Glacial river veins wend and meander through these aerial photographs of Iceland by photographer Stas Bartnikas. Rivers naturally change their course over time, but here seasonal melts and the slow grinding of glaciers adds further chaos to the scene. Captured from above, these landscapes show the scars of past flows. (Image credit: S. Bartnikas; via Colossal)
Earth and Mars are well-known for their dust storms, but a new source of extraterrestrial dust storms is joining them: Saturn’s moon Titan. Titan already shares unusual similarities to Earth: it is the only other place known to currently have stable liquid bodies at its surface. On Earth, water makes up our lakes and oceans; on Titan, it’s methane.
The evidence that Titan may also have dust storms dates from several Cassini flybys in 2009 and 2010. Cassini observed short-lived infrared bright spots in a dune-covered equatorial region. After considering several other possible sources for these temporary bright spots, researchers concluded that the most likely explanation was dust clouds suspended by high winds. This suggests that the dune fields on Titan are still actively changing, just like those on Earth and Mars! (Image credit: artist’s concept for Titan dust storm – NASA/ESA/IPGP/Labex UnivEarthS/University Paris Diderot; research credit: S. Rodriguez et al.; submitted by jpshoer)
Leidenfrost drops – which skitter almost frictionlessly across extremely hot surfaces on a thin layer of their own vapor – are notoriously mobile. We’ve seen numerous methods of controlling their propulsion, often using specially-shaped surfaces. But it turns out that some Leidenfrost drops can self-propel even on a smooth, flat surface (top image).
Internally, large Leidenfrost drops have complicated, but symmetric flows that are driven by temperature and surface tension variations across the drop. But as the drop evaporates, that symmetry eventually gets broken, leaving behind a single large circulating flow.
Beneath the drop, that internal circulation affects the vapor layer. It causes the layer to take on an overall tilt, and the rotation, along with that slight angle in the vapor layer, causes the Leidenfrost drop to roll away like a wheel. (Image and research credit: A. Bouillant et al.; via NYTimes)
Manta rays spend much of their time leisurely cruising through the water with their meter-wide mouths open. As they swim, they filter plankton, which makes up most of their diet, from the water. And they do so without ever clogging.
The inside of the manta’s mouth is lined with gill rakers (upper right), a series of comb-like teeth. When flow hits the leading edge of these (bottom), it creates a vortex that accelerates any particles caught in the flow. They essentially ricochet along the top of the gill rakers, getting led straight into the manta’s digestive system – while excess water gets deflected between the gill rakers and back out the manta’s gills. To drive this, all the manta has to do is swim; with the right flow speed, the shape of the gill rakers handles all the filtration with no additional effort. (Image credit: manta ray – G. Flood; gill rakers – M. Paig-Tran; flow vis – R. Divi et al., source; research credit: M. Paig-Tran et al.; via The Atlantic; submitted by Kam-Yung Soh)
In 2016, a senior talent show launched a new viral craze: water bottle flipping. As improbable as it seems at first glance, physics is actually on your side when it comes to pulling this trick off. As explained in this classroom-oriented paper and the video abstract below, the sloshing of the water in the bottle as it flips slows its rate of rotation, which creates the stable landing. You don’t even need water to make the trick possible. Using two tennis balls will also give a stable flip – provided they have room to spread out. When they fly apart, they change the bottle’s moment of inertia and that slows down the rotation rate. All in all, it’s a great lesson in conservation of angular momentum.
And, in case you’re wondering whether the water helps with sticking that landing, we’ve got you covered there, too. (Image credit: A. Johnson, source; video and research credit: P. Dekker et al.)
In this month’s FYFD/JFM video, we explore some intersections between the animal kingdom and our own lives. Learn about designing better buildings with inspiration from termites; see the fascinating superpower of the star-nosed mole; and learn what goes into products like the toothpaste you (hopefully) use daily. All this and more in the latest video! Missed one of our previous ones? Good news: we’ve got you covered. (Image and video credit: N. Sharp and T. Crawford)
During the recent Perseid shower, photographer Petr Horálek caught an awesome timelapse of an exploding meteor and the vortex ring it created. This is a type of persistent train left when meteors pass through the upper atmosphere. The exact physics are not well understood because such events are difficult to observe; catching them at all is basically just happenstance. But one interpretation is that we’re seeing trails of plasma left by the ionization of parts of the meteor. When the meteor hits the upper atmosphere, there’s an extremely strong hypersonic shock wave. The jump in temperature across that shock wave is enough to pull atoms apart, creating a plasma. The train left by this meteor’s demise was faintly visible even an hour after the fireball. (Image credit: P. Horálek, video version; via APOD; submitted by Andrea S.)
Sound can manipulate fluids in fascinating ways, from levitation to vibration. Here researchers use sound to levitate and manipulate droplets and turn them into bubbles. Increasing the acoustic pressure on the levitating droplet flattens it, then slowly causes the drop to buckle. When the buckled film encloses a critical volume, the sound waves resonate inside it. That causes a big jump in acoustic pressure, which makes the drop snap closed into a bubble. (Image and research credit: D. Zang et al.; via Science News; submitted by Kam-Yung Soh)
In “Hydrophytes,” industrial designer Nicole Hone imagines a future in which we’ve designed aquatic plants to counter some of the effects of climate change. To create her plants, Hone designed them with digital tools, then printed them with multi-material 3D printers. Their movements are brought to life with pneumatic pumps that fill and collapse them in response to external interactions. The motion and character of these imagined plants is astounding; they truly seem to be alive. It’s an incredible intersection of science, art, and technology. Check out the full film below. (Image and video credit: N. Hone; via Colossal)
In the latest JFM/FYFD video, we tackle some of the less pleasant aspects of summer weather: stopping invasive insects, understanding how plants dispense poison, and looking at the physics behind jellyfish stings. And if you’ve missed any of our previous videos, we’ve got you covered. (Image and video credit: T. Crawford and N. Sharp)