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arXiv · 1503.08412

Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles

Thomas Speck·Andreas M. Menzel·Julian Bialké·Hartmut Löwen
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Abstract

Recently, we have derived an effective Cahn-Hilliard equation for the phase separation dynamics of active Brownian particles by performing a weakly non-linear analysis of the effective hydrodynamic equations for density and polarization [Phys. Rev. Lett. 112, 218304 (2014)]. Here we develop and explore this strategy in more detail and show explicitly how to get to such a large-scale, mean-field description starting from the microscopic dynamics. The effective free energy emerging from this approach has the form of a conventional Ginzburg-Landau function. On the coarsest scale, our results thus agree with the mapping of active phase separation onto that of passive fluids with attractive interactions through a global effective free energy (mobility-induced phase transition). Particular attention is paid to the square-gradient term necessary for the dynamics. We finally discuss results from numerical simulations corroborating the analytical results.

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BibTeXRIS

Thomas Speck, Andreas M. Menzel, Julian Bialké, Hartmut Löwen. 2015-03-29. Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles. https://doi.org/10.1063/1.4922324

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