Traveling fronts in vibrated polar disks: At the crossroad between polar ordering and jamming

We investigate experimentally the collective motion of polar vibrated disks in an annular geometry, varying both the packing fraction and the amplitude of the angular noise. For low enough noise and large enough density, an overall collective motion takes place along the tangential direction. The spatial organization of the flow reveals the presence of polar bands of large density, as expected from the commonly accepted picture of the transition to collective motion in systems of aligning polar active particles. However, in our case, the low density phase is also polar, consistent with what is observed when jamming takes place in a very high density flock. Interestingly, while in that case the particles in the high density bands are arrested, resulting in an upstream propagation at a constant speed, in our case the bands travel downstream with a density-dependent speed. We demonstrate from local measurements of the packing fraction, alignment, and flow speeds that the bands observed here result both from a polar ordering process and a motility induced phase separation mechanism.

PHYSICAL REVIEW E

By: Caleb J. Anderson, Olivier Dauchot, and Alberto Fernandez-Nieves.

Phys. Rev. E 109, 054610 – Published 29 May 2024

DOI: https://doi.org/10.1103/PhysRevE.10...


Top



See also...

Mean arc theorem for exploring domains with randomly distributed arbitrary closed trajectories

A remarkable result from integral geometry is Cauchy’s formula, which relates the mean path length of ballistic trajectories randomly crossing a (…) 

> More...

Dynamics of a colloidal particle coupled to a Gaussian field: From a confinement-dependent to a non-linear memory

The effective dynamics of a colloidal particle immersed in a complex medium is often described in terms of an overdamped linear Langevin equation (…) 

> More...