Electrical current density in a sheared dilute gas

Electrical current density of charged particles across a rarefied gas of ne utral particles under shear How is analyzed in the limit of small electric fields. The concentration of the charged species is assumed to be much smal ler than that of the neutral species so that the interactions of charged-ne utral and neutral-neutral type are the dominant ones. The study is made fro m the exact Boltzmann equation for Maxwell molecules as well as from a kine tic model for general repulsive interactions. By performing a perturbation expansion around a nonequilibrium state, the current density is explicitly evaluated in the first order of the external field. We get a generalized Oh m's law. where an electrical conductivity tensor can be identified. The non zero elements of this tensor are nonlinear functions of the shear rate, the mass ratio, the force constant ratio, and the interaction parameter. (C) 1 999 Published by Elsevier Science B.V. All rights reserved.