Active nematic flows on curved surfaces

TL;DR

This paper develops a hydrodynamic theory for active nematic gels on curved surfaces, revealing how curvature influences tissue flow patterns and transitions, with implications for understanding tissue biophysics.

Contribution

It introduces a novel hydrodynamic model for active nematic monolayers on curved surfaces, highlighting the impact of curvature on flow behavior and transitions.

Findings

Curvature induces thresholdless flows in active nematic monolayers.

Flow transition can switch from continuous to discontinuous due to curvature.

Surface properties control flow patterns from shear to vortex chains.

Abstract

Cell monolayers are a central model system to tissue biophysics. In vivo, epithelial tissues are curved on the scale of microns, and curvature's role in the onset of spontaneous tissue flows is still not well-understood. Here, we present a hydrodynamic theory for an apical-basal asymmetric active nematic gel on a curved strip. We show that surface curvature qualitatively changes monolayer motion compared to flat space: the resulting flows can be thresholdless, and the transition to motion may change from continuous to discontinuous. Surface curvature, friction and active tractions are all shown to control the flow pattern selected: from simple shear to vortex chains.