Beating of grafted chains induced by active Brownian particles

TL;DR

This study explores how active Brownian particles induce beating-like oscillations in grafted chains, revealing a relationship between propelling force, chain length, and oscillation dynamics through simulations and theory.

Contribution

It introduces a theoretical framework explaining the beating phenomenon of grafted chains caused by active particles, supported by simulation data.

Findings

Increased propelling force enhances ABP accumulation and chain oscillations.

Chain length affects oscillation period, increasing with length.

Theoretical predictions match simulation results for oscillation behavior.

Abstract

We study the interplay between active Brownian particles (ABPs) and a hairy surface in two dimensional geometry. We find that the increase of propelling force leads to and enhances inhomogeneous accumulation of ABPs inside the brush region. Oscillation of chain bundles (beating like cilia) is found in company with the formation and disassembly of dynamic cluster of ABPs at large propelling forces. Meanwhile chains are stretched and pushed down due to the effective shear force by ABPs. The decrease of the average brush thickness with propelling force reflects the growth of the beating amplitude of chain bundles. Furthermore, the beating phenomenon is investigated in a simple single-chain system. We find that the chain swings regularly with a major oscillatory period, which increases with chain length and decreases with the increase of propelling force. We build a theory to describe the phenomenon and the predictions on the relationship between period and amplitude for various chain lengths and propelling forces agree very well with simulation data.