Experimental and Numerical Studies of Granular Flows in a Rotating Drum

Granular flow in a rotating drum is studied by experiments and by Computation Fluid Dynamics (CFD) simulations. The particulate phase is modelled based on the Continuum Eulerian Approach (CEA) in the simulation. The particulate phase CEA prediction using the common Gidaspow granular kinetic viscosity or the Syamlal-O’brien granular kinetic viscosity fails to predict the measured dynamic angle of repose of the granular flow in the rotating drum. When the size of particulate phase decreases from 0.775 mm to 0.274 mm, the measured dynamic angle of repose is approximately 39-60% higher than the CEA predictions using the Gidaspow or the Syamlal-O’brien kinetic viscosity model. The dynamic angle of repose-best-fitted particle collisional and kinetic (C+K) viscosities indicate that C+K viscosity value increases with the increasing of the particle size and the decreasing of the speed of the rotating drum except for the drum at 30 rpm. The dynamic angle of repose best-fitted C+K viscosity values are used to simulate binary mixture (0.775 mm + 0.385 mm) segregation in the rotating drum. The formation of the radial core and the axial bands qualitatively agrees with the experimental observations. The smaller particle segregation structure of a central band and two side wings also agree well with reported experimental results.