No abstract

The durability of super-hydrophobic surfaces in fully immersed conditions is a major obstacle to their application in engineering applications. We perform an experimental study to measure the friction factor f d as a function of time for a new super-hydrophobic surface that is capable of recovering the Cassie-Baxter wetting state. Values of f d were obtained by measuring the pressure drop and volume flux of a turbulent water flow in a 1.5 metre long duct containing one super-hydrophobic wall. The Reynolds number of the flow was approximately 4.5 × 10 4 for all experiments. Reductions in f d were 29-36 % relative to a hydraulically smooth surface. The Cassie-Baxter state could be recovered blowing air through the porous surface for 10 minutes. The durability of the drag-reduction, as quantified by the relaxation time T in which the surface loses its superhydrophobic characteristics, were measured to be between 10-60 minutes depending on the initial head. The relaxation time T was highly dependent on the pressure difference across the surface. In contrast to models based on Darcy flow through a porous medium, the study indicates that there seems to be a critical pressure difference beyond which the Cassie-Baxter state cannot be sustained for the material under consideration.

Solar energy is the basis for life on earth [...]

Hematology Reports published its first volume in 2009, which included 10 publications: 8 original articles and 2 reviews [...]

The development of new hardware has never been as accessible as it is today [...]