Abstract In this paper we compare three frameworks for modeling flows of complex fluids: (i) local conservations of mass, momentum and energy, (ii) GENERIC, and (iii) Onsager principle. The first is based on the mass, momentum, and energy conservation implied by mechanics, the second on the observed approach (in the state space) of externally unforced fluids to thermodynamic equilibrium states, and the third on the approach (in the space of vector fields) of externally driven fluids to dynamics involving less details. The comparison is illustrated on isothermal polymeric fluids.
Miroslav Grmela (Sat,) studied this question.