CFD simulation of bubble column hydrodynamics with a novel drag model based on EMMS approach

Drag model is of critical importance for CFD simulation of flow characteristics in bubble columns. In this study, a novel drag model termed DBS-Local for the ratio of effective drag coefficient to bubble diameter is derived from the Dual-Bubble-Size (DBS) model based on Energy-Minimization Multi-Scale (EMMS). A thorough comparison demonstrates that without adjustable parameters, both the DBS-Local model and the DBS-Global model are capable of improving the prediction of total and local gas holdup as well as the flow characteristics in different flow regimes. By contrast, other drag models either overestimate or underestimate the total or local gas holdup in certain flow regimes. Moreover, the centerline liquid velocity predicted by DBS-Local model shows best agreement with experiments, whereas the other models, especially the Ishii-Zuber model, over-estimate liquid velocity. This study demonstrates the significance of modeling the bubble-swarm effect based on EMMS approach. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study introduces a new drag model termed DBS-Local derived from the Dual-Bubble-Size (DBS) model based on Energy-Minimization Multi-Scale (EMMS), which improves the prediction of gas holdup and flow characteristics in bubble columns. The DBS-Local model demonstrates the best agreement with experimental results for centerline liquid velocity compared to other drag models.