Three-Dimensional DEM Analysis of Granular Flows Under Different Gravity Levels in Rotating Cylinders

The investigation of granular flows is of great significance to industrial production, e.g., rotary dryers, ball mills and mixing drums, as well as the prevention of natural disasters, e.g., landslides, mudslides and avalanches. The rotating cylinder model is capable to capture the macro characteristics of granular flowing modes transition in laboratory tests, which is the most classic experimental method to study granular flows. However, it is difficult to observe the micro characteristics on granular flowing motions in physical model tests. Therefore, the Distinct Element Method (DEM) is employed to study the motion mode of particles in cylinders with focus on the gravity effect in this study. The results show that DEM has an obvious advantage in simulating granular flows tests with the contact model considering rolling and twisting resistances. The dynamic angle of repose increases with the gravity level, which implies that motion mode of particles evolves from the slumping motion to the rolling motion. Moreover, the maximum velocity of the particles flow increase with the gravity level. But when the gravity level is larger than 1 g, the maximum velocity of the particles increases slowly.