Self-propelled particles with fluctuating speed and direction of motion

TL;DR

This paper investigates active motion in two dimensions with independent fluctuations in speed and direction, revealing complex transient behaviors, additive diffusion corrections, and characteristic time-scale effects in velocity autocorrelation.

Contribution

It introduces a model for active particles with uncorrelated speed and direction fluctuations, analyzing transient regimes and diffusion properties.

Findings

Identification of complex transient motion regimes

Additive corrections to the diffusion coefficient

Velocity autocorrelation as a sum of exponential forms

Abstract

We study general aspects of active motion with fluctuations in the speed and the direction of motion in two dimensions. We consider the case in which fluctuations in the speed are not correlated to fluctuations in the direction of motion, and assume that both processes can be described by independent characteristic time-scales. We show the occurrence of a complex transient that can exhibit a series of alternating regimes of motion, for two different angular dynamics which correspond to persistent and directed random walks. We also show additive corrections to the diffusion coefficient. The characteristic time-scales are also exposed in the velocity autocorrelation, which is a sum of exponential forms.