æŸä¸ªå¤šç›¸æµæ²¹è—ã€æ°”è—ã€å˜åœ¨æ°´åŠ›åŽ‹è£‚è£‚ç¼ç‰æƒ…å†µä¸ºä¾‹è¿›è¡Œç ”ç©¶ã€‚ç ”ç©¶è¡¨æ˜Ž,å¯ç”¨æœ¬æ–‡æ–¹æ³•é¢„æµ‹å²©çŸ³æ¸—å‚¨ç‰©æ€§åŠ¨æ€å˜åŒ–ã€åº”åŠ›åº”å˜ã€åŠå…¶å¯¹ç”Ÿäº§çš„å½±å“ã€‚è¿™é‡Œä»‹ç»çš„æ–¹æ³•åœ¨çŸ³æ²¹å·¥ç¨‹æ–¹é¢å…·æœ‰å¹¿é˜”çš„åº”ç”¨å‰æ™¯ã€‚
On the fluid mechanics of fires
Energy Technology Data Exchange (ETDEWEB)
TIESZEN,SHELDON R.
2000-02-29
Fluid mechanics research related to fire is reviewed with focus on canonical flows, multiphysics coupling aspects, experimental and numerical techniques. Fire is a low-speed, chemically-reacting, flow in which buoyancy plans an important role. Fire research has focused on two canonical flows, the reacting boundary-layer and the reacting free plume. There is rich, multi-lateral, bi-directional, coupling among fluid mechanics and scalar transport, combustion, and radiation. There is only a limited experimental fluid-mechanics database for fire due to measurement difficulties in the harsh environment, and the focus within the fire community on thermal/chemical consequences. Increasingly, computational fluid dynamics techniques are being used to provide engineering guidance on thermal/chemical consequences and to study fire phenomenology.
Direct simulation of particle-laden fluids
Energy Technology Data Exchange (ETDEWEB)
COOK,BENJAMIN K.; NOBLE,DAVID R.; PREECE,DALE S.; WILLIAMS,J.R.
2000-05-10
Processes that involve particle-laden fluids are common in geomechanics and especially in the petroleum industry. Understanding the physics of these processes and the ability to predict their behavior requires the development of coupled fluid-flow and particle-motion computational methods. This paper outlines an accurate and robust coupled computational scheme using the lattice-Boltzmann method for fluid flow and the discrete-element method for solid particle motion. Results from several two-dimensional validation simulations are presented. Simulations reported include the sedimentation of an ellipse, a disc and two interacting discs in a closed column of fluid. The recently discovered phenomenon of drafting, kissing, and tumbling is fully reproduced in the two-disc simulation.
DEFF Research Database (Denmark)
Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter
We study possible motivations for co-entrepenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and postdissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse â€“ most commonly the female â€“ has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...
DEFF Research Database (Denmark)
Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter
2015-01-01
We study possible motivations for co-entreprenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse â€“ most commonly the female â€“ has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...
DEFF Research Database (Denmark)
Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter
We study possible motivations for co-entrepenurial couples to start up a joint firm, us-ing a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse - most commonly the female - has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...
Solving Fluid Structure Interaction Problems with an Immersed Boundary Method
Barad, Michael F.; Brehm, Christoph; Kiris, Cetin C.
2016-01-01
An immersed boundary method for the compressible Navier-Stokes equations can be used for moving boundary problems as well as fully coupled fluid-structure interaction is presented. The underlying Cartesian immersed boundary method of the Launch Ascent and Vehicle Aerodynamics (LAVA) framework, based on the locally stabilized immersed boundary method previously presented by the authors, is extended to account for unsteady boundary motion and coupled to linear and geometrically nonlinear structural finite element solvers. The approach is validated for moving boundary problems with prescribed body motion and fully coupled fluid structure interaction problems. Keywords: Immersed Boundary Method, Higher-Order Finite Difference Method, Fluid Structure Interaction.
Coupled seismic and electromagnetic wave propagation
Schakel, M.D.
2011-01-01
Coupled seismic and electromagnetic wave propagation is studied theoretically and experimentally. This coupling arises because of the electrochemical double layer, which exists along the solid-grain/fluid-electrolyte boundaries of porous media. Within the double layer, charge is redistributed, creat
Pardini, J.A.; Brubaker, R.C.; Rusnak, J.J.
1982-09-20
Disclosed is a remotely operable releasable sealing coupling which provides fluid-tight joinder of upper and a lower conduit sections. Each conduit section has a concave conical sealing surface adjacent its end portion. A tubular sleeve having convex spherical ends is inserted between the conduit ends to form line contact with the concave conical end portions. An inwardly projecting lip located at one end of the sleeve cooperates with a retaining collar formed on the upper pipe end to provide swivel capture for the sleeve. The upper conduit section also includes a tapered lower end portion which engages the inside surface of the sleeve to limit misalignment of the connected conduit sections.
Hydrodynamics of anisotropic quark and gluon fluids
Florkowski, Wojciech; Maj, Radoslaw; Ryblewski, Radoslaw; Strickland, Michael
2013-03-01
The recently developed framework of anisotropic hydrodynamics is generalized to describe the dynamics of coupled quark and gluon fluids. The quark and gluon components of the fluids are characterized by different dynamical anisotropy parameters. The dynamical equations describing such mixtures are derived from kinetic theory, with the collisional kernel treated in the relaxation-time approximation, allowing for different relaxation times for quarks and gluons. Baryon number conservation is enforced in the quark and antiquark components of the fluid, but overall parton number nonconservation is allowed in the system. The resulting equations are solved numerically in the (0+1)-dimensional boost-invariant case at zero and finite baryon density.
Hydrodynamics of anisotropic quark and gluon fluids
Florkowski, Wojciech; Ryblewski, Radoslaw; Strickland, Michael
2012-01-01
The recently developed framework of anisotropic hydrodynamics is generalized to describe the dynamics of coupled quark and gluon fluids. The quark and gluon components of the fluids are characterized by different dynamical anisotropy parameters. The dynamical equations describing such mixtures are derived from kinetic theory with the collisional kernel treated in the relaxation-time approximation. Baryon number conservation is enforced in the quark and anti-quark components of the fluid, but overall parton number non-conservation is allowed in the system. The resulting equations are solved numerically in the (0+1)-dimensional boost-invariant case at zero and finite baryon density.
Modelling anisotropic fluid spheres in general relativity
Boonserm, Petarpa; Visser, Matt
2015-01-01
We argue that an arbitrary general relativistic anisotropic fluid sphere, (spherically symmetric but with transverse pressure not equal to radial pressure), can nevertheless be successfully modelled by suitable linear combinations of quite ordinary classical matter: an isotropic perfect fluid, a classical electromagnetic field, and a classical (minimally coupled) scalar field. While the most general decomposition is not unique, a preferred minimal decomposition can be constructed that is unique. We show how the classical energy conditions for the anisotropic fluid sphere can be related to energy conditions for the isotropic perfect fluid, electromagnetic field, and scalar field components of the model. Furthermore we show how this decomposition relates to the distribution of electric charge density and scalar charge density throughout the model that is used to mimic the anisotropic fluid sphere. Consequently, we can build physically reasonable matter models for almost any spherically symmetric spacetime.
Interfacial gauge methods for incompressible fluid dynamics.
Saye, Robert
2016-06-01
Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of "gauge freedom" to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena.
Unsteady fluid flow in smart material actuated fluid pumps
John, Shaju; Cadou, Christopher
2005-05-01
Smart materials' ability to deliver large block forces in a small package while operating at high frequencies makes them extremely attractive for converting electrical to mechanical power. This has led to the development of hybrid actuators consisting of co-located smart material actuated pumps and hydraulic cylinders that are connected by a set of fast-acting valves. The overall success of the hybrid concept hinges on the effectiveness of the coupling between the smart material and the fluid. This, in turn, is strongly dependent on the resistance to fluid flow in the device. This paper presents results from three-dimensional unsteady simulations of fluid flow in the pumping chamber of a prototype hybrid actuator powered by a piezo-electric stack. The results show that the forces associated with moving the fluid into and out of the pumping chamber already exceed 10% of the piezo stack blocked force at relatively low frequencies ~120 Hz and approach 40% of the blocked force at 800 Hz. This reduces the amplitude of the piston motion in such a way that the volume flow rate remains approximately constant above operating frequencies of 500 Hz while the efficiency of the pump decreases rapidly.
DEFF Research Database (Denmark)
RezaNejad Gatabi, Javad; Forouzbakhsh, Farshid; Ebrahimi Darkhaneh, Hadi
2010-01-01
and with measuring its travel time between two different positions, its velocity could be calculated. Given the velocity of the auxiliary fluid, the velocity of the main fluid could be calculated. Using this technique, it is possible to measure the velocity of any kind of fluids, if an appropriate auxiliary fluid...
Fluid mechanics in fluids at rest.
Brenner, Howard
2012-07-01
Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.
Videotapes and Movies on Fluid Dynamics and Fluid Machines
Carr, Bobbie; Young, Virginia E.
1996-01-01
Chapter 17 of Handbook of Fluid Dynamics and Fluid Machinery: Experimental and Computational Fluid Dynamics, Volume 11. A list of videorecordings and 16mm motion pictures about Fluid Dynamics and Fluid Machines.
Kryachko, Eugene S.
The general features of the nonadiabatic coupling and its relation to molecular properties are surveyed. Some consequences of the [`]equation of motion', formally expressing a [`]smoothness' of a given molecular property within the diabatic basis, are demonstrated. A particular emphasis is made on the relation between a [`]smoothness' of the electronic dipole moment and the generalized Mulliken-Hush formula for the diabatic electronic coupling.
