A drop of fluorescent dye falling into quiescent water forms fantastical structures that are a mixture of vorticity, turbulence, and molecular diffusion. The horseshoe-like shape near the front of the drop is a typical shape for two fluids strained by moving past one another. The main section of the drop billows outward like a parachute, but the turbulence of its wake stretches the dye into fine threads that quickly disperse in the water. (Photo credit: D. Quinn et al.)
Tag: fluids as art
“Levitating Water”
Al Seckel, a cognitive neuroscientist and expert on illusions, created this “Levitating Water” installation, in which multiple streams of water appear as a series of levitating droplets thanks to a strobing light. The well-timed strobe lighting tricks the brain into seeing many different falling droplets as the same, nearly stationary droplet. The effect is similar to the one created by vibrating a stream of falling water. (Video credit: wunhanglo)
Incense in Transition
A buoyant plume of smoke rises from a stick of incense. At first the plume is smooth and laminar, but even in quiescent air, tiny perturbations can sneak into the flow, causing the periodic vortical whorls seen near the top of the photo. Were the frame even taller, we would see this transitional flow become completely chaotic and turbulent. Despite having known the governing equations for such flow for over 150 years, it remains almost impossible to predict the point where flow will transition for any practical problem, largely because the equations are so sensitive to initial conditions. In fact, some of the fundamental mathematical properties of those equations remain unproven. (Photo credit: M. Rosic)
Bubble Lenses
In this video, artist Jesse Zanzinger experiments with the lens-like refractive properties of bubbles. Though focused on the bending of light, there’s plenty here in terms of coalescence, surface tension, and miscibility. He has a similar video that includes a shot of his set-up here. (Video credit: J. Zanzinger)
Fluids Round-up – 25 May 2013
Sometimes I come across cool links and stories about fluid dynamics that don’t quite fit into a typical FYFD post, but I’d like to start sharing those semi-regularly with round-up posts. Here’s some fun stuff I’ve seen lately:
- We’ve talked before about penguins and fluid dynamics, but this IOP talk from Helen Czerski is a great take on how they use fluids to escape predators.
- Over at FlowViz, Richard has a great video demonstrating deep versus shallow water waves side-by-side.
- io9 shows off the vibrational modes of mercury as well as explaining why birds can be good at flying or swimming but not both.
- Giant paint explosions (specifically here) may be fun to watch but the dangers are not for squeamish viewers.
- Dylan G sent us this 512K real-time fluid particle simulation that’s a fun distraction.
- xckd’s Randall Munroe answers all kinds of physics questions at his What If? blog, but occasionally there are some fluids ones. Two of my favorites consider a hypersonic steak and what happens if the glass is literally half full.
- Finally, for the cyclists and triathletes among you, the recent news that bicycle manufacturer Specialized has built its own wind tunnel has generated lots of discussion of aerodynamics in sport. Mark Cote (@MITAeroBike) and Chris Yu (@chrisyuinc) of Specialized’s aero R&D have been answering questions on Slowtwitch, Twitter, and in live chats.
And, yes, that last Specialized video chat includes an FYFD shout-out about 49 minutes in. 🙂
(Photo credit: Specialized)
Magnetic Putty
For a little Friday fun, enjoy this timelapse of magnetic putty consuming magnets. Really this is a bit of slow-motion magnetohydrodynamics. The magnet’s field exerts a force on the iron-containing putty, which, because it is a fluid, cannot resist deformation under a force. As a result, the putty will flow around the magnet, eventually coming to a stop once it reaches equilibrium, with its iron equally distributed around the magnet. Assuming the putty is homogeneously ferrous (i.e. the iron is mixed equally in the putty), that means the putty will stop moving when the magnet is at its center of mass. (Video credit: J. Shanks; submitted by Neil K.)
Tears of Wine
Wine drinkers may be familiar with the “tears of wine” often seen on the wall’s of a glass. The effect is a combination of evaporation and surface tension. As the low-surface-tension alcohol evaporates from the wine film left by swirling the glass, the higher local surface tension draws wine up the walls of the glass. Eventually enough wine gathers that droplets form and slide back down. This timelapse video shows how the beads form and move, almost dancing around the glass. The video’s author, Dan Quinn, has a second video with an awesome visual explanation of the behavior that’s well worth watching, too! (Video credit and submission: D. Quinn)
Liquid Sculptures
Water droplet art celebrates the infinite forms created from the impact of drops with a pool and rebounding jets. It’s a still life captured from split second interactions between inertia, momentum, and surface tension. These examples from photographer Markus Reugels are among some of the most complex shapes I’ve seen captured. Be sure to check out his website for more beautiful examples of liquids frozen in time. (Photo credits: Markus Reugels; via Photigy)
Skittering Droplets
Water splattered onto a a hot skillet will skitter and skip across the surface on a thin layer of vapor due to the Leidenfrost effect. The partial vaporization of the droplet provides a low-friction cushion for the droplet to glide on and acts as an insulating layer that delays the vaporization of the rest of the droplet. Modernist Cuisine shows us how serene this common and sometimes explosive effect looks at 3,000 frames per second. (On the topic of cooking, you can use the Leidenfrost effect to see if your skillet is hot enough when making pancakes. If a few droplets of water skitter across the pan before sizzling away, then your pan is ready for batter!) (Video credit: Modernist Cuisine; submitted by Eban B.)
Colorful Spirals
Artist Fabian Oefner captures these colorful portraits of fluid instability by dripping acrylic paints onto a metal rod, which is connected to a drill. When the drill is switched on, paint is flung away from the rod, creating these snapshots of centripetal force and surface tension. Note how droplets gather at the ends of the spiral arms like in a Plateau-Rayleigh or a rimming instability. For more, check out Oefner’s webpage, which includes a video showing how the images are made, or his previously featured work, “Millefiori”. (Photo credit: F. Oefner; submitted by Stephen D.)
