The percolation of liquid through a compliant seal-an experimental and theoretical study

New apparatus is described to simulate a compliant seal interface, allowing the percolation of liquid to be viewed by a fluorescence microscope. A model, based on the boundary element (BE) methodology, is used to provide a theoretical explanation of the observed behavior. The impact of contact pressure, roughness, and surface energy on percolation rates are characterized. For hydrophilic surfaces, percolation will always occur provided a sufficient number of roughness length scales are considered. However, for hydrophobic surfaces, the inlet pressure must overcome the capillary pressure exerted at the minimum channel section before flow can occur.