Simple models for heterogeneous granular avalanches

Chris Johnson – Univ. of Manchester, RU.

Debris flows and pyroclastic flows are examples of heterogeneous granular flows, with a flow composition (particle size distribution and pore fluid content) that vary in space and time. In this seminar, I’ll discuss two processes which can cause these variations in composition, specifically grain size segregation and the relative motion between grains and pore fluid. I’ll show through simple models how these processes can lead to distinct features of debris flow morphology, such as dry flow fronts and large-particle lateral levees, which have a profound effect on the flow dynamics and hazard posed by such natural avalanches.