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Fluid Dynamics Seminar

Monday, Feb 22, 2010, 4:00 PM
Cullimore Lecture Hall, Room 611
New Jersey Institute of Technology

The mechanism of a splash

Shreyas Mandre

School of Engineering and Applied Sciences, Harvard University

Abstract

Splashing of droplets, due to its ubiquity in natural and technological phenomena and the captivating beauty of the resulting geometrical forms, has inspired many meticulous studies. Yet, a clear theoretical understanding of the mechanism of splashing on dry surfaces has eluded us for more than a century. The origin of the splash has been traced to a thin sheet of fluid ejected near the impact point, with the ejected sheet disintegrating into smaller droplets. But what causes this liquid sheet to be ejected in the first place?

I will present analysis showing that a micron thick layer of surrounding air gets trapped between the drop and the surface and cushions the impact. The sheet is ejected as a result of the cushioning before the drop touches the surface. Quanitative predictions can be made about the precise moment and location of sheet ejection, and the thickness and the speed of the sheet. This information allows us to elucidate the mechanism for the splash and map out the parameters promoting splashing.