Incollection,
Density inhomogeneity of a quasi two-dimensional granular gas in a vibrating box
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Abstract
We studied the behavior of a collection of balls bouncing inelastically in a vertically vibrating thin box with height several time the ball diameter. By treating the collection of the balls as a quasi two-dimensional granular gas in the horizontal plane, we measured the ball density (defined as the number of ball per unit area) as a function of the total number of ball $N$ in the box. When the vertical height of the box is different at different regions, the ball density will be different in these regions. We found that the density ratio $\alpha$ between the ball density in a thin region of smaller vertical height to that in a thick region of larger vertical height was less than one at small $N$. As $N$ increased, $\alpha$ went through a maximum value that was larger than one
and then approached one at large $N$. Such behavior was successfully reproduced in molecular dynamic simulations and possible explanation of the observed $\alpha(N)$ was proposed.
