DEM Simulation on Mixing Characteristics and Macroscopic/Microscopic Flow Behaviors of Different-Shaped Sphero-Cylinders in a Rotating Drum

In this paper, the mixing process and flow behavior of different-shaped sphero-cylinders with a filling level of 40.5% in the rotating drum were numerically studied by the discrete element method. The effects of rotation speed and particle aspect ratio (AR) on the mixing and flow processes were analyzed. Various macro- and microscopic characteristics of structures during mixing were systematically investigated and their dependences on the rotation speed and AR were quantified, and the corresponding flow dynamics were illustrated. The results show that sphero-cylinders with different ARs can reach well-mixed states under sufficient rotation conditions. Both the macro- and microscopic properties change with the rotation speed and AR; however, when AR > 3, its influence becomes less obvious. The mechanism affecting the flow behavior of sphero-cylindrical systems lies in the fact that the interlocking restricts the movement of particles, which makes the particles detached from the drum wall at a high position, thus accelerating the transition of the flow regime.