(233e) DEM-Based Prediction of Critical Impact Velocities of Aggregation and Breakage and Daughter Distributions of Cohesive Powders

Flowing, cohesive particles are subject to the formation and breakage of agglomerates. One approach to the continuum modelling of such flows is the population balance coupled with kinetic-theory-based conservation equations. The population balance includes sink and source terms representing aggregation and breakage. These sink and source terms depend on the success factors of aggregation and breakage, which quantify the fraction of collisions that result in aggregation and breakage. Further, the source term due to breakage includes a daughter distribution, which gives the sizes of agglomerates formed when a large agglomerate undergoes breakage. Previous works have shown that the success factors of aggregation and breakage, as well as the daughter distribution, depend on impact velocity. In this work, a fundamental approach is taken to relating the success factors and daughter distributions to the granular temperature (continuum variable in kinetic-theory-based balances), which is a measure of the impact velocity. Next, many-particle discrete element method (DEM) simulations are utilized to determine the critical impact velocities of agglomeration and breakage and the daughter distribution as a function of impact velocity and over a range of agglomerate sizes. Collectively, this work demonstrates a new DEM-based methodology for extracting the closures needed for the population balance.