Transport of topological defects in a biphasic mixture of active and passive nematic fluids

Fuente: arXiv
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Autori principali: Chaithanya, KVS, Ardaševa, Aleksandra, Meacock, Oliver J., Durham, William M., Thampi, Sumesh P., Doostmohammadi, Amin
Natura: Preprint
Pubblicazione: 2024
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author Chaithanya, KVS
Ardaševa, Aleksandra
Meacock, Oliver J.
Durham, William M.
Thampi, Sumesh P.
Doostmohammadi, Amin
author_facet Chaithanya, KVS
Ardaševa, Aleksandra
Meacock, Oliver J.
Durham, William M.
Thampi, Sumesh P.
Doostmohammadi, Amin
contents Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate $+1/2$ defects and expel $-1/2$ defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As $+1/2$ and $-1/2$ defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact.
format Preprint
id arxiv_https___arxiv_org_abs_2405_00547
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Transport of topological defects in a biphasic mixture of active and passive nematic fluids
Chaithanya, KVS
Ardaševa, Aleksandra
Meacock, Oliver J.
Durham, William M.
Thampi, Sumesh P.
Doostmohammadi, Amin
Biological Physics
Soft Condensed Matter
Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate $+1/2$ defects and expel $-1/2$ defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As $+1/2$ and $-1/2$ defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact.
title Transport of topological defects in a biphasic mixture of active and passive nematic fluids
topic Biological Physics
Soft Condensed Matter
url https://arxiv.org/abs/2405.00547