Dewetting on porous media with aspiration

Abstract

We consider a porous solid covered with a water film (or with a drop) in situations where the liquid is pumped in, either spontaneously (if the porous medium is hydrophilic) or mechanically (by an external pump). The dynamics of dewetting is then strongly modified. We analyse a few major examples: a) horizontal films, which break at a certain critical thickness, b) the "modified Landau-Levich problem" where a porous plate moves up from a bath and carries a film: aspiration towards the plate limits the height H reached by the film, c) certain situation where the hysteresis of contact angles is important.Comment: Revised version: The analysis of the 'modified Landau-Levich problem' (section 3) has been significantly revised. It is now treated as a singular perturbation problem (using boundary-layer techniques), leading to a more accurate physical pictur