2008/05/24 by Patrick T. Underhill, Juan P. Hernández-Ortiz, Michael D. Graham · 1 citation
Physics and Astronomy · #cond-mat.soft
paper · pdf · doi:10.1103/physrevlett.100.248101
published as Phys. Rev. Lett. 100, 248101 (2008) · 10 pages, 3 figures, to be published in Phys. Rev. Lett
arxiv created 2008/05/24 · arxiv updated 2009/12/01
Populations of swimming microorganisms produce fluid motions that lead to dramatically enhanced diffusion of tracer particles. Using simulations of suspensions of swimming particles in a periodic domain, we capture this effect and show that it depends qualitatively on the mode of swimming: swimmers ``pushed'' from behind by their flagella show greater enhancement than swimmers that are ``pulled'' from the front. The difference is manifested by an increase, that only occurs for pushers, of the diffusivity of passive tracers and the velocity correlation length with the size of the periodic domain. A physical argument supported by a mean field theory sheds light on the origin of these effects.