Compaction of highly porous granular matter by impacts on a hard wall

A granular mechanics model study of the influence of non-spherical shape on aggregate collisions

Collisions between granular aggregates influence the size distribution of dust clouds. Granular aggregates may possess non-spherical shapes as a result of, for instance, previous collision processes. Here, we study aggregate collisions using a granular mechanics simulation code. Collisions between spherical aggregates are compared to collisions of ellipsoidal aggregates of equal mass. As the most prominent result, we find that the growth velocity, i.e., the velocity above which the post-collision aggregates are smaller than before collision, is generally reduced for ellipsoidal aggregates. The reason hereto lies in the less compact structure of ellipsoids which allows for a larger degree of fragmentation in a 'rim peel-off' mechanism. On the other hand, relative fragment distributions are only little influenced by aggregate shape.