Tuning the distance to equipartition by controlling the collision rate

in a driven granular gas experiment

G. Castillo1 S. Merminod2, E. Falcon3 and M. Berhanu3
1Instituto de Ciencias de la Ingienera, Universidad O'Higgins, 2841959 Rancagua, Chile
2Brandeis University, Martin A. Fisher School of Physics, Waltham, MA 02453, USA
Université de Paris, Univ Paris Diderot, MSC, UMR 7057 CNRS, F-75 013 Paris, France

Reference: Physical Review 101, 032903 (2020)    

URL: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.101.032903
DOI: https://doi.org/10.1103/PhysRevE.101.032903

In a granular gas experiment of magnetized particles confined in a thin layer, the rate of dissipative collisions is tuned by adjusting the amplitude of an external magnetic field. The velocity statistics are analyzed using the dynamic and static structure factors of transverse velocity modes. Using the fluctuating hydrodynamics theory, we measure the deviation from kinetic energy equipartition in this out-of-equilibrium system as a function of the dissipative collision rate. When the collision rate is decreased, the distance to equipartition becomes smaller, meaning that the dynamical properties of this granular gas approach by analogy those of a molecular gas in thermal equilibrium.

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