Instabilities in relativistic two-component (super)fluids
Haber, Alexander; Stetina, Stephan
2016-01-01
We study two-fluid systems with nonzero fluid velocities and compute their sound modes, which indicate various instabilities. For the case of two zero-temperature superfluids we employ a microscopic field-theoretical model of two coupled bosonic fields, including an entrainment coupling and a non-entrainment coupling. We analyse the onset of the various instabilities systematically and point out that the dynamical two-stream instability can only occur beyond Landau's critical velocity, i.e., in an already energetically unstable regime. A qualitative difference is found for the case of two normal fluids, where certain transverse modes suffer a two-stream instability in an energetically stable regime if there is entrainment between the fluids. Since we work in a fully relativistic setup, our results are very general and of potential relevance for (super)fluids in neutron stars and, in the non-relativistic limit of our results, in the laboratory.
Lipidomics by Supercritical Fluid Chromatography
Directory of Open Access Journals (Sweden)
Laurent Laboureur
2015-06-01
Full Text Available This review enlightens the role of supercritical fluid chromatography (SFC in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC. It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering or highly specific (mass spectrometry detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides defined by the LIPID MAPS consortium.
Lipidomics by Supercritical Fluid Chromatography
Laboureur, Laurent; Ollero, Mario; Touboul, David
2015-01-01
This review enlightens the role of supercritical fluid chromatography (SFC) in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC). It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering) or highly specific (mass spectrometry) detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides) defined by the LIPID MAPS consortium. PMID:26090714
Interacting Gauge-Fluid system
Banerjee, Rabin; Mitra, Arpan Krishna
2016-01-01
A gauge-fluid relativistic model where a non-isentropic fluid is coupled to a dynamical Maxwell ($U(1)$) gauge field, has been studied. We have examined in detail the structures of energy momentum tensor, derived from two definitions, {\\it{ie.}} the canonical (Noether) one and the symmetric one. In the conventional equal-time formalism, we have shown that the generators of the spacetime transformations obtained from these two definitions agree, modulo the Gauss constraint. This equivalence in the physical sector has been achieved only because of the dynamical nature of the gauge fields. Subsequently we have explicitly demonstrated the validity of the Schwinger condition. A detailed analysis of the model in lightcone formalism has also been done where several interesting features are revealed.
Energy Technology Data Exchange (ETDEWEB)
Rawlinson, A.P.; Whitby, R.D.; White, J.
1989-04-11
A composition for the preparation of a soluble oil for use in a cutting fluid comprises a mineral oil and, as an emuslifier, an effective amount of a sulfonate of a branched polymer of a C/sub 3/ to C/sub 5/ olefin. Preferably the polyolefin chain of the sulphonate has an average molecular weight in the range 275 to 560 and the polyolefin is polyisobutene. A soluble oil can be prepared from the above composition by the addition of a conventional corrosion inhibitor and diluted with water to make a cutting fluid. Advantages of the novel emulsifier are that it is resistant to breakdown by micro-organisms and does not require the addition of a coupling agent.
Fluid structure interaction in piping systems
Energy Technology Data Exchange (ETDEWEB)
Svingen, Bjoernar
1996-12-31
The Dr. ing. thesis relates to an analysis of fluid structure interaction in piping systems in the frequency domain. The governing equations are the water hammer equations for the liquid, and the beam-equations for the structure. The fluid and structural equations are coupled through axial stresses and fluid continuity relations controlled by the contraction factor (Poisson coupling), and continuity and force relations at the boundaries (junction coupling). A computer program has been developed using the finite element method as a discretization technique both for the fluid and for the structure. This is made for permitting analyses of large systems including branches and loops, as well as including hydraulic piping components, and experiments are executed. Excitations are made in a frequency range from zero Hz and up to at least one thousand Hz. Frequency dependent friction is modelled as stiffness proportional Rayleigh damping both for the fluid and for the structure. With respect to the water hammer equations, stiffness proportional damping is seen as an artificial (bulk) viscosity term. A physical interpretation of this term in relation to transient/oscillating hydraulic pipe-friction is given. 77 refs., 72 figs., 4 tabs.
A Solution to Inductive Power Coupling in a Time-Cycled Atom Trap for Beta Decay
Lawrence, Liam; Behr, John; Anholm, Melissa; McNeil, James
2016-09-01
The TRINAT group at TRIUMF uses lasers and magnetic fields to confine, cool, and polarize a cloud of beta-decaying neutral alkali atoms to test weak force asymmetry. To alternate between trapping and polarizing the atoms, the trapping magnetic field must be switched on and off. This time-changing magnetic field, created by a pair of co-axial coils, produces eddy currents-and consequentially resistive heating-in nearby conductors. This heating may cause undesirable effects, including damage to the delicate pellicle mirrors which are to be used in future experiments. Previously, the current waveform in the coils consisted of two periods of a sinusoid during the on time of the trapping field (this reduces leftover field from eddy currents during the polarization time). We have calculated the relative power coupled to the pellicle mirror mount for various waveforms, and determined that using half a period of a lower-frequency sinusoid couples an order of magnitude less power than the original waveform, and approximately 2 times less than a trapezoidal wave. We measured the lifetime of the trap subject to this new waveform and found it is possible to achieve a lifetime comparable to that of a continuous trap, our best result differing by less than 5 percent.
Bianchi - Euler system for relativistice fluids and Bel - Robinson type energy
Choquet-Bruhat, Y; Choquet-Bruhat, Yvonne; York, James W.
2002-01-01
We write a first order symmetric hyperbolic system coupling the Riemann with the dynamical acceleration of a relativistic fluid. W determine the associated, coupled, Bel - Robinson energy, and the integral equality that it satisfies.
Effects of Fluid Directions on Heat Exchange in Thermoelectric Generators
DEFF Research Database (Denmark)
Suzuki, Ryosuke; Sasaki, Yuto; Fujisaka, Takeyuki
2012-01-01
Thermal fluids can transport heat to the large surface of a thermoelectric (TE) panel from hot and/or cold sources. The TE power thus obtainable was precisely evaluated using numerical calculations based on fluid dynamics and heat transfer. The commercial software FLUENT was coupled with a TE model...
Spinodal decomposition in multicomponent fluid mixtures: A molecular dynamics study
DEFF Research Database (Denmark)
Laradji, Mohamed; Mouritsen, Ole G.; Toxvaerd, SÃ¸ren
1996-01-01
We have investigated the effect of the number p of components on the dynamics of phase separation in two-dimensional symmetric multicomponent fluids. In contrast to concentrated two-dimensional binary fluids, where the growth dynamics is controlled by the coupling of the velocity held to the orde...
3D, parallel fluid-structure interaction code
CSIR Research Space (South Africa)
Oxtoby, Oliver F
2011-01-01
Full Text Available â€“Eulerian (ALE) reference frame. A preconditioned GMRES algorithm is developed for matrix-free solver acceleration. The fluid and structural domains are strongly coupled with a fast mesh-movement technique employed in the fluid domain. The solver is parallelised...
Multiscale modelling of fluid-immersed granular media
ClÃ©ment, Christian Paul AndrÃ© RenÃ©
2010-01-01
In this thesis we present numerical simulation studies of fluid-immersed granular systems using models of varying scales and complexities. These techniques are used to examine the effects of an interstitial fluid on the dynamics of dense granular beds within a number of vibrated systems. After an introduction to the field of granular materials, we present the techniques used to model both the granular dynamics and the fluid flow. We introduce various multiscale techniques to couple the mo...
Institute of Scientific and Technical Information of China (English)
åˆ˜ç¨‹ç†™; é»„å€©; é’Ÿçº¯çœŸ; æ›¹è‰³è
2011-01-01
This paper focuses on Corra's paper which established a mixed FEM form for the coupled Dar-cy-Stokes and extends it to non-conforming CR element and establishes a stablized non-conforming form, and then proves the existence and uniqueness of the solution and gives the error estimation.%ä½œè€…å°†Corraé’ˆå¯¹è€¦åˆçš„Darcy-Stokesæ–¹ç¨‹è€Œå»ºç«‹çš„ä¸€è‡´åè°ƒçš„æ··åˆæœ‰é™å…ƒæ ¼å¼æŽ¨å¹¿è¿ç”¨åˆ°éžåè°ƒCRæœ‰é™å…ƒé€¼è¿‘,ä»Žè€Œå»ºç«‹äº†ä¸€ç§ç¨³å®šåŒ–éžåè°ƒçš„ç¦»æ•£æ ¼å¼,å¹¶è¯æ˜Žäº†ç¦»æ•£é—®é¢˜è§£çš„å˜åœ¨å”¯ä¸€æ€§,ç»™å‡ºäº†è¯¯å·®ä¼°è®¡.
Institute of Scientific and Technical Information of China (English)
çŽ‹å¯; åˆ˜ç»§è¡Œ; å™å…´ä¼Ÿ
2014-01-01
æ°´å†·ç³»ç»Ÿå…·æœ‰ä½“ç§¯å°ã€æ•£çƒæ•ˆçŽ‡é«˜ç‰ä¼˜ç‚¹ï¼Œæ˜¯è§£å†³ç”µä¸»è½´æ•£çƒé—®é¢˜ä¸çš„é‡è¦é€”å¾„ã€‚æ–‡ç« ä»¥æ•°å€¼ä¼ çƒå¦ä¸ºåŸºç¡€ï¼Œåˆ©ç”¨æœ‰é™å…ƒåˆ†æžæ–¹æ³•å¯¹ç”µä¸»è½´ç»“æž„å¸¸ç”¨çš„èžºæ—‹æ°´å¥—ä¸Žè½´å‘æ°´å¥—ä¸¤ç§å†·å´ç³»ç»Ÿæ–¹æ¡ˆè¿›è¡Œæµå›ºè€¦åˆå¯¹æ¯”åˆ†æžï¼Œç»™å‡ºäº†ä¸¤ç§å†·å´æ–¹æ¡ˆåœ¨å†·å´æ•ˆæžœä¸Šçš„å·®å¼‚ã€‚ä¸ºç”µä¸»è½´è®¾è®¡è¿‡ç¨‹å†·å´ç³»ç»Ÿé€‰å–åŠç”µä¸»è½´çƒåˆ†æžæä¾›å‚è€ƒã€‚%Water cooling system has advantages of small volume, high cooling efficiency, and has been an important way to solve heat dissipation problem of electric spindle. This article basing on a numerical heat transfer theory analysis comparatively axial and spiral water channel using frequently in the cooling system for fluid-structure interaction, gives the cooling effect differences between two kinds of cooling systems, and provide references for cooling system selection and heat transfer analysis in electric spindle design process.
