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1000 results for “fluiddyn”
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The Twin Roles of Turbulence in Fusion
Inside a fusion reactor, magnetically-contained plasma gets heated to more than one hundred million degrees. That heat, researchers observed, spreads much faster than originally predicted. Now a team from Japan has measurements showing how turbulence manages this feat.
The researchers show that the multiscale nature of turbulence allows it to transport heat in two ways. The first is familiar: acting locally, turbulence spreads heat little by little as small eddies mix and pass the heat along. But turbulence can also be nonlocal, they show, able to connect physically distant parts of a flow more rapidly than expected. This happens through turbulence’s larger scales, which can rapidly carry heated plasma from one side of the vessel to another.
The researchers illustrate the two roles of turbulence through a metaphor of American football (can you believe it?). In their metaphor, the quarterback acts as turbulence and the ball represents heat. The quarterback can pass the ball to reach distant parts of the field quickly — just as nonlocal turbulence does–or they can hand off the ball to a running back, who carries the ball down the field more slowly, through local interactions with other nearby players. (Image credit: National Institute for Fusion Science; research credit: N. Kenmochi et al., via Gizmodo and EurekAlert)
#fluidDynamics #magnetohydrodynamics #physics #plasma #science #turbulence -
LeidenForce quiz of the day: can you solve our Fake or Fact?
In our Fake or Fact series, we test your science knowledge about the Leidenfrost effect!
#FluidDynamics #DailyScience #LeidenfrostEffect #Physics #FakeOrFact #HeatTransfer
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A Soft Cell in Microgravity
There are many shapes that can be tiled to fill space, but nearly all of them have sharp corners. Last year, mathematicians identified a new class of shapes, known as “soft cells,” that feature curved edges and faces but very few sharp corners. Like traditional polyhedrals, soft cells can tile to fill a space completely without overlapping or gapping.
Now the researchers, with some help from astronauts aboard the ISS, have brought one of their soft cells to life. Using an edge skeleton to guide the shape, astronaut Tibor Kapu filled the skeleton with water, which, in microgravity, formed a perfect soft cell, complete with faces curved by surface tension to their minimal area. See it in action below. (Image and video credit: HUNOR/NASA; research credit: G. Domokos et al.; via Oxford Mathematics)
https://www.youtube.com/shorts/EyMbqPUKl80
#fluidDynamics #mathematics #microgravity #physics #science #surfaceTension -
“Melting Snowflake”
It’s hard to preserve something as ephemeral as a snowflake, as seen in this microphotograph by Michael Robert Peres. Despite the old adage, it is possible to make identical snowflakes, but it requires mirroring the freezing conditions exactly, including both temperature and humidity. Here, the snowflake’s crystalline structure survives as a ghost in a melting droplet. (Image credit: M. Peres; via Ars Technica)
#fluidDynamics #fluidsAsArt #freezing #melting #physics #science #snowflakes
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Quantum Rayleigh-Taylor Instability
The Rayleigh-Taylor instability–typically marked by mushroom-shaped plumes–occurs when a dense fluid accelerates into a less dense one. But researchers have now demonstrated the effect at quantum scales, too.
For their experiment, the group used a Bose-Einstein condensate of sodium atoms and made the interface between them by exciting half of the atoms into a spin-up state and half into a spin-down one. With the interface is place, they reversed the magnetic field gradient, inducing a force on the atoms equivalent to the buoyant force seen in conventional Rayleigh-Taylor instabilities. As shown above, the interface first warped, then developed Rayleigh-Taylor mushrooms and eventually became turbulent. (Image and research credit: Y. Geng et al.; via Physics World)
#fluidDynamics #instability #physics #quantumMechanics #rayleighTaylorInstability #science #turbulence
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Quantum Rayleigh-Taylor Instability
The Rayleigh-Taylor instability–typically marked by mushroom-shaped plumes–occurs when a dense fluid accelerates into a less dense one. But researchers have now demonstrated the effect at quantum scales, too.
