On flows of an incompressible fluid with a discontinuous power-law-like rheology

We establish the mathematical theory for steady and unsteady flows of fluids with discontinuous constitutive equations. We consider a model for a fluid that at certain critical values of the shear rate exhibits jumps in the generalized viscosity of a power-law type. Using tools such as Young measures, maximal monotone operators, compact embeddings and energy equality, we prove the existence of a solution to the problem under consideration. In this approach, Galerkin approximations converge strongly to the solution of the original problem. (C) 2007 Elsevier Ltd. All rights reserved.