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Compressible Fluid (compressible + fluid)

Distribution by Scientific Domains
Mathematics and Statistics50%
Engineering37%

Terms modified by Compressible Fluid

  • compressible fluid flow
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    Selected Abstracts

    Three-dimensional models of reservoir sediment and effects on the seismic response of arch dams

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2004
    O. Maeso
    Abstract The important effects of bottom sediments on the seismic response of arch dams are studied in this paper. To do so, a three-dimensional boundary element model is used. It includes the water reservoir as a compressible fluid, the dam and unbounded foundation rock as viscoelastic solids, and the bottom sediment as a two-phase poroelastic domain with dynamic behaviour described by Biot's equations. Dynamic interaction among all those regions, local topography and travelling wave effects are taken into account. The results obtained show the important influence of sediment compressibility and permeability on the seismic response. The former is associated with a general change of the system response whereas the permeability has a significant influence on damping at resonance peaks. The analysis is carried out in the frequency domain considering time harmonic excitation due to P and S plane waves. The time-domain results obtained by using the Fourier transform for a given earthquake accelerogram are also shown. The possibility of using simplified models to represent the bottom sediment effects is discussed in the paper. Two alternative models for porous sediment are tested. Simplified models are shown to be able to reproduce the effects of porous sediments except for very high permeability values. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Symbolic methods for invariant manifolds in chemical kinetics

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2006
    Simon J. Fraser
    Abstract Chemical reactions show a separation of time scales in transient decay due to the stiffness of the ordinary differential equations (ODEs) that describe their evolution. This evolution can be represented as motion in the phase space spanned by the concentration variables of the chemical reaction. Transient decay corresponds to a collapse of the "compressible fluid" representing the continuum of possible dynamical states of the system. Collapse occurs sequentially through a hierarchy of nested, attracting, slow invariant manifolds (SIMs), i.e., sets that map into themselves under the action of the phase flow, eventually reaching the asymptotic attractor of the system. Using a symbolic manipulative language, explicit formulas for the SIMs can be found by iterating functional equations obtained from the system's ODEs. Iteration converges geometrically fast to a SIM at large concentrations and, if necessary, can be stabilized at small concentrations. Three different chemical models are examined in order to show how finding the SIM for a model depends on its underlying dynamics. For every model the iterative method provides a global SIM formula; however, formal series expansions for the SIM diverge in some models. Repelling SIMs can be also found by iterative methods because of the invariance of trajectory geometry under time reversal. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

    Surface roughness effects on thermo-hydrodynamic lubrication of journal bearings lubricated with bubbly oil

    LUBRICATION SCIENCE, Issue 1 2006
    A. M. A. El-Butch
    In this paper, the combined effect of surface roughness and bubbles content on the hydrodynamic performance of journal bearings is studied. In the analysis, it is assumed that the bearing and shaft surfaces are covered with homogeneous isotropic roughness, the air bubbles are evenly distributed through the lubricant and the bubble size is very small. The modified Reynolds equation governing the pressure generation in the bearing gap for compressible fluid is solved simultaneously with the energy equation. Temperature and pressure distributions, coefficient of friction, bearing load capacity and attitude angle as affected by surface roughness, bubble content and some bearing parameters are presented. Results showed that the bearing load carrying capacity is higher at higher values of average roughness and higher bubble content as a direct consequence of the higher pressure values attained, and the average roughness and the bubbles content had no significant effect on the attitude angle. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Diffusion in poro-plastic media

    MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 18 2004
    R. E. Showalter
    Abstract A model is developed for the flow of a slightly compressible fluid through a saturated inelastic porous medium. The initial-boundary-value problem is a system that consists of the diffusion equation for the fluid coupled to the momentum equation for the porous solid together with a constitutive law which includes a possibly hysteretic relation of elasto-visco-plastic type. The variational form of this problem in Hilbert space is a non-linear evolution equation for which the existence and uniqueness of a global strong solution is proved by means of monotonicity methods. Various degenerate situations are permitted, such as incompressible fluid, negligible porosity, or a quasi-static momentum equation. The essential sufficient conditions for the well-posedness of the system consist of an ellipticity condition on the term for diffusion of fluid and either a viscous or a hardening assumption in the constitutive relation for the porous solid. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    On diffusion of a single-phase, slightly compressible fluid through a randomly fissured medium

    MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 11 2001
    Steve Wright
    In this paper, the Douglas,Peszy,ska,Showalter model of diffusion through a partially fissured medium is given a stochastic formulation using the framework for problems in random media as set forth by Jikov, Kozlov and Oleinik. The concept of stochastic two-scale convergence in the mean is then used to homogenize the randomized micromodels which result. As a consequence of this homogenization procedure, exact stochastic generalizations of results obtained by Clark and Showalter on diffusion through periodically fissured media are derived. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    A splitting positive definite mixed element method for miscible displacement of compressible flow in porous media

    NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 3 2001
    Danping Yang
    Abstract A miscible displacement of one compressible fluid by another in a porous medium is governed by a nonlinear parabolic system. A new mixed finite element method, in which the mixed element system is symmetric positive definite and the flux equation is separated from pressure equation, is introduced to solve the pressure equation of parabolic type, and a standard Galerkin method is used to treat the convection-diffusion equation of concentration of one of the fluids. The convergence of the approximate solution with an optimal accuracy in L2 -norm is proved. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17: 229,249, 2001 [source]

    The immersed/fictitious element method for fluid,structure interaction: Volumetric consistency, compressibility and thin members

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2008
    Hongwu Wang
    Abstract A weak form and an implementation are given for fluid,structure interaction by the immersed/fictitious element method for compressible fluids. The weak form is applicable to models where the fluid is described by Eulerian coordinates while the solid is described by Lagrangian coordinates, which suits their intrinsic characteristics. A unique feature of the method is the treatment of the fictitious fluid by a Lagrangian description, which simplifies the interface conditions. Methods for enforcing volumetric consistency between the fluid and solid and treating thin members are given. Although a compressible viscous fluid is considered here, the new developments can be applied to incompressible fluids. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Large time behaviour of flows of compressible, viscous, and heat conducting fluids

    MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 11 2006
    Eduard Feireisl
    Abstract We give a complete description of large time behaviour of admissible variational solutions to the Navier,Stokes,Fourier system describing flows of viscous compressible fluids under action of arbitrarily large potential and non-potential stationary forces. The pressure is supposed to be an affine function of temperature with coefficients depending on density and the system is thermally and mechanically isolated. Copyright © 2006 John Wiley & Sons, Ltd. [source]