Physical Mathematics Seminar, 11-30-99

Clustering and Segregation in Granular Flows

Arshad Kudrolli
Clark University

Granular materials when poured or shaken display a surprising range of
liquid-like behavior such as convection and pattern formation. However,
hydrodynamics approches cannot be applied to the flow of granular
matter. We use high-speed and high-resolution imaging to examine
granular materials in various geometries to determine their properties
under external mechanisms of adding energy. We study the influence of
dissipation on the density and velocity distribution of particles. We
show that inelastic collisions between the partices led to clustering
and pattern formation. We find that the velocity distributions of the
particles are strongly non-Gaussian even at low densities. We also
report experiments on the size segregation instabilities in the emptying
and filling of granular matter from a silo. An important variable is the
presence of interstitial fluid which has a major impact not only on the
jamming and flow of the media, but also on the progress of segregation.