Surface textures and surface fraction

On hydrophobic surfaces, surface textures are generated, which typically look like this:
Cross section of textures at the surface of superhydrophobic surfaces.
Water is sitting at the top of the posts, so the contact area between the drop and the surface is effectively reduced by a factor Φ called the surface fraction.
The real wetted area is s. The apparent wetted area is S. The surface fraction is Φ=s/S.


See also...

Photoinduced hydrophilicity of TiO2

Left: normal glass; right: with alternating rain and sunshine, self cleaning glass stays cleaner (and hydrophilic) (Saint-Gobain).TiO2 is known (...) 

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Drops that always turn to the right

Here is a flat surface on which drops always go in the same direction. Instead of spreading evenly they spread only in one and the same (...) 

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Practical information

Sciences et Ingénierie de la Matière Molle

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