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Search results for: “art”

  • Racing Dunes

    Racing Dunes

    The deserts of Namibia are home to some of the fastest and most consistent winds in the world. As a result, they’re also home to some of the fastest-moving dunes on Earth. Dunes are shaped and moved by the wind, which pushes sand up the dune’s windward side and dumps it down the leeward side. As the process repeats, the entire dune moves. The bigger a dune is, the slower it moves.

    Animation of Landsat images showing dune movement between April 2013 and April 2022.
    Animation of Landsat images showing dune movement between April 2013 and April 2022.

    In this animation, showing dune motion from 2013 to 2022, the largest dunes move about 9 meters per year. In contrast, the smallest dunes move as fast as 83 meters a year! Check out the right side of the image, and you’ll see the dark specks of small dunes racing up and past their bigger brethren. (Image credit: top – E. Böhtlingk, animation – J. Stevens; via NASA Earth Observatory)

  • Swimming Intermittently

    Swimming Intermittently

    Many fish do not swim continuously; instead, they use an intermittent motion, swimming in a sudden burst and then coasting. This intermittent swimming is tough to simulate, due to its unsteady nature, but a new study does so using some clever computational techniques.

    Animation showing a fish swimming in a burst-and-coast pattern.
    Animation showing a fish swimming in a burst-and-coast pattern.

    Researchers suspected that the energy intensity of a fish’s burst could be balanced by the low-drag, low-effort phase of coasting. And, indeed, that’s consistent with the team’s results. But they found that the swimming method does require careful optimization; with the wrong cadence, the burst-and-coast technique can be incredibly energy intensive. In nature, of course, fish have had millions of years to optimize their technique, but the results serve as a warning to those building fish-based robots. Those biorobots will need careful optimization to benefit from this swimming style. (Image credit: tetra – Adobe Stock Images, simulation – G. Li et al.; research credit: G. Li et al.; via APS Physics; submitted by Kam-Yung Soh)

  • Beneath the Cavity

    Beneath the Cavity

    When a drop falls into a pool of liquid, it creates a distinctive cavity, followed by a jet. From above the surface, this process is well-studied. But this poster offers us a glimpse of what goes on beneath the surface, using particle image velocimetry. This technique follows the paths of tiny particles in the fluid to reveal how the fluid moves.

    As the cavity grows, fluid is pushed away. But the cavity’s reversal comes with a change in flow direction. The arrows now point toward the shrinking cavity — and they’re much larger, indicating a strong inward flow. It’s this convergence that creates the Worthington jet that rebounds from the surface. And, as the jet falls back, its momentum gets transferred into a vortex ring that drifts downward from the point of impact. (Image credit: R. Sharma et al.)

  • Surface Fat Gives Chocolate’s Mouthfeel

    Surface Fat Gives Chocolate’s Mouthfeel

    Understanding the interactions of food and our mouths is incredibly difficult. There are lots of changes going on: shape changes from chewing, viscosity changes as saliva lubricates the food, and, sometimes, phase changes from the heat of our bodies. Add to that the sensitivity of our papillae-covered tongues, and it’s a lot to manage all at once. Recently, researchers have turned to 3D-printing to create a more realistic lab version of our mouths.

    The team 3D-printed a papillae pattern matching the size and distribution of an actual human tongue, then molded that pattern onto a silicone elastomer. The result? A replica tongue that matches a human one in terms of softness, wettability, and surface roughness. They then attached their tongue to a rheometer to measure the friction between the tongue and dark chocolate.

    Their experiments simulated licking, eating, and swallowing the confection. During licking and eating, they found that the chocolate was lubricated by a layer of fat directly between the tongue and the food. Their results suggest that one way to make healthier chocolate options is to concentrate fat into the surface layer of the chocolate while lowering the fat content inside the bar. (Image credit: D. Ramoskaite; research credit: S. Soltanahmadi et al.; via APS Physics)

