Momentum and heat transfer across freely-falling turbulent liquid films

This work centers on the transport processes in turbulent liquid films undergoing heating or surface evaporation. A new semi-empirical turbulence model is presented. It consists of a single continuous eddy-viscosity profile which spans the entire liquid layer. Numerical calculations reveal good agreement with experimental data for freely-falling films. It was found that it is impossible to obtain universal correlations for different fluids in terms of Reynolds and Prandtl numbers alone since the heat transfer data display strong dependence on the Kapitza number below Re = 10,000. The Kapitza number accounts for the effects of surface tension and viscosity on the turbulence structure near the free surface of the film. Turbulent-film correlations similar to those used in conventional internal or external flows are recommended for higher Reynolds numbers.