FYFD

Tag: science

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    Pumping Through Liquid Tubes

    As the tubes carrying a liquid get smaller, it becomes harder and harder to keep fluids flowing. Friction between the fluid and the wall brings flow there to a standstill and means that moving fluid through tiny tubes requires enormous forces. To alleviate this issue, a new study uses a clever arrangement of magnets to create a tube with ferrofluid walls instead of solid ones.

    The researchers call their liquid-walled pipes “antitubes” and show off just how useful they can be. Because the ferrofluid allows liquid to slip by it, flow through the antitubes is nearly frictionless. As seen in the last animation, honey flows about as easily through the antitube as it does with no tube in place at all!

    The antitubes are also easy to modify into valves and pumps just by applying (and/or moving) a magnet (Images 1 and 2). Combined with their low friction, these features make antitubes perfect for applications like pumping blood outside the human body without damaging delicate cells. You can see a demonstration of that in the video above. (Video, image, and research credit: P. Dunne et al.; via Physics World; submitted by Kam-Yung Soh)

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    A Hand in Hot Oil

    In this video, Dianna from Physics Girl demonstrates a feat no one should try at home: dipping her hand into boiling oil. To stay safe, she’s relying on the Leidenfrost effect, the tendency of liquids exposed to temperatures well above their boiling point to vaporize and create a layer of gas that insulates against further heat transfer.

    We’ve seen a lot of cool behaviors from Leidenfrost droplets, like surfing on herringbone surfaces, digging through sand, vibrating like a star, and, well, violently exploding. We know a lot about what can happen in this Leidenfrost state, but there are also some major unknowns, like exactly what the Leidenfrost temperature is for many liquids. That’s part of what makes Dianna’s demo so dangerous; the temperature needed to see the Leidenfrost effect — even just for water — varies wildly depending on the experimental set-up. (Video and image credit: Physics Girl)

  • Audubon Photography Awards

    Audubon Photography Awards

    Several of this year’s Audubon-Photography-Award-winning photos feature birds interacting with fluids. The Grand Prize Winner, by Joanna Lentini, features a diving double-crested cormorant. Like many other species, these cormorants launch themselves into shallow waters from above and endure some incredible forces to do so. They’re no slackers underwater, either; when I encountered a flightless cormorant while snorkeling in the Galapagos, it outswam me in an instant.

    The other prize winners above are a little more splashy. The American dipper’s splash curtain comes from sticking its head underwater in search of prey. The Anna’s hummingbird seen in the last image is playing in the spray of a fountain and showing off its aerial agility while doing so! (Image credits: cormorant – J. Lentini, dipper – M. Fuller-Morris, hummingbird – B. Ghosh; via DPReview; submitted by Kam-Yung Soh)

  • Shedding Light on Martian Dust Storms

    Shedding Light on Martian Dust Storms

    In 2018, Mars was enveloped by a global dust storm that lasted for months. Although such storms had been seen before, the 2018 storm offered an unprecedented opportunity for observation from five orbiting spacecraft and two operating landers. As researchers comb through that data, they’re gaining new insights into the mechanisms that drive these extreme events.

    At NASA Ames, a team of researchers used observations of dust columns as input to a simulation of Mars’ global climate, then watched as the digital storm unfolded. Simulations like these have an important advantage over observations: the simulations allow scientists to track the transport of dust from one region to another.

    That dust tracking is critical for some of the team’s results. They found feedback patterns between dust lifting and deposition in different regions. For example, early in the storm dust was largely supplied from the Arabia/Sabaea regions, but once that dust was deposited in the Tharsis region, it kicked off a massive lifting event from Tharsis that put twice as much dust into the atmosphere as had landed there. Later, dust deposited back in Arabia by the Tharsis lofting generated new dust uplifts. As long as more dust got lifted than deposited, the intense storms continued. (Image credits: NASA, T. Bertrand/A. Kling/NASA Ames; research credit: T. Bertrand et al.; see also JGR Planets and AGU; submitted by Kam-Yung Soh)

  • 10 Years of FYFD

    10 Years of FYFD

    10 years. 2,590 posts. 21 original videos. 378,000+ followers. Countless hours spent blogging and more than 1,000 journal articles read. When I started FYFD ten years ago as a PhD student, I never imagined the impact the blog would have on my life, my career, or my field. It’s been a wild ride, and I’d like to take a moment today to thank each and every one of you for contributing to this journey, whether it’s by supporting on Patreon, liking a post, sharing content, submitting ideas, leaving a comment, sending an email, or saying hi at an event. FYFD would have petered out long ago if not for your support!

