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:: By Megan Lisagor

:: Photo credit: Courtesy Lei Xu

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Investigations ::

Fig. 1

Splash away

Splish sans splash—you can have one without the other. University physicists have discovered how to lose the splatter: eliminate the air. Liquid naturally splashes, scattering droplets, when it hits a flat surface. But as atmospheric pressure lowers, the droplets diminish, graduate student Lei Xu, SM’03, reported at a March 22 meeting of the American Physical Society.

photo:  fig1

Using methanol, ethanol, and 2-propanol, Xu demonstrated the phenomenon with Sidney Nagel, the Stein-Freiler distinguished service professor in physics, and assistant professor Wendy Zhang. The images above show an alcohol drop en route to strike smooth glass and after impact. As the air pressure decreases, so does the splash—until finally, at the lowest pressure in the last frame, there’s none at all.

Air’s drag, the team believes, plays a role in breaking up the fluid. The findings could lead to applications in internal-combustion engines, ink-jet printing, and industrial washing.