FYFD

Author: Nicole Sharp

  • Making Bubbles in Magma

    Making Bubbles in Magma

    When bubbles form in magma deep below the earth, volcanic eruptions follow. Scientists believe this happens when decompression of the magma allows volatile compounds to come out of solution and form bubbles–just as opening a bottle of seltzer allows carbon dioxide to bubble out. But a new study indicates that decompression may not be the only source of bubbles.

    Video of bubbles nucleating when a magma analog supersaturated with CO2 gets sheared.

    The team found that supersaturated fluids can nucleate bubbles when they’re sheared–even without decompression. They demonstrated this in the lab, not with magma but with a low-temperature magma analog, seen above. The more saturated with volatiles the fluid is, the less shear is needed to trigger bubbles.

    Viscous shear is everywhere for magma, so this bubble formation mechanism is likely common. Better understanding how and when bubbles form in magma directly affects predictions for eruptions–especially for determining whether they’re likely to be explosive or effusive. (Image credit: volcano – A. Bonnerdeaux, experiment – O. Roche et al.; research credit: O. Roche et al.; via Physics World)

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    Flow Through Granular Beds

    We often rely on water draining through beds of grains, whether it’s the soil foundation beneath a building or the sand-and-gravel-filter used in water treatment. But how does water move through these tortuous porous passages? That’s what we see in this video, which places grains in a jig resembling an ant farm and lets us watch as water–and air–drain through the grains. The result is more complicated than you might imagine, with dry pockets, weak spots, and developing sinkholes. (Video and image credit: J. Choi et al.)

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  • Radiant Waves

    Radiant Waves

    Photographer Kevin Krautgartner captures the powerful waves of Western Australia from above. His latest series, Waves | Ocean Forces, features luminous turquoise waves, crystalline foam, and brilliant beaches. I could delight in staring at them for hours. Fortunately, he sells prints on his website! (Image credit: K. Krautgartner; via Colossal)

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  • Toward Predicting Rogue Waves

    Toward Predicting Rogue Waves

    Rogue waves were once the stuff of nautical legend. Tales of giant lone waves were considered sailors’ tall tales, until an oil rig in the North Sea was hit by a 25.6-meter wave on 1 January 1995. The wave was more than twice the height of any others around it and much steeper, too. Since then, scientists have been working to understand how and why these rogue waves form.

    A recent study, like many others, attributes rogue waves to the subtle nonlinearities of ocean waves, which don’t match a smooth sinusoid even though they are sometimes modeled that way. When it comes to rogue waves, the sharpness of a wave’s peak and flattening of its trough affect whether waves come together into a lone giant.

    The study is based on 18 years worth of wave data collected at an offshore platform in the North Sea. With such an extensive data set, researchers were able to find patterns in the waves that precede the arrival of a rogue wave. That’s an important step toward being able to predict a rogue wave, which would help protect platforms, ships, and personnel. (Image credit: C. Wou; research credit: S. Knobler et al.; via SciAm)

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    Inside a Bubble’s Burst

    When bubbles burst at an interface, both their exterior and interior get spread into the air. Here, researchers watch as a fog-filled bubble rises through silicone oil and settles as the surface. Instabilities ripple down the bubble’s cap as it thins, and, once the bubble bursts, the fog from within is pushed upward, curling into a vortex as it goes. (Video and image credit: R. Shabtay and I. Jacobi; via GFM)

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  • Necroprinting By Mosquito

    Necroprinting By Mosquito

    Engineers have been adapting biological materials into robotics in recent years. One of the latest versions of this trend is “necroprinting,” in which researchers built a microscale 3D printer around a mosquito’s proboscis. Made to pierce thick skin to reach blood, the mosquito proboscis offered the kind of size, geometry, and stiffness needed for small-scale printing. The team found that their necroprinter performed well at the ~20 micron scale, with the mosquito-based nozzle costing only a fraction of what a conventional human-made nozzle would. (Image credit: NIAID; research credit: J. Puma et al.; via Ars Technica)

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    Wavy Water Entry

    When an object like a sphere enters the water, it drags air into the water behind it, creating a cavity. Depending on the sphere’s impact speed, the cavity might close first under the water, forming a deep seal, or at the surface with a surface seal. But, as this video points out, water often isn’t still. Here, they explore how the sphere’s entry changes when there are ripples on the water surface. (Video and image credit: M. Ibrahim et al.; via GFM)

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  • A Drop of Algae

    A Drop of Algae

    Spheres of a Volvox colonial algae glow green inside a droplet in this award-winning microphotograph by Jan Rosenboom. Pinned on an inclined surface, the droplet is frozen in a balance between gravity and surface tension that keeps its shape–and its contact angles–asymmetric. Droplets will also take on a shape similar to this when air is blowing past them. (Image credit: J. Rosenboom; via Ars Technica)

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  • Thermal Tides Drive Venusian Winds

    Thermal Tides Drive Venusian Winds

    Venus is a world of extremes. A full rotation of the world takes 243 Earth days, but winds race around the planet at a speed that makes a Category 5 hurricane look sedate. Just what drives these winds has been an ongoing question for planetary scientists. A recent study suggests that tides are a major contributor to this superrotation.

    Unlike Earth’s tides, Venus’s are not gravitational in origin. Instead, Venusian tides are thermal, driven by heating in the sunward side of the atmosphere. This creates a diurnal tide, which cycles once per Venusian day and pumps momentum toward the tops of Venus’s clouds. The new analysis–rooted in both observations and numerical simulation–finds that diurnal tides are the primary driver behind the planet’s incredibly fast winds. (Image credit: NASA/JPL-Caltech; research credit: D. Lai et al.; via Eos)

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    ExaWind Simulation

    Large-scale computational fluid dynamics simulations face many challenges. Among them is the need to capture both large physical scales–like those of Earth’s atmospheric boundary layer–and small scales–like those of tiny eddies moving around a wind-turbine blade. Capturing all of these scales for a problem like four wind turbines in a wind farm requires using the full computing power of every processor in a large supercomputer. That’s the level of power behind the simulation visualized in this video. The results, however, are stunning. (Video and image credit: M. da Frahan et al.)

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