Effect of Surface Dynamics on the Process of Droplet Formation from Supported and Free Liquid Cylinders

Abstract

The formation of droplets from cylindrical oil films supported by oleophilic filaments has been studied experimentally. In the absence of surfactant, the initial rate of growth of a disturbance on the cylindrical fluid surface was shown to depend on the interfacial tension, the film thickness, cylinder radius and liquid viscosity (as expected by theory). It was shown by theory and experiment that the effect of surfactant is to increase the resistance of the surface against dilational and compres- sional deformation in such a way that the initial rate of growth of droplets can be decreased by a factor of 4 as compared with the rate for a clean surface. It is argued that the effect of the presence of surfactant will be more important in the final than in the initial stages of droplet formation. This is most obvious for droplet formation from free cylinders, a process relevant to emulsification.