Thermodynamically consistent coarse-graining of polar active fluids

Scott Weady, David B. Stein, Michael J. Shelley

Research output: Contribution to journalArticlepeer-review


We introduce a closure model for coarse-grained kinetic theories of polar active fluids. Based on a quasiequilibrium approximation of the particle distribution function, the model closely captures important analytical properties of the kinetic theory, including its linear stability and the balance of conformational entropy production and dissipation. Nonlinear simulations show the model reproduces the qualitative behavior and nonequilibrium statistics of the kinetic theory, unlike commonly used closure models. We use the closure model to simulate highly turbulent suspensions in both two and three dimensions in which we observe complex multiscale dynamics, including large concentration fluctuations and a proliferation of polar and nematic defects.

Original languageEnglish (US)
Article number063301
JournalPhysical Review Fluids
Issue number6
StatePublished - Jun 2022

ASJC Scopus subject areas

  • Computational Mechanics
  • Modeling and Simulation
  • Fluid Flow and Transfer Processes


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