Direct quadrature method of moments (DQMOM) approach for vertical gas-liquid bubbly flows of large pipe

Gas-liquid bubbly flows with wide range of bubble sizes are commonly encountered in many industrial gas-liquid flow systems. The performance of direct quadrature method of moments (DQMOM) has been assessed against the homogeneous MUlti-SIze-Group (MUSIG) model and Average Bubble Number Density (ABND) approach in tracking the changes of bubble size distribution and gas volume fraction under complex flow conditions. Numerical studies have been performed to validate predictions from the different population balance approaches against experimental measurements of vertical bubbly flows in a large diameter pipe. In general, predictions of DQMOM were in good agreement with experimental data. The encouraging results demonstrated the capability of DQMOM in capturing the dynamical changes of bubbles size due to bubble interactions and the transition from wall peak to core peak gas volume fraction profiles caused by the presence of small and large bubbles. Predictions of the DQMOM appeared to offer substantial reduction of computational times in reaching a converged solution when compared to MUSIG for the computation of vertical bubbly flows in large diameter pipe.