Flow of a thin liquid film coating a horizontal stationary cylinder

Abstract

An experimental and theoretical study of the flow of liquid films around a stationary horizontal cylinder is reported. The film presents two different behaviors: The flow is stable in the upper zone (up to aprox. 150 degrees with the vertical) and Rayleigh-Taylor-like instabilities appear in the lower zone. For the stable region, film thickness evolution could be described by numerically integrating an evolution equation obtained using a lubrication approximation. For the unstable region, a linear stability analysis allows us to determine the maximum growth wavelength for the Rayleigh-Taylor instability. Approximate analytical solutions were obtained for generatrices at an angle with the vertical theta = 0 (stable region) and theta = 180 degrees (where the instability appears).