Bubbly flow in stirred tanks: Euler-Euler/RANS modeling

Aerated stirred tanks are frequently used equipment in industries ranging from chemical engineering and biotechnology to minerals processing. In principle, CFD simulation of such equipment on industrial scales is feasible within the Euler-Euler framework of interpenetrating continua. Practical application, however, requires suitable closure models to account for phenomena on the scale of individual bubbles, which are not resolved in this approach. The present work applies a set of closure relations that was previously used with good success to describe bubbly flows in pipes and bubble columns. It turns out that model extensions are needed concerning turbulence and the drag force. To validate the model a comprehensive set of experimental data including gas fraction as well as liquid velocity and turbulence has been assembled from different literature sources. The finally proposed extended model compares reasonably well with this dataset.