Biphasic, Lyotropic, Active Nematics

TL;DR

This paper investigates the complex behaviors of active nematic fluids coexisting with isotropic fluids through simulations, revealing interface instabilities, defect dynamics, and phase separation driven by activity.

Contribution

It introduces a simulation framework for active lyotropic nematics, highlighting novel interface phenomena and defect behaviors not previously characterized.

Findings

Active nematic drops elongate and develop effective anchoring.

Interface becomes unstable and undulates due to activity.

Active stirring causes phase domains to elongate and break apart.

Abstract

We perform dynamical simulations of a two-dimensional active nematic fluid in coexistence with an isotropic fluid. Drops of active nematic become elongated, and an effective anchoring develops at the nematic-isotropic interface. The activity also causes an undulatory instability of the interface. This results in defects of positive topological charge being ejected into the nematic, leaving the interface with a diffuse negative charge. Quenching the active lyotropic fluid results in a steady state in which phase-separating domains are elongated and then torn apart by active stirring.