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A spray in a vacuum does not make a splash, researchers in Chicago have found. Their results could lead to cleaner ink-jet printing and smoother spraying of surfaces.
When a liquid droplet hits a solid surface, it throws up a crown-shaped rim of liquid, which breaks up into tiny drops. Harold Edgerton, the pioneer of high-speed photography, captured this corona in his famous photo of a milk splash.
But splashing can be a nuisance, as it scatters the liquid. Without splashing, each droplet sprayed from an ink-jet printer would produce a smooth circular dot, rather than one with a ragged edge.
Now Sidney Nagel and his colleagues at the University of Chicago, Illinois, have shown that lowering the air pressure in which a spray is projected can reduce and even eliminate splashing.
They fired drops of alcohol on to a glass slide, the researchers report on arXiv1. And they found that the splashy corona disappears completely if the air pressure is reduced to around one-third of normal atmospheric pressure.
To read more about this story, click here: http://www.nature.com/news/2005/050207/full/050207-1.html
Posted: Mar 02, 2005 9:35AM by Joe
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