Forced dewetting on porous media

TL;DR

This paper investigates the dewetting process on a porous plate, identifying a critical capillary number beyond which stationary contact lines cannot exist, supported by numerical and analytical models.

Contribution

It introduces a combined numerical and analytical approach to determine the critical capillary number for dewetting on porous media, revealing a 3/2 power law dependence.

Findings

Existence of a critical capillary number for dewetting

Analytical model matches numerical results for large parameters

Critical capillary number depends on plate angle with a 3/2 power law

Abstract

We study the dewetting of a porous plate withdrawn from a bath of fluid. The microscopic contact angle is fixed to zero and the flow is assumed to be parallel to the plate (lubrication approximation). The ordinary differential equation involving the position of the water surface is analysed in phase space by means of numerical integration. We show the existence of a critical value of the capillary number $\eta U / \gamma$, above which no stationary contact line can exist. An analytical model, based on asymptotic matching is developed, that reproduces the dependence of the critical capillary number on the angle of the plate with respect to the horizontal for large control parameters (3/2 power law).