Institute of Scientific and Technical Information of China (English)
ä¸›è…¾é¾™; ç”°æ–‡å–œ; ç§‹ç©—æ£; è‹å…‰è¾‰
2014-01-01
The 3D flow characteristics in SG can provide input for the analysis of flow induced vibration (FIV ) . The secondary side flow field was simulated based on the porous media model with FLUENT solver .The flow resistances of flow along and cross tubes as well as flow resistances of downcomer ,support plates and separators were added to the momentum equation .T he 3D heat transfer from primary to secondary side fluid was calculated during iteration and set as the energy source of secondary side fluid , and the calculation results agree well with the design values .Meanwhile ,the results show that the resultant localized thermal-hydraulic characteristics were unevenly distrib-uted .The maximum and minimum flow vapor qualities flowing into the primary separa-tors are 0.75 and 0.07 ,respectively .The average heat transfer coefficients of primary and secondary sides are 15 856.5 and 63 623.0 W/(m2 Â· K) ,respectively .The maxi-mum heat transfer coefficient of secondary side is 122 862.9 W/(m2 Â· K ) .T he average heat flux of U-tube is 149.9 kW/m2 .T he maximum cross flow velocity and cross flow energy (Ïu2 ) through the U-bend region are 4.06 m/s and 1 145 J/m3 ,respectively .%è’¸æ±½å‘ç”Ÿå™¨ï¼ˆSG ï¼‰å†…ä¸‰ç»´ä¸¤ç›¸æµåœºå¯ä¸ºæµè‡´æŒ¯åŠ¨åˆ†æžæä¾›è¾“å…¥æ¡ä»¶ã€‚æœ¬æ–‡åŸºäºŽ FL U EN T é‡‡ç”¨å¤šå”ä»‹è´¨æ¨¡åž‹å¯¹SGäºŒæ¬¡ä¾§æµåœºè¿›è¡Œæ±‚è§£ã€‚åœ¨åŠ¨é‡æ–¹ç¨‹ä¸æ·»åŠ ç®¡æŸé™„åŠ é˜»åŠ›ï¼Œåˆ†åˆ«è®¡ç®—æ¨ªæµå’Œé¡ºæµç®¡æŸé˜»åŠ›ï¼ŒåŒæ—¶è€ƒè™‘äº†ä¸‹é™æ®µã€æ”¯æ‰¿æ¿å’Œæ±½æ°´åˆ†ç¦»å™¨é˜»åŠ›ã€‚åœ¨èƒ½é‡æ–¹ç¨‹ä¸ï¼Œå°†ä¸€ã€äºŒæ¬¡ä¾§æ¢çƒé‡ä¸‰ç»´åˆ†å¸ƒä½œä¸ºäºŒæ¬¡ä¾§æµåœºçš„èƒ½é‡æºé¡¹ï¼Œåœ¨è®¡ç®—ä¸é‡‡ç”¨è€¦åˆè¿ä»£æ±‚è§£ã€‚è®¡ç®—ç»“æžœä¸Žæ€»ä½“è®¾è®¡å€¼ç¬¦åˆè¾ƒå¥½ã€‚è®¡ç®—ç»“æžœåŒæ—¶æ˜¾ç¤ºï¼ŒäºŒæ¬¡ä¾§æµåœºåˆ†å¸ƒæžä¸å‡åŒ€ï¼›è¿›å…¥ç¬¬ä¸€çº§æ±½æ°´åˆ†ç¦»å™¨çš„å·¥è´¨æœ€å¤§ã€æœ€å°æµåŠ¨å«æ±½çŽ‡åˆ†åˆ«ä¸º0.75å’Œ0.07ï¼›ä¸€ã€äºŒæ¬¡ä¾§å¹³å‡æ¢çƒç³»æ•°åˆ†åˆ«ä¸º15856.5å’Œ63623.0 W/ï¼ˆm2Â· K ï¼‰ï¼ŒäºŒæ¬¡ä¾§æœ€å¤§æ¢çƒç³»æ•°ä¸º122862.9 W/ï¼ˆm2Â· K ï¼‰ï¼ŒUåž‹ç®¡å¤–å
Simulation based engineering in fluid flow design
Rao, J S
2017-01-01
This volume offers a tool for High Performance Computing (HPC). A brief historical background on the subject is first given. Fluid Statics dealing with Pressure in fluids at rest, Buoyancy and Basics of Thermodynamics are next presented. The Finite Volume Method, the most convenient process for HPC, is explained in one-dimensional approach to diffusion with convection and pressure velocity coupling. Adiabatic, isentropic and supersonic flows in quasi-one dimensional flows in axisymmetric nozzles is considered before applying CFD solutions. Though the theory is restricted to one-dimensional cases, three-dimensional CFD examples are also given. Lastly, nozzle flows with normal shocks are presented using turbulence models. Worked examples and exercises are given in each chapter. Fluids transport thermal energy for its conversion to kinetic energy, thus playing a major role that is central to all heat engines. With the advent of rotating machinery in the 20th century, Fluid Engineering was developed in the form o...
Superconfinement tailors fluid flow at microscales.
Setu, Siti Aminah
2015-06-15
Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices. Here we report measurements of advancing fluid fronts in such a regime, which we dub superconfinement. We find that the strong coupling between contact-line friction and geometric confinement gives rise to a new stability regime where the maximum speed for a stable moving front exhibits a distinctive response to changes in the bounding geometry. Unstable fronts develop into drop-emitting jets controlled by thermal fluctuations. Numerical simulations reveal that the dynamics in superconfined systems is dominated by interfacial forces. Henceforth, we present a theory that quantifies our experiments in terms of the relevant interfacial length scale, which in our system is the intrinsic contact-line slip length. Our findings show that length-scale overlap can be used as a new fluid-control mechanism in strongly confined systems.
Thermal Tides in Fluid Extrasolar Planets
Arras, Phil
2009-01-01
Asynchronous rotation and orbital eccentricity lead to time-dependent irradiation of the close-in gas giant exoplanets -- the hot Jupiters. This time-dependent surface heating gives rise to fluid motions which propagate throughout the planet. We investigate the ability of this "thermal tide" to produce a quadrupole moment which can couple to the stellar gravitational tidal force. While previous investigations discussed planets with solid surfaces, here we focus on entirely fluid planets in order to understand gas giants with small cores. The Coriolis force, thermal diffusion and self-gravity of the perturbations are ignored for simplicity. First, we examine the response to thermal forcing through analytic solutions of the fluid equations which treat the forcing frequency as a small parameter. In the "equilibrium tide" limit of zero frequency, fluid motion is present but does not induce a quadrupole moment. In the next approximation, finite frequency corrections to the equilibrium tide do lead to a nonzero qua...
Superconfinement tailors fluid flow at microscales
Setu, Siti Aminah; Dullens, Roel P.A.; HernÃ¡ndez-Machado, Aurora; Pagonabarraga, Ignacio; Aarts, Dirk G.A.L.; Ledesma-Aguilar, Rodrigo
2015-01-01
Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices. Here we report measurements of advancing fluid fronts in such a regime, which we dub superconfinement. We find that the strong coupling between contact-line friction and geometric confinement gives rise to a new stability regime where the maximum speed for a stable moving front exhibits a distinctive response to changes in the bounding geometry. Unstable fronts develop into drop-emitting jets controlled by thermal fluctuations. Numerical simulations reveal that the dynamics in superconfined systems is dominated by interfacial forces. Henceforth, we present a theory that quantifies our experiments in terms of the relevant interfacial length scale, which in our system is the intrinsic contact-line slip length. Our findings show that length-scale overlap can be used as a new fluid-control mechanism in strongly confined systems. PMID:26073752
Institute of Scientific and Technical Information of China (English)
è®¸å®; çŽ‹é›ªå³°; å¼ æŸ±é“¶; çŽ‹å›; é»„å»ºå†›; è‚–æ…§; éƒ…æ™“
2016-01-01
ä»¥æŸçƒ§ç»“ç –éš§é“çª‘ä¸ºç ”ç©¶å¯¹è±¡ï¼Œä¸ºèŽ·å¾—éš§é“çª‘å†·å´å¸¦æ•£çƒæ¸©åº¦åœºæ•°æ®ï¼Œå»ºç«‹äº†éš§é“çª‘çª‘å£-ç –å—-æµä½“è€¦åˆä¼ çƒç‰©ç†æ¨¡åž‹ä¸Žæ•°å¦æ¨¡åž‹ï¼Œé‡‡ç”¨FLUENTæµä½“è®¡ç®—è½¯ä»¶å¯¹å…¶è¿›è¡Œäº†éš§é“çª‘çª‘å£-ç –å—-æµä½“è€¦åˆä¼ çƒä»¿çœŸï¼ŒèŽ·å¾—äº†çª‘å†…æ•´ä½“æ¯”è¾ƒç²¾ç¡®ç›´è§‚çš„æ¸©åº¦åœºåˆ†å¸ƒã€‚ä»¿çœŸçš„ç»“æžœè¡¨æ˜Žï¼šé£Žé€Ÿä¸º5 m/sã€å”éš™çŽ‡ä¸º0.5ä»¥åŠç –å—é€‚å½“ç¨€ç æ—¶ï¼Œéš§é“çª‘å†·å´å¸¦é™æ¸©æ•ˆæžœè¾ƒå¥½ï¼Œå…¶ä¸Žéš§é“çª‘çƒ§æˆæ›²çº¿å†·å´æ®µå»åˆä¹Ÿè¾ƒå¥½ï¼Œä¸ºé£Žé€Ÿè°ƒæ•´ã€ç ç –æ–¹å¼å’Œå”éš™çŽ‡çš„é€‰æ‹©æä¾›äº†ç†è®ºä¾æ®ï¼Œæé«˜äº†çƒ§æˆè´¨é‡å’Œç”Ÿäº§æ•ˆçŽ‡ã€‚%In order to obtain the cooling temperature ifeld data in the tunnel kiln cooling zone, the tunnel kiln wall bricks-lfuid coupling heat transfer physical model and mathematic model were established, taking a sintered brick tunnel kiln as the research object. The tunnel kiln wall bricks-lfuid coupling heat transfer simulations were performed by commercial software FLUENT, and the overall accurate intuitive temperature ifeld distribution was obtained. The simulation results show: the cooling effect on the tunnel kiln cooling zone is better when the draft speed is 5 m/s, the pore rate is 0.5, and the bricks arrangement is sparse, and that is also agreeable with the tunnel kiln ifring curveâ€™s cooling segment. This information provides a theoretical basis for the adjustment of the draft speed, pore rate and bricks arrangement to improve the quality of bricks ifring and productivity.
