The Clogging Transition in a 2D Granular Silo

The flow of granular material through a silo or hopper has been studied for many years. In addition to its great practical importance in many industrial processing situations, it is also thought to be a model system for other bottleneck flows such as blood flow, crowd egress, and traffic merges. In recent times, advances in computing and high-speed imaging have allowed detailed study of these flows. We present results from a high-speed imaging study of silo flow. Specifically, we report on how metrics such as velocity fluctuations, non-affine motion, and dynamical heterogeneities change on approach to the clogging point. We do find systematic changes in these metrics on approach to the clogging point. We compare and contrast the clogging transition to the jamming transition in light of these results. We will also summarize some extensions to this work involving obstacles and soft particles.