Numerical simulation on the interaction of buoyant drops with a fluid-fluid interface

The fully three-dimensional interactions of one or two buoyant drops with a fluid-fluid interface are studied numerically at the moderate Reynolds number and Bond number. This complex interaction process is successfully simulated using the three-dimensional level set approach to deal with the deformable inter face and drops. The characteristics of vortex ring generated at the coalescence between the interface and the drop depend upon the viscosity ratio between two fluids, and they have much to do with a jet formation process. In the case of two drops, the motion of the trailing drop is influenced hy the deformation of interfaces through the coalescence of the leading drop with its homophase. The behavior of the trailing drop is also classified into two types with respect to the viscosity ratio. These studies show that the investigation in the viewpoint of vorticity is effective on the understanding of the interaction between drops and an interface.