For their experiment, the group used a Bose-Einstein condensate of sodium atoms and made the interface between them by exciting half of the atoms into a spin-up state and half into a spin-down one. With the interface is place, they reversed the magnetic field gradient, inducing a force on the atoms equivalent to the buoyant force seen in conventional Rayleigh-Taylor instabilities. As shown above, the interface first warped, then developed Rayleigh-Taylor mushrooms and eventually became turbulent. (Image and research credit: Y. Geng et al.; via Physics World)
#fluidDynamics #instability #physics #quantumMechanics #rayleighTaylorInstability #science #turbulence
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Quantum Rayleigh-Taylor Instability
The Rayleigh-Taylor instability–typically marked by mushroom-shaped plumes–occurs when a dense fluid accelerates into a less dense one. But researchers have now demonstrated the effect at quantum scales, too.
For their experiment, the group used a Bose-Einstein condensate of sodium atoms and made the interface between them by exciting half of the atoms into a spin-up state and half into a spin-down one. With the interface is place, they reversed the magnetic field gradient, inducing a force on the atoms equivalent to the buoyant force seen in conventional Rayleigh-Taylor instabilities. As shown above, the interface first warped, then developed Rayleigh-Taylor mushrooms and eventually became turbulent. (Image and research credit: Y. Geng et al.; via Physics World)
#fluidDynamics #instability #physics #quantumMechanics #rayleighTaylorInstability #science #turbulence
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How to Keep Water From Freezing
When supercooled, water can remain a liquid even below its freezing point. As explained in this Minute Physics video, this happens because of a tug-of-war between effects in the water. Generally speaking, having impurities in the water or smacking the bottle will shift that battle enough for freezing to win out. But it’s possible–theoretically, at least–to create a situation where supercooled water can never freeze. (Video and image credit: Minute Physics)
#fluidDynamics #freezing #iceFormation #physics #science #supercooling
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How to Keep Water From Freezing
When supercooled, water can remain a liquid even below its freezing point. As explained in this Minute Physics video, this happens because of a tug-of-war between effects in the water. Generally speaking, having impurities in the water or smacking the bottle will shift that battle enough for freezing to win out. But it’s possible–theoretically, at least–to create a situation where supercooled water can never freeze. (Video and image credit: Minute Physics)
#fluidDynamics #freezing #iceFormation #physics #science #supercooling
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How to Keep Water From Freezing
When supercooled, water can remain a liquid even below its freezing point. As explained in this Minute Physics video, this happens because of a tug-of-war between effects in the water. Generally speaking, having impurities in the water or smacking the bottle will shift that battle enough for freezing to win out. But it’s possible–theoretically, at least–to create a situation where supercooled water can never freeze. (Video and image credit: Minute Physics)
#fluidDynamics #freezing #iceFormation #physics #science #supercooling
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How to Keep Water From Freezing
When supercooled, water can remain a liquid even below its freezing point. As explained in this Minute Physics video, this happens because of a tug-of-war between effects in the water. Generally speaking, having impurities in the water or smacking the bottle will shift that battle enough for freezing to win out. But it’s possible–theoretically, at least–to create a situation where supercooled water can never freeze. (Video and image credit: Minute Physics)
#fluidDynamics #freezing #iceFormation #physics #science #supercooling
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A Rough Day
Winds from the north made for wild conditions at Nazaré in Portugal. Photographer Ben Thouard caught these crashing waves in the late afternoon, when the low sun angle illuminated the spray of the surf. Every year teratons of salt and biomass move from the ocean to the atmosphere, much of it through turbulent wave action driven by the wind. Here, the wind rips droplets off of wave crests, but smaller droplets reach the atmosphere when bubbles–trapped underwater by crashing waves–reach the surface and burst. (Image credit: B. Thouard/OPOTY; via Colossal)
#fluidDynamics #fluidsAsArt #ocean #oceanWaves #physics #science #turbulence
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A Rough Day
Winds from the north made for wild conditions at Nazaré in Portugal. Photographer Ben Thouard caught these crashing waves in the late afternoon, when the low sun angle illuminated the spray of the surf. Every year teratons of salt and biomass move from the ocean to the atmosphere, much of it through turbulent wave action driven by the wind. Here, the wind rips droplets off of wave crests, but smaller droplets reach the atmosphere when bubbles–trapped underwater by crashing waves–reach the surface and burst. (Image credit: B. Thouard/OPOTY; via Colossal)
