FYFD

Category: Phenomena

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    How COVID-19 Affects the Lungs

    One of the best known COVID-19 symptoms of this pandemic is difficulty breathing, and while you’ve likely heard a lot about ventilators used to help patients get oxygen, you may not know much about the processes that cause the breathing problems. This video from Deep Look provides a solid overview of the infection route and how lung damage occurs during infection. Perhaps unsurprisingly — this is FYFD, after all — fluid dynamics plays a major role in this process, both under normal conditions and when air sacs in the lungs get damaged by the body’s immune system responding to the virus. (Image and video credit: Deep Look)

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    Holding Pipes in Place

    Newton’s 3rd law states that any action has an equal and opposite reaction. Often engineers use this to our advantage; the thrust from expelling propellants is what lifts our rockets to space. But sometimes those reactions are undesirable, as illustrated in this Practical Engineering video with underground pipes.

    Anytime flow through the pipe is forced to change direction, the flow causes an equal and opposite force on the joint. Just as with rockets, engineers refer to this reaction force as thrust. And if the thrust goes unaccounted for, it will force pipe joints apart. Civil engineers use several methods to fix pipelines against these forces, including concrete blocks that distribute the force to the surrounding soil and flange fittings that resist pipe movement. (Video and image credit: Practical Engineering)

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    Singing in the MRI

    We rarely consider just how complex the process is when we speak or sing. Sound waves produced in our larynx are shifted and amplified by the geometry of our throats, mouths, sinus cavities, tongues, and lips. This video provides a glimpse of that hidden complexity through a trained vocalist singing inside an MRI machine. He sings the same aria in four distinctly different vocal styles, and it’s incredible to watch all the changes his tongue, lips, and soft palette go through to produce those different sounds. (Image and video credit: T. Ross; via Flow Vis)

  • Icy Swirls

    Icy Swirls

    Rafts of sea ice follow swirling eddies in this satellite image of the Gulf of St. Lawrence. Just as with phytoplankton blooms and sediment, this thin sea ice can be moved by wind and currents to reveal hidden flow patterns. Experimentalists use many similar diagnostics that introduce bubbles, particles, smoke, and other tracers into flows to visualize motion that’s otherwise invisible. (Image credit: J. Stevens/NOAA/NASA; via NASA Earth Observatory)

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    Choosing Swimming Over Flight

    When studying modern birds it quickly becomes apparent that they can either be good at swimming or at flying, but not at both. The characteristics that make wings good for flying are diametrically opposed to those that make for a good swimmer. So most species have chosen to invest in one strategy or the other. Penguin ancestors chose the swimming route tens of millions of years ago, in the aftermath of the extinction event that emptied our oceans of the large reptilian predators that had ruled them during the age of the dinosaurs. This video explores what we know about the fossil record of these birds, and it’s pretty incredible. Did you know there used to be 2-meter-tall penguins? (Image and video credit: PBS Eons)

  • Crisscrossing Wave Clouds

    Crisscrossing Wave Clouds

    Crisscrossing lines of wave clouds mark the wake of the Sandwich Islands in this satellite image. The tallest islands in the chain thrust rocky peaks more than 1000 meters above sea level, disrupting winds flowing across the ocean. Incoming air is forced up and over the mountain, which puts it at odds with the surrounding air at that height.

    Due to differences in temperature and density, the disrupted air will continue to rise and sink periodically as it flows onward. At some heights it will cool enough to condense its water vapor into clouds, and at others, it will warm enough to lose any cloud cover. This is what creates the bands of clouds we see behind each individual island. (Image credit: L. Dauphin/NASA; via NASA Earth Observatory)

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    Tektites and Spinning Fluids

    Tektites, like obsidian, are a naturally-occurring glass formed from molten rock. But tektites are often dumbbell or figure-8-shaped because they form in midair from spinning bits of fluid sent skyward after the crash of a meteor. In this video, Steve Mould takes us through the process and discusses some recent work by scientists who’ve created artificial tektites in the lab by levitating and spinning candle wax and other fluids. (Video and image credit: S. Mould; research credit: K. Baldwin et al.)

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    Why Compressed Air Cans Get Cold

    Anyone who’s used a can of compressed air to clean their computer or keyboard knows that the can quickly gets quite cold to the touch. This Minute Physics video explores some of the thermodynamics behind that process. Henry first identifies a few explanations that don’t quite line up with observations, before focusing in on the contents of the can: 1,1-difluoroethane. Inside the sealed can, this chemical sits in an equilibrium of part-liquid, part-vapor. But when pressure is released by opening the nozzle, the liquid boils, generating extra vapor and cooling whatever remains in the reservoir.

    Although it’s not a good explanation for the compressed air can’s cooling, the cooling of an expanding gas is very important in applications like supersonic wind tunnels. That first equation you see at 0:36 in the video (for isentropic adiabatic expansion) is key to what happens in a nozzle with supersonic flow. As the flow accelerates to supersonic speeds, its temperature drops dramatically. When I was in graduate school, we actually had to preheat our hypersonic wind tunnel (in pretty much the same way you would preheat your oven at home) before we ran at Mach 6 because otherwise the temperature inside the test section would drop so low that the oxygen would liquefy out of the air! (Image and video credit: Minute Physics)

  • Eroding Ice

    Eroding Ice

    When glaciers form, they do so in layers, with clear blue ice sandwiched between sediment and air-bubble-filled white ice. Because each of these layers absorbs sunlight differently, they don’t melt evenly. The spikes and ridges seen in this ice formed because of this differential melting between layers. The blue ice is particularly good at absorbing visible wavelengths of light, and so erodes more easily than the other layers.

    Although the results look somewhat similar to the penitente ice seen at high altitudes, the formation mechanisms are a little different. Penitentes rely heavily on sublimation — where their ice and snow change directly into a gas — rather than the melting seen here. That said, both eroded forms depend strongly on how different layers within them absorb and scatter sunlight. (Image credit: J. Van Gundy; via EPOD; submitted by Kam-Yung Soh)

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    Unsinkable Hydrophobic Metal

    Although we typically describe hydrophobic surfaces as “water-repelling,” we could just as easily focus on the fact that they’re “air-attracting.” This video from The Action Lab demonstrates that property nicely with a hydrophobic-coated “boat” that’s effectively unsinkable, thanks to its ability to trap air pockets.

    Even punching holes through the boat doesn’t sink it because its surface is so chemically and physically attractive to air that the bubble won’t budge. In fact, as the video demonstrates, the only effective way to remove the hydrophobicity is to remove the air bubble by using a vacuum chamber. But even then, the effect only lasts until air is reintroduced to the boat. (Image and video credit: The Action Lab)

    P.S. – No, this is not an April Fool’s joke, just actual science! – Nicole