ABSTRACT
As is evident from Table 2.7, constitutive equations must be formulated for ρ, S, jA, and RA for an N-component system to be able to utilize the field equations to solve for the field variables p, v, and ωA. In this chapter, the general principles or axioms which govern the formulation of constitutive equations are introduced. These principles, which are the physical and mathematical requirements which must be satisfied by every constitutive equation, are used to show how constitutive equations can be formulated for ρ, S, jA, and RA for a special class of fluids, purely viscous fluids. Additionally, some aspects of constitutive relations for S and jA for viscoelastic fluids are considered. Note that for systems with a chemically reactive surface, a constitutive equation must also be supplied for rA; however, the general formulation of constitutive equations for surface properties is not covered here.
