Introductory remarks on the concept of interaction pressure

Abstract

The pressure tensor of interaction of two bodies can be correctly defined as the complementary term to their individual pressure tensors in the total pressure tensor. If two bodies occupy separate volumes, their interaction pressure can be expressed, inside one or the other of the bodies, as a function of the macroscopic electromagnetic fields. No similar expression exists for two mixed bodies. The interaction pressure of two constituents of a fluid chemical mixture has a field component if the mixture is non-ideal, and a kinetic component if the constituents diffuse. For the practical study of pressure in a chemical mixture, the true individual pressures of the components and the interaction pressure might be a better basis for empirical modelling than the partial pressures, which are additive but have no physical significance.