There has been much research on the stability of a thin The dynamic rupture process of a thin liquid film on a cylinder liquid film on the cylindrical surface (9-14). However, little is investigated numerically. First a nonlinear differential equation has been reported on the effect of the van der Waals potenthat describes the long-wave evolution of the interface shape is tial. Also, there has been some other research focused on derived. After the evolution equation is solved and analyzed, the the adhesion and spreading of liquids on a cylinder. They results reveal that a decrease in the cylinder radius will induce a used the static theory to predict the critical condition of stronger lateral capillary force and consequently will accelerate spreading. Gelfand and Lipowsky (15) studied a fluid system the rupture process. Moreover, the tendency of acceleration bein contact with a uniformly curved substrate, such as a cylincomes more explicit in the case of large surface tension. แญง 1996 Academic Press, Inc.
der or a sphere. By using the interface model and the Landau Key Words: nonlinear rupture; thin liquid film; van der Waals theory, they found that the effects of curvature may be subpotential.
sumed into an effective bulk field. Upton et al. (16) used the Landau theory to study the wetting phenomena on spherical and cylindrical substrates with the critical temperature 1 To whom correspondence should be addressed. the methods of linear analysis and nonlinear numerical calcu-564