Semiflexible polymer conformation, distribution and migration in microcapillary flows

TL;DR

This study uses particle-based simulations to explore how semiflexible polymers behave, distribute, and migrate in microchannel flows, revealing complex dynamics influenced by bending rigidity and flow velocity.

Contribution

It provides new insights into the flow-induced conformations and migration patterns of semiflexible polymers in microchannels, highlighting the interplay of hydrodynamic lift and steric effects.

Findings

Polymer migration depends on bending rigidity and flow velocity.

Maximum monomer and center-of-mass distributions shift with flow speed.

Complex dynamical behavior arises from competing forces.

Abstract

The flow behavior of a semiflexible polymer in microchannels is studied using Multiparticle Collision Dynamics (MPC), a particle-based hydrodynamic simulation technique. Conformations, distributions, and radial cross-streamline migration are investigated for various bending rigidities, with persistence lengths Lp in the range 0.5 < Lp/Lr < 30. The flow behavior is governed by the competition between a hydrodynamic lift force and steric wall-repulsion, which lead to migration away from the wall, and a locally varying flow-induced orientation, which drives polymer away from the channel center and towards the wall. The different dependencies of these effects on the polymer bending rigidity and the flow velocity results in a complex dynamical behavior. However, a generic effect is the appearance of a maximum in the monomer and the center-of-mass distributions, which occurs in the channel center for small flow velocities, but moves off-center at higher velocities.