Energy and hydrodynamic analyses of coalescence-induced jumping droplets

We report our dynamic analysis of coalescence-induced jumping on superhydrophobic surfaces with a full 3D numerical model supported with experiments. The analysis shows that approximately half (40%-60%) of the released surface energy during the coalescence is converted to kinetic energy before the detachment starts. The rapid increase in the kinetic energy at the beginning is initiated from low pressure associated with the high negative curvature of a liquid bridge. The asymmetric nature of the droplet evolution with a superhydrophobic wall generates high pressure at the bottom, which provides driving force to make the merged droplet spontaneously jump from the wall. (C) 2013 AIP Publishing LLC.