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1000 results for “fluiddyn”
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Stunning Interstellar Turbulence
The space between stars, known as the interstellar medium, may be sparse, but it is far from empty. Gas, dust, and plasma in this region forms compressible magnetized turbulence, with some pockets moving supersonically and others moving slower than sound. The flows here influence how stars form, how cosmic rays spread, and where metals and other planetary building blocks wind up. To better understand the physics of this region, researchers built a numerical simulation with over 1,000 billion grid points, creating an unprecedentedly detailed picture of this turbulence.
The images above are two-dimensional slices from the full 3D simulation. The upper image shows the current density while the lower one shows mass density. On the right side of the images, magnetic field lines are superimposed in white. The results are gorgeous. Can you imagine a fly-through video? (Image and research credit: J. Beattie et al.; via Gizmodo)
#astrophysics #compressibility #flowVisualization #fluidDynamics #fluidsAsArt #magnetohydrodynamics #numericalSimulation #physics #science #turbulence
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Escape From Yavin 4
In an ongoing tradition, let’s take another look at some Star Wars-inspired aerodynamics. This year it’s the TIE fighter’s turn. Here, researchers simulate the spacecraft trying to escape Yavin 4’s atmosphere at Mach 1.15. The research poster’s blue contours show pressure contours, with darker colors connoting higher pressures. The bright low pressure region immediately behind the craft suggests a difficult, high-drag ascent and a turbulent, subsonic wake despite the craft’s supersonic velocity. (Image credit: A. Martinez-Sanchez et al.)
#flowVisualization #fluidDynamics #numericalSimulation #physics #science #starWars #supersonic #turbulence
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Kolmogorov Turbulence
Turbulent flows are ubiquitous, but they’re also mindbogglingly complex: ever-changing in both time and space across length scales both large and small. To try to unravel this complexity, scientists use simplified model problems. One such simplification is Kolmogorov flow: an imaginary flow where the fluid is forced back and forth sinusoidally. This large-scale forcing puts energy into the flow that cascades down to smaller length scales through the turbulent energy cascade. Here, researchers depict a numerical simulation of a turbulent Kolmogorov flow. The colors represent the flow’s vorticity field. Notice how your eye can pick out both tiny eddies and larger clusters in the flow; those patterns reflect the multi-scale nature of turbulence. (Image credit: C. Amores and M. Graham)
#2024gofm #flowVisualization #fluidDynamics #Kolmogorov #numericalSimulation #physics #science #turbulence #turbulentEnergyCascade
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Galloping Bubbles
A buoyant bubble rises until it’s stopped by a wall. What happens, this video asks, if that wall vibrates up and down? If the vibration is large enough, the bubble loses its symmetry and starts to gallop along the wall. Using numerical simulations, the team determined the flow around the bubble. They also demonstrate several possible applications for this behavior: sorting bubbles by size, traversing mazes, and cleaning a surface. (Video and image credit: J. Guan et al.)
#2024gofm #bubbles #experimentalFluidDynamics #fluidDynamics #numericalSimulation #physics #science #vibration
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Why Icy Giants Have Strange Magnetic Fields
When Voyager 2 visited Uranus and Neptune, scientists were puzzled by the icy giants’ disorderly magnetic fields. Contrary to expectations, neither planet had a well-defined north and south magnetic pole, indicating that the planets’ thick, icy interiors must not convect the way Earth’s mantle does. Years later, other researchers suggested that the icy giants’ magnetic fields could come from a single thin, convecting layer in the planet, but how that would look remained unclear. Now a scientist thinks he has an answer.
When simulating a mixture of water, methane, and ammonia under icy giant temperature and pressure conditions, he saw the chemicals split themselves into two layers — a water-hydrogen mix capable of convection and a hydrocarbon-rich, stagnant lower layer. Such phase separation, he argues, matches both the icy giants’ gravitational fields and their odd magnetic fields. To test whether the model holds up, we’ll need another spacecraft — one equipped with a Doppler imager — to visit Uranus and/or Neptune to measure the predicted layers firsthand. (Image credit: NASA; research credit: B. Militzer; via Physics World)
#convection #fluidDynamics #Neptune #numericalSimulation #phaseSeparation #physics #planetaryScience #science #Uranus
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Paint drops form “fried egg” patterns if concentration, temp is just right - Enlarge / As paint drops dry, they can look like a “fried egg” (left) o... - https://arstechnica.com/?p=1972460 #coffeeringeffect #chemicalphysics #fluiddynamics #chemistry #colloids #science #physics
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How do fluids really slip on surfaces?
