Wicking of liquids into sagged fabrics

Abstract

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.

A review on advanced imaging technologies for the quantification of wicking in textiles

“…The use of such high-speed image acquisition can also be applied to woven fabrics. Another imaging method on nonwoven materials that can be extended to woven fabrics is the one presented in Monaenkova et al 37,38 The group imaged simultaneously the front and the profile of a sagged non-woven fabric during wicking by using a set of mirrors. Their setup and resulting image are shown in Figure 5.…”

Bernoulli catenary and elasto-capillary effect in partially wet fibrous materials

“…The last situation can be achieved in experiments, where a freely suspended sample absorbs liquid from one end. For such situation, following the analysis of Bernoulli 19 and Freeman, 23 and integrating the second expression of Equation (3), 17 one can show that the sample profile can be defined using a combination of catenary equations describing dry and wet parts of the sample (Figure 1(b), inset):…”

“…The unknown parameters a AE , x AE min , Y AE min can be found from the boundary conditions and the front position s* is obtained by numerical integrating the kinetic equation as discussed elsewhere. 17 The pressure in the moving liquid column is a combination of the hydrostatic and capillary pressure and reads 17…”

“…In our recent paper 17 we have discussed a problem of liquid flow through a freely suspended fibrous material. In the experiment, the liquid driven by capillarity and hydrostatic forces wicks along the sample, which continuously adjusts its shape according to the level of saturation (Figure 1(a)).…”

“…The results on wicking kinetics in these fabrics have been discussed in our recent paper. 17 The main parameters of the experiment (see Figure 1(b)) are summarized in Table 1. In the Appendix, we describe the experimental conditions in detail.…”