Two-group interfacial drag force model for gas-liquid dispersed flows in large-diameter pipes

The prediction of heat and mass transfer rates is indispensable in two-phase flow industrial processes. One-dimensional system analysis codes commonly use the two-fluid model for system design, performance evaluation, and accident analysis. The interfacial drag force (hereafter referred to as IDF) term is the dominant contributor to the total interfacial momentum transfer term in the gas and liquid momentum equations. The drag characteristics for spherical and distorted (group one, G1) bubbles significantly differ from those of cap, slug, and churn-turbulent (group two, G2) bubbles. This study developed a two-group (2G) IDF model using two approaches for dispersed gas-liquid flows in large-diameter pipes. The first approach developed a 2G IDF model based on the drag coefficient. The second approach extended Andersen and Chu's 1G IDF model based on drift-flux parameters to a 2G IDF model. This study developed a 2G drag coefficient model that accounted for the acceleration of G1 bubbles in the wake region of G2 bubbles. Moreover, the shape factor for different bubble shapes was analytically investigated. Results demonstrated that the shape factor significantly decreased with increasing the void fraction. This study introduced a 2G shape factor model and highlighted its significance for accurate predictions in dispersed flows. The errors for the G1 and G2 IDF models based on the extended Andersen and Chu's approach were 21.6% and 22.8%, respectively. The corresponding errors for the G1 and G2 IDF models based on the drag coefficient approach were 26.0% and 25.4%, respectively. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.