Spreading and splashing during a single drop impact on an inclined wetted surface

Experimental observations concerning spreading and splashing processes during a single liquid drop impact on an inclined wetted surface are performed using a high-speed digital camera at 10,000 frames per second. The range of the impact angles is 28.0A degrees-74.7A degrees. A 30 vol.% glycerol/water solution, butanol and heptane are selected as experimental fluids. Experimental observations show that both surface tension and viscosity can largely affect the spreading and splashing behaviors. Thereinto, the initiatory spreading velocity is mainly discussed quantitatively, which increases with the increasing of both the impact velocity and the impact angle. Surface tension is the main resistance for splashing, while low viscosity results in prompt splashing and high viscosity should be responsible for delayed splashing. Finally, the splashing thresholds are studied, and normal critical Weber numbers are suggested to denote splashing occurrence.