CFD simulation of large-scale bubble plumes: Comparisons against experiments

Computational fluid dynamics (CFD) simulations have been carried out to simulate a turbulent, bubble plume in a liquid pool. A two-fluid enhanced k  –ɛɛ model has been used, with the extra source terms introduced to account for the interaction between the bubbles and the liquid and transient calculations have been performed to study the plume growth, the acceleration of the liquid due to viscous drag, and the approach to steady-state conditions. In order to obtain correct spreading of the plume observed experimentally, it was observed that interfacial forces like lift and turbulent dispersion plays important role. The sensitivity analysis for drag coefficient and two different turbulent dispersion forces is presented. The development of the flow variables has been compared with the experimental data. From the CFD predictions obtained in the present work, it can be concluded that a two-dimensional (2D) axisymmetric assumption in this case is justified, with 2D model predictions in good agreement with the experimental data and those of a three-dimensional (3D) model, except for the shear stresses and turbulent kinetic energy. In general, quantitative comparison with the experimental data has revealed that, by applying proper models of inter-phase momentum transfer, and performing simulations based on the two-fluid model, satisfactory predictions of mean flow quantities can be obtained for this application away from the injector.