Verification of mesoscopic models of viscoelastic fluids with a non-monotonic flow curve

Abstract

The non-monotonic flow curve of a 1 wt.% polyacrylonitrile solution in dimethyl sulfoxide is described by two mesoscopic models: the modified Vinogradov-Pokrovsky model and the model proposed by Remmelgas, Harrison and Leal. To obtain an adequate description of the experimental curve, we have selected suitable internal parameters for these models. Analytical solutions for the Couette-Poiseuille flow problems are determined in parametric form, which allows us to plot the distribution of stress components and anisotropy tensor as well as the velocity profiles containing closed loops and weak tangential discontinuities. It is shown that both models predict a similar qualitative picture of structure evolution, but exhibit a significant discrepancy in the quantitative description of the magnitude of molecular chain stretching.