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arXiv · 2511.00642

Controlling Vortex Rotation in Dry Active Matter

Felipe P. S. Júnior·Jorge L. C. Domingos·W. P. Ferreira·F. Q. Potiguar
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Abstract

We investigate the rotation of a vortex around a circular obstacle in dry active matter in the presence of M half-circles distributed around the obstacle. To quantify this effect, we define the parameter {\Pi}M , which is the ratio between the mean angular velocity of the controlled vortex and the root-mean-square angular velocity of the isolated vortex. We identify two rotational regimes determined by the obstacle configuration. In the first regime, where {\Pi}M < 0 corresponding to the flat side of the half-circles facing the vortex, the rotation is clockwise. In the second regime ({\Pi}M > 0), it corresponding to the curved sides facing the vortex, the rotation becomes counterclockwise. We further analyze the impact of this control on vortex stability, showing that the configuration of semi-circles can enhance or suppress stability depending on their geometry and distance from the central obstacle. Our results demonstrate a possible setup to control the spontaneous rotation of dry active matter around circular obstacles.

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Felipe P. S. Júnior, Jorge L. C. Domingos, W. P. Ferreira, F. Q. Potiguar. 2025-11-01. Controlling Vortex Rotation in Dry Active Matter. https://doi.org/10.1103/sjy3-qzp8

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