Model for force fluctuations in bead packs
Disordered geometric packings of granular materials  have fascinated researchers for many years . Such studies, with their applicability to the geometry of glass-forming sys tems, initially were concerned with categorizing the void shapes and densities. More recently, partly in recognition of the ubiquity of granular materials and their importance to a wide variety of technological processes, interest has focused on how the forces supporting the grains are distributed. Vi sualizations of two-dimensional granular systems  demon strate weight concentration into “ force chains.” It is natural to expect that similar concentrations of forces will occur in three dimensions. The distinctive forces in bead packs also give rise to distinctive boundary-layer flow  and novel sound-propagation properties .