摘要:

This article is the combination of a review and some new results of kinetic theoretical studies on the half-space problem of evaporation and condensation. A semi-infinite expanse of a gas uniform at infinity and bounded by its plane condensed phase is considered. Steady flow, evaporating from or condensing onto the condensed phase depending on the parameters of the condensed phase and the infinity, and the relation among the parameters that allows a steady solution are studied. Special attention is paid to the difference of the character of the relation, depending on evaporation, subsonic condensation, or supersonic condensation, and analytic structure of the transition of the relation and solution from evaporation to subsonic condensation or from subsonic condensation to supersonic one.

ISSN:0041-1450    

DOI:10.1080/00411450008205874

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We present a general statistical mechanical theory of multispecies lattice gas automata (LGA) for reaction-diffusion systems. We describe how reactive and elastic collisions and free streaming of molecules between collisions are modeled by LGA chemical transformation, mixing and propagation steps. We characterize these steps in terms of microdynamical variables and transition probabilities. From these steps we construct diffusion and reaction-diffusion automaton dynamics. We describe these dynamics in terms of LGA microdynamical equations and discrete lattice Boltzmann equations. From the LGA discrete Boltzmann equations we derive the corresponding LGA macroscopic diffusion and reaction-diffusion PDEs. By comparing these equations with those arising from phelattice gas research J.P. Boon, D. Dab, K. Diemer, D. Gruner, B. Hasslacher, R. Kapral, P. Masiar, S. Ponce-Dawson and J.P. Voroney.

ISSN:0041-1450    

DOI:10.1080/00411450008205875

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

An effective deterministic method based on the Fast Fourier Transform (FFT) for the Boltzmann equation with Maxwell molecules is considered. The global existence, uniqueness and limitedness of the discrete solution is proved. An effective procedure for the conservation of the macroscopic quantities is described. The results of some numerical tests are presented.

ISSN:0041-1450    

DOI:10.1080/00411450008205876

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The Euler-Maxwell equations as a hydrodynamic model of charge transport of semiconductors in an electromagnetic field are studied. The global approximate solutions to the initial-boundary value problem are constructed by the fractional Godunov scheme. The uniform hound andH−1compactness are proved. The approximate solutions are shown convergent by weak convergence methods. Then, with some new estimates due to the presence of electromagnetic fields, the existence of a global weak solution to the initial-boundary value problem is established for arbitrarily large initial data in L∞

ISSN:0041-1450    

DOI:10.1080/00411450008205877

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We study the asymptotic behavior of the spherically symmetric solutions for a viscous polytropic gas in a bounded annulus domain. For any initial data, and suitably small external force generated by some scalar steady potential, the solution is proved to exponentially tend towards the corresponding stationary solution as time tends to infinity.

ISSN:0041-1450    

DOI:10.1080/00411450008205878

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We give a comparison of various differential cross-section models for a classical polyatomic gas for a homogeneous relaxation problem and the shock wave profiles at Mach numbers 1.71 and 12.9. Besides the standard Borgnakke-Larsen model and its generalization to an energy dependent coefficient to control the amount of rotationally elastic and completely inelastic collision, we discuss some new models recently proposed by the same authors. Moreover, we present numerical algorithms to implement the models in a particle or Monte-Carlo code and compare the numerical shock wave profiles with existing experimental data.

ISSN:0041-1450    

DOI:10.1080/00411450008205879

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We introduce two space-frequency adaptive strategies for the numerical approximation of the solutions ofquantum hydrodynamic modelsfor semiconductors, based respectively on wavelets and wavelet packets. The two strategies are compared on a test case, and wavelet packets perform better in approximating with fewer degrees of freedom the high frequency dispersive oscillations of the solution.

ISSN:0041-1450    

DOI:10.1080/00411450008205880

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The linear Vlasov-Poisson system for homogeneous, stable equilibria is solved by means of a novel integral transform that is a generalization of the Hilbert transform. The integral transform provides a means for describing the dynamics of the continuous spectrum that is well-known to occur in this system. The results are interpreted in the context of Hamiltonian systems theory, where it is shown that the integral transform defines a canonical transformation to action-angle variables for this infinite degree-of-freedom system. A means for attaching Kren (energy) signature to a continuum eigenmode is given.

ISSN:0041-1450    

DOI:10.1080/00411450008205881

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We consider some recently developed unconditionally stable numerical schemes for the Boltzmann equation, called Time Relaxed (TR) schemes. They share the important property of providing the correct fluid dynamic limit. Stability analysis of the schemes is performed, and theA-stability andL-stability of the schemes is studied. Monte Carlo methods based on TR discretizations are briefly reviewed. In particular, first and second order particle schemes are compared with a hybrid scheme, in which the equilibrium part of the distribution is described analytically.

ISSN:0041-1450    

DOI:10.1080/00411450008205882

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper we introduce a new smoothed scheme derived from the spectral Fourier method for the homogeneous Boltzmann equation recently introduced in [14, 15]. More precisely we show that using suitable smoothing filters the method can be designed in such a way that the spectral solution remains positive in time and preserves the total mass. Several numerical examples are given to illustrate the previous analysis.

ISSN:0041-1450    

DOI:10.1080/00411450008205883

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor