A two fluid modeling study of bubble collapse due to bubble interaction in a fluidized bed

Abstract

Two fluid modeling (TFM) has been widely used to simulate large-scale fluidized beds. Previous studies showed that TFM can capture bubble dynamic behavior like splitting and coalescence. Recently, a real-time magnetic resonance imaging (MRI) study found that two anomalous bubble collapse phenomena occurred when two bubbles are injected into incipiently fluidized beds such that the bubbles interact. Herein, TFM simulations matching the MRI experiments were performed. The simulation results reproduce the bubble collapse phenomenon and reveal that for side-by-side injection, the initially smaller bubble collapses due to gas flow channeling preferentially to the larger bubble; for consecutive injection, the lower, smaller bubble collapses due to increased gas leakage in a dilated bubble wake. The results also show that beyond a critical bubble volume, the initially smaller bubble can survive to the bed surface for side-by-side injection and the lower, smaller bubble coalesces with the upper, larger bubble for consecutive injection.