Model of Sand Transport by Consecutive Disk Collisions on 2D Disordered Packing
Résumé
We study successive collisions of incident energetic beads with granular packing in the context of Aeolian saltation transport. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyze the features of the consecutive collision processes. We used a molecular dynamics method known as DEM (soft Discrete Element Method) with a static packing of 20000 2D particles. The packing is created randomly in a box of dimension 250×60 disk diameters. The incident disks are launched at a given velocity ranging between 25 and 100 (normalized by sqrt(g [center-dot] d)) and an angle of 15° with random position on top of the flowing zone. In previous studies, the classical “splash function” was obtained with one bead hitting a fully static dense packing. In this new approach, the quasi-fluidized upper layer of the packing creates a completely different behavior for a “dynamic splash function.” The dilation of the upper surface due to the previous collisions is responsible for a need of less input energy for launching new disks from the static bed.