Theories of Transport in Fluids

Abstract

The object of this paper is to establish the equivalence of the Kubo‐type transport coefficients with those obtained by the method of Chapman and Enskog. Kubo‐type coefficients are derived by a simple method, based on classical mechanics, and these are found to be in general agreement with those found by Mori, who has, however, discarded some important relaxation terms. The neglect of these terms by Kubo and other authors has the effect of leaving their coefficients of diffusion and electrical conductivity divergent. It is shown quite generally that the computation of the corrected Kubo‐type coefficients for dilute gases leads to the same results, and even the same calculations, as the method of Chapman and Enskog. The equivalence of the two methods for dense systems is also briefly discussed.