Casimir effect in active matter systems

D. Ray, C. Reichhardt, and C. J. Olson Reichhardt
Phys. Rev. E 90, 013019 – Published 23 July 2014

Abstract

We numerically examine run-and-tumble active matter particles in Casimir geometries composed of two finite parallel walls. We find that there is an attractive force between the two walls of a magnitude that increases with increasing run length. The attraction exhibits an unusual exponential dependence on the wall separation, and it arises due to a depletion of swimmers in the region between the walls by a combination of the motion of the particles along the walls and a geometric shadowing effect. This attraction is robust as long as the wall length is comparable to or smaller than the swimmer run length, and is only slightly reduced by the inclusion of steric interactions between swimmers. We also examine other geometries and find regimes in which there is a crossover from attraction to repulsion between the walls as a function of wall separation and wall length.

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  • Received 11 March 2014

DOI:https://doi.org/10.1103/PhysRevE.90.013019

©2014 American Physical Society

Authors & Affiliations

D. Ray1,2, C. Reichhardt1, and C. J. Olson Reichhardt1

  • 1Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  • 2Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA

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Issue

Vol. 90, Iss. 1 — July 2014

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