Diffusion in different models of active Brownian motion

Abstract

Active Brownian particles (ABP) have served as phenomenological models ofself-propelled motion in biology. We study the effective diffusion coefficient of two one-dimensional ABP models(simplified depot model and Rayleigh-Helmholtz model) differing in theirnonlinear friction functions. Depending on the choice of the friction function the diffusion coefficientdoes or does not attain a minimum as a function of noise intensity. We furthermore discuss the case of an additional bias breaking the left-rightsymmetry of the system. We show that this bias induces a drift and that it generally reduces thediffusion coefficient. For a finite range of values of the bias, both models can exhibit a maximum inthe diffusion coefficient vs. noise intensity. © EDP Sciences/Societè Italiana di Fisica/Springer-Verlag 2008.