Granular Flow in partially filled slowly rotating drums
Many industrial mixing, coating and grinding processes involve
rotating a large mass of granular material in a drum.
The adjacent figure shows a mathematical model for the steady
mixing of monodisperse red and blue granular materials.
can also view a jpeg animation of the solution by clicking here (5244 K).
As in many granular flows this problem involves a fluid-solid phase transition.
Close to the inclined free surface there is a rapid thin granular avalanche,
that transports material downslope, and beneath it there is a large solid
body region that slowly rotates with the drum providing a net transport
upslope. At the interface between the two regions there is strong mass
transfer. Initially the granular material is divided into two equal regions
of red and blue grains by a straight interface. As the drum rotates, particles
at different levels in the avalanche perform circuits around the drum at
different speeds and the interface is deformed.
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Page last modified: December 22, 2000