Theory of transport processes in dense fluids

Abstract

The projection operator methods of Mori and Zwanzig are used to construct kinetic equations for the single-particle distribution functions of a fluid mixture. The particle interactions are pair-additive sums of hard-core and soft, continuous potentials. The mean field kinetic equations obtained by discarding the multicomponent memory functions are identical in form to van Beijeren and Ernst’s revised Enskog equations for a hard sphere mixture, but incorporate the radial and direct correlation functions characteristic of the composite interaction. The 13-moments methods is used to construct an approximate solution of the mean field kinetic equation for a simple fluid and to relate the associated, zero-frequency transport coefficients to those of the conventional Enskog theory. Our choice of interaction parameters optimally mimicks a Lennard-Jones 12-6 fluid and yields excellent estimates of viscosity.