A critical analysis of drag force modelling for disperse gas-liquid flow in a pipe with an obstacle

The accuracy of the modelling of gas-liquid flows depends strongly on a suitable modelling of the inter-facial forces. Among these, drag is dominant. Most drag models reported in the literature have been derived and validated only for laminar or low-turbulent flow conditions. In this study, we numerically evaluated several drag models from the literature for high-turbulent gas-liquid flow around an obstacle in a pipe that creates a distinct vortex region. We performed Computational Fluid Dynamics (CFD) sim-ulations and compared the void fraction and gas velocity profiles with experimental data obtained by ultrafast X-ray computed tomography. We found that all models, except Schiller&Naumann and Feng, predicted the void fraction well compared to experimental data upstream of the obstacle, i.e., for a devel-oped two-phase pipe flow with axial symmetry. However, the void fraction downstream is greatly over-estimated by all models except those that appropriately consider the turbulence effects. Based on the results, a hybrid drag model is proposed that significantly improves the prediction of the void fraction. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study compared several drag models for high-turbulent gas-liquid flows and found that most models performed well upstream of the obstacle but overestimated the void fraction downstream. A hybrid drag model was proposed to improve the prediction of void fraction based on the results.