Interfacial shear stress in wavy stratified gas-liquid flow in horizontal pipes

The scope of this study was to improve the Andritsos-Hanratty model for estimating interfacial friction factor and pressure drop in horizontal stratified gas-liquid two-phase flow. New experimental results (focusing on the effects of gas density and surface tension), combined with experimental data available in the literature, permit the development of semi-theoretical correlations for the transition from smooth stratified to 2-D wave region and from the latter to large-amplitude wave region and of different empirical relations for the interfacial friction factor in the two wave regions. The transition correlations agree reasonably well with existing and new data obtained in this work and the modified relations give improved predictions for both liquid holdup and pressure drop during gas-liquid stratified flow in horizontal and slightly downward pipelines as deduced from a statistical analysis of the results.