Interaction, Spreading and Splashing of Multiple Droplets on a Surface

Yarin and Weiss[357] also determined the number and size of secondary droplets, as well as the total ejected mass during splashing. Their experimental observations by means of a computer-aided charge-coupled-device camera and video printer showed that the dependence of the critical impact velocity, at which splashing initiates, on the physical properties (density, viscosity, and surface tension) and the frequency of the droplet train is universal, and the threshold velocity may be estimated by  

Comparing this splashing criterion to that derived by Stow and Hadfield13961 for single droplet impact (Eq. 44b), the scaling 

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