Self-Propelled Rods near Surfaces

TL;DR

This study investigates the behavior of self-propelled nano- and micro-rods confined between parallel walls, revealing strong surface accumulation influenced by hydrodynamics and thermal fluctuations, supported by simulations and scaling laws.

Contribution

It introduces combined simulation and scaling analysis of self-propelled rods near surfaces, accounting for hydrodynamics and thermal effects, with validated scaling laws.

Findings

Self-propelled rods exhibit strong surface accumulation in confined geometries.

Hydrodynamic interactions significantly influence rod behavior.

Scaling laws accurately predict dependence on wall distance, rod length, and propulsion force.

Abstract

We study the behavior of self-propelled nano- and micro-rods in three dimensions, confined between two parallel walls, by simulations and scaling arguments. Our simulations include thermal fluctuations and hydrodynamic interactions, which are both relevant for the dynamical behavior at nano- to micrometer length scales. In order to investigate the importance hydrodynamic interactions, we also perform Brownian-dynamics-like simulations. In both cases, we find that self-propelled rods display a strong surface excess in confined geometries. An analogy with semi-flexible polymers is employed to derive scaling laws for the dependence on the wall distance, the rod length, and the propulsive force. The simulation data confirm the scaling predictions.