Vertical upward intermediate scale Taylor flow: Experiments and kinematic closure

•The intermediate scale Taylor flow pattern is not fully characterized.•High-speed photography is employed to measure key Taylor flow parameters.•A Taylor bubble rise velocity model is developed for microscale to large scale flows.•Kinematic closure models are formed for intermediate scale Taylor flow.

The vertical upward Taylor flow regime has been extensively studied at the capillary and large channel scale limits. However, flow behavior at the intermediate scale (5≲Bo≲405≲Bo≲40, or 6mm≲D≲17mm for ambient gas–water flows) is comparatively poorly characterized. This regime is fundamentally different because classes of forces conventionally associated with either small or large Bond number flows are all relevant. In this investigation, air–water Taylor-flow experiments are conducted in 6.0, 8.0, and 9.5 mm diameter tubes. High-speed video data are collected, and automated image analysis algorithms are developed to measure flow parameters including: bubble rise velocity, liquid film thickness, void fraction, and Taylor bubble and liquid slug lengths. New correlations and flow models are developed to predict these parameters at the intermediate scale. Results from this study enable kinematic closure of intermediate scale Taylor flows.