Improved Eulerian–Lagrangian modeling of bubble coalescence and breakup in bubble columns

This study presents an improved Eulerian–Lagrangian modeling of bubble dynamics, including coalescence and breakup in bubble columns. The influences of bubble coalescence and breakup models on simulations are investigated. A hard-sphere collision model is employed to track bubble interactions, with bubble breakup governed by a critical Weber number and coalescence modeled using the critical coalescence velocity model and film drainage models. The simulation framework is validated against experimental data from Deen et al. [“Comparison of PIV and LDA measurement methods applied to the gas-liquid flow in a bubble column,” in 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics, 2000, Vol. 1] and Lau et al. [“Experimental study of the bubble size distribution in a pseudo-2D bubble column,” Chem. Eng. Sci. 98, 203–211 (2013)]. Results show that the breakup model with a critical Weber number of 0.2, combined with the Tomiyama lift force and stochastic dispersion models, produces predictions closest to experimental data, although further improvements are still needed under various flow conditions, incorporating more detailed turbulence effects. Moreover, a comparative analysis of coalescence efficiency shows that the critical coalescence velocity model gives more accurate results than both film drainage models and the Eulerian–Eulerian Prince model, particularly in high-turbulence regions. Simulation results indicate that at lower superficial gas velocities (5–10 mm/s), the bubble size distribution is unimodal, while at higher velocities (15–20 mm/s), it becomes bimodal due to enhanced breakup and coalescence effects. Additionally, this study presents statistical coalescence efficiency results and compares with those using the widely adopted Prince model in the Eulerian–Eulerian framework, offering insights into discrepancies between Eulerian–Lagrangian and Eulerian–Eulerian models. The findings highlight the advantages of using a physically based approach to model bubble dynamics and provide a valuable reference for refining the coalescence model in the population balance method in the Eulerian–Eulerian framework.