Active Model H: Scalar Active Matter in a Momentum-Conserving Fluid

2015/04/28 by Adriano Tiribocchi, Raphael Wittkowski, Davide Marenduzzo +1 · 1 citation
Physics and Astronomy · #cond-mat.soft #cond-mat.stat-mech #physics.bio-ph #physics.flu-dyn

paper · pdf · doi:10.1103/physrevlett.115.188302

published as Phys. Rev. Lett. 115, 188302 (2015) · 7 pages, 4 figures

arxiv created 2015/04/28 · arxiv updated 2015/11/18

Abstract

We present a continuum theory of self-propelled particles, without alignment interactions, in a momentum-conserving solvent. To address phase separation we introduce a scalar concentration field ϕ with advective-diffusive dynamics. Activity creates a contribution Σ_ij=-ζ((∂_iϕ)(∂_jϕ)-(∇ϕ)²δ_ij/d) to the deviatoric stress, where ζ is odd under time reversal and d is the number of spatial dimensions; this causes an effective interfacial tension contribution that is negative for contractile swimmers. We predict that domain growth then ceases at a length scale where diffusive coarsening is balanced by active stretching of interfaces, and confirm this numerically. Thus the interplay of activity and hydrodynamics is highly nontrivial, even without alignment interactions.

Cited by

• Active Cahn-Hilliard theory for nonequilibrium phase separation: quantitative macroscopic predictions and a microscopic derivation