Evolution of meniscus structures in hydrophobic granular systems

• Smooth and irregular particles have different wetting behaviour when hydrophobic. Sharp particle edges produce increasing apparent contact angles with drop volume. Concave convex liquid bridges can co-exist between hydrophobic particles. Liquid form over micron-scale distances particle. Attraction repulsion occur on bridge formation. Hydrophobic soils, which naturally in arid regions or after forest fires, be problematic for land managers engineers as they are often associated impeded preferential flow paths, increased surface runoff soil erosion. However, the reduced rainwater infiltration capacity of water-repellent soils also result improvement stability slopes, landfills capillary barrier cover systems, amongst others. Understanding hydraulic conditions within these materials is critical if issues seepage to become tractable. Traditional understanding unsaturated suggests that water menisci, so positive pressures, should limited experimental results presented literature do not support this theory. In work, effect shape formation evolution meniscus structures investigated at macro (multiple particles) scales, contrasting behaviours spherical glass beads angular sand grains. The spreading a sessile macro-scale examined found angularity grains has significant angle deposited mono-layer At scale, Environmental Scanning Electron Microscopy was used investigate retention hysteresis during two drying cycles. Again, it shown roughness controlling factors both stable concave menisci simultaneously surfaces. Additionally, nature allowed across much larger separation than could achieved through film coalescence hydrophilic surfaces, possible consequences imbibition modelling and, more broadly, manufacturing processes relying substrates. Lastly, qualitatively exhibited overall less curve their counterparts.