Dynamical regimes of a granular gas in microgravity : A molecular dynamics study

Abstract

We propose a numerical model, based on molecular dynamics, which is able to reproduce the behavior of a dissipative granular gas in microgravity. Granular material is confined in a cubic box of side length L following a sinusoidal motion of amplitude A and angular velocity ω = 2πf along the z-axis. The simulations are performed using the parameters of earlier Texus experiments [15]. Our results are in excellent agreement with experimental data. Moreover, we discovered various dynamical regimes and the physical conditions for their appearance : a gaseous state, the formation of either small or large clusters, the collective motion of grains. Phase diagrams are drawn where transitions between these different granular states are emphasized. Transitions are discussed by considering Statistical Physics models.