171 research outputs found
A particle scheme for the numerical solution of the Enskog equation
No full textIt is shown that the kinetic equation proposed by Enskog for a dense hard sphere gas can be solved numerically by a particle simulation method. The technique can be extension of the well known DSMC method used to solve the Boltzmann euation. Unlike a recently proposed Nanbu-like particle scheme, the present method exactly preserves momentum and energy. The calculation of the density profile in a dense gas in equilibrium near a hard wall is presented as an example. © 1997 American Institute of Physics
Boundary conditions at the vapor-liquid interface
No full textThe paper aims at presenting a review of kinetic theory applications to evaporation condensation problems. The main results for monatomic and polyatomic gases and mixtures are described. The role of boundary conditions at the vapor-liquid interface is discussed and a description of molecular dynamics studies aimed at formulating vapor-liquid interaction models is given
Non-equilibrium structure of the vapor-liquid interface of a binary fluid
No full textThe evaporation of a binary liquid mixture of monatomic species into near vacuum has been investigated by molecular dynamics simulations. It has been assumed that atomic interaction forces can be derived by Lennard-Jones potentials. Results are presented about surface composition changes induced by evaporation, the shape of the distribution functions of evaporating atoms. Estimates of evaporation coefficients are given
DSMC Simulation of the Vertical Structure of Planetary Rings
No full textA statistical Monte Carlo method (DSMC) is developed to simulate
granular flows occurring in dense planetary rings. The accuracy
of the method is assessed through a comparison with existing
molecular dynamics simulations of the vertical structure of
planetary rings with and without self-gravity effects
Monte Carlo simulation of the heat flow in a dense hard sphere gas
No full textThe one-dimensional steady heat flow in a dense hard sphere gas is studied solving the Enskog equation numerically by a recently proposed DSMC-like particle scheme. The accuracy of the solutions is assessed through a comparison with solutions obtained from a semi-regular method which combines finite difference discretization with Monte Carlo quadrature techniques. It is shown that excellent agreement is found between the two numerical methods. The solutions obtained from the Enskog equation have also been found in good agreement with the results of molecular dynamics simulations. © Elsevier, Paris
Molecular dynamics and Enskog theory calculation of one dimensional problems in the dynamics of dense gases
No full textThe Enskog equation is solved by a numerical method which combines finite difference discretization with Monte Carlo quadrature techniques for the evaluation of the collision integral. The method is applied to the study of two one-dimensional problems in the kinetic theory of a dense hard sphere gas. The Enskog theory solutions are also compared with molecular dynamics simulations
Numerical study of the strong evaporation of a binary mixture
No full textThe problem of the one-dimensional evaporation of a binary mixture is investigated by numerically solving a system of two coupled Boltzmann equations. The numerical method is based on the direct discretization of the Boltzmann equation and the Monte Carlo evaluation of the collision integrals. It is assumed that the fluid flows between an evaporating plate and a totally absorbing plate. The spatial profiles of macroscopic quantities as well as evaporation rates have been calculated for values of the Knudsen number between 1 2 and 1 20. © 1991
A numerical investigation of the steady evaporation of a polyatomic gas
No full textThe evaporation and condensation of a polyatomic vapor in contact with its condensed phase has received much less attention
than the monatomic case. In this paper we investigate the structure of the Knudsen layer formed in the steady evaporation of a
vapor whose molecules behave as rigid rotators. The vapor motion is obtained by the numerical solution of the Boltzmann equation
by the Direct Simulation Monte Carlo (DSMC) method. The obtained results are also compared with the solutions of a simplified
kinetic BGK-like model equation. It is shown that density and temperature drops across the Knudsen layer are reasonably well
reproduced by approximate methods proposed in the literature
Molecular dynamics and Enskog theory calculation of shock profiles in a dense hard sphere gas
No full textNormal shock profiles a dense hard sphere gas are obtained by solving numerically the Enskog kinetic equation. The results of the Enskog theory are compared with "exact" shock profiles obtained from molecular dynamics symulations. It is shown that, at least in the range of the flow parameters examined, the Enskog equation provides a remarkably good description of the shock propagation
The propagation of infinitesimal disturbances in an ultrarelativistic gas according to the method of elementary solutions
No full textIt has recently been shown that a linearized relativistic BGK model can be reduced, in the ultrarelativistic limit, to a system of three uncoupled transport equations for thermal, sound, and shear waves. The equation describing the propagation of thermal waves is the well-known one-speed neutron transport with isotropic scattering in the conservative case. In this paper the solution of the half-space problem for the equation describing the propagation of shear and sound waves is given according to Case's elementary solutions method. © 1987 Plenum Publishing Corporation
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