Distributions and Correlations in a Vibrated Granular Layer

Jeff Urbach, Alexis Prevost, Georgetown University

Recent results from an experimental investigation of the dynamics of a layer of uniform metallic spheres on
a horizontal plate that is oscillating vertically are reported. We have investigated the role of the
forcing by comparing the behavior of the layer on a rough plate to that on a flat plate. In the fully
fluidized regime the spatial correlations of the granular fluid on either plate are indistinguishable from
an analogous equilibrium fluid at the same density. The velocity distributions are also similar, but differ
significantly from the equilibrium fluid. Also unlike the equilibrium system, significant velocity
correlations are observed in both cases, but their form is strongly dependent on the forcing.