Splashing of impacting drops

We investigate the impact velocity beyond which the ejection of smaller droplets from the main droplet (splashing) occurs for droplets impacting a smooth surface. We examine its dependence on the surface wetting properties and droplet surface tension. We show that the splashing velocity is independent of the wetting properties of the surface, but increases roughly linearly with increasing surface tension of the liquid. A preexisting splashing model is considered that predicts the splashing velocity by incorporating the air viscosity. The model is consistent with our data, but the calculation is complex. To address this issue, we propose a simplification, assuming atmospheric conditions and low viscosities, and show that the simplification gives an equally good prediction of the splashing velocity from a simple analytical formula.