Eric Falcon1, Stéphan Fauve1 & Claude Laroche2
1 Laboratoire de
Physique
Statistique, École Normale Supérieure, 24 rue Lhomond,
75005
Paris, France.
2 Laboratoire de
Physique,
École Normale Supérieure de Lyon, 46 allée
d'Italie, 69364 Lyon Cedex 07, France.
European Physical Journal B, 9, 183-186 (1999)
We report experimental results on the
behavior
of an ensemble of inelastically colliding particles, excited by a
vibrated
piston in a vertical cylinder. When the particle number is increased,
we
observe a transition from a regime where the particles have erratic
motions ("granular gas") to a collective behavior where all the
particles bounce
like a nearly solid body. In the gas-like regime, we measure the
density
of particles as a function of the altitude and the pressure as a
function
of the number N of particles. The atmosphere is found to be
exponential
far enough from the piston, and the "granular temperature", T,
dependence
on the piston velocity, V, is of the form 
, where 
is a decreasing function of N. This may
explain previous conflicting
numerical results.
, where is a decreasing function of N. This may
explain previous conflicting
numerical results. PACS
45.70.-n Granular systems - 83.70.Fn Granular solids - 05.20.Dd Kinetic
theory - 83.10.Pp Particle dynamics
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