Numerical simulation of the dynamic flow behaviour in a bubble column: comparison of the bubble-induced turbulence models in K-epsilon model

Numerical simulations of the gas-liquid bubbly flow in a bubble column were conducted with the commercial CFD package CFX-4.4 to investigate the performance of three models (Pfleger and Becker, 2001; Sato and Sekoguchi, 1975; Troshko and Hassan, 2001) to account for the bubble-induced turbulence in the k-e model. Furthermore, the effect of two different interfacial closure models was investigated. All the predicted results were compared with experimental data. All three approaches could produce good solutions for the time-averaged velocity. The models of Troshko and Hassan (2001) and Pfleger and Becker (2001) resolve more details of the bubbly flow than the model of Sato and Sekoguchi (1975) does. In the top part of the column, the models of Troshko and Hassan and Pfleger and Becker under-predicts the liquid phase vertical velocity. Based on the comparison of the results for two columns of different aspect ratio (H/D = 3 and H/D = 6), it was found that the model of Pfleger and Becker (2001) performs better than the model of Troshko and Hassan (2001), while the model of Sato and Sekoguchi (1975) performs the worst. Furthermore, it was found that the interfacial closure model proposed by Tomiyama et al (2002) performs better for the tall column.