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Title: Water bell and sheet instabilities

Description: This movie illustrates several instabilities that may arise when a fluid jet impacts a solid surface to form a water bell or sheet. In our study, glycerol-water solutions were pumped through a source nozzle and struck the center of a circular steel plate. An adjustable lip adjoining the plate determined the take-off angle.

Under steady source conditions, two separate water bell instabilities are observed. The first is marked by a periodic rupture and regeneration of the bell, the second by a jellyfish-like oscillation without rupture. Following a decrease in the source flux, a third instability may occur: the bell breaks, and a smaller water bell is formed. Note the associated cusp structures.

Our investigation revealed that, over a range of take-off angles and for steady source conditions, one may generate conical sheets with quasisteady cusps along their upper edge. At low viscosity, both cusps and capillary waves are present. Finally, we demonstrate the effect of surfactant on the stability of a fluid sheet.

Credits: Jeffrey M. Aristoff, Chad Lieberman, Erica Chan and John W. M. Bush

References:

Web Page: http://pof.aip.org/pof/gallery/video/2006/912609phfenhanced.mov

Contributed By: Tausif Billah