%0 Journal Article
%T Density Patterns in Granular Media
%A G. Ristow
%A H. J. Herrmann
%J Physics
%D 1993
%I arXiv
%X Recent experiments by Baxter et al. showed the existence of density waves in granular material flowing out of a hopper. We show, using Molecular Dynamics Simulations, that this effect is a consequence of static friction and find that these density fluctuations follow a $1/f$ spectrum. The effect is enhanced when the opening angle of the hopper decreases.
%U http://arxiv.org/abs/cond-mat/9302005v1