Collision Detection and Administration Methods for Many Particles with Different Sizes

This paper deals with the calculation of the motion and the administration of the contacts for systems with many colliding bodies of round shape and possibly large size-differences. Both two dimensional (2D) and three dimensional (3D) cases are investigated, while the efficiency of the employed algorithms is compared. For the integration of the equations of motion, standard methods are used, but to reduce the effort for collision detection, more sophisticated administration algorithms for the neighborhood search are prosented. Especially for large systems with many particles and a wide, polydisperse size distribution, this is a challenge. Three methods, the Verlet-Neighbor List (VL), the Linked Cell (LC) method, and the Linked Linear List (LLL), are discussed and compared for 2D and 3D. Only LLL performs well for strongly different particle sizes. keywords: contact detection; neighborhood search; molecular dynamics (MD); discrete element method (DEM); polydisperse size-distribution