Interaction between two drops ascending in a linearly stratified fluid

Three-dimensional numerical simulations of the interaction between two drops rising in a thermally stable stratified fluid are presented. The governing equations are solved using a finite-volume/front-tracking method. The influence of stratification on the dynamics of two drops moving in line and side by side is studied. For the case of nearly spherical drops ascending side by side, drops remain in the horizontal alignment during the interaction; but the rate of separation, after their initial collision, decreases for stronger stratifications. We demonstrate that, in contrast to the case of a homogeneous fluid, two drops moving in tandem in a strongly stratified fluid retain their in-line configuration.