Eur. Phys. J. Special Topics 224, 1275-1286 (2015)
https://doi.org/10.1140/epjst/e2015-02459-x

Regular Article

Motion of two micro-wedges in a turbulent bacterial bath

¹ Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
² Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA

Received: 26 February 2015
Revised: 18 May 2015
Published online: 24 July 2015

Abstract

The motion of a pair of micro-wedges (“carriers”) in a turbulent bacterial bath is explored using computer simulations with explicit modeling of the bacteria and experiments. The orientation of the two micro-wedges is fixed by an external magnetic field but the translational coordinates can move freely as induced by the bacterial bath. As a result, two carriers of same orientation move such that their mutual distance decreases, while they drift apart for an anti-parallel orientation. Eventually the two carriers stack on each other with no intervening bacteria exhibiting a stable dynamical mode where the two micro-wedges follow each other with the same velocity. These findings are in qualitative agreement with experiment on two micro-wedges in a bacterial bath. Our results provide insight into understanding self-assembly of many micro-wedges in an active bath.