A new effect of the nongradient transport in relaxation zones

Dorodnicyn Computing Centre of the Russian Academy of Sciences - Moscow, Russia

Corresponding authors: aristov@ccas.ru afrol@ccas.ru serge@ccas.ru

Received: 16 July 2009
Accepted: 22 October 2009

Abstract

The nontraditional transfer properties in the spatially nonuniform relaxation regions are studied by the methods of kinetic theory applied to gas mixtures and gases with inner degrees of freedom. Direct numerical methods for solving the Boltzmann and kinetic model equations are used. The influence of the nonequilibrium boundary distribution functions and consequently of boundary fluxes of dissipative values on the gradients of some moments is studied. It is found that in the relaxation zones which are formed by the supersonic nonequilibrium boundary conditions the gradients of velocity and temperature can have the same signs as the appropriate component of the nonequilibrium stress tensor and heat flux, respectively, which is an example of the nongradient transport differing from the classic Stokes and Fourier transport. The physical sense of this formulation of the problem is discussed. 1D and 2D nonuniform relaxation problems are considered and examples of the anomalous transport are presented.