Hydrodynamic bend instability of motile particles on a substrate

Fuente: arXiv
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Main Authors: Kumar, Sameer, Sousa, Niels de Graaf, Doostmohammadi, Amin
Format: Preprint
Published: 2025
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author Kumar, Sameer
Sousa, Niels de Graaf
Doostmohammadi, Amin
author_facet Kumar, Sameer
Sousa, Niels de Graaf
Doostmohammadi, Amin
contents The emergence of hydrodynamic bend instabilities in ordered suspensions of active particles is widely observed across diverse living and synthetic systems, and is considered to be governed by dipolar active stresses generated by the self-propelled particles. Here, using linear stability analyses and numerical simulations, we show that a hydrodynamic bend instability can emerge in the absence of any dipolar active stress and solely due to the self-propulsion force acting on polar active units suspended in an incompressible fluid confined to a substrate. Specifically, we show analytically, and confirm in simulations, that a uniformly ordered state develops bend instability above a critical self-propulsion force. Numerical simulations show that a further increase in the self-propulsion strength leads the system towards a disorderly flow state. The results offer a new route for development of hydrodynamic instabilities in two-dimensional self-propelled materials that are in contact with a substrate, with wide implications in layers of orientationally ordered cells and synthetic active particles.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07392
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hydrodynamic bend instability of motile particles on a substrate
Kumar, Sameer
Sousa, Niels de Graaf
Doostmohammadi, Amin
Soft Condensed Matter
The emergence of hydrodynamic bend instabilities in ordered suspensions of active particles is widely observed across diverse living and synthetic systems, and is considered to be governed by dipolar active stresses generated by the self-propelled particles. Here, using linear stability analyses and numerical simulations, we show that a hydrodynamic bend instability can emerge in the absence of any dipolar active stress and solely due to the self-propulsion force acting on polar active units suspended in an incompressible fluid confined to a substrate. Specifically, we show analytically, and confirm in simulations, that a uniformly ordered state develops bend instability above a critical self-propulsion force. Numerical simulations show that a further increase in the self-propulsion strength leads the system towards a disorderly flow state. The results offer a new route for development of hydrodynamic instabilities in two-dimensional self-propelled materials that are in contact with a substrate, with wide implications in layers of orientationally ordered cells and synthetic active particles.
title Hydrodynamic bend instability of motile particles on a substrate
topic Soft Condensed Matter
url https://arxiv.org/abs/2507.07392