... bursae (fluid-filled sacs in the joints), and tendon sheaths. After the joint area is cleaned, the ... HS. Synovial fluid analysis, synovial biopsy, and synovial pathology. In: Firestein GS, Budd RC, Gabriel SE, McInnes ...
Amniotic fluid surrounds the growing fetus in the womb and protects the fetus from injury and temperature changes. ... of fetal movement and permits musculoskeletal development. The amniotic fluid can be withdrawn in a procedure called amniocentsis ...
... help diagnose the cause of inflammation of the pericardium (pericarditis) and/or fluid accumulation around the heart ( ... pressure within blood vessels or inflammation of the pericardium. An initial set of tests, including fluid protein ...
... staining a sample of fluid taken from the pericardium. This is the sac surrounding the heart to ... sample of fluid will be taken from the pericardium. This is done through a procedure called pericardiocentesis . ...
Shinbrot, Marvin
2012-01-01
Readable and user-friendly, this high-level introduction explores the derivation of the equations of fluid motion from statistical mechanics, classical theory, and a portion of the modern mathematical theory of viscous, incompressible fluids. 1973 edition.
Van Dam, Jeremy Daniel; Turnquist, Norman Arnold; Raminosoa, Tsarafidy; Shah, Manoj Ramprasad; Shen, Xiaochun
2015-09-29
An electric machine is presented. The electric machine includes a hollow rotor; and a stator disposed within the hollow rotor, the stator defining a flow channel. The hollow rotor includes a first end portion defining a fluid inlet, a second end portion defining a fluid outlet; the fluid inlet, the fluid outlet, and the flow channel of the stator being configured to allow passage of a fluid from the fluid inlet to the fluid outlet via the flow channel; and wherein the hollow rotor is characterized by a largest cross-sectional area of hollow rotor, and wherein the flow channel is characterized by a smallest cross-sectional area of the flow channel, wherein the smallest cross-sectional area of the flow channel is at least about 25% of the largest cross-sectional area of the hollow rotor. An electric fluid pump and a power generation system are also presented.
Jendrzejczyk, Joseph A.
1982-01-01
An electrical fluid force transducer for measuring the magnitude and direction of fluid forces caused by lateral fluid flow, includes a movable sleeve which is deflectable in response to the movement of fluid, and a rod fixed to the sleeve to translate forces applied to the sleeve to strain gauges attached to the rod, the strain gauges being connected in a bridge circuit arrangement enabling generation of a signal output indicative of the magnitude and direction of the force applied to the sleeve.
Engineering Fracking Fluids with Computer Simulation
Shaqfeh, Eric
2015-11-01
There are no comprehensive simulation-based tools for engineering the flows of viscoelastic fluid-particle suspensions in fully three-dimensional geometries. On the other hand, the need for such a tool in engineering applications is immense. Suspensions of rigid particles in viscoelastic fluids play key roles in many energy applications. For example, in oil drilling the ``drilling mud'' is a very viscous, viscoelastic fluid designed to shear-thin during drilling, but thicken at stoppage so that the ``cuttings'' can remain suspended. In a related application known as hydraulic fracturing suspensions of solids called ``proppant'' are used to prop open the fracture by pumping them into the well. It is well-known that particle flow and settling in a viscoelastic fluid can be quite different from that which is observed in Newtonian fluids. First, it is now well known that the ``fluid particle split'' at bifurcation cracks is controlled by fluid rheology in a manner that is not understood. Second, in Newtonian fluids, the presence of an imposed shear flow in the direction perpendicular to gravity (which we term a cross or orthogonal shear flow) has no effect on the settling of a spherical particle in Stokes flow (i.e. at vanishingly small Reynolds number). By contrast, in a non-Newtonian liquid, the complex rheological properties induce a nonlinear coupling between the sedimentation and shear flow. Recent experimental data have shown both the shear thinning and the elasticity of the suspending polymeric solutions significantly affects the fluid-particle split at bifurcations, as well as the settling rate of the solids. In the present work, we use the Immersed Boundary Method to develop computer simulations of viscoelastic flow in suspensions of spheres to study these problems. These simulations allow us to understand the detailed physical mechanisms for the remarkable physical behavior seen in practice, and actually suggest design rules for creating new fluid recipes.
Topology optimization of fluid-structure-interaction problems in poroelasticity
DEFF Research Database (Denmark)
Andreasen, Casper Schousboe; Sigmund, Ole
2013-01-01
with the deformation of the elastic skeleton through a macroscopic Darcy-type flow law. The method allows to impose pressure loads for static problems through a one way coupling, while transient problems are fully coupled modeling the interaction between fluid and solid. The material distribution is determined...
Homogenizing the Darcy/Stokes coupling
Gruais, Isabelle; Polisevski, Dan
2011-01-01
We study a fluid flow traversing a porous medium and obeying the Darcy's law in the case when this medium is fractured by a periodical distribution of fissures filled with a Stokes fluid. These two flows are coupled by a Beavers-Joseph type interface condition. As the small period of the distribution shrinks to zero, the resulting asymptotic behaviour is implicitely described by two underlying macroscopic quantities: the limit of the Stokes velocity and the limit of the Darcy pressure, soluti...
Michell, S J
2013-01-01
Fluid and Particle Mechanics provides information pertinent to hydraulics or fluid mechanics. This book discusses the properties and behavior of liquids and gases in motion and at rest. Organized into nine chapters, this book begins with an overview of the science of fluid mechanics that is subdivided accordingly into two main branches, namely, fluid statics and fluid dynamics. This text then examines the flowmeter devices used for the measurement of flow of liquids and gases. Other chapters consider the principle of resistance in open channel flow, which is based on improper application of th
Directory of Open Access Journals (Sweden)
Guy N.
2013-02-01
Full Text Available Modeling Steam Assisted Gravity Drainage (SAGD can involve significant CPU (Central Processing Unit time when both thermal fluid flow and geomechanics are coupled in order to take into account variations of permeability and porosity inside the reservoir due to stress changes. Here, a numerical procedure that performs thermo-hydro-mechanical simulations, in an efficient way, is presented. This procedure relies on an iterative coupling between a thermal reservoir simulator based on a finite volume method and a geomechanical one based on a finite element method. A strong feature of this procedure is that it allows handling the case when the reservoir simulations are performed using Adaptive Mesh Refinements (AMR. It thus provides an accurate description of the steam front evolution and allows taking geomechanical effects into account without performing the geomechanical simulations on a refined mesh. The efficiency of this coupling procedure is illustrated on a synthetic but realistic SAGD test case. La modÃ©lisation du procÃ©dÃ© SAGD (Steam Assisted Gravity Drainage peut impliquer un temps de calcul important lorsque lâ€™Ã©coulement thermique et la gÃ©omÃ©canique sont couplÃ©s pour tenir compte des variations de permÃ©abilitÃ© et de porositÃ© Ã lâ€™intÃ©rieur du rÃ©servoir induites par lâ€™Ã©volution des contraintes. Une procÃ©dure numÃ©rique qui effectue des simulations thermo-hydro-mÃ©caniques, dâ€™une maniÃ¨re efficace, est prÃ©sentÃ©e. Cette procÃ©dure repose sur un processus de couplage itÃ©ratif entre un simulateur rÃ©servoir thermique basÃ© sur la mÃ©thode des volumes finis et un simulateur gÃ©omÃ©canique basÃ© sur une discrÃ©tisation par Ã©lÃ©ments finis. Une caractÃ©ristique forte de cette procÃ©dure est quâ€™elle permet de traiter des cas oÃ¹ les simulations de rÃ©servoir sont rÃ©alisÃ©es en utilisant un raffinement de maillage adaptatif. Elle fournit ainsi une description prÃ©cise de lâ€™Ã©volution du front de vapeur dâ€™eau et permet
Fluid cooled electrical assembly
Rinehart, Lawrence E.; Romero, Guillermo L.
2007-02-06
A heat producing, fluid cooled assembly that includes a housing made of liquid-impermeable material, which defines a fluid inlet and a fluid outlet and an opening. Also included is an electrical package having a set of semiconductor electrical devices supported on a substrate and the second major surface is a heat sink adapted to express heat generated from the electrical apparatus and wherein the second major surface defines a rim that is fit to the opening. Further, the housing is constructed so that as fluid travels from the fluid inlet to the fluid outlet it is constrained to flow past the opening thereby placing the fluid in contact with the heat sink.
Miller, Jan D; Hupka, Jan; Aranowski, Robert
2012-11-20
A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.
