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Search results for: “waves”

  • Frozen Waves

  • Watching Waves on the Nanoscale

    Watching Waves on the Nanoscale

    It’s tough to simulate nonlinear wave dynamics, so scientists often test theories in wave flumes, where they can create more controlled waves than what we see in the wild. But conventional wave flumes are big–meters-long, complicated equipment–and can only test a small range of conditions. To reach more extreme nonlinear dynamics, researchers have turned to a chip-based approach. These 100-micron-long wave flumes carry a film of superfluid helium less than 7 nanometers thick. But despite that tiny size, the system can reach levels of nonlinearity five orders of magnitude greater than their full-sized counterparts. (Image and research credit: M. Reeves et al.; via Physics Today)

    Labeled diagram of a 100-micron-long wave flume.
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  • Seeing Sound Waves

  • 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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  • Radiant Waves

  • Waves Over Sand Ripples

    Waves Over Sand Ripples

    Look beneath the waves on a beach or in a bay, and you’ll find ripples in the sand. Passing waves shape these sandforms and can even build them to heights that require dredging to keep waterways passable to large ships. To better understand how the sand interacts with the flow, researchers build computer models that couple the flow of the water with the behavior of individual sand grains. One recent study found that sand grains experienced the most shear stress as the flow first accelerates and then again when a vortex forms near the crest of the ripple. (Image credit: D. Hall; research credit: S. DeVoe et al.; via Eos)

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  • Roll Waves in Debris Flows

    Roll Waves in Debris Flows

    When a fluid flows downslope, small disturbances in the underlying surface can trigger roll waves, seen above. Rather than moving downstream at the normal wave speed, roll waves surge forward — much like a shock wave — and gobble up every wave in their way.

    Such roll waves are fairly innocuous when flowing down a drainage ditch but far more problematic in the muddy debris flows of a landslide. Debris flows are harder to predict, too, thanks to their combined ingredients of water, small grains, and large debris.

    A new numerical model has shed some light on such debris flows, after showing good agreement with a documented landslide in Switzerland. The model suggests that roll waves get triggered in muddy flows at a higher flow speed than in a dry granular flow but a lower flow speed than is needed in pure water.

    For a great overview of roll waves, complete with videos, check out this post by Mirjam Glessner. (Image credit: M. Malaska; research credit: X. Meng et al.; see also M. Glessmer; via APS)

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  • Capturing River Waves

    Capturing River Waves

    Rainfall, ice jams, and dam breaks create surges of high flow that make their way down a river in a wave that stretches tens to thousands of kilometers in length. Traditionally, scientists monitor such flow waves using river gauges, which measure river height at specific locations. But gauges are few and far between on many rivers, so a group of researchers are supplementing that data with the SWOT (Surface Water and Ocean Topography) spacecraft. SWOT bounces microwaves off the water to precisely measure the water’s height, giving researchers a glimpse of the flow wave’s shape along the entire river.

    In their paper, the team identify and describe flow waves on three different rivers — the Yellowstone, Colorado, and Ocmulgee rivers — ranging in height up to 9 meters and stretching up to 400 kilometers. (Image credit: CNES; research credit: H. Thurman et al.; via Gizmodo)

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  • “Skimming the Waves”

    “Skimming the Waves”

    Common terns are gregarious sea birds that cruise low over the water to fish. When they spot prey, they will dip down to grab a fish from the surface, or they will fold their wings to plunge-dive to depths of half a meter. Compared to gannets and boobies, these are slower, shallower dives that involve less impact risk. Presumably the birds’ choice of dive height reflects the typical swim depth of their preferred fish. (Image credit: N. Kovo/WPOTY; via Colossal)

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