(630d) The Role of Friction in Pattern Formation in Pulsed Fluidized Beds

Christine Hrenya’s work beautifully demonstrates the importance of introducing the correct physics of gas-solid systems to represent phenomena at multiple scales, all the way down to particle surface roughness at the nanoscale. Her work also involves measurements to validate and parameterize physical models that advance our fundamental understanding of fluidization yet, in addition, it allows us to practically apply these findings in industrial settings. In this presentation, I embrace a similar philosophy in our study of dynamically structured pattern formation in pulsed fluidized beds. The different conditions under which regular patterns appear in shallow granular layers and deep bubbling beds are used to compare the assumptions underpinning different modelling approaches with experimental observations. In particular, the effect of particle friction on pattern nucleation and propagation in dynamically structured fluidized beds is investigated, showing no appreciable effect in pattern nucleation, but a key role in a bubble pattern’s propagation. These dynamic viscoplastic flows involve spatiotemporally, periodically structured zones that are dense and quasi-stationary, as well as other, more dilute ones that remain active and mobile, and are responsible for micromixing. A detailed investigation offers new insights into the fundamentals of fluidization at mesoscopic scales, incorporating microscopic information, and relevant to simulate macroscopic gas-solid systems.