Thermodynamics of diffusing mixtures

We present a formal description of a set of field equations for the thermodynamics of mixtures, proceeding from an integral formulation of the balance and imbalance laws to local equations. Our treatment is general in that we include volume-change as a kinematic descriptor and special in that we exclude multipolar effects. We apply the theory to derive restrictions on constitutive equations for a mixture of two fluids and a mixture of a solid and a fluid.