Velocity Distributions of Granular Gases with Drag and with
Long-Range Interactions
K. Kohlstedt, A. Snezhko, M.V. Sapozhnikov, I. S. Aranson,
J. S. Olafsen, and E. Ben-Naim
We study velocity statistics of electrostatically driven granular
gases. For two different experiments: (i) non-magnetic particles in a
viscous fluid and (ii) magnetic particles in air, the velocity
distribution is non-Maxwellian, and its high-energy tail is
exponential, $P(v)\sim \exp\left(-|v|\right)$. This behavior is
consistent with kinetic theory of driven dissipative particles. For
particles immersed in a fluid, viscous damping is responsible for the
exponential tail, while for magnetic particles, long-range
interactions cause the exponential tail. We conclude that velocity
statistics of dissipative gases are sensitive to the fluid environment
and to the form of the particle interaction.
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