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).