Institute of Scientific and Technical Information of China (English)
æŽæœ¯æ‰; å‘¨æ¯…; æŽåˆ©å¹³; å¼ éªž; å®‹æ›™å…‰; æŽæ™¯é¾™; çŽ‹å‡¯; çŽ‹åº†ç€š
2012-01-01
A new similar material for fluid-solid coupling has been developed through hundreds of compounding tests based subsea on the theory of fluid-solid coupling on geomechanics model test and the exploration data of the Qingdao Kiaochow Bay tunnel. It is mixed with sand, barite powder, talc powder, cement, vaseline and silicone oil. The effect of different mixing ratios on the properties of the samples has been systematically studied and the main components controlling the material properties have been determined through large numbers of laboratory tests. The test results indicate that the new material's strength and elastic modulus are controlled by cement and vaseline; its cohesion is mainly effected by vaseline; its permeability coefficient can be adjusted by the ratio of vaseline and silicone oil. Water retention and compactness improvement are also the role of silicone oil. Deformation characteristics and permeability of the material are regulated by different compositions and the interaction is slight. So the properties of the material can be controlled comprehensively. The new material can simulate low-strength and medium-strength rock materials with different permeabilities, which is an ideal similar material for fluid-solid coupling. This material has been used in the Qingdao Kiaochow Bay subsea tunnel water-inflow model test, and its mechanical properties and permeability has met the test requirements. The new material ensures good test results.%ä¾æ‰˜é’å²›èƒ¶å·žæ¹¾æµ·åº•éš§é“çš„çŽ°åœºå‹˜æŽ¢èµ„æ–™,åº”ç”¨åœ°è´¨åŠ›å¦æ¨¡åž‹è¯•éªŒçš„æµ-å›ºè€¦åˆç›¸ä¼¼ç†è®º,é€šè¿‡å¤§é‡çš„é…æ¯”è¯•éªŒ,ç ”åˆ¶å‡º ç§ç”±ç ‚ã€é‡æ™¶çŸ³ç²‰ã€æ»‘çŸ³ç²‰ã€æ°´æ³¥ã€å‡¡å£«æž—ã€ç¡…æ²¹å’Œé€‚é‡æ‹Œåˆæ°´ç»„æˆçš„æ–°åž‹æµ-å›ºè€¦åˆç›¸ä¼¼ææ–™(SCVO).é€šè¿‡å¤§é‡çš„å®¤å†…è¯•éªŒ,ç³»ç»Ÿåœ°ç ”ç©¶ä¸åŒé…æ¯”å¯¹ææ–™å‚æ•°çš„å½±å“è§„å¾‹,ç¡®å®šæŽ§åˆ¶ç›¸ä¼¼ææ–™å„æ€§èƒ½çš„ä¸»è¦ç»„åˆ†.è¯•éªŒè¡¨æ˜Ž,ææ–™çš„å¼ºåº¦å’Œå¼¹æ€§æ¨¡é‡ä¸»è¦ç”±æ°´æ³¥å’Œå‡¡å£«æž—æŽ§åˆ¶ï¼›é»èšåŠ›å—å‡¡å£«æž—å½±å
Sensitivity analysis of fluid-structure interaction problems
Energy Technology Data Exchange (ETDEWEB)
Etienne, S.; Pelletier, D. [Ecole Polytechnique de Montreal, Montreal, Quebec (Canada)]. E-mail: stephane.etienne@polymtl.ca
2004-07-01
Interactions between solids and fluids (FSI) have been a topic of interest for engineers for many years. The behavior of vessels subject to wave loads, of planes in flight condition as well as submarine or transmission lines are but a few examples. In an attempt to address these problems, the present paper presents a formulation which allows to treat interactions between an incompressible flow and a structure undergoing large displacements. We assume existence and unicity of the solution. The interested reader is referred, for a mathematical discussion of existence and unicity. The approach to coupling can be addressed in two ways: weakly-coupled methods for which algorithms for structure and fluid are segregated, as is commonly done for simplicity and often because engineers have access to existing structural and fluid codes; and tightly-coupled or monolithic methods, for which the formulation guarantees satisfaction of equilibrium of the interface between the fluid and the solid. The latter has been chosen as it allows for quadratic convergence of Newton's method. The paper begins with the description of the steady state governing equations for laminar incompressible fluids, hyperelastic solid behaviour, pseudo-solid mapping and fluid-structure interfaces. The weak forms of the equations are then presented. We proceed with the description of the continuous sensitivity equations for fluid-structure interactions problems. The following sections detail the adaptive finite element procedure for the fluid-structure interaction and sensitivity problems. Results are presented and the paper ends with conclusions and discussions. (author)
Energy Technology Data Exchange (ETDEWEB)
Marty, N
2006-11-15
The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)
[A test for sperm cell survival in peritoneal fluid].
Radwan, J; Niwald, W; Bielak, A; Pawlicki, J; Banaszczyk, R; MakuÅ‚a, D
1995-06-01
The role of the peritoneal fluid in the physiology of reproduction, as well as in the transportation and survival of gametes, is little known. The authors have examined interactions between spermatozoa and the peritoneal fluid, collected during laparoscopy in the, so-called, survival test, from 42 infertile couples. The studied survival of spermatozoa in the peritoneal fluid was relatively high--19% after 48 hours--longer than in Menezo B2 fluid. Values of the test have been indicated, especially in cases of endometriosis-caused and idiopathic infertility.
Finite Element Harmonic Solution of the Coupled Rotor-bearing System
Institute of Scientific and Technical Information of China (English)
æ—
2002-01-01
Fluid-solid interaction problems have been studied q uite extensively in the past years. Rotor-bearing system is a typical example. Fluid field is changed under the exciting of rotor vibration. On the same ti me, a net force caused by fluid pressure exerts on rotor, which will change roto r vibration. So, the fluid-solid coupled analysis method must be used. Traditionally, numerical difference method was used to solve fluid problems. The coupled fluid-solid equation could not be set up based on the me...
Institute of Scientific and Technical Information of China (English)
å™æ–‡å›; çŽ‹å¦æ°‘; æ¨é¹å¿—; çŽ‹è“‰è“‰
2015-01-01
ä»¥é’å²›æµ·åº•éš§é“è¯•éªŒæ®µä¸ºå·¥ç¨‹èƒŒæ™¯ï¼ŒåŸºäºŽæµå›ºè€¦åˆç†è®ºå¯¹æµ·åº•éš§é“åˆæœŸæ”¯æŠ¤å®‰å…¨æ€§çš„å½±å“å› ç´ è¿›è¡Œåˆ†æžï¼Œç»“è®ºè¡¨æ˜Žï¼š(1)æ³¨æµ†åŠ å›ºæ˜¾è‘—æ”¹å–„äº†æ´žå‘¨åœŸä½“å¼ºåº¦å’Œæ•´ä½“æ€§ï¼Œå¡‘æ€§åŒºèŒƒå›´å¾—åˆ°æœ‰æ•ˆæŽ§åˆ¶ï¼›(2)æ³¨æµ†åŠ å›ºä¼˜åŒ–äº†æ”¯æŠ¤ç»“æž„çš„å—åŠ›ï¼Œéšç€åŠ å›ºåœˆåŽšåº¦çš„å¢žåŠ ï¼Œæ´žå‘¨ä½ç§»å‡ºçŽ°ä¸åŒç¨‹åº¦çš„è¡°å‡ï¼ŒåŠ å›ºåœˆåŽšåº¦å¯¹å‡å°æ°´åŽ‹çš„è´¡çŒ®ä¾æ¬¡ä¸ºï¼šæ‹±é¡¶>æ‹±è…°>æ‹±è„š>ä»°æ‹±ï¼›(3)éšç€åŠ å›ºåœˆæ¸—é€ç³»æ•°çš„å¢žå¤§ï¼Œæ´žå‘¨æ°´åŽ‹åŠ›éšä¹‹å¢žå¤§ï¼›(4)åœ¨æµå›ºè€¦åˆä½œç”¨ä¸‹ï¼Œä»°æ‹±å¤„çš„åœŸåŽ‹åŠ›è¿œå¤§äºŽå…¶ä»–éƒ¨ä½ï¼›(5)çŽ°è¡Œæ”¯æŠ¤å‚æ•°æ¡ä»¶ä¸‹ï¼Œæµ·åº•éš§é“åˆæœŸæ”¯æŠ¤ç»“æž„æ»¡è¶³å®‰å…¨æ€§è¦æ±‚ï¼ŒçŽ°åœºå®žæµ‹ä¸Žæ•°å€¼è®¡ç®—åŸºæœ¬ç›¸ç¬¦ã€‚%With reference to Jiaozhouwan subsea tunnel in Qingdao and based on the coupled fluid-solid theory, the impact factors are studied on initial support safety in subsea tunnel. The results show that:(1)The strength and integrity of surrounding rock are improved significantly by grouting reinforcement and the plastic zone is effectively controlled; ( 2 ) The force of the supporting structure is optimized by grouting reinforcement ring, with the increase of the reinforcement thickness, the displacement attenuates in a certain degree, and the thickness of the reinforced ring contributes to the reduction of water pressure in such a sequence: arch top to arch web to arch foot to inverted arch; ( 3 ) With the increase of the permeability coefficient of reinforced ring, the water pressure around the tunnel is increasing;( 4 ) The earth pressure at the inverted arch is much bigger than anywhere else under couple fluid-mechanical;(5)The initial support structure meets the requirement for safety with the current support parameters, and the site measurements agree basically with the numerical calculations.
