Influence of liquid properties on the oblique splashing threshold of drops

This report investigates how different splashing mechanisms affect the oblique splash threshold of drops impacting a dry solid surface. The splashing behaviors of water, ethanol, and a water/ethylene glycol solution are observed over a wide range of drop diameters (0.7 mm < D < 2.2 mm) and Weber numbers (10 < We < 1040), and several published models are tested in order to predict the thresholds between deposition, one-sided splashing, and two-sided splashing. We found that the splash threshold of liquids that exhibit the corona splashing mechanism can be readily predicted by existing models. However, for liquids such as water that exhibit prompt splashing, the oblique splash threshold is not successfully predicted by any presently established correlation. Hence, our findings identify a critical knowledge gap in the drop impact field, since the behavior of water is of fundamental importance to countless engineering problems. Finally, combining our own results with others reported in the literature, we address some contradictory reports about the influence of liquid viscosity on the splash threshold and demonstrate that the presence or lack of thin-sheet in different experiments could explain the contradictions present in the literature.