Hydrodynamics and Heat Transfer of Vertical Falling Liquid Films : Part 1, Classification of Flow Regimes

Hydrodynamics of a vertical falling liquid film has been the subject of not a few papers in which the film is analyzed in the same way as in the single phase flow without a free surface. A study for improving this situation is reported in a series of papers including this one on an experimental study on the wavy flow of falling films of water and highly viscous fluids. By analyzing the experimental study it is concluded that the flow of a vertical falling liquid film is classified as follows. 1. Purely laminar flow ; there is no wavy motion on the liquid film. 2. First transition region. 3. Stable wavy flow ; there are stable wavy motions on the liquid film in which turbulence is found. 4. Second transition region. 5. Fully turbulent low ; the flow becomes shear-flow type, and its wall law is identical with that of the turbulent boundary layer.