Kinetic Energy Fluctuations and Diffusivity in a 2D Vibrated Granular Packing

We present an experimental realization of a 2D vibrated granular packing. The new agitation method allows a spatially non synchronized influx of energy and the study of the vibrated packing at steady state. By image analysis of fast-camera movies, we obtain the velocity fluctuation spectra at different, vertical levels and then. we separate the agitation velocities from the velocity fluctuations correspondiug to the "thermalized" degrees of freedom. By measuring the corresponding particle diffusivities, we show that, in spite of a large heterogeneity and anisotropy of the vibration, a relation between diffusivity and fluctuating kinetic energy call be identified.