The DEM simulation tool Rocky is a very quick and comparatively easy tool to use for the study of particle interactions.
The purpose of this particular simulation was to experiment with prescribed motion, and for this, the bucket of a front loader was chosen. Rocky can also do erosion modeling and collision statistics and in this case, the mean normal impact velocity was plotted on the bucket.
Rocky can use arbitrary shapes for the particles in the simulation, so in time for Halloween, a pumpkin was selected.
In the animation sequence there are a few things happening:
At time 0 s, the particles are initialized with what’s called a volume fill. Since this is an arbitrary particle Rocky will make a bounding box around the particle, to prevent overlap, and stack the volume with the bounding boxes. So as soon as the simulation starts, bounding boxes disregarded, physics takes over and the particles start to interact with gravity, the skip and ground, and themselves.
As soon as particles move outside of the domain they are removed from the simulation in order to save time. This is very noticeable when the pumpkins roll off the edge of the ground.
As for the bucket, it was just brought in as a very coarse STL. Any better meshing than that is not strictly required, but any plot on the bucket surface will look better with higher resolution.
