Droplet bouncing and merging on a wet spherical surface

The impact of droplets on surfaces of varying characteristics has seen a plethora of investigations owing to its practical relevance in many natural and industrial processes. Of particular interest is liquid droplets that either coalesce or completely rebound when impacting a thin layer of the same liquid which typically occurs at low impact Weber numbers. Several studies have established regimes of impact outcomes for which the transition between bouncing and merging may occur upon changing film thickness normalized by drop radius, h^*. These studies however focus on impact on a thin film on a planar surface. Herein we present an experimental investigation on liquid droplets impinging a thin film on curved surface with h^* ranging from 0.01-0.05 and discuss the effects of viscosity on the location of the inertial limit transition boundary.