Johnson-Segalman model with a diffusion term in cylindrical Couette flow

We study the Johnson-Segalman (JS) model as a paradigm for some complex flu ids which are observed to phase separate, or "shear band" in flow. We analy ze the behavior of this model in cylindrical Couette flow and demonstrate t he history dependence inherent in the local JS model. We add a simple gradi ent term to the stress dynamics and demonstrate how this term breaks the de generacy of the local model and prescribes a much smaller (discrete, rather than continuous) set of banded steady state solutions. We investigate some of the effects of the curvature of Couette flow on the observable steady s tate behavior and kinetics, and discuss some of the implication for metasta bility. (C) 2000 The Society of Rheology. [S0148-6055(00)00802-6].