(189r) Effect of Dem Parameters on the Collision Distribution of a Small Shearing Region below the Surface of a Rotating Drum

Traditionally, DEM simulations are validated via particle trajectories and velocity fields using experimental techniques such as PIV or PEPT. However, some researchers use DEM simulations to extract particle-scale measurements such as collision frequency. It is unclear whether a validation of a macroscopic velocity field also implies a validation of particle-scale measurements. In this study, measurements of solid fraction, shear rate, and collision frequency and impact velocity are made in a small region just below the free surface in a rotating drum. The effects of periodic drum length, particle stiffness, coefficient of restitution, and particle size are investigated. It is found that the solid fraction and shear rate within the studied region are unaffected by variations in particle stiffness and coefficient of restitution over the range of values studied. However, the rate of collisions increases for both increasing particle stiffness and coefficient of restitution. Also, the mean collision speed decreases with increasing stiffness, and decreasing coefficient of restitution. The shear rate within the region decreases as particle size increases, while the mean collision velocity remains unaffected. These findings suggest that care must be taken in choosing DEM force models and model parameters in order to accurately model collision distributions, while particle size need not be matched exactly.