Nonhydrostatic behavior in packing of frictionless discs

Imre M. Janosi

Department of Physics of Complex Systems, Lorand Eotvos University, P.O. Box 32. H-1518 Budapest, HUNGARY

Simplifications in modeling of granular media help to reveal the effects of various material parameters, such as size, shape, density, friction, etc. Probably the final level of idealization is reached in a collection of frictionless discs in a container of frictionless walls, where the only surviving material property is geometric disorder. We can naively think that such assemblies are trivial, e.g. obeying hydrostatics. Here we review recent results of a few groups and demonstrate that anomalous behavior is rather a rule even in these oversimplified model systems.