Exploring analogies between granular materials and fluids

The direct application of fluid-system approaches to particles oftentimes leads to spectacular failures; e.g. shaking mixes miscible fluids, while it can result in extreme segregation of particles. Nevertheless, much can be learned through analogies between these disparate systems and here we adapt concepts from fluid behavior and explore their application in industrially-relevant particle processes---such as mixing/segregation, heat transfer and flowability.;Adhesion is commonly found in operations involving fine powders and strongly impacts mixing/segregation of these materials. We develop both a Particle Dynamics (PD) model capable of simulating dry adhesive interactions as well as a characterization tool---the van der Waals Granular Bond Number. Using these tools we predict the asymptotic state of materials in a mixing drum and subsequently test these predictions.;Beyond predicting the asymptotic state of a system, the next natural step is to explore controlling that state. With this purpose, we propose the addition of "helper" particles to either promote mixing or segregation. These amphiphilic helper particles---also called Janus particles---act as bridges between the base particles, alternatively promoting mixing in a system that would otherwise segregate (surfactant helpers) or separating a specific kind of particle from a mixture (extractant helpers). Again, predictions are made and then tested against results obtained by simulation.;The presence of adhesive forces in granular materials can also affect the flowability of a granular material. Flow aids are frequently added to dry cohesive powders to improve their flow properties/handling, but are identified purely on an ad hoc basis industrially. Using our PD model and characterization tools, flow aids are, instead, rationally designed.;Finally, we study heat transfer within granular materials. Specifically, we examine the conditions necessary to achieve conduction-dominated versus convection-dominated heat transfer. Interestingly, when conduction is the dominant mechanism, increasing the mixing rate seems to have a positive impact on the heating rate, while under convection-dominated conditions the opposite is often true. Dimensionless numbers are used to correlate the results and a surprising degree of similarity is found when compared to analogous fluid correlations.;Keywords. granular materials, mixing, segregation, adhesion, flowability, heat transfer mechanisms.