Intra-Particle Coating Variation: Analysis and DEM Simulation

An analytical model is presented that describes the intra-particle coating variability of a single particle by a uniform spray. For uniformly random orientations, the film thickness coefficient of variation is proportional to the number of coating trials raised to the -1/2 power, and thus the coefficient of variation asymptotes to zero as the number of coating trials increases. However, if the particle has a preferred orientation while in the spray zone, the limiting value of the coefficient of variation is non-zero. Finally, intra-particle coating distributions from discrete element method (DEM) computer simulations of spherical and non-spherical (glued-sphere) particles in a rotating drum is examined in light of the developed theory.