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Main Authors:	Memarian, Fereshteh L., Hammar, Derek, Sabbir, Md Mainul Hasan, Elias, Mark, Mitchell, Kevin A., Hirst, Linda
Format:	Preprint
Published:	2024
Subjects:	Soft Condensed Matter
Online Access:	https://arxiv.org/abs/2401.04363
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author	Memarian, Fereshteh L. Hammar, Derek Sabbir, Md Mainul Hasan Elias, Mark Mitchell, Kevin A. Hirst, Linda
author_facet	Memarian, Fereshteh L. Hammar, Derek Sabbir, Md Mainul Hasan Elias, Mark Mitchell, Kevin A. Hirst, Linda
contents	This work examines self-mixing in active nematics, a class of fluids in which mobile topological defects drive chaotic flows in a system comprised of biological filaments and molecular motors. We present experiments that demonstrate how geometrical confinement can influence the braiding dynamics of the defects. Notably, we show that confinement in cardioid-shaped wells leads to realization of the golden braid, a maximally efficient mixing state of exactly three defects with no defect creation or annihilation. We characterize the golden braid state using different measures of topological entropy and the Lyapunov exponent. In particular, topological entropy measured from the stretching rate of material lines agrees well with an analytical computation from braid theory. Increasing the size of the confining cardioid produces a transition from the golden braid, to the fully chaotic active turbulent state.
format	Preprint
id	arxiv_https___arxiv_org_abs_2401_04363
institution	arXiv
publishDate	2024
record_format	arxiv
spellingShingle	Controlling chaos: Periodic defect braiding in active nematics confined to a cardioid Memarian, Fereshteh L. Hammar, Derek Sabbir, Md Mainul Hasan Elias, Mark Mitchell, Kevin A. Hirst, Linda Soft Condensed Matter This work examines self-mixing in active nematics, a class of fluids in which mobile topological defects drive chaotic flows in a system comprised of biological filaments and molecular motors. We present experiments that demonstrate how geometrical confinement can influence the braiding dynamics of the defects. Notably, we show that confinement in cardioid-shaped wells leads to realization of the golden braid, a maximally efficient mixing state of exactly three defects with no defect creation or annihilation. We characterize the golden braid state using different measures of topological entropy and the Lyapunov exponent. In particular, topological entropy measured from the stretching rate of material lines agrees well with an analytical computation from braid theory. Increasing the size of the confining cardioid produces a transition from the golden braid, to the fully chaotic active turbulent state.
title	Controlling chaos: Periodic defect braiding in active nematics confined to a cardioid
topic	Soft Condensed Matter
url	https://arxiv.org/abs/2401.04363

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