Disintegration of tablets

A MATLAB™-based DEM (discrete element method) code was developed to study the particle motion in a pan coating device. The code was developed as a stand-alone program and provides simulation, visualization (GUI interface), and post-processing statistical analysis of particle movement. Results of DEM simulations are compared with those obtained from video-imaging experiments for 9 mm spherical polystyrene balls in a 58 cm diameter pan. The parameters compared are dynamic angle of repose and particle velocities in the x- (axial) and y- (parallel to cascading layer) directions within the spray zone in the cascading layer. The effects of pan loading and pan speed (6, 9, 12 rpm) on particle motion are compared and discussed. Good agreement was obtained between the DEM simulation and experimental results. The dynamic angle was found to increase with increasing pan speed and pan loading. The average cascading velocity was found to increase linearly with pan speed for both DEM and experiments. The velocity distributions both in the x- and y-direction were compared from simulation and experiments and found to be in good agreement. Velocity profiles along the entire top cascading layer of particles were also obtained using DEM. The particles in the cascading layer were found to reach their maximum velocity at positions close to the mid-point of the cascading surface. Comparison of simulated velocity profiles showed good agreement with published scaling laws for rotating drums, and a new correlation for scaling with respect to the pan loading is proposed.