Simulation of Bubbly Flow and Mass Transfer in a Turbulent Gas-Liquid Stirred Tank with CFD-PBM solver in OpenFOAM: EQMOM application

In the present paper, the oxygen dispersion in a laboratory scale (3 litres) bioreactor is modelled using open source Computational Fluid Dynamic (CFD) package OpenFOAM (Open Source Operation and Manipulation). The combined effect of the bubble breakup and coalescence in the tank is accounted by a novel method of Population Balance Model (PBM) called Extended Quadrature Method of Moments (EQMOM). The three dimensional simulation is made within a Multiple Reference Frame (MRF), which is a well established method for the modelling of mixers. Dispersed gas and bubbles dynamics in the turbulent flow are modelled using Eulerian-Eulerian (E-E) approach with mixture k-epsilon turbulent model. A modified Tomiyama drag coefficient was used for the momentum exchange, as well. Parallel computing is employed to make efficient use of computational power to predict the spatial distribution of gas phase fraction, Sauter mean bubble diameter (d32), Number Density Function (NDF), oxygen mass fraction in water and flow structure. The numerical results are compared with experimental data, and good agreement is achieved.