CFD modeling of the hydrodynamic characteristics of a bubble column in different flow regimes

Gas-liquid two-phase flows are used in industrial systems over a range of flow regimes that have different bubble size distributions. In this work, the Eulerian-Eulerian (E-E) Computational Fluid Dynamics (CFD) model using the discrete bubble population balance model (PBM) with 1, 2 and 3 bubble phases was used to simulate the gas-liquid two-phase flows in different flow regimes in bubble columns. Furthermore, a modified air inlet bound-ary condition was proposed based on commonly observed dual-bubble size distributions in the churn-turbulent regime. A comparison was made with experimental results from the literature to evaluate the suitability of the proposed numerical model. Different interfacial force models were also tested. In the homogeneous flow regime, the homogeneous discrete population balance model was found to be sufficient. In the churn-turbulent regime, the model with the higher number of bubble phases was found to give better results. The model with modified inlet boundary conditions was able to predict higher bubble number density as expected in the churn-turbulent flow regime and the predicted gas-holdup and axial liquid velocity agree with the experimental data. The model also was used to simulate other geometries from literature.