Dewetting on porous media with aspiration

TL;DR

This paper investigates how dewetting dynamics on porous media are altered by liquid aspiration, analyzing critical film stability, film transport limits, and contact angle hysteresis in various scenarios.

Contribution

It introduces a theoretical analysis of dewetting on porous media considering aspiration effects, extending classical models to include new boundary conditions and stability criteria.

Findings

Horizontal films break at a critical thickness.

Aspiration limits the film height on moving plates.

Contact angle hysteresis influences dewetting behavior.

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.