Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Kelvin-Helmholtz Instability
The Kelvin-Helmholtz instability occurs when velocity shear is present in a single fluid or when two different fluids have a velocity difference across their interface. As shown in this numerical simulation, the instability produces a fractal-like pattern of eddies turning over on themselves. The Kelvin-Helmholtz instability is commonly found in nature between cloud layers. #…
Physics Tattoos
This is a man with great commitment to fluid dynamics. He writes: This, on my leg, is the incompressible form of the conservation of mass equation in a fluid, also known as the continuity equation. When people ask what it means, I say it defines flow. Sometimes I say it means you should have studied…
The Leidenfrost Effect
The Leidenfrost effect occurs when a liquid comes in contact with a mass significantly hotter than the liquid’s boiling point. Upon contact, a thin layer of the liquid will be vaporized, forming a lubricating gas layer that temporarily insulates the hot mass from the cold liquid. This effect is responsible for water skittering across a…
Flutter and the Tacoma Narrows Bridge
Sixty years ago yesterday the original Tacoma Narrows Bridge (a.k.a. Galloping Gertie) collapsed as a result of aeroelastic flutter during 42 mph winds. Flutter is a phenomenon in which the fluid dynamics and structural dynamics of a system are closely coupled, in this case resulting in a dramatic failure. The high sustained winds provided an…
Reader Question
loscheiner asks: So the video about the ooblek was clearly filmed at CU Boulder. Do you go to school here? Also, you should enable disqus comments or replies to your posts! Nope! I have connections to three different universities (one of which has been featured here), but none of them is CU Boulder. I just found…
Protecting an Egg with Oobleck
Using non-Newtonian fluids as “liquid armor” is an active area of research and development. Here students demonstrate the efficacy of shear-thickening as a defense against sudden impact by dropping a bag of oobleck containing a raw egg from different heights.
Ferrofluid Art
Hi there, Regarding ferrofluids, check out these lovely picture via Linden G. Her flickr photostream is full of beautiful ferrofluid pics. http://www.flickr.com/photos/13084997@N03/5134495790/ His photostream does have some lovely ferrofluid shots as well as some water figures. I especially like the surrealism of this one. Thanks for sharing!
Morpho Towers
Artists Sachiko Kodama and Yasushi Miyajima use ferrofluids and magnetic fields to create their “Morpho Towers – Two Standing Spirals” artwork. Ferrofluids are formed from a suspension of ferrous material in a oil or water and are a popular subject for fluid dynamics as art. You can even make your own ferrofluid at home. (via…
Bell’s Powered Kite
Inventor Alexander Graham Bell is best known for the telephone but also made many contributions to early aeronautics. This man-carrying kite, the Cygnet III, was a powered kite with a “wing” made of 3,393 tetrahedral cells; it managed enough lift to fly on March 1, 1912. National Geographic is featuring photos from the early days…
The No-Slip Condition
Viscosity plays an important role near surfaces in fluid mechanics. Friction between the fluid and the solid surface creates a “no slip” condition at the wall. In the video, dye injected near the wall remains there because there is little or no velocity of the fluid near the wall. As the dye filament is pulled…