Title
Particle size segregation, shock waves and pattern formation in granular avalanches
Speaker
J.M.N.T. Gray (University of Manchester)
Abstract
Hazardous natural flows such as snow avalanches, debris-flows, lahars
and pyroclastic flows are part of a much wider class of granular
avalanches, that frequently occur in industrial processes and in our
kitchens! Granular avalanches are very efficient at sorting particles
by size, with the larger ones rising towards the free surface and the
smaller ones percolating down to the base, to create inversely-graded
layers. When these are brought to rest by the propagation of shock
waves, or by basal deposition, many beautiful and complex patterns are
formed in the deposits. This talk will review some of the recent
advances that have been made in modelling particle size segregation
and show how these theories can be incorporated into existing
avalanche models. In particular, the segregation of particles with
different material properties has important segregation mobility
feedback effects on the bulk flow, which are responsible for the
spontaneous formation of lateral levees, the selection of the petal
wavelength in rotating drums and stratification patterns in a granular
heap. This talk will show how such fully coupled models can be
constructed.
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