Institute of Scientific and Technical Information of China (English)
å™æ–‡æ–Œ; å¼ å£«å·; æŽæ¨æ¨; è·¯ç•…
2015-01-01
æ¨¡æ‹Ÿæ·±éƒ¨å¼€é‡‡åº•æ¿å²©å±‚çš„è£‚éš™æ¼”åŒ–ç‰¹å¾æ˜¯æ·±å…¥æŽ¢è®¨ç…¤å±‚å¼€é‡‡åº•æ¿çªæ°´è§„å¾‹å’Œæ¼”åŒ–æœºåˆ¶ç ”ç©¶çš„å…³é”®ï¼Œä¸ºå¼€å±•æ·±éƒ¨å¼€é‡‡é«˜æ°´åŽ‹åº•æ¿çªæ°´é€šé“å½¢æˆçš„æ¨¡åž‹è¯•éªŒï¼ŒåŸºäºŽå›ºæµè€¦åˆç›¸ä¼¼ç†è®ºï¼Œä»¥å›ºä½“ææ–™ç ”ç©¶ä¸ºåŸºç¡€ï¼Œç ”åˆ¶äº†æ–°åž‹çš„é€‚ç”¨äºŽæ·±äº•æ¡ä»¶ä¸‹çš„ç›¸ä¼¼ææ–™ï¼Œæå‡ºé€‚åº”è¯¥ææ–™æ¸—é€ç³»æ•°çš„æµ‹é‡æ–¹æ³•ï¼Œå¾—åˆ°ä¸åŒé…æ¯”å¯¹ææ–™åŠ›å¦æ€§è´¨çš„å½±å“è§„å¾‹ï¼Œå°†è¯¥ææ–™åº”ç”¨äºŽåº•æ¿çªæ°´æ¨¡æ‹Ÿè¯•éªŒï¼Œæç¤ºç›¸ä¼¼ææ–™çš„ç ´åç‰¹å¾å’Œæ·±éƒ¨åº•æ¿çªæ°´é€šé“çš„æ¼”åŒ–ç‰¹å¾ï¼Œå³å—é‡‡åŠ¨å½±å“å¼€åˆ‡çœ¼å¤„è£‚éš™å‘è‚²è¿…é€Ÿè€Œä¸”ç¨‹åº¦è¾ƒé«˜ï¼Œè§£é‡Šäº†æ¤å¤„çªæ°´æ¦‚çŽ‡å¤§æ˜“å‘ç”Ÿçªæ°´å±é™©ï¼Œå¯¹è§£å†³å®žé™…å·¥ç¨‹é—®é¢˜å…·æœ‰ä¸€å®šçš„æŒ‡å¯¼æ„ä¹‰ã€‚%The simulation of floor rock fracture evolution characteristics in deep mining is the key of research on laws and evolution mechanism of water-inrush. In order to launch the model test on emergence ofwater-inrush channel in deep mining floor under high water pressure,based on the similarity theory for solid-fluid coupling and the study of solid materials,a new similar material for solid-fluid coupling was developed. This material is suitable for conditions of deep mining. The measuring method for the permeability coefficient of this material was put forward. The influence law that diverse ratios affected mechanical properties of materials was concluded. The material was applied to the simulation test of water-inrush in floor,which revealed failure characteristics of similar materials and evolution characteristics of water-inrush channel in floor. Fracture developed rapidly and with higher degree affected by mining in open-off cut. This explained the greater probability of water inrush,this place is prone to result in water inrush risk. The method has some practical meaning for coal mining engineering.
Institute of Scientific and Technical Information of China (English)
æŽè‹—; è®¡ç§‰çŽ‰
2014-01-01
The study of percolation theory and deliverability analysis for two-stepped horizontal well is imperfect at home and abroad. Based on the horizontal well unstable flow model and the potential superposition principle,the two-stepped horizontal well unstable flow model is established by using a semi-analytical method and by considering the variable mass flow within the wellbore pressure loss,the solution of the coupling model is presented under the bottomhole constant pressure. The research results of the real examples show that the productivity index distribution along the borehole is non-uniform,which is the asymmetricâ€œUâ€shaped pattern. The productivity index at the heel is slightly higher than that at the toe. There is an obvious step on the curve of pressure difference distribution along the wellbore,which shows that the pressure loss at the connection section is larger. The results are meaningful and provide a theoretical basis for the two-stepped horizontal well casing design,and for designing the field development project,computing development indicators,formulating development adjustment programs, and therefore,to efficiently develop the complex oil and gas fields.%é’ˆå¯¹å›½å†…å¤–å¯¹åŒå°é˜¶æ°´å¹³äº•æ¸—æµè§„å¾‹åŠäº§èƒ½åˆ†æžç ”ç©¶ç›¸å¯¹æ¬ ç¼ºçš„æƒ…å†µï¼Œä»¥æ°´å¹³äº•ä¸ç¨³å®šæ¸—æµæ¨¡åž‹ä¸ºåŸºç¡€ï¼Œæ ¹æ®åŠ¿å åŠ åŽŸç†ï¼Œé‡‡ç”¨åŠè§£æžæ–¹æ³•å»ºç«‹äº†åŒå°é˜¶æ°´å¹³äº•ä¸ç¨³å®šæ¸—æµæ¨¡åž‹ï¼ŒåŒæ—¶è€ƒè™‘äº†äº•ç’å†…å˜è´¨é‡æµåŠ¨åŽ‹é™æŸå¤±å½±å“ï¼Œç»™å‡ºäº†å®šåŽ‹ç”Ÿäº§æ¡ä»¶ä¸‹è€¦åˆæ¨¡åž‹è§£æ³•ã€‚é€šè¿‡å®žä¾‹è®¡ç®—ï¼Œç»“æžœè¡¨æ˜ŽåŒå°é˜¶æ°´å¹³äº•æ¯”äº§èƒ½æŒ‡æ•°æ²¿äº•ç’é•¿åº¦ä¸æ˜¯å‡åŒ€åˆ†å¸ƒçš„ï¼Œå¤§è‡´å‘ˆéžå¯¹ç§°â€œUâ€åž‹åˆ†å¸ƒï¼Œä¸”è·Ÿç«¯çš„æ¯”äº§èƒ½æŒ‡æ•°ç•¥é«˜äºŽè¶¾ç«¯ï¼›äº•ç’æ²¿ç¨‹åŽ‹å·®åˆ†å¸ƒæ›²çº¿æ˜Žæ˜¾æœ‰ä¸€ä¸ªå°é˜¶ï¼Œè¯´æ˜ŽåŽ‹é™æŸå¤±ä¸»è¦é›†ä¸åœ¨ä¸é—´å¤¹å±‚è¿žæŽ¥æ®µå¤„ï¼Œä¸»è¦ä¸ºé‡åŠ›åŽ‹é™æŸå¤±ã€‚è¯¥æˆæžœä¸ºåŒå°é˜¶æ°´å¹³äº•äº•èº«ç»“æž„è®¾è®¡ï¼ŒåŠåˆç†åˆ©ç”¨åŒå°é˜¶æ°´å¹³äº•è¿›è¡Œå¼€å‘æ–¹æ¡ˆè®¾è®¡ã€è®¡ç®—å¼€å‘æŒ‡æ
Institute of Scientific and Technical Information of China (English)
éƒä¸‡æž—; çŽ‹ç´
2012-01-01
Nanoscale materials and devices are distinctly different in both properties and functions from their macroscopic counterparts. Having an insight into their exceptional properties and functions are crucial for innovative nanotechnology. In this paper, based on our experience for ten years physical mechanics study on the coupling between external fields and the intrinsic local fields of low-dimensional functional nanomaterials, we review the advance in our understanding of the mechanical-electric-magnetic-thermal-fluid coupling and physical mechanical behaviors in functional nanomaterials, such as carbon nanotubes, graphene, boron nitride and ZnO nanostructures and so on. A brief perspective on the development and potential applications of functional nanomaterials and devices is finally provided.%åœ¨çº³å°ºåº¦,ææ–™å’Œå™¨ä»¶å…·æœ‰ä¸Žå®è§‚ææ–™å’Œå™¨ä»¶è¿¥ç„¶ä¸åŒçš„å¥‡å¼‚ç‰¹æ€§,æŽŒæ¡å…¶è§„å¾‹æ˜¯å®žçŽ°çº³ç±³æŠ€æœ¯åˆ›æ–°çš„å…³é”®.æœ¬æ–‡ç»“åˆè¿‘åå¹´å…³äºŽä½Žç»´çº³ç±³åŠŸèƒ½ææ–™å±€åŸŸåœºä¸Žå¤–åœºè€¦åˆå’Œç‰©ç†åŠ›å¦è¡Œä¸ºçš„ç ”ç©¶,ä»‹ç»è¯„è¿°ç¢³çº³ç±³ç®¡ã€çŸ³å¢¨çƒ¯ã€æ°®åŒ–ç¡¼ã€æ°§åŒ–é”Œç‰ä½Žç»´çº³ç±³åŠŸèƒ½ææ–™çš„åŠ›-ç”µ-ç£-çƒ-æµè€¦åˆç‰¹æ€§å’Œç‰©ç†åŠ›å¦è¡Œä¸ºçš„ç ”ç©¶è¿›å±•,å¹¶å±•æœ›åŸºäºŽè¿™ç±»ç‰¹æ®Šæ€§èƒ½çš„æ–°åž‹çº³ç±³å™¨ä»¶çš„å‘å±•å‰æ™¯.
Coupled Aeroheating and Ablative Thermal Response Simulation Tool Project
National Aeronautics and Space Administration â€” A predictive tool with tight coupling of the fluid and thermal physics will give insights into the conservatism of the uncoupled design process and could lead to...
Metalworking and machining fluids
Erdemir, Ali; Sykora, Frank; Dorbeck, Mark
2010-10-12
Improved boron-based metal working and machining fluids. Boric acid and boron-based additives that, when mixed with certain carrier fluids, such as water, cellulose and/or cellulose derivatives, polyhydric alcohol, polyalkylene glycol, polyvinyl alcohol, starch, dextrin, in solid and/or solvated forms result in improved metalworking and machining of metallic work pieces. Fluids manufactured with boric acid or boron-based additives effectively reduce friction, prevent galling and severe wear problems on cutting and forming tools.
Modelling of fluid-structure interaction with multiphase viscous flows using an immersed-body method
Yang, P.; Xiang, J.; Fang, F.; Pavlidis, D.; Latham, J.-P.; Pain, C. C.
