Anomalous mobility of a driven active particle in a steady laminar flow

TL;DR

This paper investigates how active particles with persistent motion behave in steady laminar flows, revealing complex mobility phenomena like negative differential and absolute mobility through extensive simulations.

Contribution

It introduces a model for active particles with colored noise and demonstrates the robustness of anomalous mobility effects in nonlinear flow regimes.

Findings

Active particles exhibit negative differential mobility.

Active particles show absolute negative mobility.

Complex force-velocity relations emerge for finite persistence times.

Abstract

We study, via extensive numerical simulations, the force-velocity curve of an active particle advected by a steady laminar flow, in the nonlinear response regime. Our model for an active particle relies on a colored noise term that mimics its persistent motion over a time scale $\tau_A$. We find that the active particle dynamics shows non-trivial effects, such as negative differential and absolute mobility (NDM and ANM, respectively). We explore the space of the model parameters and compare the observed behaviors with those obtained for a passive particle ($\tau_A=0$) advected by the same laminar flow. Our results show that the phenomena of NDM and ANM are quite robust with respect to the details of the considered noise: in particular for finite $\tau_A$ a more complex force-velocity relation can be observed.