Pathological Rheology of Non-Stretching Entangled Polymers: Finite-Time Blow-Up Predictions

The non-stretching approximation of polymer rheology simplifies a constitutive equation but fundamentally changes its behavior in fast flows, and the circumstances under which fast flows emerge cannot always be predicted a-priori. In this paper, we consider two simple flows for which shear rates are bounded in the original RP model but diverge to infinity in finite time for the non-stretching RP model. The disparity between the full and non-stretching models can be resolved by extending the non-stretching approximation to second order in accuracy.