2016-09-01
An immersed-body method is developed here to model fluid-structure interaction for multiphase viscous flows. It does this by coupling a finite element multiphase fluid model and a combined finite-discrete element solid model. A coupling term containing the fluid stresses is introduced within a thin shell mesh surrounding the solid surface. The thin shell mesh acts as a numerical delta function in order to help apply the solid-fluid boundary conditions. When used with an advanced interface capturing method, the immersed-body method has the capability to solve problems with fluid-solid interfaces in the presence of multiphase fluid-fluid interfaces. Importantly, the solid-fluid coupling terms are treated implicitly to enable larger time steps to be used. This two-way coupling method has been validated by three numerical test cases: a free falling cylinder in a fluid at rest, elastic membrane and a collapsing column of water moving an initially stationary solid square. A fourth simulation example is of a water-air interface with a floating solid square being moved around by complex hydrodynamic flows including wave breaking. The results show that the immersed-body method is an effective approach for two-way solid-fluid coupling in multiphase viscous flows.
Electrorheological fluids and methods
Energy Technology Data Exchange (ETDEWEB)
Green, Peter F.; McIntyre, Ernest C.
2015-06-02
Electrorheological fluids and methods include changes in liquid-like materials that can flow like milk and subsequently form solid-like structures under applied electric fields; e.g., about 1 kV/mm. Such fluids can be used in various ways as smart suspensions, including uses in automotive, defense, and civil engineering applications. Electrorheological fluids and methods include one or more polar molecule substituted polyhedral silsesquioxanes (e.g., sulfonated polyhedral silsesquioxanes) and one or more oils (e.g., silicone oil), where the fluid can be subjected to an electric field.
Nedyalkov, Ivaylo
2016-11-01
After fifteen years of experience in rap, and ten in fluid mechanics, "I am coming here with high-Reynolds-number stamina; I can beat these rap folks whose flows are... laminar." The rap relates fluid flows to rap flows. The fluid concepts presented in the song have varying complexity and the listeners/viewers will be encouraged to read the explanations on a site dedicated to the rap. The music video will provide an opportunity to share high-quality fluid visualizations with a general audience. This talk will present the rap lyrics, the vision for the video, and the strategy for outreach. Suggestions and comments will be welcomed.
Shivamoggi, Bhimsen K
1998-01-01
"Although there are many texts and monographs on fluid dynamics, I do not know of any which is as comprehensive as the present book. It surveys nearly the entire field of classical fluid dynamics in an advanced, compact, and clear manner, and discusses the various conceptual and analytical models of fluid flow." - Foundations of Physics on the first edition. Theoretical Fluid Dynamics functions equally well as a graduate-level text and a professional reference. Steering a middle course between the empiricism of engineering and the abstractions of pure mathematics, the author focuses
Fiszdon, W
1965-01-01
Fluid Dynamics Transactions, Volume 2 compiles 46 papers on fluid dynamics, a subdiscipline of fluid mechanics that deals with fluid flow. The topics discussed in this book include developments in interference theory for aeronautical applications; diffusion from sources in a turbulent boundary layer; unsteady motion of a finite wing span in a compressible medium; and wall pressure covariance and comparison with experiment. The certain classes of non-stationary axially symmetric flows in magneto-gas-dynamics; description of the phenomenon of secondary flows in curved channels by means of co
Long-range boundary effects in simple fluids
Nieuwoudt, J. C.; Kirkpatrick, T. R.; Dorfman, J. R.
1984-01-01
We discuss long-range boundary effects in simple two- or three-dimensional fluids. These boundary effects are due to the existence of long-range correlations in nonequilibrium fluids and can be computed either by means of kinetic theory or phenomenological mode-coupling theories. In particular, we use kinetic theory to compute the stress tensor and heat flux vector for a fluid in a nonequilibrium steady state in a finite geometry and show that both the effective shear viscosity and effective heat conductivity have contributions due to the walls of the container that influence the behavior of the system far into the fluid. We also show that the mechanocaloric effect is present in the bulk of a three-dimensional fluid and that there are normal stresses in a fluid whenever the temperature gradient is nonzero.
System and method for determining velocity of electrically conductive fluid
Polzin, Kurt A. (Inventor); Korman, Valentin (Inventor); Markusic, Thomas E. (Inventor); Stanojev, Boris Johann (Inventor)
2008-01-01
A flowing electrically-conductive fluid is controlled between an upstream and downstream location thereof to insure that a convection timescale of the flowing fluid is less than a thermal diffusion timescale of the flowing fluid. First and second nodes of a current-carrying circuit are coupled to the fluid at the upstream location. A current pulse is applied to the current-carrying circuit so that the current pulse travels through the flowing fluid to thereby generate a thermal feature therein at the upstream location. The thermal feature is convected to the downstream location where it is monitored to detect a peak associated with the thermal feature so-convected. The velocity of the fluid flow is determined using a time-of-flight analysis.
Heat Transfer in Complex Fluids
Energy Technology Data Exchange (ETDEWEB)
Mehrdad Massoudi
2012-01-01
fluids show Newtonian (linear) behavior for a given range of parameters or geometries; there are many empirical or semi-empirical constitutive equations suggested for these fluids. There have also been many non-linear constitutive relations which have been derived based on the techniques of continuum mechanics. The non-linearities oftentimes appear due to higher gradient terms or time derivatives. When thermal and or chemical effects are also important, the (coupled) momentum and energy equations can give rise to a variety of interesting problems, such as instability, for example the phenomenon of double-diffusive convection in a fluid layer. In Conclusion, we have studied the flow of a compressible (density gradient type) non-linear fluid down an inclined plane, subject to radiation boundary condition. The heat transfer is also considered where a source term, similar to the Arrhenius type reaction, is included. The non-dimensional forms of the equations are solved numerically and the competing effects of conduction, dissipation, heat generation and radiation are discussed. It is observed that the velocity increases rapidly in the region near the inclined surface and is slower in the region near the free surface. Since R{sub 7} is a measure of the heat generation due to chemical reaction, when the reaction is frozen (R{sub 7}=0.0) the temperature distributions would depend only on R{sub 1}, and R{sub 2}, representing the effects of the pressure force developed in the material due to the distribution, R{sub 3} and R{sub 4} viscous dissipation, R{sub 5} the normal stress coefficient, R{sub 6} the measure of the emissivity of the particles to the thermal conductivity, etc. When the flow is not frozen (RP{sub 7} > 0) the temperature inside the flow domain is much higher than those at the inclined and free surfaces. As a result, heat is transferred away from the flow toward both the inclined surface and the free surface with a rate that increases as R{sub 7} increases. For a
Fluid Stretching as a Levy Process
Dentz, Marco; Borgne, Tanguy Le; de Barros, Felipe P J
2016-01-01
We uncover deformation dynamics that lead to power-law stretching of material lines in heterogeneous flow. This evidences the existence of a broad spectrum of algebraic stretching behaviors in fluids from sub- to superlinear beyond the linear (shear flow) and exponential (chaotic flow) elongation paradigms. Formulating fluid deformation in two-dimensional steady flow in stream-line coordinates, we show that stretching results from the non-linear coupling between Lagrangian shear deformation and velocity fluctuations. Casting the stretching process in the frame of a continuous time random walk, this coupling links the magnitude of elongation events to their persistence through the transit times of material strips. As a consequence, for broad transit time distributions stretching obeys Levy dynamics. We derive explicit expressions for the mean elongation which predict a broad range of power-law stretching behaviors depending on the velocity distribution and the relation between shear rate and velocity along str...
Practical thermodynamics of Yukawa systems at strong coupling
Energy Technology Data Exchange (ETDEWEB)
Khrapak, Sergey A. [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum fÃ¼r Luft- und Raumfahrt, Oberpfaffenhofen (Germany); Aix-Marseille-UniversitÃ©, CNRS, Laboratoire PIIM, UMR 7345, 13397 Marseille Cedex 20 (France); Kryuchkov, Nikita P.; Yurchenko, Stanislav O. [Bauman Moscow State Technical University, 2-nd Baumanskaya St. 5, Moscow 105005 (Russian Federation); Thomas, Hubertus M. [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum fÃ¼r Luft- und Raumfahrt, Oberpfaffenhofen (Germany)
2015-05-21
Simple practical approach to estimate thermodynamic properties of strongly coupled Yukawa systems, in both fluid and solid phases, is presented. The accuracy of the approach is tested by extensive comparison with direct computer simulation results (for fluids and solids) and the recently proposed shortest-graph method (for solids). Possible applications to other systems of softly repulsive particles are briefly discussed.
Space Station fluid management logistics
Dominick, Sam M.
1990-01-01
Viewgraphs and discussion on space station fluid management logistics are presented. Topics covered include: fluid management logistics - issues for Space Station Freedom evolution; current fluid logistics approach; evolution of Space Station Freedom fluid resupply; launch vehicle evolution; ELV logistics system approach; logistics carrier configuration; expendable fluid/propellant carrier description; fluid carrier design concept; logistics carrier orbital operations; carrier operations at space station; summary/status of orbital fluid transfer techniques; Soviet progress tanker system; and Soviet propellant resupply system observations.
The Fluid Dynamics of Competitive Swimming
Wei, Timothy; Mark, Russell; Hutchison, Sean
2014-01-01
Nowhere in sport is performance so dependent on the interaction of the athlete with the surrounding medium than in competitive swimming. As a result, understanding (at least implicitly) and controlling (explicitly) the fluid dynamics of swimming are essential to earning a spot on the medal stand. This is an extremely complex, highly multidisciplinary problem with a broad spectrum of research approaches. This review attempts to provide a historical framework for the fluid dynamics-related aspects of human swimming research, principally conducted roughly over the past five decades, with an emphasis on the past 25 years. The literature is organized below to show a continuous integration of computational and experimental technologies into the sport. Illustrations from the authors' collaborations over a 10-year period, coupling the knowledge and experience of an elite-level coach, a lead biomechanician at USA Swimming, and an experimental fluid dynamicist, are intended to bring relevance and immediacy to the review.
