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  • Open Access

Flocking through a sea of rods

Abhishek Sharma and Harsh Soni*

  • *Contact author: harsh@iitmandi.ac.in
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APS Open Sci. 1, 000156 – Published 1 October, 2026

DOI: https://doi.org/10.1103/m93c-1kmm

This article was published on 1 October, 2026. Please update your links.

Abstract

We investigate the collective behavior of motile rods immersed in a monolayer of apolar rods confined between vertically vibrating plates using numerical simulations. We uncover an antidiffusive phenomenon whereby motile rods segregate from the apolar medium and form anisotropic flocks whose size increases with the medium concentration. Remarkably, enhanced segregation leads to a reduction of the global polar order, giving rise to an anomalous dependence of the polar order on the medium concentration and the angular noise of the motile rods. The flock structure is strongly influenced by the anisotropy of the medium rods. For small aspect ratios, the flocks are elongated perpendicular to the mean direction of motion, whereas for larger aspect ratios they elongate along the direction of motility. We rationalize the emergence of segregation-induced disorder using a minimal mean-field model.

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APS Open Sci. 1, 000156– Published 1 October, 2026
Vol. 1
  • Received 31 March 2026
  • Accepted 14 September 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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