Cluster formation, pressure and density measurements in a granular medium fluidized by vibrations
Laboratoire de Physique Statistique, École Normale Supérieure, 24 rue Lhomond,
75231 Paris Cedex 05, France
2 Laboratoire de Physique, École Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France
Published online: 15 May 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 θ 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
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999