  • Featured Video Play Icon

    Paint Ejection

    Shaking paint on a speaker cone and filming it in high speed is an oldie but a goodie. Here, artist Linden Gledhill films paint ejection at 10,000 frames per second, giving us a glorious view of the process. As the paint flies upward, accelerated by the speaker, it stretches into long ligaments. As the ligaments thin, surface tension concentrates the paint into droplets, connected together by thinning strands. When those strands break, they snap back toward the remaining paint, imprinting swirling threads of different colors, thanks to their momentum. Eventually, surface tension wins the tug-of-war and transforms all the paint into droplets. (Video and image credit: L. Gledhill)

  • Flamingo Fluid Dynamics

    Flamingo Fluid Dynamics

    Flamingos strut and dance and bob, but there’s more to these comical birds than meets the eye. Flamingos can thrive in nutrient-poor environments that other birds eschew, like salt flats and alkaline lakes. Their secret, it turns out, is a mastery of fluid dynamics.

    Researchers studying the behaviors of the Nashville Zoo’s flamingo flock discovered that their seemingly silly behaviors all had fluid dynamical consequences. When the birds stomped and danced in small circles, it stirred up the muck in the water they eat from. With their beaks below the surface, the birds then opened and closed their mouths, darting their tongues in and out; this generated suction to carry food particles toward them. Periodically, they’d bob their heads up, creating a vortex for extra suction. Even their walking, which they did while skimming the water surface with their bills facing backward, generated flows that helped carry food to their mouths. (Image credit: cshong; research credit: V. Ortega-Jiménez et al.; via Science; submitted by Kam-Yung Soh)

  • Featured Video Play Icon

    “Turbulence”

    In his recent short film, artist Roman De Giuli explores turbulence using metallic paints and inks in a fishtank. The effects are beautiful: sparkling pigments dispersing in clouds, mushroom- and umbrella-shaped Rayleigh-Taylor instabilities, and lots of swirling eddies. It’s exactly the kind of eyecandy to kick off your weekend with! (Image and video credit: R. De Giuli)

  • Mixing in a Winter Lake

    Mixing in a Winter Lake

    A frozen winter lake can hide surprisingly complex flows beneath its placid surface. Since water is densest at 4 degrees Celsius — just above the freezing point — mixing two water sources can lead to counterintuitive effects. A cold lake, for example, may contain water below 4 degrees Celsius, while a stream running into the lake is a bit warmer than 4 degrees Celsius. When the two parcels of water meet, they mix to form water at an intermediate temperature. But because of water’s density anomaly, that mixed water can wind up denser than the average of its parents. This is known as cabbeling.

    Mixing patterns within a cold lake with a slightly warmer inflow. Image from A. Grace et al.
    Mixing patterns within a cold lake with a slightly warmer inflow. Image from A. Grace et al.

    As shown in a recent study, this newly mixed water sinks to the bottom of the lake, forming a warm current that heats the lake from below. The researchers were able to model this current and its behavior over a range of conditions. Understanding these winter circulation patterns is key to tracking both nutrient transport and how pollutants spread in the ecosystem. (Image credit: lake – G. Murry, simulation – A. Grace et al.; research credit: A. Grace et al.; via APS Physics)

  • Rippling Airglow

    Rippling Airglow

    Though we rarely notice it, our sky is always aglow. Washed in solar radiation, the oxygen and nitrogen molecules at high altitude get broken apart during the daytime and recombine at night, producing a luminescent glow that forms a uniform backdrop against the sky. In this image, the airglow forms a bull’s-eye-like set of rings, thanks to atmospheric gravity waves left behind by a thunderstorm. (Image credit: J. Dai; via APOD)

  • Chilly Soap Films

    Chilly Soap Films

    Evaporation is a well-known effect in soap films and bubbles. It’s responsible for the ever-changing thickness reflected in the film’s many colors. But evaporation does more than change the bubble’s thickness: it affects its temperature, too. Just as sweat evaporating off our skin cools us, the soap film’s evaporation makes it cooler than the surrounding air.

    Researchers found that their soap films could be as much as 8 degrees Celsius cooler than the surrounding air! They also found that the film’s glycerol content affect how much cooler the soap film is; films with more glycerol had higher temperatures, which could impact their overall stability. (Image credit: E. Škof; research credit: F. Boulogne et al.; via APS Physics)

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