Regular Article

The European Physical Journal E

, 35:95

Self-regulation in self-propelled nematic fluids

  • A. BaskaranAffiliated withMartin Fisher School of Physics, Brandeis University Email author 
  • , M. C. MarchettiAffiliated withPhysics Department and Syracuse Biomaterials Institute, Syracuse University

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Topical Collection
Active Matter

Abstract

We consider the hydrodynamic theory of an active fluid of self-propelled particles with nematic aligning interactions. This class of materials has polar symmetry at the microscopic level, but forms macrostates of nematic symmetry. We highlight three key features of the dynamics. First, as in polar active fluids, the control parameter for the order-disorder transition, namely the density, is dynamically convected by the order parameter via active currents. The resulting dynamical self-regulation of the order parameter is a generic property of active fluids and destabilizes the uniform nematic state near the mean-field transition. Secondly, curvature-driven currents render the system unstable deep in the nematic state, as found previously. Finally, and unique to self-propelled nematics, nematic order induces local polar order that in turn leads to the growth of density fluctuations. We propose this as a possible mechanism for the smectic order of polar clusters seen in numerical simulations.
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Keywords

Regular Article - Topical issue: Active Matter