Escape kinetics of self-propelled particles from a circular cavity

TL;DR

This study numerically explores how active particles escape from a circular cavity, revealing different mechanisms influenced by propulsion and damping, and identifying conditions for optimal escape rates.

Contribution

It provides new insights into escape dynamics of active particles in confined geometries, highlighting the role of persistence length and damping in escape mechanisms.

Findings

Escape mechanisms depend on propulsion and damping parameters.

Optimal persistence length maximizes escape rate.

Escape dynamics are largely unaffected by window size and arrangement.

Abstract

We numerically investigate the mean exit time of an inertial active Brownian particle from a circular cavity with single or multiple exit windows. Our simulation results witness distinct escape mechanisms depending upon the relative amplitudes of the thermal length and self-propulsion length compared to the cavity and pore sizes. For exceedingly large self-propulsion lengths, overdamped active particles diffuse on the cavity surface, and rotational dynamics solely governs the exit process. On the other hand, the escape kinetics of a very weakly damped active particle is largely dictated by bouncing effects on the cavity walls irrespective of the amplitude of self-propulsion persistence lengths. We show that the exit rate can be maximized for an optimal self-propulsion persistence length, which depends on the damping strength, self-propulsion velocity, and cavity size. However, the optimal persistence length is insensitive to the opening windows' size, number, and arrangement. Numerical results have been interpreted analytically based on qualitative arguments. The present analysis aims to understand the transport controlling mechanism of active matter in confined structures.