Excitable Patterns in Active Nematics

TL;DR

This paper investigates how active nematic systems exhibit complex spatiotemporal behaviors, including oscillations and chaos, due to the interplay of nematic order, activity, and flow in a two-dimensional setting.

Contribution

It introduces a model showing how non-uniform nematic order and activity lead to oscillatory and chaotic dynamics in active nematics.

Findings

Spatially modulated relaxation oscillations observed

System exhibits bursts of activity with elastic distortions

High activity leads to chaotic behavior

Abstract

We analyze a model of mutually-propelled filaments suspended in a two-dimensional solvent. The system undergoes a mean-field isotropic-nematic transition for large enough filament concentrations and the nematic order parameter is allowed to vary in space and time. We show that the interplay between non-uniform nematic order, activity and flow results in spatially modulated relaxation oscillations, similar to those seen in excitable media. In this regime the dynamics consists of nearly stationary periods separated by "bursts" of activity in which the system is elastically distorted and solvent is pumped throughout. At even higher activity the dynamics becomes chaotic.