الفهرس 
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Abstract
SuperhyDROPhobic surfaces are the surfaces capable of producing large apparent contact angles when liquid DROPlets are disposed on it. This phenomenon appears in many plants and birds as a way of self cleaning method. SuperhyDROPhobic surfaces contain millions of hyDROPhobic micro or nano rough elements which makes it difficult for the liquid to penetrate through the air gaps between them. This is because the surface tension forces have the dominant effect in such very small scale dimensions. Also the great number of rough elements magnify the surface tension forces greatly.
The current work is an effort to derive a phenomenological model of DROPlet dynamics over superhyDROPhobic surfaces. The sessile DROPlet technique is used to form the profile of the DROPlets resting on superhyDROPhobic surfaces in order to know the base area of the DROPlet. All interaction forces between DROPlet and wall are revisited. This includes forces in both normal and tangential directions to the surface. Forces in the normal direction to the surface includes surface tension forces (due to the creation of a large wetted perimeters in the rough elements) and hydrostatic forces (due to penetration of the rough elements through the liquid). Forces in the tangential direction include frictional shear force (which is not as simple as normal flat surfaces) and drag force of surrounding air as the DROPlet moves.
For all these forces simplified phenomenological models were proposed to investigate fluid behavior in such complicated flow fields. The proposed models are based on either order of magnitude analysis or detailed 3D simulation (using OpenFOAM computational fluid dynamics software). The obtained simple forms were successful in reproducing, at least qualitatively, observed behavior. The problem has also been experimentally investigated in this work. It appears that with a limited number of adjusting model parameters, acquiring reasonable values, simplified models derived in this work can predict observed behavior.