#fluidDynamics #fluidsAsArt #ocean #oceanWaves #physics #science #turbulence
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A Rough Day
Winds from the north made for wild conditions at Nazaré in Portugal. Photographer Ben Thouard caught these crashing waves in the late afternoon, when the low sun angle illuminated the spray of the surf. Every year teratons of salt and biomass move from the ocean to the atmosphere, much of it through turbulent wave action driven by the wind. Here, the wind rips droplets off of wave crests, but smaller droplets reach the atmosphere when bubbles–trapped underwater by crashing waves–reach the surface and burst. (Image credit: B. Thouard/OPOTY; via Colossal)
#fluidDynamics #fluidsAsArt #ocean #oceanWaves #physics #science #turbulence
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A Rough Day
Winds from the north made for wild conditions at Nazaré in Portugal. Photographer Ben Thouard caught these crashing waves in the late afternoon, when the low sun angle illuminated the spray of the surf. Every year teratons of salt and biomass move from the ocean to the atmosphere, much of it through turbulent wave action driven by the wind. Here, the wind rips droplets off of wave crests, but smaller droplets reach the atmosphere when bubbles–trapped underwater by crashing waves–reach the surface and burst. (Image credit: B. Thouard/OPOTY; via Colossal)
#fluidDynamics #fluidsAsArt #ocean #oceanWaves #physics #science #turbulence
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Frosted
Frost forms hexagonal columns on a wooden rail in this microphotograph by Gregory B. Murray. Like in snowflakes, when water molecules freeze they position themselves to form six-sided crystals. From this perspective, it looks like a miniature version of the Giant’s Causeway. (Image credit: G. Murray; via Ars Technica)
#fluidDynamics #fluidsAsArt #freezing #frost #physics #science
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Our Best Look Yet at a Solar Flare
Scientists have unveiled the sharpest images ever captured of a solar flare. Taken by the Inouye Solar Telescope, the image includes coronal loop strands as small as 48 kilometers wide and 21 kilometers thick–the smallest ones ever imaged. The width of the overall image is about 4 Earth diameters. The captured flare belongs to the most powerful class of flares, the X class. Catching such a strong flare under the perfect observation conditions is a wonderful stroke of luck.
Although astronomers had theorized that coronal loops included this fine-scale structure, the Inouye Solar Telescope is the first instrument with the resolution to directly observe structures of this size. Confirming their existence is a big step forward for those working to understand the details of our Sun. (Video and image credit: NSF/NSO/AURA; research credit: C. Tamburri et al.; via Gizmodo)
https://www.youtube.com/watch?v=WnoAq4rpLg4
#fluidDynamics #fluidsAsArt #magnetohydrodynamics #physics #science #sun
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Buccaneer Archipelago
Off western Australian, hundreds of low-lying islands and coral reefs jut into the ocean as part of the Buccaneer Archipelago. Tides here have a range of nearly 12 meters, so water rips through the narrow channels as the tide ebbs and flows. These fast flows lift sediment that dyes the water a bright turquoise. (Image credit: M. Garrison; via NASA Earth Observatory)
#fluidDynamics #oceanTides #physics #satelliteImage #science #tides
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Buccaneer Archipelago
Off western Australian, hundreds of low-lying islands and coral reefs jut into the ocean as part of the Buccaneer Archipelago. Tides here have a range of nearly 12 meters, so water rips through the narrow channels as the tide ebbs and flows. These fast flows lift sediment that dyes the water a bright turquoise. (Image credit: M. Garrison; via NASA Earth Observatory)
#fluidDynamics #oceanTides #physics #satelliteImage #science #tides
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Buccaneer Archipelago
Off western Australian, hundreds of low-lying islands and coral reefs jut into the ocean as part of the Buccaneer Archipelago. Tides here have a range of nearly 12 meters, so water rips through the narrow channels as the tide ebbs and flows. These fast flows lift sediment that dyes the water a bright turquoise. (Image credit: M. Garrison; via NASA Earth Observatory)
#fluidDynamics #oceanTides #physics #satelliteImage #science #tides
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Buccaneer Archipelago
Off western Australian, hundreds of low-lying islands and coral reefs jut into the ocean as part of the Buccaneer Archipelago. Tides here have a range of nearly 12 meters, so water rips through the narrow channels as the tide ebbs and flows. These fast flows lift sediment that dyes the water a bright turquoise. (Image credit: M. Garrison; via NASA Earth Observatory)
#fluidDynamics #oceanTides #physics #satelliteImage #science #tides
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We are recruiting a PhD for LeidenForce (Horizon Europe) — ESPCI Paris - PSL & @UniversitedeLiege
France + Belgium • Experimental physics • Fluid & heat transfer
One of the final opportunities in the MSCA Doctoral Network.
