Scaling Law Breaking in Unequal-size Droplet Coalescence

This Letter examines the coalescence of two unequal-size spherical liquid droplets in the inviscid regime. We find that the liquid bridge evolution exhibits a breaking from the classical 1/2 power-law scaling [Phys. Rev. Lett. 95, 164503 (2005)]. Employing an energy balance analysis, we attain a theoretical model to collapse bridge evolution data of different droplet size ratios. This model reveals an exponential dependence of the bridge's radial growth on time, which is intrinsically scaling-free owing to the asymmetric movement of the liquid bridge.