14 - Active Particles

Summary

Active particles self-propel through some intrinsic mechanism. First, a simple one-dimensional model is introduced for which the density profile between confining walls and the pressure exerted on these walls can be calculated analytically. In three dimensions, run-and-tumble particles, active Brownian particles, and active Ornstein–Uhlenbeck particles constitute three classes of models that can be described by Langevin equations. The identification of entropy production in the steady state is shown to be ambiguous. The continuum limit of a thermodynamically consistent discrete model shows that Langevin descriptions contain some implicit coarse-graining which prevents the recovery of the full physical entropy production.