We need You to share this call within your network.🗓️ Application deadline
November 15, 2025👉 Apply now | Please share
• Application form: https://www.leidenforce.eu/upload/docs/application/pdf/2025-11/phd_position_dc9__leidenforce_espci_paris__university_of_liege.pdf
• More info: https://www.leidenforce.eu#fluiddynamics #PhDposition #MSCA #HorizonEurope #leidenfrosteffect
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Kirigami Parachutes
In kirigami, careful cuts to a flat surface can morph it into a more complicated shape. Researchers have been exploring how to use this in combination with flow; now they’ve created a new form of parachute. Like a dandelion seed, this parachute is porous, with a complex but stable wake structure. This allows the parachute to drop directly over its target, unlike conventional parachutes, which require a glide angle to avoid canopy-collapsing turbulence.
When dropping conventional parachutes, users either have to tolerate random landings far off target or invest in complicated active control systems that guide the parachute. Kirigami parachutes, in contrast, offer a potentially simple and robust option for accurately delivering, for example, humanitarian aid. (Image and research credit: D. Lamoureux et al.; via Physics World)
#fluidDynamics #kirigami #parachutes #physics #porousFlow #science
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@ColinTheMathmo
Ah, rabbit-hole explorer, eh? I confess I'm pretty deep in this warren myself. I believe it's for trim, is used in normal flight (but isn't itself the elevator, which might be what you were asking, that's a separate control surface), and has no flaps (basically they're on the wings). Happy to be corrected; I write in a relatively amateur capacity. You may enjoy this thread: https://homebuiltairplanes.com/threads/designing-a-removable-one-piece-horizontal-stabilizer-with-advanced-composites-self-study.37764 Fair warning: it may lead to wanting to build little airplanes.*edited to add: I think post #31 in that thread (first post of page 2) is particularly pertinent to your question. I believe the author spent much of their career in vibration engineering (I don't know the proper name for their subspecialty, but anyway, suffice to say they're a switched-on cookie).
#aviation #aerospace #aircraftDesign #aeroplanes #airplanes #systemArchitecture #fluidDynamics #engineering
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Predicting Sea States
Transferring cargo between ships and landing aircraft on carriers requires predicting how the waves will behave for the next few minutes. That’s a notoriously difficult task for several reasons: rough seas can hide a ship radar’s view and the inherent nonlinearity of ocean waves means that they can occasionally coalesce unexpectedly large (“rogue“) waves, seemingly from nowhere.
A new study describes a technique for improving sea state predictions. In their model, the team first use multiple radar returns to average out gaps in the current wave state data, then feed that interpolated data into a prediction algorithm that includes nonlinearities up to the third-order. The results, they found, gave far better predictions than current techniques, some of which had errors 3 times as high. (Image credit: R. Ding; research credit: J. Yao et al.; via APS News)
#fluidDynamics #nonlinearDynamics #oceanWaves #physics #science
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Tracing the Origins of Ocean Waters
The Sub-Antarctic Mode Waters (SAMW) lie in the southern Indian Ocean and the east and central Pacific Ocean, where they serve as an important sink for both heat and carbon dioxide. Scientists have long debated the origins of the SAMW’s waters, and a new study may have an answer.
