Model kinetic equations and macroscopic description of gas fluxes for various relaxation stages

Abstract

Various relaxation stages of gas flows with physical and chemical processes are considered in zero- and first-order approximations of the modified Chapman Enskog method in terms of intensive parameters which are conjugated to governing extensive ones for this relaxation stage. To simplify the transport processes investigation, the model kinetic equations are used. In these equations the BGK-type operator substitutes a group of collision operators which describe the forming of the quasi-stationary distribution functions on the relaxation stage under review. Proposed model equations can be used for the study of any equilibrium and non-equilibrium regimes of the flows when strong deviations from the equilibrium distributions over chemical species and part of internal energy are observed along with weak deviations from equilibrium of translational energy and remaining part of the internal energy. The expressions for transport fluxes are given in terms of intensive parameters. The formula for sound velocity (as the velocity of propagation of small perturbations) with coefficient æ which is not constant in considered conditions is given.