A mixture model of poroelastic materials

Chemically-reacting porous materials are investigated within the theory of mixtures. The key idea is that for incompressible constituents, the volume fractions satisfy balance equations strictly analogous to those of mass densities. As a consequence, upon compatibility with thermodynamics, constitutive models are established where the evolution of the volume fractions is governed by the conservation of mass and need not be given by additional balance equations. Next an analogous scheme is developed for materials with voids where chemical reactions no longer occur. Compressible constituents are also considered and the concentrations are used as the variables characterizing the immiscibility. Some comments are given about the approaches where further fields occur, such as equilibrated forces and stresses, and are associated with additional balance equations.