Coexistence of active and hydrodynamic turbulence in two dimensional active nematics

TL;DR

This paper demonstrates that in two-dimensional active nematics, active forcing can induce hydrodynamic turbulence, leading to a coexistence of active and inertial turbulence, especially in highly active, extensile flow-aligning systems.

Contribution

It reveals the coexistence of active and hydrodynamic turbulence in 2D active nematics driven solely by activity, a phenomenon not previously characterized.

Findings

Active forcing triggers hydrodynamic turbulence in 2D active nematics.

Coexistence of active and inertial turbulence observed.

Inverse energy cascade promoted by extensile nematics with high flow-aligning parameter.

Abstract

In active nematic liquid crystals activity is able to drive chaotic spatiotemporal flows referred to as active turbulence. Active turbulence has been characterized through theoretical and experimental work as a low Reynolds number phenomenon. We show that, in two-dimensions, the active forcing alone is able to trigger hydrodynamic turbulence leading to the coexistence of active and inertial turbulence. This type of flows develops for sufficiently active and extensile flow-aligning nematics. We observe that the combined effect of an extensile nematic and large values of the flow-aligning parameter leads to a broadening of the elastic energy spectrum that promotes a growth of kinetic energy able to trigger an inverse energy cascade.