Pressure and flow of exponentially self-correlated active particles.

Abstract

Microscopic swimming particles, which dissipate energy to execute persistent directed motion, are a classic example of a nonequilibrium system. We investigate the noninteracting Ornstein-Uhlenbeck Particle (OUP), which is propelled through a viscous medium by a force which is correlated over a finite time. We obtain an exact expression for the steady-state phase-space density of a single OUP confined by a quadratic potential, and use the result to explore more complex geometries, both through analytical approximations and numerical simulations. In a "Casimir"-style setup involving two narrowly spaced walls, we describe a particle-trapping phenomenon, which leads to a repulsive effective interaction between the walls, while in a two-dimensional annulus geometry, we observe net stresses which resemble the Laplace pressure.