Spontaneous flows in active smectics with dislocations

TL;DR

This paper develops a hydrodynamic theory for active smectic A materials in 2D, revealing how dislocation dynamics induce flow transitions, including a first-order transition to turbulence, distinct from known shear instabilities.

Contribution

It introduces a comprehensive hydrodynamic framework incorporating dislocation creation, annihilation, and motility in active smectics, highlighting new flow transition mechanisms.

Findings

Dislocation motility can trigger flow transitions.

Flow transitions include a first-order jump to turbulence.

Analytical criteria for flow onset are derived.

Abstract

We construct a hydrodynamic theory of active smectics A in two-dimensional space, including the creation/annihilation and motility of dislocations with Burgers' number $\pm1$. We derive analytical criteria on the set of parameters that lead to flows. We show that the motility of dislocations can lead to flow transitions with distinct features from the previously reported active Helfrich--Hurault shear instability with, notably, a first-order transition in the velocity from quiescence to turbulence.