Inertia-Dominated Coalescence of Drops

During the coalescence of a drop with a planar interface, a hole is generated in the microscopic film that separates the drop from the interface. A bridge forms, connecting the droptotheliquidbulk.Anexperimentalstudyhasbeenperformedtoinvestigatethetime dependence of the behavior of the bridge. A high-speed digital camera recorded the process from underneath the interface. During film rupture, the radius of the bridge demonstrated a power-law time dependence. These results agree with the power-law behavior predicted for drop/drop coalescence and we show that when using correct dimensionless forms, they fully agree with numerical simulations for variety of fluid combinations.