Heterogeneity-Induced Oscillations in Active Nematics

Fuente: arXiv
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Autori principali: Houston, Alexander J. H., Grinfeld, Michael, McKay, Geoff, Mottram, Nigel J.
Natura: Preprint
Pubblicazione: 2025
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author Houston, Alexander J. H.
Grinfeld, Michael
McKay, Geoff
Mottram, Nigel J.
author_facet Houston, Alexander J. H.
Grinfeld, Michael
McKay, Geoff
Mottram, Nigel J.
contents One of the defining features of active nematics is that above a critical activity the quiescent state becomes unstable to a distorted, flowing one. We show that spatial variations in activity can fundamentally change the nature of this instability, affecting the symmetry of the unstable mode and producing spontaneous oscillations. We analytically identify a dynamical system for the evolution of the odd and even director modes, with the leading-order coefficients dependent on the activity profile, allowing a quantitative connection between the spatially-heterogeneous activity and dynamics, which we verify numerically. In the context of constant gradients in activity, we determine a phase diagram for the active response and highlight how variation of the activity profile causes the oscillations to vary from almost harmonic to relaxational. Our results indicate a novel route to spatio-temporal structure in active nematics and suggest experiments on controllable light-activated systems.
format Preprint
id arxiv_https___arxiv_org_abs_2512_11123
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Heterogeneity-Induced Oscillations in Active Nematics
Houston, Alexander J. H.
Grinfeld, Michael
McKay, Geoff
Mottram, Nigel J.
Soft Condensed Matter
One of the defining features of active nematics is that above a critical activity the quiescent state becomes unstable to a distorted, flowing one. We show that spatial variations in activity can fundamentally change the nature of this instability, affecting the symmetry of the unstable mode and producing spontaneous oscillations. We analytically identify a dynamical system for the evolution of the odd and even director modes, with the leading-order coefficients dependent on the activity profile, allowing a quantitative connection between the spatially-heterogeneous activity and dynamics, which we verify numerically. In the context of constant gradients in activity, we determine a phase diagram for the active response and highlight how variation of the activity profile causes the oscillations to vary from almost harmonic to relaxational. Our results indicate a novel route to spatio-temporal structure in active nematics and suggest experiments on controllable light-activated systems.
title Heterogeneity-Induced Oscillations in Active Nematics
topic Soft Condensed Matter
url https://arxiv.org/abs/2512.11123