Semi-mechanistic model for the interfacial velocity of gravity-driven laminar wavy film flow and its validation using infrared particle tracing velocimetry

Interfacial velocity is an important parameter in the modeling of momentum transfer for prediction of heat- and mass-transfer during film-wise condensation. In this study, the interfacial velocity is modeled using an empirical power-law velocity profile with the assumption that the interfacial shear stress is negligible compared with the wall shear stress. A non-intrusive infrared particle tracking velocimetry (IR-PTV) measurement technique is used to validate a newly proposed semi-mechanistic model for the interfacial velocity of a gravity-driven laminar wavy film flow. The proposed model predicts measured interfacial velocities reasonably well and could serve as a closure relation in estimating the film-wise condensation heat transfer coefficient.