Simulating the Formation of Granular Jets

This study focuses on simulating the formation and growth of granular jets under the impact of a heavy intruder on a bed of small particles. A discrete particle method to track the motion of 150 million individual particles in the bed, coupled with computational fluid dynamics to model the motion of the surrounding air, is used to obtain these predictions. The main idea of this research was to model the large impacting intruder by gluing together particles of the same size as those in the bed to approximate the form of a large sphere, which resulted in an efficient neighbor search and collision calculations. It also allowed a fine resolution of air flow. Our numerical results agreed with the experimental observation that the height of the jet diminishes from atmospheric to vacuum conditions. The effect of other parameters, such as initial intruder size and velocity, shows the same trends as those observed experimentally.