(121a) A Study of Structured Bubble Patterns in Pseudo 2D Pulsed Fluidized Beds Using CFD-DEM Framework

Bubble formation and evolution in fluidized beds are a central concern driving the development of equipment modifications such as pulsation of the flow rate. This technique has shown the ability to produce structured patterns of bubbles in certain regimes of oscillation, opening the possibility of controlling the fluid dynamics in the bed. While experimental works have documented the phenomenon in certain parameter range, model predictions have met with limited success. This investigation explores the use of computational fluid dynamics with discrete element method (CFD-DEM) to shed light into the mechanism behind the formation of staggered rows of bubbles in pseudo 2D beds. The CFD-DEM approach is able to capture the regular phenomenon, forming a 1-2-1 type of pattern for the conditions used in this study, and to demonstrate the role of existing bubbles in inducing the position shift of the incoming void structures. Simulations show that the pressure field distortion, due to the presence of bubbles, generates undulations on the “interface” of the forming void wave and the emulsion phase. This favors the appearance of bubbles in the peak regions, which are shifted with respect to the preceding row of bubbles.