Exploitation of the Second Law: Coleman-Noll and Liu procedure in comparison

A comparison is made between two classical methods for the exploitation of the second lawof thermodynamics: the Coleman–Noll and the Liu procedure.On the example of a rigid heat conductor with general entropy flux, it is shown that the two procedures are equivalent. This equivalence is demonstrated in the case of a state space including the wanted fields, only, as well as in the case of gradients being relevant for constitutive equations, too.Also, the possible importance of an internal variable or an internal degree of freedom is considered.