Sparkling bubbles in chiral active fluids

TL;DR

This paper investigates an inertial chiral active fluid with odd interactions, revealing inhomogeneous phases of rotating bubbles that exhibit spontaneous sparkling behavior due to nonlinear collective dynamics.

Contribution

It introduces a coarse-grained hydrodynamic theory predicting bubble formation and instability in chiral active fluids, highlighting novel non-linear collective phenomena.

Findings

Bubbles form at an optimal packing fraction in the chiral active fluid.

Bubbles can be dynamically unstable, breaking and reforming in steady state.

The phenomena are explained by a nonlinear hydrodynamic theory.

Abstract

We study an inertial chiral active fluid, formed by repulsive particles that transfer angular momentum through odd interactions, i.e. transverse forces. Chirality induces an inhomogeneous phase, consisting of rotating bubbles, whose formation is favored at an optimal packing fraction. In this regime, we discover that bubbles may be dynamically unstable, breaking up and reforming in the steady state, thereby showing a spontaneous sparkling-like behavior reminiscent of supersaturated liquids. Bubbles and sparkling bubbles are predicted by a coarse-grained hydrodynamic theory, revealing the intrinsic non-linearity of these collective phenomena, and call for experimental verifications in granular spinners or spinning colloids.