Numerical investigation of crater phenomena in a particle stream impact onto a granular bed

This paper presents an experimental and numerical study of the impact of a particle stream onto a particle bed using a 2D slot model. The numerical simulation is performed by means of the discrete element method (DEM). The results show that the DEM simulation can reproduce the experimental results well under comparative conditions. The dynamics in the formation of a crater is then analyzed in terms of velocity field, force structure, bottom stress distribution and energy exchange based on the DEM results. It is shown that as a result of impact by the falling particles, the particles in the top central region of the particle bed have relatively large velocities and contact forces. The velocities and forces propagate into the bed, and reach the bottom of the base layer quickly. They then continue to propagate leftwards and rightwards to create a crater. During the impact process, most of the energy from the falling particles is dissipated due to the inelastic collision and frictional contacts between particles, and only a small amount of the energy contributes to the formation of the crater. The crater size is shown to be affected by the discharging rate, discharging height and materials properties, and be related to the ratio of the input energy from the falling stream to the inertial energy from the original packing.