Active turbulence and spontaneous phase separation in inhomogeneous extensile active gels

Renato Assante, Dom Corbett*, Davide Marenduzzo*, Alexander Morozov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We report numerical results for the hydrodynamics of inhomogeneous lyotropic and extensile active nematic gels. By simulating the coupled Cahn-Hilliard, Navier-Stokes, and Beris-Edwards equation for the evolution of the composition, flow and orientational order of an active nematic, we ask whether composition variations are important to determine its emergent physics. As in active gels of uniform composition, we find that increasing either activity or nematic tendency (e.g., overall active matter concentration) triggers a transition between an isotropic passive phase and an active nematic one. We show that composition inhomogeneities are important in the latter phase, where we find three types of possible dynamical regimes. First, we observe regular patterns with defects and vortices: these exist close to the passive-active transition. Second, for larger activity, or deeper in the nematic phase, we find active turbulence, as in active gels of uniform composition, but with exceedingly large composition variation. In the third regime, which is uniquely associated with inhomogeneity and occurs for large nematic tendency and low activity, we observe spontaneous microphase separation into active and passive domains. The microphase separated regime is notable in view of the absence of an explicit demixing term in the underlying free energy which we use, and we provide a theoretical analysis based on the common tangent construction which explains its existence. We hope this regime can be probed experimentally in the future.
Original languageEnglish
Pages (from-to)189-198
Number of pages10
JournalSoft Matter
Volume19
Issue number2
Early online date1 Dec 2022
DOIs
Publication statusPublished - 4 Jan 2023

Keywords / Materials (for Non-textual outputs)

  • cond-mat.soft
  • physics.flu-dyn

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