Researchers combined data from ocean observations with a model of the Southern Ocean to essentially trace the SAMW’s ingredients back to their respective origins. The results showed that about 70% of the Indian Ocean’s SAMWs came from subtropical waters, but those waters contributed to only about 40% of the Pacific’s SAMWs. Pacific SAMWs had their largest contributions from upwelling circumpolar waters.
Understanding where a SAMW’s waters came from helps scientists predict how those waters will mix and how much heat and carbon they can absorb. (Image credit: NASA; research credit: B. Fernández Castro et al.; via Eos)
#fluidDynamics #mixing #numericalSimulation #oceanography #physics #planetaryScience #science
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Ice Discs Surf on Herringbones
Inspired by the roaming rocks of Death Valley, researchers went looking for ways to make ice discs self-propel. Leidenfrost droplets can self-propel on herringbone-etched surfaces, so the team used them here, as well. On hydrophilic herringbones, they found that meltwater from the ice disc would fill the channels and drag the ice along with it.
But on hydrophobic herringbone surfaces, the ice disc instead attached to the crest of the ridges and stayed in place–until enough of the ice melted. Then the disc would detach and slingshot (as shown above) along the herringbones. This self-propulsion, they discovered, came from the asymmetry of the meltwater; because different parts of the puddle had different curvature, it changed the amount of force surface tension exerted on the ice. Thus, when freed, the ice disc tried to re-center itself on the puddle.
The team is especially interested in how effects like this could make ice remove itself from a surface. After all, it requires much less energy to partially melt some ice than it does to completely melt it. (Image and research credit: J. Tapochik et al.; via Ars Technica)
#fluidDynamics #ice #melting #physics #science #selfPropulsion #superhydrophobic
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Striations on the Sun
One of the perpetual challenges for fluid dynamicists is the large range of scales we often have to consider. For something like a cloud, that means tracking not only the kilometer-size scale of the cloud, but the large eddies that are about 100 meters across and smaller ones all the way down to the scale of millimeters. In turbulent flows, all of these scales matter. That problem is even harder for something like the Sun, where the sizes range from hundreds of thousands of kilometers down to only a few kilometers.
It’s those fine-scale features that we see captured here. This colorized image shows light and dark striations on solar granules. Scientists estimate that each one is between 20 and 50 kilometers wide. They’re reflections of the small-scale structure of the Sun’s magnetic field as it shapes the star’s hot, conductive plasma. (Image credit: NSF/NSO/AURA; research credit: D. Kuridze et al.; via Gizmodo)
#fluidDynamics #magneticField #magnetohydrodynamics #physics #science #solarDynamics #sun #turbulence
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A Braided River
The Yarlung Zangbo River winds through Tibet as the world’s highest-altitude major river. Parts of it cut through a canyon deeper than 6,000 meters (three times the depth of the Grand Canyon). And other parts, like this section, are braided, with waterways that shift rapidly from season to season. The swift changes in a braided river’s sandbars come from large amounts of sediment eroded from steep mountains upstream. As that sediment sweeps downstream, some will deposit, which narrows channels and can increase their scouring. The river’s shape quickly becomes a complicated battle between sediment, flow speed, and slope. (Image credit: M. Garrison; animation credit: R. Walter; via NASA Earth Observatory)
#fluidDynamics #geophysics #physics #rivers #satelliteImage #science #sedimentTransport #sedimentation
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A Braided River
The Yarlung Zangbo River winds through Tibet as the world’s highest-altitude major river. Parts of it cut through a canyon deeper than 6,000 meters (three times the depth of the Grand Canyon). And other parts, like this section, are braided, with waterways that shift rapidly from season to season. The swift changes in a braided river’s sandbars come from large amounts of sediment eroded from steep mountains upstream. As that sediment sweeps downstream, some will deposit, which narrows channels and can increase their scouring. The river’s shape quickly becomes a complicated battle between sediment, flow speed, and slope. (Image credit: M. Garrison; animation credit: R. Walter; via NASA Earth Observatory)
#fluidDynamics #geophysics #physics #rivers #satelliteImage #science #sedimentTransport #sedimentation