The hydrodynamics of thin liquid films flowing over a rotating disc

Abstract

This study is concerned with flow and stability of thin liquid films flowing over the surface of a disc rotating about a vertical axis. The work consists of a theoretical and experimental investigation into the flow of the steady-state film, and the waves which occur on it. The theoretical model is investigated in its steady-state form (no waves present) using both asymptotic and numerical techniques. The unsteady problem is also examined, using asymptotic methods, for the inception and propagation of waves of small amplitude with respect to the mean film thickness. The experimental investigation employs a light absorption technique to obtain accurate film thickness measurements across individual three dimensional wave profiles. The results are used to test the validity of the small amplitude assumption of the theoretical model, which is found to be restrictive, and to give both qualitative and quantitative data about the large amplitude waves that are often observed.