Computational Fluid Dynamics Simulation of Regime Transition in Bubble Columns Incorporating the Dual-Bubble-Size Model

This article investigates the two regime transition points for bubble columns with the so-called dual-bubble-size (DBS) model featuring the utilization of a stability condition to analyze the compromise between dominant mechanisms. Our previous work indicated that the second point could be reasonably predicted and physically interpreted by the DBS model for various gas-liquid systems. This work further clarifies the relationship between the bifurcation of energy dissipation and of structural parameters and the regime transition. It is found that the bifurcation of energy dissipation exists for both the gas-liquid and gas-solid systems and call be used to predict and understand regime transition in multiphase flow. Then the DBS model is incorporated into the two-fluid model for calculating interphase coupling, and I computational fluid dynamics (CFD) calculation is performed to simulate I bubble column. The "shoulder" on the gas hold-up curve can be observed in the simulation with the new coupling method, and the second transition point predicted from the CFD simulation is consistent with experiments and the calculation of the DBS model. Sparger effects are investigated through the two simulation cases for uniform aeration and local aeration, and the radial distribution of local hydrodynamic parameters is comparable with experimental data in the literature.