Penetration of a hydrophilic yield stress fluid in hydrophobic porous media

Understanding how fluids interact with various superhydrophobic structures and undergo a wetting transition is necessary to improve water resistance or ensure good penetration. Among these interactions is the penetration of fluids inside porous fibrous hydrophobic structures, which is an ubiquitous phenomenon in cosmetics, building renovations, electronics or textiles. While simple fluids entering these media are the subject of numerous studies, complex fluids are not.



The aim of our study is to give insight on the interaction between complex fluids and hydrophobic porous media, beginning with yield stress fluids and simple porous structures. We set up a quasi-static experiment to measure the critical pressure required to make a model yield stress fluid penetrate a regular one-layer hydrophobic mesh. We first present how we use simple fluids to validate and calibrate the experiment. We then focus on the role of yield stress and mesh size on critical penetration pressure. We finally investigate the impact of granularity on this pressure by adding beads inside the yield stress fluid.