Search results for: “liquid jet”

Splash Sheets
When a falling liquid jet hits a horizontal impacter, it is deflected into a sheet. The shape of the sheet is dependent upon the velocity of the jet and the viscosity of the fluid. At sufficiently high speeds the sheet will be circular; at lower speeds it may sag into a bell-shape. The circular sheets can also develop an instability that causes them to become polygonal, as shown in the photos above. The fluid then flows out along the sheet, into and along the rim, and then spouts outward in jets at the polygon’s corners. For some conditions, the jets at the corners even form a sort of fluid chain (top photo). (Photo credit: R. Buckingham and J. W. M. Bush; via 14-billion-years-later)
December 27, 2011
Cavity Collapse
When a solid object is driven into a quiescent liquid, a cavity is formed. As the cavity collapses jets–a type of singularity–form. In this video, researchers explore the effect of the geometry of a disk being driven into water on the shape of the cavity formed and how it collapses. As in this video of droplet impacts on posts of different geometries, there’s a lovely symmetry in the results. (Video credit: O. Enriquez et al)
December 6, 2011
Atomization
Atomization–breaking a flowing liquid into a fine spray–is important for fuel injection in a variety of engines, including automobiles, jet engines, ramjets, scramjets, and rockets. The more effectively a liquid fuel can be dispersed as a spray in an engine, the more efficient and stable the combustion will be. The apparatus in this high-speed video injects an annular water sheet with concentric jets of air on either side of the water. The video series shows the effects of increasing the outer and inner air velocities relative to the water on the breakup of the liquid. What to the naked eye looks like a deluge, high-speed video reveals as a complex undulating structure.
September 9, 2011
Fluid Sculpture
Droplet collisions captured instantaneously create beautiful fluid sculptures that, though common, are too fast for the human eye. Here a bubble was blown onto the surface of the fluid, then a droplet was released to fall into the center of the bubble, bursting it. As that droplet rebounded in a Worthington jet, a second droplet was released and impacted the jet, creating the umbrella-like shape in the center. See Liquid Droplet Art for more photos. (Photo credit: Corrie White and Igor Kliakhandler) #
September 5, 2011
Effects of Viscosity
[original media no longer available]
Today’s video demonstrates the effect of viscosity, which measures a fluid’s resistance to deformation. On the left is a column of highly viscous fluid; the fluids become less viscous as one moves right. When a jet of dye is released into the highly viscous fluid, the jet is very slow to penetrate, whereas, in the rightmost column, the dye expands quickly into a turbulent jet. Between these extremes, we see a laminar dye jet entering the liquid. The mushroom-like shape the laminar jet takes is the result of the Rayleigh-Taylor instability, which occurs when a denser fluid is on top of a lighter fluid in a gravitational field.
October 27, 2010
Whipping Instabilities
When jets of liquid are introduced into an electrified medium in a process known as electrospinning, they can exhibit behavior known as whipping instabilities.
August 24, 2010

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