Experimental validation of DEM in rotating drums using Positron Emission Particle Tracking

Despite the widespread use of the Discrete Element Method (DEM) to simulate industrial rotating drum flows, comparatively little work has been done to evaluate its accuracy. To bridge this gap, Positron Emission Particle Tracking (PEPT) was employed to benchmark tuned DEM simulations. Two granular mixtures of mono-sized glass beads (31% filling), run at 60 and 75% of critical speed, were used. To ensure an equitable comparison, both DEM and PEPT data were coarse grained. The comparisons include the free surface (average RMS error = 2.6 mm), equilibrium surface (average RMS error = 3.3 mm), bin-by-bin comparisons of the solids fraction (15% relative error) and velocity (10% relative error), and equivalent comparisons along slices drawn orthogonal to the free surface that produced complete statistical agreement between PEPT and DEM. The results suggest a strong statistical agreement between the tuned DEM and coarse grained PEPT data.