This study proposes a method to estimate slip length and reconstruct flow fields from limited data.
A key step to better understand flows where friction at the wall nearly vanishes.
#fluiddynamics #interfacialflows #SlipLength #hydrodynamics #physics
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How do fluids really slip on surfaces?
This study proposes a method to estimate slip length and reconstruct flow fields from limited data.
A key step to better understand flows where friction at the wall nearly vanishes.
#fluiddynamics #interfacialflows #SlipLength #hydrodynamics #physics
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How do fluids really slip on surfaces?
This study proposes a method to estimate slip length and reconstruct flow fields from limited data.
A key step to better understand flows where friction at the wall nearly vanishes.
#fluiddynamics #interfacialflows #SlipLength #hydrodynamics #physics
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How do fluids really slip on surfaces?
This study proposes a method to estimate slip length and reconstruct flow fields from limited data.
A key step to better understand flows where friction at the wall nearly vanishes.
#fluiddynamics #interfacialflows #SlipLength #hydrodynamics #physics
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When a drop or object hits water, a narrow high-speed jet can shoot upward: the Worthington jet. This study reveals universal scaling laws that govern how these jets form and evolve across different impact conditions.
🔗 https://journals.aps.org/prfluids/abstract/10.1103/2vdb-tqj6
#FluidDynamics #DropImpact #WorthingtonJet #Physics #InterfacialFlows
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When a drop or object hits water, a narrow high-speed jet can shoot upward: the Worthington jet. This study reveals universal scaling laws that govern how these jets form and evolve across different impact conditions.
🔗 https://journals.aps.org/prfluids/abstract/10.1103/2vdb-tqj6
#FluidDynamics #DropImpact #WorthingtonJet #Physics #InterfacialFlows
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When a drop or object hits water, a narrow high-speed jet can shoot upward: the Worthington jet. This study reveals universal scaling laws that govern how these jets form and evolve across different impact conditions.
🔗 https://journals.aps.org/prfluids/abstract/10.1103/2vdb-tqj6
#FluidDynamics #DropImpact #WorthingtonJet #Physics #InterfacialFlows
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When a drop or object hits water, a narrow high-speed jet can shoot upward: the Worthington jet. This study reveals universal scaling laws that govern how these jets form and evolve across different impact conditions.
🔗 https://journals.aps.org/prfluids/abstract/10.1103/2vdb-tqj6
#FluidDynamics #DropImpact #WorthingtonJet #Physics #InterfacialFlows
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When a drop or object hits water, a narrow high-speed jet can shoot upward: the Worthington jet. This study reveals universal scaling laws that govern how these jets form and evolve across different impact conditions.
🔗 https://journals.aps.org/prfluids/abstract/10.1103/2vdb-tqj6
#FluidDynamics #DropImpact #WorthingtonJet #Physics #InterfacialFlows
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A key takeaway for LeidenForce: surface wettability radically reshapes the surface–bubble–flow coupling—smaller bubbles, higher detachment frequency, stronger vortical flows.
🔗 https://journals.aps.org/prfluids/abstract/10.1103/jvxz-8mzv
#FluidDynamics #MultiphaseFlow #InterfacialFlows #LeidenfrostEffect #wettability
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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)
#adhesion #biology #chemistry #fluidDynamics #icing #physics #polarBears #science
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My 🐘 #introduction 👋
I'm a researcher at Roskilde University (#RUC) in 🇩🇰. My background is #physics and research I do revolves around #fluiddynamics 🌊 💦 using #CFD and #theory. Much of my work is focused on #thinfilms or #droplets. My perferred #CFD tool is #LBM but I started using #VOF with #openfoam. I try to be open when it comes to coding which is why I switch languages for different tasks #julialang, #python, #C++, #JS.
