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Three-dimensional (3-D) Euler/Euler simulations of two-phase (gas/liquid) transient flow were performed using a multiphase flow algorithm based on the finite-volume method. These numerical simulations cover laboratory-scale bubble columns of different diameters, operated over a range of superficial gas velocities in the churn-turbulent regime (8 to 30 cm/s) and at different operating pressures (up to 1 MPa). The bubble population balance equation (BPBE) is implemented in the two-fluid model (TFM) and algebraic slip mixture model (ASMM). Simulated time-averaged axial liquid velocity, turbulence stress, and gas holdup are compared with experimental data of Chen et al., Ong, and Shaikh et al. Moreover, to

CFD simulations of bubble columns have received much attention, and several multiphase models have been developed, tested, and validated through comparison with experimental data. It is well-known that bubble coalescence and breakup can lead to significant variations in the bubble size distribution and that, to model the evolution of the dispersed gas phase, the population balance equation has to be solved. In this work, a classes method (CM) and a method of moments (MOM) are investigated and compared. The MOM represents an attractive alternative in which, instead of tracking the entire bubble distribution, only the lowerorder moments of the distribution are tracked. The above two approaches have been implemented in the commercial CFD code FLUENT, version 6.0, in conjunction with the Eulerian multiphase model. CFD simulations of bubble columns have received much attention, and several multiphase models have been developed, tested, and validated through comparison with experimental data. It is well-known that bubble coalescence and breakup can lead to significant variations in the bubble size distribution and that, to model the evolution of the dispersed gas phase, the population balance equation has to be solved. In this work, a classes method (CM) and a method of moments (MOM) are investigated and compared. The MOM represents an attractive alternative in which, instead of tracking the entire bubble distribution, only the lower-order moments of the distribution are tracked. The above two approaches have been implemented in the commercial CFD code FLUENT, version 6.0, in conjunction with the Eulerian multiphase model. Disciplines Chemical Engineering | Process Control and Systems Comments

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