A mixture theory for geophysical fluids
Directory of Open Access Journals (Sweden)
A. C. Eringen
2004-01-01
Full Text Available A continuum theory is developed for a geophysical fluid consisting of two species. Balance laws are given for the individual components of the mixture, modeled as micropolar viscous fluids. The continua allow independent rotational degrees of freedom, so that the fluids can exhibit couple stresses and a non-symmetric stress tensor. The second law of thermodynamics is used to develop constitutive equations. Linear constitutive equations are constituted for a heat conducting mixture, each species possessing separate viscosities. Field equations are obtained and boundary and initial conditions are stated. This theory is relevant to an atmospheric mixture consisting of any two species from rain, snow and/or sand. Also, this is a continuum theory for oceanic mixtures, such as water and silt, or water and oil spills, etc.
Effective field theory of dissipative fluids
Crossley, Michael; Liu, Hong
2015-01-01
We develop an effective field theory for dissipative fluids which governs the dynamics of gapless modes associated to conserved quantities. The system is put in a curved spacetime and coupled to external sources for charged currents. The invariance of the hydrodynamical action under gauge symmetries and diffeomorphisms suggests a natural set of dynamical variables which provide a mapping between an emergent "fluid spacetime" and the physical spacetime. An essential aspect of our formulation is to identify the appropriate symmetries in the fluid spacetime. Our theory applies to nonlinear disturbances around a general density matrix. For a thermal density matrix, we require an additional Z_2 symmetry, to which we refer as the local KMS condition. This leads to the standard constraints of hydrodynamics, as well as a nonlinear generalization of the Onsager relations. It also leads to an emergent supersymmetry in the classical statistical regime, with a higher derivative version required for the full quantum regim...
Interfacial gauge methods for incompressible fluid dynamics
Saye, Robert
2016-01-01
Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of â€œgauge freedomâ€ to reduce the...
Dynamics of Complex Fluid-Fluid Interfaces
Sagis, L.M.C.
2016-01-01
This chapter presents an overview of recent progress in modelling the behaviour of complex fluidâ€“fluid interfaces with non-equilibrium thermodynamics. We will limit ourselves to frameworks employing the Gibbs dividing surface model, and start with a general discussion of the surface excess variables
Geerts, Bart
2011-01-01
Patients in the intensive care unit (ICU) and in the peri-operative phase are dependent on physicians and nurses for their fluid intake. Volume status optimization is required to maximize oxygen delivery to vital organs. Unnecessary fluid administration can, however, lead to general and pulmonary
Geerts, Bart
2011-01-01
Patients in the intensive care unit (ICU) and in the peri-operative phase are dependent on physicians and nurses for their fluid intake. Volume status optimization is required to maximize oxygen delivery to vital organs. Unnecessary fluid administration can, however, lead to general and pulmonary oe
Culture - peritoneal fluid ... sent to the laboratory for Gram stain and culture. The sample is checked to see if bacteria ... The peritoneal fluid culture may be negative, even if you have ... diagnosis of peritonitis is based on other factors, in addition ...
Applications of fluid dynamics
Energy Technology Data Exchange (ETDEWEB)
Round, G.R.; Garg, V.K.
1986-01-01
This book describes flexible and practical approach to learning the basics of fluid dynamics. Each chapter is a self-contained work session and includes a fluid dynamics concept, an explanation of the principles involved, an illustration of their application and references on where more detailed discussions can be found.
Geerts, Bart
2011-01-01
Patients in the intensive care unit (ICU) and in the peri-operative phase are dependent on physicians and nurses for their fluid intake. Volume status optimization is required to maximize oxygen delivery to vital organs. Unnecessary fluid administration can, however, lead to general and pulmonary oe
Energetics of Synchronization in Coupled Oscillators
Izumida, Yuki; Seifert, Udo
2016-01-01
We formulate the energetics of synchronization in coupled oscillators by unifying the nonequilibrium aspects with the nonlinear dynamics via stochastic thermodynamics. We derive a concise and universal expression of the energy dissipation rate using nonlinear-dynamics quantities characterizing synchronization, and elucidate how synchronization/desynchronization between the oscillators affects it. We apply our theory to hydrodynamically-coupled Stokes spheres rotating on circular trajectories that may be interpreted as the simplest model of synchronization of coupled oscillators in a biological system, revealing that the oscillators gain the ability to do more work on the surrounding fluid as the degree of phase synchronization increases.
Energy Technology Data Exchange (ETDEWEB)
Jakaboski, Juan-Carlos [Albuquerque, NM; Hughs, Chance G [Albuquerque, NM; Todd, Steven N [Rio Rancho, NM
2012-01-10
A fluid blade disablement (FBD) tool that forms both a focused fluid projectile that resembles a blade, which can provide precision penetration of a barrier wall, and a broad fluid projectile that functions substantially like a hammer, which can produce general disruption of structures behind the barrier wall. Embodiments of the FBD tool comprise a container capable of holding fluid, an explosive assembly which is positioned within the container and which comprises an explosive holder and explosive, and a means for detonating. The container has a concavity on the side adjacent to the exposed surface of the explosive. The position of the concavity relative to the explosive and its construction of materials with thicknesses that facilitate inversion and/or rupture of the concavity wall enable the formation of a sharp and coherent blade of fluid advancing ahead of the detonation gases.
Amniotic fluid water dynamics.
Beall, M H; van den Wijngaard, J P H M; van Gemert, M J C; Ross, M G
2007-01-01
Water arrives in the mammalian gestation from the maternal circulation across the placenta. It then circulates between the fetal water compartments, including the fetal body compartments, the placenta and the amniotic fluid. Amniotic fluid is created by the flow of fluid from the fetal lung and bladder. A major pathway for amniotic fluid resorption is fetal swallowing; however in many cases the amounts of fluid produced and absorbed do not balance. A second resorption pathway, the intramembranous pathway (across the amnion to the fetal circulation), has been proposed to explain the maintenance of normal amniotic fluid volume. Amniotic fluid volume is thus a function both of the amount of water transferred to the gestation across the placental membrane, and the flux of water across the amnion. Membrane water flux is a function of the water permeability of the membrane; available data suggests that the amnion is the structure limiting intramembranous water flow. In the placenta, the syncytiotrophoblast is likely to be responsible for limiting water flow across the placenta. In human tissues, placental trophoblast membrane permeability increases with gestational age, suggesting a mechanism for the increased water flow necessary in late gestation. Membrane water flow can be driven by both hydrostatic and osmotic forces. Changes in both osmotic/oncotic and hydrostatic forces in the placenta my alter maternal-fetal water flow. A normal amniotic fluid volume is critical for normal fetal growth and development. The study of amniotic fluid volume regulation may yield important insights into the mechanisms used by the fetus to maintain water homeostasis. Knowledge of these mechanisms may allow novel treatments for amniotic fluid volume abnormalities with resultant improvement in clinical outcome.
Critical asymmetry in renormalization group theory for fluids.
Zhao, Wei; Wu, Liang; Wang, Long; Li, Liyan; Cai, Jun
2013-06-21
The renormalization-group (RG) approaches for fluids are employed to investigate critical asymmetry of vapour-liquid equilibrium (VLE) of fluids. Three different approaches based on RG theory for fluids are reviewed and compared. RG approaches are applied to various fluid systems: hard-core square-well fluids of variable ranges, hard-core Yukawa fluids, and square-well dimer fluids and modelling VLE of n-alkane molecules. Phase diagrams of simple model fluids and alkanes described by RG approaches are analyzed to assess the capability of describing the VLE critical asymmetry which is suggested in complete scaling theory. Results of thermodynamic properties obtained by RG theory for fluids agree with the simulation and experimental data. Coexistence diameters, which are smaller than the critical densities, are found in the RG descriptions of critical asymmetries of several fluids. Our calculation and analysis show that the approach coupling local free energy with White's RG iteration which aims to incorporate density fluctuations into free energy is not adequate for VLE critical asymmetry due to the inadequate order parameter and the local free energy functional used in the partition function.
Testing Structure Formation in the Universe via Coupled Matter Fluids
African Journals Online (AJOL)
kagoyire
Kenya. 2The Astrophysics ... matter density that mimics recently published results from halo theory of N-body ... understanding the way in which structures such as galaxies form, still ... observational data with a minimum number of free parameters.
Multiscale Simulation Framework for Coupled Fluid Flow and Mechanical Deformation
Energy Technology Data Exchange (ETDEWEB)
Hou, Thomas [California Inst. of Technology (CalTech), Pasadena, CA (United States); Efendiev, Yalchin [Stanford Univ., CA (United States); Tchelepi, Hamdi [Texas A & M Univ., College Station, TX (United States); Durlofsky, Louis [Stanford Univ., CA (United States)
2016-05-24
Our work in this project is aimed at making fundamental advances in multiscale methods for flow and transport in highly heterogeneous porous media. The main thrust of this research is to develop a systematic multiscale analysis and efficient coarse-scale models that can capture global effects and extend existing multiscale approaches to problems with additional physics and uncertainties. A key emphasis is on problems without an apparent scale separation. Multiscale solution methods are currently under active investigation for the simulation of subsurface flow in heterogeneous formations. These procedures capture the effects of fine-scale permeability variations through the calculation of specialized coarse-scale basis functions. Most of the multiscale techniques presented to date employ localization approximations in the calculation of these basis functions. For some highly correlated (e.g., channelized) formations, however, global effects are important and these may need to be incorporated into the multiscale basis functions. Other challenging issues facing multiscale simulations are the extension of existing multiscale techniques to problems with additional physics, such as compressibility, capillary effects, etc. In our project, we explore the improvement of multiscale methods through the incorporation of additional (single-phase flow) information and the development of a general multiscale framework for flows in the presence of uncertainties, compressible flow and heterogeneous transport, and geomechanics. We have considered (1) adaptive local-global multiscale methods, (2) multiscale methods for the transport equation, (3) operator-based multiscale methods and solvers, (4) multiscale methods in the presence of uncertainties and applications, (5) multiscale finite element methods for high contrast porous media and their generalizations, and (6) multiscale methods for geomechanics.