    Ten years seems like a good time for a little retrospective, so I went back through the archive in search of the most popular post (based on Tumblr’s notes) from each of those ten years. Here’s what I found:

    Year 1: The Vortex Street
    Year 2: Wave Clouds Over Alabama
    Year 3: Surface Tension in Action
    Year 4: Why Honeycomb is Hexagonal
    Year 5: Bioluminescence
    Year 6: Self-Pouring Fluids
    Year 7: Watching Radiation
    Year 8: The Swimming of a Dead Fish
    Year 9: Seeing the Song
    Year 10: Collective Catfish Convection

    If you’d rather enjoy something random rather than something “popular”, you can always use the shortcut https://fyfluiddynamics.com/random to explore posts in the archive.

    And in case you’re more interested in watching videos, here are the top FYFD videos (by YouTube views):

    (Wow, my editing and production skills have evolved since some of those earlier vids!)

    So what are your favorite FYFD memories and posts? Let me know in the comments! (Image and video credits: N. Sharp)

  • The Tolling of the Atmosphere

    The Tolling of the Atmosphere

    Strum a musical instrument and you create a host of vibrations at many different frequencies. The same is true of our atmosphere, which rings at frequencies far too low for us to hear. The first theoretical descriptions of this atmospheric ringing date back two centuries to Pierre-Simon Laplace. A new study provides the first experimental evidence of this atmospheric ringing by analyzing 38 years’ worth of hourly atmospheric data.

    The authors found good agreement with the structures predicted by classical theory, but they point out that understanding the mechanisms that drive the ringing requires more research. Since studies of vibrations in the Earth and sun have revealed new dynamics in those systems, it’s likely analyses like these can teach us much more about how our atmosphere functions. (Image credit: NASA; research credit: T. Sakazaki and K. Hamilton; submitted by K. Hamilton)

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    How N95 Masks Work

    You might imagine N95 masks as essentially a strainer intended to catch small particles, but as Minute Physics shows in this video, what these masks do is actually much more clever. A dense, strainer-like mask with tiny openings to block microscopic particles would be very tough to breathe through. Instead, N95 masks take advantage of one of the characteristics of tiny things: they’re very sticky. Thanks to van der Waals forces particles that touch a fiber will stick there.

    By creating an array of fibers between the particle and a person’s mouth, N95 masks do an excellent job of catching both large particles and tiny ones. They have a harder time with medium-sized particles because airflow around the fibers helps these particles avoid them.

    But, luckily, N95 masks have a solution for that problem, too. The fibers of the mask have an electric charge, which helps them attract particles of all sizes and capture them. Of course, as with all masks, they’ll work when worn as intended. (Video and image credit: Minute Physics)

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    “Oooh !! My Delicious Coffee”

    I’m not a coffee person, but Thomas Blanchard’s “Oooh !! My Delicious Coffee” manages to capture my favorite part of the beverage – watching cream and coffee mix. From feathery flows driven by surface tension to droplets floating like miniature cappuccinos, the short film features many of the fantastical landscapes we find when staring into a coffee cup. But don’t get too eager to drink it; Blanchard used a combination of coffee, oil, and paint to achieve those effects! (Image and video credit: T. Blanchard)

  • Crocodilian-Inspired Aerodynamics

    Crocodilian-Inspired Aerodynamics

    Inspired by crocodilians, young scientist Angela Rofail designed attachments to reduce wind loads on high-rise buildings. When crocodilians swim, the ridges on their back help hide their motion from observation above the surface. Rofail wondered whether similar ridges would reduce the wind-induced swaying of high-rise buildings. Using a scale-model and crocodile-inspired knobs, the Year 10 student (read “high-school freshman” for U.S. readers) conducted wind tunnel tests that showed her modifications reduced drag on the model and kept it from moving in windy conditions. (Image credit: H. Roettger; video credit: CSIRO; via CSIRO; submitted by Kam-Yung Soh)

  • The Challenges of Being Small

    The Challenges of Being Small

    For juvenile fish, feeding is a challenge. Their small size — often less than 5 mm in length — makes hydrodynamically capturing prey much harder because of viscosity’s relatively larger effect on them. But size may not be the only factor in determining their success, as a new study shows.

    Researchers studied feeding behaviors of two, equally-sized species’ larvae: zebrafish and guppies. The biggest difference between these two species is their developmental time prior to beginning to hunt on their own. Guppies develop five times longer than zebrafish larvae before they start feeding.

    Both fish have the same hydrodynamic limitations to overcome. If you look closely at the first image, you’ll see fluid being pushed ahead of the fish as it swims. The researchers refer to this as a bow wave, and it effectively announces to any prey that the fish is approaching. To sneak up on prey, the fish has to be able to generate enough suction force to pull its food in from beyond the bow wave’s reach. The experiments showed that guppies were able to do this reliably, while zebrafish could not. The subsequent difference in their feeding success was stark: the guppies’ success rate was almost five times that of the zebrafish! (Image and research credit: T. Dial and G. Lauder, source; via G. Lauder)