FYFD

Tag: surface tension

  • Programmable Capillary Action

    Programmable Capillary Action

    Capillary action combines the cohesive forces within a liquid and the adhesive forces between a liquid and solid to enable a liquid to fill narrow spaces, even against the force of gravity. To control capillary action, researchers are 3D-printing what they call “unit cells,” tiny structures that water and other liquids can climb. There’s no pump raising the liquid through these structures, just capillary action.

    In a particularly neat demonstration of the technology, the researchers built a tree-like structure out of many open-walled unit cells and placed the “root” system in a closed reservoir. Capillary action drew liquid up the structure to the tips of its branches, where the dyed water evaporated. The process is similar to transpiration in trees, though in trees, capillary action provides much less of the lift. (Image and research credit: N. Dudukovic et al.; via Nature; submitted by Kam-Yung Soh)

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    Metallic Magma

    Metallic paint flows like silver lava in this macro video from Chemical Bouillon. The paint has been mixed with an unknown fluid (my guess is alcohol) to produce the flows we see here. My suspicion is that we’re seeing solutal convection where variations in surface tension create convective flow within the liquid. What do you think? (Video and image credit: Chemical Bouillon)

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    “Geodaehan”

    In “Geodaehan” Roman De Giuli’s macro fluid art mimics massive landscapes. The film takes us over deltas, rivers, glaciers, and landslides. Some look like earthbound locations, others look like something from Mars or Titan. All are, in fact, paint, ink, and glitter on paper! It’s truly incredible how artists capture large-scale fluid physics on such a tiny canvas. (Image and video credit: R. De Giuli)

  • “Liquid Skies”

    “Liquid Skies”

    “Liquid Skies” by Roman De Giuli is full of colorful but nebulous fluid imagery. The visuals consist of liquids like paint, ink, and alcohol filmed in macro atop paper. You can catch a behind-the-scenes glimpse of De Giuli at work here. (Image and video credit: R. De Giuli)

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    The Unsinkable Pygmy Gecko

    The Brazilian pygmy gecko is a tiny inhabitant of the Amazon rainforest, growing to no longer than 24 mm. But these tiny lizards have some incredible superpowers when it comes to surviving the rainforest’s deluges. The gecko’s surface is superhydrophobic — water repellent — thanks to millions of tiny hairs that create air pockets between water and the gecko’s skin. This superhydrophobic surface, combined with the gecko’s tiny stature, allow it to sit atop water, supported entirely by surface tension. (Image and video credit: BBC Earth)

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    “Flux Capacitor”

    Sandro Bocci’s short film “Flux Capacitor” explores the geometry and dynamics of soap films. When you dip wire models into soapy solution, the films that cling to the model can form complicated shapes as surface tension works to minimize the overall surface area. Bocci’s macro photography highlights the intense flows going on in the narrow regions where films meet. It’s a different take on soap films and neat to see! (Image, video, and submission credit: S. Bocci et al.)

  • Gathering Droplets

    Gathering Droplets

    In deserts around the world, plants have adapted to collect as much moisture as they can. Geometry aids them in this endeavor because droplets on the tip of a cone will move toward its thicker base. The motion takes place due to a imbalance in surface tension forces on either end of the droplet.

    As the droplet moves up a cone, it changes shape from a barrel-like drop that fully covers the conical surface to a clamshell-shaped droplet that hangs only from the bottom of the cone. (Image and research credit: J. Van Hulle et al.)

  • Why Food Sticks to Nonstick Pans

    Why Food Sticks to Nonstick Pans

    Whether you’re cooking with ceramic, Teflon, or a well-seasoned cast iron pan, it seems like food always wants to stick. It’s not your imagination: it’s fluid dynamics.

    As the thin layer of oil in your pan heats up, it doesn’t heat evenly. The oil will be hotter near the center of the burner, which lowers the surface tension of the oil there. The relatively higher surface tension toward the outside of the pan then pulls the oil away from the hotter center, creating a hot dry spot where food can stick.

    To avoid this fate, the authors recommend a thicker layer of oil, keeping the burner heat moderate, using a thicker bottomed pan (to better distribute heat), and stirring regularly. (Image and research credit: A. Fedorchenko and J. Hruby)

  • Bubble Array

    Bubble Array

    Surface tension tries to minimize a bubble‘s surface area, which is why bubbles assume a spherical shape. But when many bubbles clump together, a curved interface is not always the most energy efficient one. In this case, bubbles can take on many shapes and sizes while still minimizing the overall surface energy. Take a close look at this image and see what shapes you discover! (Image credit: M. Adil)

  • Stabilizing Foams

    Stabilizing Foams

    Bubbles in a pure liquid don’t last long, but with added surfactants or multiple miscible liquids, bubbles can form long-lasting foams. In soapy foams, surfactants provide the surface tension gradients necessary to keep the thin liquid layers between bubbles from popping. But what stabilizes a surfactant-free foam?

    New work finds that foams in mixtures of two miscible fluids only form when the surface tension depends nonlinearly on the concentration of the component liquids. When this is true, thinning the wall between bubbles creates changes in surface tension that stabilize the barrier and keep it from popping.

    In mixtures without this nonlinearity, foams just won’t form. The new results are valuable for manufacturing, where companies can avoid unintentional foams simply by careful selection of their fluids. (Image credit: G. Trovato; research credit: H. Tran et al.; via APS Physics; see also Ars Technica, submitted by Kam-Yung Soh)