Wicking of liquids into sagged fabrics†
The classical Bernoulli problem of a freely hanging fabric sagged between two posts is used for the analysis of wicking phenomena. We show that wicking of a wetting liquid into a Bernoulli catenary is an instructive nontrivial experiment illustrating an unusual coupling between mechanical and capillary forces. When the liquid wicks into the material, it causes the catenary to sway back and forth. We studied theoretically and experimentally the kinetics of wicking into sagged nonwoven materials. The proposed experiment can be used for the analysis of transport and tensile properties of thin porous films.