Transition to a labyrinthine phase in a driven granular medium

S. Merminod, T. Jamin, E. Falcon and M. Berhanu
Univ Paris Diderot, Sorbonne Cité, MSC, CNRS, UMR 7057, F-75 013 Paris, France

Reference: Physical Review E 92, 062205  (2015)



Labyrinthine patterns arise in two-dimensional physical systems submitted to competing interactions, in fields ranging from solid-state physics to hydrodynamics. For systems of interacting particles, labyrinthine and stripe phases were studied in the context of colloidal particles confined into a monolayer, both numerically by means of Monte Carlo simulations and experimentally using superparamagnetic particles. Here we report an experimental observation of a labyrinthine phase in an out-of-equilibrium system constituted of macroscopic particles. Once sufficiently magnetized, they organize into short chains of particles in contact and randomly orientated. We characterize the transition from a granular gas state towards a solid labyrinthine phase, as a function of the ratio of the interaction strength to the kinetic agitation. The spatial local structure is analyzed by means of accurate particle tracking. Moreover, we explain the formation of these chains using a simple model.

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Supplemental Material :

Merminod_Movie.mp4   Setting-up of the labyrinthine phase when the magnetic field is linearly increased from 0 to 200 G. The particle area fraction equals 0.5 and the acceleration equals 21.9 m/s^2.

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