Hairy fluid mechanics: interfacial flows in networks of flexible fibres

In natural systems, surfaces are often textured with arrays of slender, filamentous structures that can be significantly deformed not only by viscous drag but also by surface tension. Interfacial flows through these systems are highly coupled: when capillary forces of the moving interface are strong enough to deflect fibres, they in turn modify local flow geometry. As a result, the ability to drain a pre-existing layer of fluid over a deformable surface can significantly differ from the undeformed reference case. By fabricating channels textured with "hairy" elastoporous media, our work here is threefold: we first characterize the mechanics of capillary flow past a confined array of rigid posts and subsequently adapt Kirchhoff beam theory to describe the deflection of beams due to Laplace pressure. Lastly, we couple the aforementioned frameworks to show the impact of deformability on drainage.