Flocking by Turning Away

Fuente: arXiv
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Hauptverfasser: Das, Suchismita, Ciarchi, Matteo, Zhou, Ziqi, Yan, Jing, Zhang, Jie, Alert, Ricard
Format: Preprint
Veröffentlicht: 2024
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author Das, Suchismita
Ciarchi, Matteo
Zhou, Ziqi
Yan, Jing
Zhang, Jie
Alert, Ricard
author_facet Das, Suchismita
Ciarchi, Matteo
Zhou, Ziqi
Yan, Jing
Zhang, Jie
Alert, Ricard
contents Flocking, as paradigmatically exemplified by birds, is the coherent collective motion of active agents. As originally conceived, flocking emerges through alignment interactions between the agents. Here, we report that flocking can also emerge through interactions that turn agents away from each other. Combining simulations, kinetic theory, and experiments, we demonstrate this mechanism of flocking in self-propelled Janus colloids with stronger repulsion on the front than on the rear. The polar state is stable because particles achieve a compromise between turning away from left and right neighbors. Unlike for alignment interactions, the emergence of polar order from turn-away interactions requires particle repulsion. At high concentration, repulsion produces flocking Wigner crystals. Whereas repulsion often leads to motility-induced phase separation of active particles, here it combines with turn-away torques to produce flocking. Therefore, our findings bridge the classes of aligning and non-aligning active matter. Our results could help to reconcile the observations that cells can flock despite turning away from each other via contact inhibition of locomotion. Overall, our work shows that flocking is a very robust phenomenon that arises even when the orientational interactions would seem to prevent it.
format Preprint
id arxiv_https___arxiv_org_abs_2401_17153
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Flocking by Turning Away
Das, Suchismita
Ciarchi, Matteo
Zhou, Ziqi
Yan, Jing
Zhang, Jie
Alert, Ricard
Soft Condensed Matter
Statistical Mechanics
Biological Physics
Flocking, as paradigmatically exemplified by birds, is the coherent collective motion of active agents. As originally conceived, flocking emerges through alignment interactions between the agents. Here, we report that flocking can also emerge through interactions that turn agents away from each other. Combining simulations, kinetic theory, and experiments, we demonstrate this mechanism of flocking in self-propelled Janus colloids with stronger repulsion on the front than on the rear. The polar state is stable because particles achieve a compromise between turning away from left and right neighbors. Unlike for alignment interactions, the emergence of polar order from turn-away interactions requires particle repulsion. At high concentration, repulsion produces flocking Wigner crystals. Whereas repulsion often leads to motility-induced phase separation of active particles, here it combines with turn-away torques to produce flocking. Therefore, our findings bridge the classes of aligning and non-aligning active matter. Our results could help to reconcile the observations that cells can flock despite turning away from each other via contact inhibition of locomotion. Overall, our work shows that flocking is a very robust phenomenon that arises even when the orientational interactions would seem to prevent it.
title Flocking by Turning Away
topic Soft Condensed Matter
Statistical Mechanics
Biological Physics
url https://arxiv.org/abs/2401.17153