288594 Fluid-Like Properties of Powders: Rheology in the Intermediate Flow Regime
Manufacture of solid dosage forms is a microcosm of powder technology, involving synthesis and processing of fine powders through a variety of particle formation, communition, blending, compaction, and coating processes. Common to these operations is the bulk flow of powders in a regime in which particles experience a range of interactions from collisions to more enduring frictional contacts with neighboring particles. This is termed the "intermediate" flow regime, and it has only recently begun to be studied with rigor. Quantitative models for industrially-relevant powder flows do not exist, and for this reason the design and scaling of these unit operations is largely empirical. To begin to address this gap, NSF funded a powder flow collaboratory, lead by the International Fine Particle Research Institute (IFPRI), to bring together a small group of experimentalists and modelers in order to explore the state of development of powder flow models. In the collaboratory, the results of two IFPRI-funded flow experiments, a particle-level study of two-dimensional hopper flows and a continuum-level study of Couette flows were provided to the modelers in order to test the fidelity of their models. The results of this effort revealed key gaps, both experimental and theoretical, in our understanding of and ability to model dense, active powder flows. I will present in this talk the key findings and a set of industrially relevant results achieved during the NSF funded program.