Transport of active ellipsoidal particles in ratchet potentials

TL;DR

This study numerically explores how active ellipsoidal particles move in asymmetric potentials, revealing shape-dependent rectification effects, optimal propulsion parameters, and potential for particle separation based on shape or propulsion speed.

Contribution

It introduces a detailed numerical analysis of active ellipsoidal particles in ratchet potentials, highlighting shape effects and optimal conditions for directed transport.

Findings

Perfect sphere particles facilitate rectification.

Needlelike particles hinder directed transport.

Optimal parameters maximize average velocity.

Abstract

Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, while for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities).