Microscopic theory for the phase separation of self-propelled repulsive disks

By Julian Bialk'e, Hartmut Löwen, Thomas Speck. 2013

266 citations recorded by the source corpus.

Motivated by recent experiments on colloidal suspensions, we study analytically and numerically a microscopic model for self-propelled particles lacking alignment interactions. In this model, even for purely repulsive interactions, a dynamical instability leading to phase separation has been reported. Starting from the many-body Smoluchowski equation, we develop a mean-field description based on a novel closure scheme and derive the effective hydrodynamic equations. We demonstrate that the microscopic origin of the instability is a force imbalance due to an anisotropic pair distribution leading to self-trapping. The phase diagram can be understood in terms of two quantities: a minimal drive and the force imbalance. At sufficiently high propulsion speeds there is a reentrance into the disordered fluid.

Subfields: Condensed Matter Physics, Materials Chemistry, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/8c110b5b9b9b26f6868785a0b29c74b4d9e1bf5f

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Citations in the corpus

The statistical physics of active matter: From self-catalytic colloids to living cells (2017, background): “In such a limit, the effect of the interactions is to renormalize the self-propulsion speed as v0 → v(ρ) = v0(1 − λρ), where λ can be expressed in terms of the pair correlation function [45,46].”
Minimal model of active colloids highlights the role of mechanical interactions in controlling the emergent behavior of active matter (2015, methodology): “This linear decay of v(ρ) with ρ has been seen in simulations [22] and justified by relating the linear decay rate to the pair correlation function [40] and by estimating it via a ki-”
Tuned, driven, and active soft matter (2015, background): “Here, the blocking mechanism was analyzed in more detail [411] and also investigated experimentally [361].”
Nonequilibrium equation of state in suspensions of active colloids (2014, unknown): “The idea that self-propulsion provides a mechanism for inducing effective attractive forces in purely repulsive systems of active particles has recently emerged [14, 16, 25, 37].”
Physics of microswimmers—single particle motion and collective behavior: a review (2014, methodology): “…have been performed to achieve a theoretical understanding of the generic principles underneath the propulsion-induced phase transitions (Bialké et al., 2013; Cates and Tailleur, 2013; Fily et al., 2014b; Fily and Marchetti, 2012; Stenhammar et al., 2014, 2013; Tailleur and Cates,…”
Pressure is not a state function for generic active fluids (2014, background): “, Sedimentation, trapping, and rectification of dilute bacteria, EPL 86, 60002 (2009) [33] Bialké, J.”
Active Particles in Complex and Crowded Environments (2016, methodology): “analysis start from the Smoluchowski equation (Bialké et al., 2013).”