  Mechanically driven glassy systems and complex fluids exhibit a wealth of
rheological behaviors that call for theoretical understanding and predictive
modeling. A distinct feature of these nonequilibrium systems is their
dynamically evolving state of structural disorder, which determines their
rheological responses. Here we highlight a recently developed nonequilibrium
thermodynamic framework in which the structural state is characterized by an
evolving effective disorder temperature that may differ from the ordinary
thermal temperature. The specific properties of each physical system of
interest are described by a small set of coarse-grained internal state
variables and their associated energies and entropies. The dynamics of the
internal variables, together with the flow of energy and entropy between the
different parts of the driven system, determine continuum-level rheological
constitutive laws. We conclude with brief descriptions of several successful
applications of this framework.
