5. Granular dynamics
examples
Chute flow
By extending the molecular dynamics approach to include frictional forces it
becomes possible to model the flow of granular materials. This is an example (in
two dimensions) of flow down an inclined chute; the larger grains are seen to
rise gradually to the top of the bulk.
Here is a short animation sequence
(350K).
Funnel flow
Flow of granular material through an opening is widely encountered in
industrial processing and storage.
Here is a short animation
sequence showing stresses experienced by the grains (1200K).
Vibrated layer
Surface waves appear when a granular layer is vibrated vertically. Here, the
container has periodic sides and the base oscillates. The type of wave depends
on the details; the self-organized behavior is fascinating to watch. Here is an animation sequence showing the
wave behavior (880K).
Axial segregation in a rotating cylinder
Axial segregation occurs in rotating horizontal cylinders that are partially
filled with mixtures of two different kinds of granular particles. The behavior
depends on the particle properties (relative size, roughness). Shown below is a
small (three-dimensional) system displaying this behavior. Here is an animation sequence showing
segregation in a smaller system (1000K).
Radial segregation
Radial segregation is another phenomenon associated with rotating cylinders. An
example of what occurs (in two dimensions) appears below. Here is an animation sequence showing
how the segregation develops (rotation is in the counterclockwise direction)
(1050K).
