Rough wetting

If a rough surface is put in contact with a wetting liquid, the roughness m ay be spontaneously invaded depending on the surface pattern and the wettin g properties of the liquid. Here, we study the conditions for observing suc h an imbibition and present practical achievements where the wetting proper ties of the surface can be predicted and tuned by the design of a solid tex ture. The contact angle of a drop on such a surface ( where solid and liqui d coexist) is discussed. Finally, the dynamics of the liquid lm is found to obey a diffusive-type law, as in the case of porous wicking.