A theoretical study of the motion of a viscous drop toward a fluid interface at low Reynolds number

In this paper we use a boundary-integral technique to numerically investigate the motion of a viscous drop toward a fluid-fluid interface at low Reynolds number. We consider only the case of a drop moving toward its homophase. The solutions include large deformations of both the drop and interface for capillary numbers in the range 0.2 [les ] Ca [les ] 10 and the viscosity ratios between 0.1 [les ] λ [les ] 10, and illustrate the approach toward a film-drainage geometry for a drop which starts at a large distance from an initially undeformed, flat interface. We also consider briefly the effect of starting the drop closer to the interface.