FYFD

Tag: science

  • Derecho-Induced Skyscraper Damage

    Derecho-Induced Skyscraper Damage

    Derechos are short-lived, intense wind storms sometimes associated with thunderstorms. Last spring, such a storm passed through Houston, leaving downtown skyscrapers with more damage than a hurricane with comparable wind speeds. Now researchers believe they know why a derecho’s 40 meter per second winds can badly damage buildings built to withstand 67 meter per second hurricane winds.

    In surveying the damage to Houston’s skyscrapers, the team noted that broken windows were concentrated in areas that faced other tall buildings. In a wind facility, the team explored how skyscrapers interfered with each other, based on their separation difference. They looked both at conditions that mimicked a hurricane’s winds as well as the downbursts — strong downward wind bursts — that are found in derechos.

    The researchers found that downbursts in between nearby buildings caused extremely strong suction forces along a building’s face — even compared to the forces seen with higher hurricane-force winds. Currently, these buildings are designed for hurricane-like conditions, but the team suggests that — at least in some regions — designers will need to take into account how downburst wind patterns affect a skyscraper, too. (Image credit: National Weather Service; research credit: O. Metwally et al.; via Ars Technica)

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    Seeing Sound

    Sound, vibration, and motion are all inextricably linked. In this BBC video, physicist Helen Czerski shows how an object’s sound and vibrations relate through the classic Chladni experiment. She vibrates a metal plate scattered with sand. At most vibration frequencies, the particles of sand bounce all over the place with no distinctive pattern. But at an object’s natural frequencies, there are standing waves and the sand gathers in spots where the standing wave has no vertical motion. The higher the vibration frequency, the more complex the pattern the sand makes. All of this plays into the sounds we hear, too. When struck, an object vibrates at many of its natural frequencies at once. That’s what gives us a rich, musical tone — all those layered frequencies. (Video and image credit: BBC)

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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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  • Ultra-Soft Solids Flow By Turning Inside Out

    Ultra-Soft Solids Flow By Turning Inside Out

    Can a solid flow? What would that even look like? Researchers explored these questions with an ultra-soft gel (think 100,000 times softer than a gummy bear) pumped through a ring-shaped annular pipe. Despite its elasticity — that tendency to return to an original shape that distinguishes solids from fluids — the gel does flow. But after a short distance, furrows form and grow along the gel’s leading edge.

    Front view of an ultra-soft solid flowing through an annular pipe. The furrows forming along the face of the gel are places where the gel is essentially turning itself inside out.
    Front view of an ultra-soft solid flowing through an annular pipe. The furrows forming along the face of the gel are places where the gel is essentially turning itself inside out.

    Since the gel alongside the pipe’s walls can’t slide due to friction, the gel flows by essentially turning itself inside out. Inner portions of the gel flow forward and then split off toward one of the walls as they reach the leading edge. This eversion builds up lots of internal stress in the gel, and furrowing — much like crumpling a sheet of paper — relieves that stress. (Image and research credit: J. Hwang et al.; via APS News)

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    Strandbeest Evolution

    Theo Jansen’s Strandbeests are massive, wind-powered kinetic sculptures designed to roam Dutch beaches. Conceived in the late 1980s as a way to kick up sand that would replenish nearby dunes, the beests have grown into a decades-long obsession for the artist and his followers. This Veritasium video charts the development and evolution of the Strandbeest from its original concept through Jansen’s increasingly self-sufficient versions. I found the leg linkage of the Strandbeest especially fascinating. How neat to find a relatively simply proportion of linkages capable of turning a small crank’s motion into a stable walking gait. Anyone else feel like building a miniature Strandbeest now? (Video and image credit: Veritasium)

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  • Anti-Icing Polar Bear Fur

    Anti-Icing Polar Bear Fur

    Despite spending their lives in and around frigid water, snow, and ice, polar bears are rarely troubled by ice building up on their fur. This natural anti-icing property is one Inuits have long taken advantage of by using polar bear fur in hunting stools and sandals. In a new study, researchers looked at just how “icephobic” polar bear fur is and what properties make it so.

    The key to a polar bear’s anti-icing is sebum — a mixture of cholesterol, diacylglycerols, and fatty acids secreted from glands near each hair’s root. When sebum is present on the hair, the researchers found it takes very little force to remove ice; in contrast, fur that had been washed with a surfactant that stripped away the sebum clung to ice.

    The researchers are interested in uncovering which specific chemical components of sebum impart its icephobicity. That information could enable a new generation of anti-icing treatments for aircraft and other human-made technologies; right now, many anti-icing treatments use PFAS, also known as “forever chemicals,” that have major disadvantages to human and environmental health. (Image credit: H. Mager; research credit: J. Carolan et al.; via Physics World)

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  • A Drop’s Shape Effects

    A Drop’s Shape Effects

    Falling raindrops get distorted by the air rushing past them, ultimately breaking large droplets into many smaller ones. This research poster shows how variable this process is by showing two different raindrops, both of the same 8-mm initial diameter. On the left, the drop is prolate — longer than it is wide — and on the right, the drop is oblate — wider than it is long. Moving from bottom to top, we see a series of snapshots of each drop’s shape as it deforms and, eventually, breaks into smaller drops. The overall process is similar for each: the drop flattens, dimples, and then inflates like a sail, with part of the drop thinning into a sheet and ultimately breaking into smaller droplets. Yet, each drop’s specific details are entirely different. (Image credit: S. Dighe et al.)

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  • Icelandic Flows

    Icelandic Flows

    Known as “The Land of Fire and Ice,” Iceland has some of the most striking landscapes around. Photographer Jennifer Esseiva captures auroras, waterfalls, geysers, rivers, and more in this series from her 2024 trip to the island. Every one of these images bears the fingerprints of fluid dynamics: plasma flows lighting up the night sky; rivers of lava that formed the land; rivers and oceans that carve through the landscape; and pressurized, superheated water that shoots up from underground plumbing. (Image credit: J. Esseiva; via Colossal)

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  • Flooding the Mediterranean

    Flooding the Mediterranean

    Nearly 6 million years ago, the Mediterranean was cut off from the ocean and evaporated faster than rivers could replenish it. This created a salty desert that persisted until about 5.3 million years ago. One hypothesis — the Zanclean megaflood — suggests that the Mediterranean refilled rapidly through an erosion channel near the Strait of Gilbraltar. A new study bolsters the concept by identifying geological features near Sicily consistent with the megaflood.

    The team point to a grouping of over 300 ridges near the Sicily Sill, once a land bridge dividing the eastern and western Mediterranean and now underwater. The ridges are layered in debris but aren’t streamlined, suggesting they were rapidly deposited by turbulent waters, and date to the period of the proposed flooding. For more on the Zanclean Flood, check out this older post. (Image credit: R. Klavins; research credit: A. Micallif et al.; via Gizmodo)

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    Dutch Water Works

    The Netherlands have a long history of extraordinary public works when it comes to water management. With much of the country’s land lying at or below sea level, massive civil engineering infrastructure is a necessity. In this Practical Engineering video, Grady takes us on a tour of Dutch water works, from the centuries-old techniques that allowed farmers to claim arable land from marshes to the unbelievably massive structures that protect the Dutch coastline from flooding and storm surges.

    For the Dutch, these projects, expensive as they are to build and maintain, are cheaper than the cost of inaction, as numerous devastating floods of the past have taught them. Although the goals are often the same — shortening the coastline, protecting land and people — the techniques are constantly evolving, especially as ecological needs of non-human species are taken into account. (Video and image credit: Practical Engineering)

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