Transport properties of polar-quadrupolar gas mixtures

Abstract

Collision integrals for polar-quadrupolar gas mixtures have been computed under two limiting approximations: (i) Collision integrals are calculated on the fixed relative orientations with a 12-6-4 potential model and then these values are averaged by giving equal weight to all orientations; (ii) the potential is "pre-averaged" over all orientations and then collision integrals are calculated. The former method is more appropriate for slow rotating molecules and the latter one for fast rotating molecules. The polar-quadrupolar interaction term in the potential energy of interaction between a polar and a quadrupolar molecule is found to contribute materially to the transport coefficients and must, therefore, be considered for calculating accurately the mixture properties. Combination rules for estimating unlike interactions are discussed briefly.