Tethered Semiflexible Polymer under Large Amplitude Oscillatory Shear

TL;DR

This study uses simulations to explore how tethered semiflexible polymers respond to large amplitude oscillatory shear, revealing nonlinear behaviors such as polymer wrapping, shrinkage, and altered normal-mode correlations.

Contribution

It introduces a detailed simulation analysis of tethered semiflexible polymers under shear, highlighting nonlinear responses and mode asymmetries not previously characterized.

Findings

Polymer wraps around fixation points at high shear rates.

Shear induces a frequency doubling in normal-mode correlations.

Asymmetry observed between Cartesian components of correlation functions.

Abstract

The properties of a semiflexible polymer with fixed ends exposed to oscillatory shear flow are investigated by simulations. The two-dimensionally confined polymer is modeled as a linear bead-spring chain, and the interaction with the fluid is described by the Brownian multiparticle collision dynamics approach. For small shear rates, the tethering of the ends leads to a more-or-less linear oscillatory response. However, at high shear rates, we found a strongly nonlinear reaction, with a polymer (partially) wrapped around the fixation points. This leads to an overall shrinkage of the polymer. Dynamically, the location probability of the polymer center-of-mass position is largest on a spatial curve resembling a lima\c{c}on, although with an inhomogeneous distribution. We found shear-induced modifications of the normal-mode correlation functions, with a frequency doubling at high shear rates. Interestingly, an even-odd asymmetry for the Cartesian components of the correlation functions appears, with rather similar spectra for odd $x$- and even $y$-modes and vice versa. Overall, our simulations yielded an intriguing nonlinear behavior of tethered semiflexible polymers under oscillatory shear flow.