Inertial two- and three-dimensional thin film flow over topography

The effect of inertia on gravity-driven thin film free-surface flow over substrates containing topography is considered. Flow is modelled using a depth-averaged form of the governing Navier–Stokes equations and the discrete analogue of the coupled equation set solved accurately using an efficient full approximation storage (FAS) and full multigrid (FMG) technique. The free-surface disturbance induced by topographic features is illustrated by considering examples of gravity-driven flow over and around peak, trench and occlusion topography. Results are presented which demonstrate how increasing Reynolds number can significantly enhance the magnitude of free-surface disturbances, a feature which may have important consequences for the wide range of coating process that aim to maximise free-surface planarity.