Tumbling motion of a single chain in shear flow: a crossover from Brownian to non-Brownian behavior

TL;DR

This paper investigates the tumbling dynamics of a single chain in shear flow, revealing a crossover from Brownian to non-Brownian behavior characterized by a change in the Peclet number dependence, supported by numerical and theoretical analysis.

Contribution

It provides a detailed numerical study of chain tumbling in shear flow and identifies a crossover in behavior driven by thermal fluctuations and shear forces.

Findings

Tumbling frequency depends on Peclet number with a power law.

The exponent shifts from 2/3 to 1 at a critical Peclet number.

Numerical results align with Jeffery's theoretical predictions.

Abstract

We present numerical results for the dynamics of a single chain in steady shear flow. The chain is represented by a bead-spring model, and the smoothed profile method is used to accurately account for the effects of thermal fluctuations and hydrodynamic interactions acting on beads due to host fluids. It is observed that the chain undergoes tumbling motions and that its dimensionless frequency F depends only on the Peclet number Pe with a power law. The exponent of Pe clearly changes from 2/3 to 1 around the critical Peclet number, indicating that the crossover reflects the competition of thermal fluctuation and shear flow. The presented numerical results agree well with our theoretical analysis based on Jeffery's work.