Artículo
Liquid film drag out in the presence of molecular forces
Fecha de publicación:
03/2013
Editorial:
American Institute Of Physics
Revista:
Physics of Fluids
ISSN:
1070-6631
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
From a practical as well as a conceptual point of view, one of the most interesting problems of physicochemical hydrodynamics is the drag out of a liquid film by a moving solid out of a pool of liquid. The basic problem, sometimes denoted the Landau-Levich problem [L. Landau and B. Levich, “Dragging of a liquid by amoving plate,” Acta Physicochim. USSR 17, 42–54 (1942)], involves an interesting blend of capillary and viscous forces plus a matching of the static solution for capillary rise with a numerical solution of the film evolution equation, neglecting gravity, on the
downstream region of the flow field. The original solution describes experimental data for a wide range of Capillary numbers but fails to match results for large and very small Capillary numbers. Molecular level forces are introduced to create an augmented version of the film evolution equation to show the effect of van derWaals forces at the lower range of Capillary numbers. A closed form solution for static capillary rise, including molecular forces, was matched with a numerical solution of the augmented film evolution equation in the dynamic meniscus region. Molecular forces do not sensibly modify the static capillary rise region, since film thicknesses are larger than the range of influence of van der Waals forces, but are determinant in shaping the downstream dynamic meniscus of the very thin liquid films. As expected, a quantitatively different level of disjoining pressure for different values of molecular constants remains in the very thin liquid film far downstream. Computational results for a wide range of Capillary numbers and Hamaker constants show a clear transition towards a region where the film thickness becomes independent of the coating speed.
Palabras clave:
Dip Coating
,
Intermolecular Forces
,
Landau-Levich
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Articulos(INTEC)
Articulos de INST.DE DES.TECNOL.PARA LA IND.QUIMICA (I)
Articulos de INST.DE DES.TECNOL.PARA LA IND.QUIMICA (I)
Citación
Schmidhalter, Ignacio; Cerro, R. L.; Giavedoni, Maria Delia; Saita, Fernando Adolfo; Liquid film drag out in the presence of molecular forces; American Institute Of Physics; Physics of Fluids; 25; 3; 3-2013; 1-13; 032105
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