doi: 10.1209/0295-5075/79/24003 An invariant distribution in static granular media

PACS 45.70.Cc – Static sandpiles; granular compaction PACS 81.05.Rm – Porous materials; granular materials Abstract – We have discovered an invariant distribution for local packing configurations in static granular media. This distribution holds in experiments for packing fractions covering most of the range from random loose packed to random close packed, for bead packs prepared both in air and in water. Assuming only that there exist elementary cells in which the system volume is subdivided, we derive from statistical mechanics a distribution that is in accord with the observations. This universal distribution function for granular media is analogous to the Maxwell-Boltzmann distribution for molecular gasses. Copyright c © EPLA, 2007 Granular materials are complex systems characterized by unusual static and dynamic properties. These systems are comprised of large numbers of dissipative macroscopic particles assembled into disordered structures. There is a very large number of microscopic configurations corre