Film drainage between colliding drops at constant approach velocity: Experiments and modeling

Experiments and modeling of the drainage of the thin liquid film between tw o deformable spherical drops approaching each other at constant velocity in another liquid are being presented. Two numerical models based on the lubr ication theory have been developed considering the cases of immobile or mob ile drop interfaces. The absolute film thickness and the thinning rate have been measured using laser interferometry for a wide range of capillary num bers. In all studied cases, the model with immobile interfaces was found to give the best predictions of the experimental time evolution of the film t hickness and radial expansion. These results made it possible to derive a t ypical time scale of the drainage process. (C) 2000 Academic Press.