Experimental Study on Droplet Splash and Receding Breakup on a Smooth Surface at Atmospheric Pressure.

Droplet impact on a smooth solid surface at atmospheric pressure was experimentally studied and physically interpreted. A particular emphasis of the study is on the effects of liquid viscosity on the transition between droplet deposition (or droplet spreading without breakup) and droplet disintegration (including droplet splash and receding breakup). Specifically, the critical Weber number separating droplet deposition from droplet disintegration decreases and then increases with increasing Ohnesorge number (Oh). The splash in the low-Oh region and the receding breakup in the high-Oh region were analyzed qualitatively based on the unbalanced forces acting on the rim of the spreading or receding liquid film. A semiempirical correlation of droplet deposition/disintegration thresholds is proposed and well fits the experimental results from previous and present studies over a wide range of liquid viscosity.