Thin liquid films flowing over external aerodynamic surfaces

Boundary-layer theories are constructed to describe the evolution of interfacial waves on thin liquid films which are driven by an air boundary layer. The theories are focused on cases which are most relevant to aircraft icing. It is found that condensed-layer solutions with film inertia adequately describe the linear evolution of interfacial waves for thinner films, whereas a triple-deck pressure displacement interaction is required for thicker films. In all cases it is found that inertia must be retained within the film, even when the film is much more viscous than the air.