Relaxation of local density fluctuations in a fluidized granular medium

¹ Polymers and Colloids Group, Cavendish Laboratory, University of Cambridge, Cambridge, CB4 0HE, UK
² Laboratoire de Physique (URA CNRS 1325), Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon, France

Received: 29 August 1996
Accepted: 31 October 1996

Abstract

Configurations of vertically vibrated, two-dimensional arrays of fluidized steel spheres have been recorded using high-speed photography. The resulting instantaneous particle positions have been used to extract statistical averages of the static structure factor and of the dynamical density autocorrelation function over a range of wave vectors. The local collective behaviour of this vibrated granular medium exhibits strong similarities with the density fluctuations in an atomistic fluid in thermal equilibrium, at the equivalent particle packing fraction.