Dynamics of a 2D Vibrated Model Granular Gas in Microgravity

Abstract

We are reporting an experimental study performed on a granular gas enclosed into a 2D cell submitted to controlled external vibrations. Experiments are performed in microgravity during parabolic flights. High-speed optical tracking allows to obtain the kinematics of the particles and the determination of all inelastic parameters as well as the translational and rotational velocity distributions. The energy into the medium is injected by submitting the experimental cell to an external and controlled vibration. Two model gases are studied beads and disks; the latter being used to study the rotational part of the particle'sdynamics. We report that the free cooling of a granular medium can be predicted if we consider the velocity dependence of the normal restitution coefficient and that the experimental ratio of translational versus rotational temperature decreases with the density of the medium but increases with the driving velocity of the cell. These experimental results are compared with existing theories. We also introduce a model that fairly predicts the equilibrium temperatures along the direction of vibration.

Hydrodynamics of granular gases of inelastic and rough hard disks or spheres. I. Transport coefficients

“…The results for HS and HD gases are given in the fourth column of Table II. In the case of λ, P N (κ 39,24,2,11,12,21) and (37,151,50,12,75,101,102) for HD and HS, respectively. It must be noted that, when setting α = β = 1 in the expressions of Table I, we took the licence of using d r = 1 2 d t (d t − 1) (which applies to both HS and HD) in order to simplify the final results for η * and λ * .…”

“…Whereas the three-dimensional is perhaps the most general, verisimilar, and intuitive geometry, a twodimensional constrained system is likely found in ordinary life, like a set of marbles moving and spinning on a plane or the pucks and strikers in the air hockey game. But the most important asset of the two-dimensional geometry resides in its ordinary use in experiments setups [31][32][33][34][35][36][37][38]. Thus, this work aims at providing testable results for the hydrodynamic transport coefficients within a general framework that encompasses the three-and twodimensional geometries of spinning particles.…”