Spatio-temporal structures in sheared polymer systems

TL;DR

This paper explores complex spatio-temporal behaviors in sheared polymer systems using a Ginzburg-Landau model, revealing chaotic fluctuations, heterogeneity, and shear-band dynamics under different conditions.

Contribution

It introduces a detailed two-dimensional model to analyze nonlinear and chaotic behaviors in sheared polymer solutions and micellar systems, highlighting new insights into their spatio-temporal structures.

Findings

Crossover from linear to nonlinear regimes with increasing shear rate.

Chaotic behavior with large-amplitude fluctuations in the nonlinear regime.

Large temporal fluctuations and disturbances in shear-band structures.

Abstract

We investigate spatio-temporal structures in sheared polymer systems by solving a time-dependent Ginzburg-Landau model in two dimensions. (i) In polymer solutions above the coexistence curve, crossover from linear to nonlinear regimes occurs with increasing the shear rate. In the nonlinear regime the solution behaves chaotically with large-amplitude composition fluctuations. A characteristic heterogeneity length is calculated in the nonlinear regime. (ii) We also study dynamics of shear-band structures in wormlike micellar solutions under the condition of fixed stress. The average shear rate exhibits large temporal fluctuations with occurrence of large disturbances in the spatial structures.