Tethered flexible polymer under oscillatory linear flow

TL;DR

This study uses numerical simulations to explore how a tethered flexible polymer behaves under oscillatory flow, revealing complex stretching, recoiling, and flipping dynamics influenced by flow conditions and polymer stiffness.

Contribution

It provides new insights into the non-equilibrium behavior of tethered flexible polymers under oscillatory flow, including detailed dynamical and conformational analysis.

Findings

Polymer stretches and recoils in response to flow oscillations.

Recoil can occur without flipping at low strains.

Center-of-mass motion exhibits frequency doubling.

Abstract

The non-equilibrium structural and dynamical properties of a flexible polymer tethered to a reflecting wall and subject to oscillatory linear flow are studied by numerical simulations. Polymer is confined in two dimensions and is modeled as a bead-spring chain immersed in a fluid described by the Brownian multiparticle collision dynamics. At high strain, the polymer is stretched along the flow direction following the applied flow, then recoils at flow inversion before flipping and elongate again. When strain is reduced, it may happen that the chain recoils without flipping when the applied shear changes sign. Conformations are analyzed and compared to stiff polymers revealing more compact patterns at low strains and less stretched configurations at high strain. The dynamics is investigated by looking at the center-of-mass motion which shows a frequency doubling along the direction normal to the external flow. The center-of-mass correlation function is characterized by smaller amplitudes when reducing bending rigidity.