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Applied Mathematics Colloquium
Friday, April 24, 11:30 am
Cullimore Lecture Hall II
New
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Particle size segregation
in granular flow
Michael Shearer
Department of Mathematics and Center for Research in Scientific Computation
Raleigh, NC
Abstract
Granular materials tend to segregate by size when placed under shear, as in an
avalanche, or when vibrated. The result of this tendency is that larger
particles rise, while smaller particles of the same density descend. A recent
continuum model of Gray and Thornton captures this phenomenon in a nonlinear
partial differential equation. In this talk, I describe fundamental properties
of the equation, such as shock formation and shock breaking, the latter
associated with an instability. I will also describe experiments in a Couette
cell, and the extent to which a suitably modified model captures the
experimental data. Naturally, the experiment has some surprises! The modified
model also has novel properties, some of which mesh with recent results on
fluid flow in a nonuniform porous medium.