Granular Gases under Extreme Driving
W. Kang, J.Machta, and E. Ben-Naim
We study inelastic gases in two-dimensions using event-driven
molecular dynamics simulations. Our focus is the nature of the
stationary state attained by rare injection of large amounts of energy
to balance the dissipation due to collisions. We find that under such
extreme driving, with the injection rate much smaller than the
collision rate, the velocity distribution has a power-law high-energy
tail. The numerically measured exponent characterizing this tail is
in excellent agreement with predictions of kinetic theory over a wide
range of system parameters. We conclude that driving by rare but
powerful energy injection leads to a spatially homogeneous gas and
constitutes an alternative mechanism for agitating granular matter. In
this distinct nonequilibrium steady-state, energy cascades from large
to small scales. Our simulations also show that when the injection
rate is comparable with the collision rate, the velocity distribution
has a stretched exponential tail.
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