000			02564aab a2200193 4500
008			240118b19901990|||mr||| |||| 00| 0 eng d
022			_a0017-9310
100			_aFatehi, M. _9872002
100			_aKaviany, M. _979300
245			_aAnalysis of Levitation of Saturated Liquid Droplets on Permeable Surfaces
300			_a983-994 p.
520			_aSteady-state evaporation of a saturated liquid droplet and its levitation over a solid surface due to momentum-induced pressure in the vapor film is studied by solving the axisymmetric governing equation numerically. A previous one-dimensional analysis shows that the distance (or gap) between the solid surface and the droplet decreases when the vapor can penetrate the solid. For porous layers, this onedimensional analysis which is based on Brinkman's extension to Darcy's law predicts momentum boundary layer thicknesses of the order of the square root of the permeability. In typical porous solids, this thickness is smaller than the pore or particle size. In the present study the Beavers-Joseph semi-empirical boundary condition at the interface of the plain (i.e. vapor underneath the droplet) and permeable layers is used instead of this one-dimensional model. The reduction in the gap size with respect to variations in permeability and thickness of the porous layer is determined for the ranges where this boundary condition is valid. The effect of vapor escape through the bottom surface of the porous layer is also studied. This axisymmetric model predicts an asymptotic value for the slip velocity and the gap size as the permeability increases beyond a certain value. This failure of the model to predict the collapse of the droplet is due to the breakdown of the Beavers-Joseph interfacial condition for high permeabilities. However, for practical applications the surface roughness is expected to dominate when the gap size approaches zero. The onedimensional model, i.e. the Brinkman extension, on the other hand, predicts an unrealistic rapid drop of the gap size when the permeability is increased beyond a certain value, because of the assumption of equal pressure gradients in the porous and plain layers.
650			_aLevitation _9880019
650			_aSaturated Liquid Droplets _9880020
650			_aPermeable Surfaces _9880021
773	0		_tInternational Journal of Heat and Mass Transfer _dNew York, U.S.A : Pergamon Subsidiary of Elsevier Science & Technology _x00179310
856			_uhttps://www.sciencedirect.com/science/article/pii/001793109090079A
942			_2ddc _n0 _cART _o14993 _pMr. Muhammad Rafique Al Haj Rajab Ali (Late)
999			_c814748 _d814748