Active nematic multipoles: flow responses and the dynamics of defects and colloids

Houston, A. J.H. and Alexander, G. P. (2023) Active nematic multipoles: flow responses and the dynamics of defects and colloids. Frontiers in Physics, 11, 1110244. (doi: 10.3389/fphy.2023.1110244)

Abstract

We introduce a general description of localised distortions in active nematics using the framework of active nematic multipoles. We give the Stokesian flows for arbitrary multipoles in terms of differentiation of a fundamental flow response and describe them explicitly up to quadrupole order. We also present the response in terms of the net active force and torque associated to the multipole. This allows the identification of the dipolar and quadrupolar distortions that generate self-propulsion and self-rotation respectively and serves as a guide for the design of arbitrary flow responses. Our results can be applied to both defect loops in three-dimensional active nematics and to systems with colloidal inclusions. They reveal the geometry-dependence of the self-dynamics of defect loops and provide insights into how colloids might be designed to achieve propulsive or rotational dynamics, and more generally for the extraction of work from active nematics. Finally, we extend our analysis also to two dimensions and to systems with chiral active stresses.

• Item Type: Articles
• Additional Information: This work was supported by the UK EPSRC through Grant No. EP/N509796/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Houston, Dr Alexander
• Authors: Houston, A. J.H., and Alexander, G. P.
• College/School: College of Science and Engineering > School of Mathematics and Statistics > Mathematics
• Journal Name: Frontiers in Physics
• Publisher: Frontiers Media
• ISSN: 2296-424X
• ISSN (Online): 2296-424X
• Copyright Holders: Copyright © 2023 Houston and Alexander
• First Published: First published in Frontiers in Physics 11:1110244
• Publisher Policy: Reproduced under a Creative Commons licence