Two-dimensional active polar semiflexible polymer under shear flow

TL;DR

This study uses numerical simulations to explore how active polar semiflexible polymers behave under shear flow, revealing conformational changes, tumbling dynamics, and activity's impact on rheology, including negative viscosity.

Contribution

It provides new insights into the nonequilibrium behavior of active semiflexible polymers under shear, highlighting activity's role in conformational and rheological properties.

Findings

Shear flow causes polymers to align and tumble.

A shear-rate dependent scaling exponent is observed.

Activity can induce negative viscosity at low shear rates.

Abstract

The nonequilibrium structural and dynamical properties of semiflexible active polar polymers subject to linear flow are studied by numerical simulations. Filaments are confined in two dimensions and immersed in a fluid described by the Brownian Multiparticle Collision Dynamics approach. The applied shear flow causes conformational changes of a polymer, aligns it along the flow direction, and induces a tumbling motion at large flow rates. In an intermediate, activity-dependent shear-rate regime, a characteristic scaling exponent for the mean-square end-to-end distance along the gradient direction is observed. This exponent appears to be determined by the semiflexibility of the polymer. The tumbling dynamics exhibits a characteristic time, with a stronger dependence on the Weissenberg number than that of flexible active or passive polymers. Activity strongly impacts the rheological properties of the semiflexible polymers, and even implies a negative viscosity for weak flows. At very large values of the shear rate, shear dominates over activity and passive-polymer behavior is assumed.