Inertial active Ornstein-Uhlenbeck particle in a non-linear velocity dependent friction

TL;DR

This paper investigates the dynamics of an active Ornstein-Uhlenbeck particle with nonlinear velocity-dependent friction, revealing activity-induced bistability and confinement effects through analytical and numerical methods.

Contribution

It provides an exact analytical and numerical analysis of the particle's behavior with nonlinear friction, highlighting activity-induced bistability and confinement mechanisms.

Findings

Particles accumulate near boundaries with increased activity duration.

In the overdamped regime, particles tend to be trapped at the mean position.

Velocity distribution in free particles mimics confining effects, decreasing with effective temperature.

Abstract

We explore the self-propulsion of an active Ornstein-Uhlenbeck particle with a non-linear velocity dependent friction. Using analytical approach and numerical simulation, we have exactly investigated the dynamical behaviour of the particle in terms of particle trajectory, position and velocity distribution functions in both underdamped as well as overdamped regimes of the dynamics. Analyzing the distribution functions, we observe that for a confined harmonic particle, with an increase in duration of self-propulsion, the inertial particle prefers to accumulate near the boundary of the confinement rather than the mean position, reflecting an activity induced bistability in the presence of nonlinear friction. On the other hand, in the overdamped or highly viscous regime, where the inertial influence is negligible small, the sharp peak structure in the distribution across the mean position of the well reveals as usual trapping of the particle with increase in the persistent duration of activity. Moreover, for a free particle, using perturbation method, we have analytically computed the velocity distribution function in the vanishing limit of noise. The distribution interestingly shows the similar attributes as in case of a harmonic well, thus providing an additional effective confining mechanism that can be explained as a decreasing function of effective temperature. In this limit, the analytically computed distribution agrees well with the simulation results.