Hydrodynamic Interaction between Spheres Coated with Deformable Thin Liquid Films

@article{citeulike:2184105, abstract = {In this article, we considered the hydrodynamic interaction between two unequal spheres coated with thin deformable liquids in the asymptotic lubrication regime. This problem is a prototype model for drop coalescence through the so-called "film drainage" mechanism, in which the hydrodynamic contribution comes dominantly from the lubrication region apart from the van der Waals interaction force. First, a general formulation was derived for two unequal coated spheres that experienced a head-to-head collision at a very close proximity. The resulting set of the evolution equations for the deforming film shapes and stress distributions was solved numerically. The film shapes and hydrodynamic interaction forces were determined as functions of the separation distance, film thickness, viscosity ratios, and capillary numbers. The results show that as the two spheres approach each other, the films begin to flatten and eventually to form negative curvature (or a broad dimple) at their forehead areas in which high lubrication pressure is formed. The dimple formation occurs earlier as the capillary number increases. For large capillary numbers, the film liquids are drained out from their forehead areas and the coated liquid films rupture before the two films "touch" each other. Meanwhile, for small capillary numbers, the gap liquid is drained out first and the two liquid films eventually coalesce.}, author = {Yang, Seung-Man and Leal, Gary L. and Kim, Young-Seok }, citeulike-article-id = {2184105}, doi = {10.1006/jcis.2002.8376}, journal = {Journal of Colloid and Interface Science}, keywords = {lubrication, qualifier}, month = {June}, number = {2}, pages = {457--465}, posted-at = {2007-12-31 22:32:34}, priority = {3}, title = {Hydrodynamic Interaction between Spheres Coated with Deformable Thin Liquid Films}, url = {http://dx.doi.org/10.1006/jcis.2002.8376}, volume = {250}, year = {2002} }

TY - JOUR ID - citeulike:2184105 L3 - citeulike-article-id:2184105 TI - Hydrodynamic Interaction between Spheres Coated with Deformable Thin Liquid Films JF - Journal of Colloid and Interface Science VL - 250 IS - 2 SP - 457 EP - 465 N2 - In this article, we considered the hydrodynamic interaction between two unequal spheres coated with thin deformable liquids in the asymptotic lubrication regime. This problem is a prototype model for drop coalescence through the so-called "film drainage" mechanism, in which the hydrodynamic contribution comes dominantly from the lubrication region apart from the van der Waals interaction force. First, a general formulation was derived for two unequal coated spheres that experienced a head-to-head collision at a very close proximity. The resulting set of the evolution equations for the deforming film shapes and stress distributions was solved numerically. The film shapes and hydrodynamic interaction forces were determined as functions of the separation distance, film thickness, viscosity ratios, and capillary numbers. The results show that as the two spheres approach each other, the films begin to flatten and eventually to form negative curvature (or a broad dimple) at their forehead areas in which high lubrication pressure is formed. The dimple formation occurs earlier as the capillary number increases. For large capillary numbers, the film liquids are drained out from their forehead areas and the coated liquid films rupture before the two films "touch" each other. Meanwhile, for small capillary numbers, the gap liquid is drained out first and the two liquid films eventually coalesce. KW - lubrication KW - qualifier AU - Yang, Seung-Man AU - Leal, Gary AU - Kim, Young-Seok PY - 2002/06/15/ UR - http://dx.doi.org/10.1006/jcis.2002.8376 ER -