In the ocean, many forces compete in driving convection, including the temperature and salinity of the water. In the laboratory, it’s possible to mimic these characteristics of oceanic circulation using two different fluids driven by temperature and concentration differences. Recently, researchers were exploring this problem—with the added twist of tilting the fluids ~1 degree—when they discovered a surprising result. After an extended time, the convection self-organized into alternating parallel columns of ascending (dark) and descending (light) fluid. The researchers nicknamed this behavior super-highway convection. Read more about it here or in their paper. (Video credit: F. Croccolo et al; submitted by A. Vailati)
Helicopter rotor wake simulation from
Black Hawk Rotor Vortex Wake
“Aft view of the UH-60 helicopter rotor detatched eddy simulation showing the 3D nature of the vortex wake. Note the separated flow leaving the centerbody in the middle of the image, and the uneven wake separation due to the blade motion.
Investigator: Neal Chaderjian, NASA Ames Research Center, Moffett Field, Ca
Visualization: Tim Sandstrom, NASA/ Ames
More info available here: www.nas.nasa.gov/SC12/demos/demo1.html
Follow us on Twitter: www.twitter.com/NASA_Supercomp ”
Animated top view here
Mushroom vortices in round jet
From the Gallery of Fluid Motion (probably somewhere deep in the archives?)
Waltzing Volvox, from the Goldstein Lab at the University of Cambridge
Volvox is a colonial green algae (more info at Wikipedia)
(And someone else has uploaded a more colorful video of dancing volvox here: http://www.youtube.com/watch?v=9pjW1cMfTz8)
Volvox, a colonial green algae (more info at Wikipedia)
From the Goldstein Lab, Department of Applied Mathematics and Theoretical Physics, University of Cambridge:
They do really, really cool research, as described by this awesome statement:
“When asked whether I am a theorist or an experimentalist, my reply is that I am a scientist. Our group seeks to understand fundamental principles that govern the behavior of nonequilibrium systems in physics and biology, using a combination of experiment and theory. This research is not easily described by a single, conventional academic label; rather, it involves the domains of condensed matter physics, physical chemistry, biological physics, fluid dynamics, applied mathematics, and geophysics. I subscribe to Poincaré’s motivation:
The scientist does not study nature because it is useful;
he studies it because he delights in it, and he delights in it because
it is beautiful. If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living.
I also believe that some of the best science is close to art, and that Glenn Gould captured this spirit when he said
The purpose of art is not the release of a momentary ejection of adrenaline but rather the gradual, lifelong construction of a state of wonder and serenity.”
UMMM and they have a YouTube channel!
In the image above we see two spheres of the same size, shape, and material being dropped into water. The left sphere has almost no splash, whereas the one on the right has a spectacular curtain-like splash. Why the big difference? It all comes down to the surface treatments. The glass sphere on the left is hydrophilic, but the right one has been treated to be hydrophobic. As a result, the water-fearing molecules of that sphere push the water away, allowing air to be entrained below the water’s surface instead. This creates a big splash that’s absent when the water moves smoothly around the hydrophilic sphere. (Photo credit: L. Bocquet et al.)
Hele-Shaw cell experiments from nervous system — with video!
Nanoscale Saffman-Taylor instabilities
Photo 1: Pola Goldberg-Oppenheimer, University of Cambridge, Dept. of Engineering (source)
“Fingering instabilities in viscoelastic liquids”
Source: José Bico, with with Ryan Welsh & Gareth McKinley
Oh my glob there’s a movie — this needs to be made into a gif
Interests include: “Experiments involving Interfacial Hydrodynamics, Wetting and Non-wetting, Complex fluids and general “Soft Matter”.”
Recent experiments include: “Spreading flowers” “Gobbling droplets” “Dripping of a jelly liquid” “Fingering instabilities in viscoelastic liquids” “Wrinkling of elastic membranes” “Liquid trains in a tube”
Can’t tell if that’s from a faculty page… or OKC profile
Place a viscous fluid in the gap between two plates of glass and you have created a Hele Shaw cell. If a less viscous fluid is then injected between the plates, a fascinating pattern of finger-like protrusions results. This is known as the Saffman-Taylor instability. Because of the relative simplicity of the set-up, it’s possible to create such experiments at home using common household fluids like glycerin, dish soap, dyed water, or laundry detergent. (Photo credits: Jessica Rosencranz, Jessica Todd, Laurel Swift et al, Andrea Fabri et al, Tanner Ladtkow et al, Mike Demmons et al, Trisha Harrison, Justin Cohee, and Erik Hansen)
Viscous fingering: Saffman-Taylor instability in a Hele-Shaw cell
Image 1: Jessica Todd. Source
Image 2: Dustin Grace, Jessica Todd, Marilyn Poon, Robert Neilson. Source: efluids image gallery
Caption: “Saffman-Taylor instability in a Hele-Shaw cell. When viscous fluid is displaced by a less viscous fluid in a thin layer, a fingering instability forms.
Contributors: Dustin Grace, Jessica Todd, Marilyn Poon and Robert Neilson, University of Colorado, Boulder.
Image created as part of Jean Hertzberg’s Flow Visualization: A Course in the Physics and Art of Fluid Flow.”
“Adaptive Mesh Simulation with a Finite Volume shallow water model (St-Cyr, Jablonowski et al., MWR 2008). The figure shows the relative vorticity field at day 6 of a barotropically unstable wave.”
Organisms are resilient patterns in a turbulent flow
Quote in context: “Imagine a child playing in a woodland stream, poking a stick into an eddy in the flowing current, thereby disrupting it. But the eddy quickly reforms. The child disperses it again. Again it reforms, and the fascinating game goes on. There you have it! Organisms are resilient patterns in a turbulent flow—patterns in an energy flow…. It is becoming increasingly clear that to understand living systems in any deep sense, we must come to see them not materialistically, as machines, but as stable, complex, dynamic organization.”
— Carl R. Woese. 2004. “A New Biology for a New Century.” Microbiol Mol Biol Rev. 2004 June; 68(2): 173–186. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC419918/
We are but whirlpools in a river of ever-flowing water. We are not stuff that abides, but patterns that perpetuate themselves. A pattern is a message, and may be transmitted as a message