An abstract formulation of the concept of entropy

Abstract

Entropy is presented as a concave function relating two sets of quantities called densities and field. It allows a simple classification of the standard relations of classical thermodynamics and yields a simple derivation of the conditions for concavity of the entropy function. It also allows a formal derivation of the equations of fluid motion. Dissipation, mixtures, and phase changes may also be included in the theory in a natural manner.