Researching Of The Drop Morphologies On Solid Surface

Wetting property is one of the important characters of surface properties of solid materials and has been attracting widely attention because of their importance in basic science and practical applications. The wetting property is closely related to drop morphology, therefore researching of the drop morphologies on solid surface is a very important and real significant work. In this paper, some issues about the drop morphologies on solid surface, such as the approximate solution of the morphology of a drop on asymmetrical curved surface, the experimental observation of the morphology and adhesion force of liquid bridge between two flat substrates are firstly studied through experiments, simulations and theoretical analysis.Firstly, the behavior of droplets on flat surface, inclined surface and curved surface and the quasistatic processes of stretching of liquid bridge were simulated by Surface Evolver program, the drop morphologies obtained from simulation were in excellent agreement with the drop morphologies measured by Dataphysics OCA20 device, it verified that Surface Evolver could describe the stable morphology of a drop on solid surface well and thereby provided data support for the theoretical model.After that, the morphology of a drop on cylinders were analyzed when the effect of gravity is insignificant, the shape of drop on cylinders was from the spherical cap into a non rotating surface. From the Surface Evolver simulation result, we could clearly observe that the drop profiles almost well fitted into a circular arc at every azimuthal cross section, then a theoretical model of the morphology of a drop on cylinders was established. By comparing the characteristic parameters of drop morphology(the maximum radius、minimum radius、height) from the theoretical model and simulation result, giving out the available range of the theoretical model. The transition condition of drops from a clam-shell to barrel conformation could be obtained based on the theoretical model.Finally, the morphology and adhesion force of liquid bridge between two flat substrates was studied through experiments and theories. The results showed that the adhesion force of liquid bridge decreased with the increase of the distance of the liquid bridge. when the stretching distance was the same, the adhesion force of liquid bridge increased with the increase of the volume of liquid bridge. Under the condition of constant volume of the total liquid bridge and no control of the three phase line, the adhesion force of one liquid bridge and total adhesion force of smaller liquid bridges remained about the same.