Interaction of two deformable viscous drops under external temperature gradient

The axisymmetric deformation and motion of interacting droplets in an impos ed temperature gradient is considered using boundary-integral techniques fo r slow viscous motion. Results showing temporal drop motion, deformations, and separation are presented for equal-viscosity fluids. The focus is on ca ses when the drops are of equal radii or when the smaller drop trails behin d the larger drop. For equal-sized drops, our analysis shows that the motio n of a leading drop is retarded while the motion of the trailing one is enc hanced compared to the undeformable case. The distance between the centers of equal-sized deformable drops decreases with time. When a small drop foll ows a large one, two patterns of behavior may exist. For moderate or large initial separation the drops separate. However, if the initial separation i s small there is a transient period in which the separation distance initia lly decreases and only afterward the drops separate. This behavior stems fr om the multiple time scales that exist in the system. (C) 2001 Academic Pre ss.