Eur. Phys. J. B 9, 183-186 (1999)
https://doi.org/10.1007/s100510050755

Cluster formation, pressure and density measurements in a granular medium fluidized by vibrations

¹ 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

Received: 1 February 1999
Published online: 15 May 1999

Abstract

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.