2012/06/30 by M. E. Cates, J. Tailleur · 1 citation
Physics and Astronomy · #cond-mat.stat-mech
paper · pdf · doi:10.1209/0295-5075/101/20010
published as EPL 101, 20010 (2013)
arxiv created 2012/11/16 · arxiv updated 2013/02/27
Active Brownian particles (ABPs, such as self-phoretic colloids) swim at fixed speed v along a body-axis \bf u that rotates by slow angular diffusion. Run-and-tumble particles (RTPs, such as motile bacteria) swim with constant \u until a random tumble event suddenly decorrelates the orientation. We show that when the motility parameters depend on density ρ but not on \bf u, the coarse-grained fluctuating hydrodynamics of interacting ABPs and RTPs can be mapped onto each other and are thus strictly equivalent. In both cases, a steeply enough decreasing v(ρ) causes phase separation in dimensions d=2,3, even when no attractive forces act between the particles. This points to a generic role for motility-induced phase separation in active matter. However, we show that the ABP/RTP equivalence does not automatically extend to the more general case of \u-dependent motilities.