Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow

A body immersed in a nematic liquid crystal disturbs the fluid's preferred molecular configuration and increases its stored elastic energy. In an active nematic, the fluid components also generate a stress in the bulk fluid. By introducing either an immersed body or boundary, a large scale flow...

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Main Authors: Thomas G. J. Chandler, Saverio E. Spagnolie
Format: Article
Language:English
Published: American Physical Society 2025-06-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/x8y2-tw4c
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author Thomas G. J. Chandler
Saverio E. Spagnolie
author_facet Thomas G. J. Chandler
Saverio E. Spagnolie
author_sort Thomas G. J. Chandler
collection DOAJ
description A body immersed in a nematic liquid crystal disturbs the fluid's preferred molecular configuration and increases its stored elastic energy. In an active nematic, the fluid components also generate a stress in the bulk fluid. By introducing either an immersed body or boundary, a large scale flow can be triggered due to anchoring boundary conditions alone—a global pressure built by active stresses at equilibrium is instantly released everywhere. The fluid then imposes viscous, elastic, and active stresses on such surfaces which, if compliant, may result in a surface deformation. We study the deformations and stresses of a linearly elastic body placed in an active nematic in two dimensions. Using complex variable techniques, exact expressions for the fluid flow, director field, surface tractions, and body deformation are derived. Qualitative differences between elastic and active stress-driven deformations are identified, depending on an active Ericksen number, anchoring conditions, and body material properties, thereby suggesting a new method for measuring mechanical stresses in active anisotropic environments. Flow profiles, external confinement, and anchoring-induced stirring are also addressed.
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spelling doaj-art-fd1d9d13a45a43e4bcc83bf67b2efe3c2025-08-20T02:39:37ZengAmerican Physical SocietyPhysical Review Research2643-15642025-06-017202326310.1103/x8y2-tw4cActive nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flowThomas G. J. ChandlerSaverio E. SpagnolieA body immersed in a nematic liquid crystal disturbs the fluid's preferred molecular configuration and increases its stored elastic energy. In an active nematic, the fluid components also generate a stress in the bulk fluid. By introducing either an immersed body or boundary, a large scale flow can be triggered due to anchoring boundary conditions alone—a global pressure built by active stresses at equilibrium is instantly released everywhere. The fluid then imposes viscous, elastic, and active stresses on such surfaces which, if compliant, may result in a surface deformation. We study the deformations and stresses of a linearly elastic body placed in an active nematic in two dimensions. Using complex variable techniques, exact expressions for the fluid flow, director field, surface tractions, and body deformation are derived. Qualitative differences between elastic and active stress-driven deformations are identified, depending on an active Ericksen number, anchoring conditions, and body material properties, thereby suggesting a new method for measuring mechanical stresses in active anisotropic environments. Flow profiles, external confinement, and anchoring-induced stirring are also addressed.http://doi.org/10.1103/x8y2-tw4c
spellingShingle Thomas G. J. Chandler
Saverio E. Spagnolie
Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow
Physical Review Research
title Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow
title_full Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow
title_fullStr Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow
title_full_unstemmed Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow
title_short Active nematic response to a deformable body or boundary: Elastic deformations and anchoring-induced flow
title_sort active nematic response to a deformable body or boundary elastic deformations and anchoring induced flow
url http://doi.org/10.1103/x8y2-tw4c
work_keys_str_mv AT thomasgjchandler activenematicresponsetoadeformablebodyorboundaryelasticdeformationsandanchoringinducedflow
AT saverioespagnolie activenematicresponsetoadeformablebodyorboundaryelasticdeformationsandanchoringinducedflow