Turbulence to order transitions in activity patterned active nematics

TL;DR

This study investigates how patterned activity influences phase transitions in active nematics, revealing mechanisms to induce ordered phases and turbulence through activity inhomogeneity.

Contribution

It demonstrates how activity patterning controls turbulence and vortex order in active nematics, revealing geometry-dependent phase transitions.

Findings

Transition from turbulence to ordered vortices with increased activity and stripe spacing

Vortex order is highly sensitive to patterning geometry

Transitions are driven by interplay between active length scale and activity density

Abstract

We numerically study two-dimensional active nematics with periodic activity patterning. For stripes of activity, we observe a transition from two-dimensional to one-dimensional active turbulence as the maximum active force and distance between activity stripes increases, followed by a transition to stable vortices ordered antiferromagnetically along the stripes and ferromagnetically transverse to the stripes. By comparing to a triangular lattice of activity circles, we find that transitions to two-dimensional active turbulence emerge from interplays between the active length scale and activity density, independent of the patterning geometry. The vortex ordering, on the other hand, is highly sensitive to patterning geometry, which we show by comparing the activity stripes to columns of activity circles, where the vortex ordering is lost. Our results provide a mechanism for inducing non-equilibrium phase transitions in active nematics using activity inhomogeneity, which can be further exploited to create activity patterned ordered phases.