Month: July 2022

“Metamorphe”
A smoke-like haze drifts over surreal landscapes in the “Metamorphe” series by Reuben Wu and Jenni Pasanen. Though fluidic in appearance, these pieces are a merger between Wu’s drone light photography and Pasanen’s AI-assisted digital creations. Even so, the images are extremely evocative of fluid motion, connected as they are to human senses (like smell, hearing, and touch) that often rely directly on fluid dynamics. For more, check out the artists’ sites and Instagram. (Image credits: R. Wu and J. Pasanen; via Colossal)
July 29, 2022
Swimming Together
Scientists have long pondered the possibilities of hydrodynamic benefits to the ways fish school. But most analyses of schooling have assumed a fixed spacing that’s far more orderly than what we observe in nature. In this experiment, researchers instead used a pair of robotic swimmers (essentially hydrofoils) to explore a range of swimming formations. What they found was a map of places where a second swimmer could easily “lock in” to a position relative to the leader and have their positioning stabilized by interactions with the leader’s wake (lower image). Interestingly, the beneficial regions extend much further downstream for fish positioned diagonally to the leader than they do for one directly following. With such a wide range of easily-stabilized following positions, it’s no wonder that schools of fish are amorphous instead of strictly crystalline! (Image credit: top – S. Pena Lambarri, map – J. Newbolt et al.; research credit: J. Newbolt et al.)
The shaded areas of this map represent areas where a second swimmer can passively “lock-in” relative to the leader’s position, shown in gray. This data is based on tests with robotic swimmers.
July 28, 2022
How Dunes Form
On its face, the idea that sand and wind can come together to form massive mountainous dunes seems bizarre. But dunes — and their smaller cousins, ripples — are everywhere, not just on Earth but on other planetary bodies where fine particles and atmospheres interact. In this video, Joe Hanson gives a great overview of sand dynamics, beginning with what sand is, how it moves, and what it can ultimately form. It’s well worth a watch, even if you know a little about dunes already; I know I learned a thing or two! (Image and video credit: Be Smart)
July 27, 2022
You’re Drunk, Toadlet
Most frogs and toads are excellent jumpers, taking off and landing with a control and grace that rivals elite athletes. Not so for the pumpkin toadlet. These species have become so miniaturized that the structures of their inner ears are too narrow for the fluid flow that helps frogs (and humans!) orient themselves in space. So while the toadlet certainly can jump, it careens through the air drunkenly and lands in any old direction. It’s hard not to laugh at their belly flops, somersaults, and straight-up head-first crashes. Fortunately, being so small, these landings don’t seem to hurt the toadlets, but one imagines they’re unpleasant nevertheless. Left to their own devices, the pumpkin toadlet prefers walking, slowly, like a chameleon; it might be the only way to stay within the limits of its inner ear. (Image credits: top – S. Kikuchi, others – R. Essner, Jr. et al.; research credit: R. Essner, Jr. et al.; via The Atlantic; submitted by Kam-Yung Soh)
July 26, 2022
Rifts in Rafts
A raft of particles floating on water has some natural cohesion from particle attraction and capillary action. But when the raft is pulled apart, what happens? Does it break cleanly in one spot? Does it stretch and deform? That’s what this video explores. It turns out that the speed you pull the raft at determines how it holds together. Every particle cluster has a preferred relaxation rate, and by choosing the pulling speed, you determine which relaxation rate — and therefore cluster size — can survive most effectively. (Image and video credit: K. Tô and S. Nagel)
July 25, 2022
Aqueous Chandeliers
Colorful dyes falling through water form chandelier-like, branching shapes. These formations are the result of a slight density difference between the heavier dyes and the surrounding water. As the dye falls, Rayleigh-Taylor instabilities cause the mushroom-like blobs and their branches. With creativity and photographic skill, Mark Mawson turns these ephemeral shapes into bold liquid sculptures, frozen in time. See more of his work in these previous posts, on his website, and on Instagram. (Image credit: M. Mawson)
July 22, 2022
Listening to the Sizzle
The sizzle of frying food is familiar to many a cook, and that sound actually conveys a surprising amount of information. In this study, researchers suspended water droplets in hot oil and observed their behavior, both with high-speed video and with microphones. They found that these vaporizing drops created three types of cavities in the oil: an exploding cavity that breaks the surface, an elongated cavity that remains submerged, and an oscillating cavity that breaks up well below the surface. All three cavities flung oil droplets upward, and all three were acoustically distinct from one another. That means, as the authors suggest, that it might be possible to measure the aerosol droplets generated during frying simply by listening! (Image credit: fries – W. Dharma, others – A. Kiyama et al.; research credit: A. Kiyama et al.; via Cosmos; submitted by Kam-Yung Soh)
July 21, 2022
Treating Water
In an ongoing series, Practical Engineering is looking at how civil engineers deal with sewage and wastewater. In this video, Grady looks at how wastewater gets treated to remove contaminants. Where possible, engineers use gravity to do this job, building infrastructure that slows the flow down and lets gravity make heavier particles settle out. Of course, sometimes gravity alone doesn’t act quickly enough, in which case engineers use a little extra help in the form of chemicals that can neutralize particles’ electric charge and help them clump together and settle faster. Check out the full video for a tour of how wastewater gets processed. (Image and video credit: Practical Engineering)
July 20, 2022
Extreme Weather
Many of the exoplanets we’ve observed so far are extreme environments. WASP-121b is known as a hot Jupiter, a gas giant so close to its star that it orbits in just 30 hours. The exoplanet is tidally-locked to its star, meaning that one side always faces toward the star and the other faces away. This constant sunlight makes the daytime side of the planet hot enough to vaporize metals. A recent study combined observations of the exoplanet with numerical simulations to model both the daytime and nighttime atmosphere of the exoplanet. The results are pretty wild. The authors found evidence of 18,000 km/h winds that blow hot gases from the dayside to the nightside, where temperatures cool enough for some metals — primarily corundum — to rain out of the atmosphere. Given the trace amounts of other elements available in the atmosphere, the authors posit that the nightside of the planet may have rainfall of liquid rubies and sapphires. (Image credit: NASA/ESA; research credit: T. Mikal-Evans et al.; via Physics World)
July 19, 2022
Submarine Eruptions
The green-blue plume on the left of this satellite image is an eruption from Kavachi, an underwater volcano in the Solomon Islands. Kavachi’s crest is currently estimated to lie 20 meters below the surface, with its base at a depth of 1.2 kilometers. Eruptions are quite common at the volcano, but that doesn’t stop wildlife — like hammerhead sharks! — from making the crater their home. Over the last century, Kavachi’s eruptions have repeatedly formed small islands at the surface, but they were quickly eroded away by wave action. (Image credit: J. Stevens/NASA/USGS; via NASA Earth Observatory)
July 18, 2022