Prediction of the dispersion of particle clusters in the nano-scale—Part II, unsteady shearing responses

A modeling approach to predict and enhance understanding of the dispersion phenomenon is presented. The discrete/distinct element method (DEM) is adopted to study the behavior of single spherical agglomerates, immersed in a simple shear flow field, in response to shearing under steady or dynamic/oscillatory flow conditions. The effects of hydrodynamic forces, which result from both the straining and rotating components of the flow, and cohesive forces of interaction, comprised of short-range van der Waals attractive and Born repulsive forces, are considered. Comparative results of simulated dispersion of nano-size silica agglomerates in response to steady and unsteady shearing are found to be in good agreement with reported experimental trends. The current three-dimensional model allows us to probe and predict the dispersion phenomenon as a function of processing conditions, agglomerate structure/morphology, and material properties and interaction forces.