Turbulence-induced clustering in compressible active fluids

TL;DR

This paper investigates a new turbulent phase in compressible active polar fluids, where dense clusters form and dissolve dynamically due to self-advection and defect topology, with cluster size linked to vortex scale.

Contribution

It introduces a continuum model capturing turbulence-induced clustering in active fluids, integrating experimental features like non-monotonic speed-density relations.

Findings

Identification of a turbulence-driven clustering phase

Cluster size correlates with vortex scale

Model aligns with bacterial suspension observations

Abstract

We study a novel phase of active polar fluids, which is characterized by the continuous creation and destruction of dense clusters due to self-sustained turbulence. This state arises due to the interplay of the self-advection of the aligned swimmers and their defect topology. The typical cluster size is determined by the characteristic vortex size. Our results are obtained by investigating a continuum model of compressible polar active fluids, which incorporates typical experimental observations in bacterial suspensions by assuming a non-monotone dependence of speed on density.