Besides that I'm into #running 🏃♂️, #gaming, #coffee ☕ and #politics. -
Variable-Nozzle Ducted Fan Provides Fluid Dynamics Lessons - Any student new to the principles of fluid dynamics will be familiar with Bernoull... - https://hackaday.com/2023/10/19/variable-nozzle-ducted-fan-provides-fluid-dynamics-lessons/ #variablenozzle #fluiddynamics #remotecontrol #dronehacks #bernoulli #brushless #ductedfan #jetengine #venturi #drone #motor
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Visualizing Unstable Flames
Inside a combustion chamber, temperature fluctuations can cause sound waves that also disrupt the flow, in turn. This is called a thermoacoustic instability. In this video, researchers explore this process by watching how flames move down a tube. The flame fronts begin in an even curve that flattens out and then develops waves like those on a vibrating pool. Those waves grow bigger and bigger until the flame goes completely turbulent. Visually, it’s mesmerizing. Mathematically, it’s a lovely example of parametric resonance, where the flame’s instability is fed by system’s natural harmonics. (Video and image credit: J. Delfin et al.; research credit: J. Delfin et al. 1, 2)
#2024gofm #combustion #combustionInstability #flame #flowVisualization #fluidDynamics #instability #parametricResonance #physics #resonance #science #thermoacousticInstability #turbulence
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Even freshwater contains trace salts and minerals that cause scaly buildups as they evaporate. Getting rid of the scale usually requires toxic chemicals and/or lots of scrubbing, neither of which are desirable at the industrial level. At the same time, we’re extremely limited in the amount of freshwater that we have available; only about 1% of Earth’s water is liquid and fresh. If we could use salt water in more industrial processes, that would preserve freshwater for drinking and agriculture. But how do we tackle the scaly buildup?
(A) On microtextured surfaces, salt from evaporating drops can work its way into the gaps, destroying the superhydrophobicity of the surface. (B) In contrast, nanotextured surfaces give the salt nowhere to adhere, resulting in “salt critters” that grow upward and detach.Enter “salt critters.” Researchers found that when salt water evaporated from microtextured surfaces designed to shed water, salt would eventually build up in the gaps, breaking the hydrophobic effect and allowing scale to build up. In contrast, a nanotextured surface left nowhere for the salt to adhere. On these surfaces, evaporating salt water built jellyfish-like salt critters that rose from the surface and, eventually, broke off and rolled away, leaving the surface pristine. (Image credit: S. McBride; research credit: S. McBride et al.; via Physics Today)
https://fyfluiddynamics.com/2024/10/self-cleaning-with-salt-critters/
#droplets #evaporation #fluidDynamics #physics #science #selfCleaning #superhydrophobic
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Even freshwater contains trace salts and minerals that cause scaly buildups as they evaporate. Getting rid of the scale usually requires toxic chemicals and/or lots of scrubbing, neither of which are desirable at the industrial level. At the same time, we’re extremely limited in the amount of freshwater that we have available; only about 1% of Earth’s water is liquid and fresh. If we could use salt water in more industrial processes, that would preserve freshwater for drinking and agriculture. But how do we tackle the scaly buildup?
(A) On microtextured surfaces, salt from evaporating drops can work its way into the gaps, destroying the superhydrophobicity of the surface. (B) In contrast, nanotextured surfaces give the salt nowhere to adhere, resulting in “salt critters” that grow upward and detach.Enter “salt critters.” Researchers found that when salt water evaporated from microtextured surfaces designed to shed water, salt would eventually build up in the gaps, breaking the hydrophobic effect and allowing scale to build up. In contrast, a nanotextured surface left nowhere for the salt to adhere. On these surfaces, evaporating salt water built jellyfish-like salt critters that rose from the surface and, eventually, broke off and rolled away, leaving the surface pristine. (Image credit: S. McBride; research credit: S. McBride et al.; via Physics Today)
https://fyfluiddynamics.com/2024/10/self-cleaning-with-salt-critters/
#droplets #evaporation #fluidDynamics #physics #science #selfCleaning #superhydrophobic
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"We discovered that the flickering snake tongue generates two pairs of small, swirling masses of air, or vortices, that act like tiny fans, pulling odors in from each side and jetting them directly into the path of each tongue tip."
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What dendritic painting has in common with “tears of wine” phenomenon - Enlarge / Japanese artist Akiko Nakayama manipulates alcohol and inks t... - https://arstechnica.com/?p=2007448 #non-newtonianfluids #dendriticpainting #fractalpatterns #marangonieffect #fluiddynamics #fractalsinart #science #physics #art
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Chaotic Hose Instability
Steve Mould is back with another video looking at wild fluid behaviors. This time he’s considering hose instabilities like the one that makes a water-carrying hose beyond a certain length to whip wildly back and forth. He tries to track down the reasoning for these flexible hoses snapping and whipping. In truth, both the hoses and the wind dancers do their thing due to interactions between the elasticity of the hose and the fluid dynamics of the flows within. These applications are ripe for a few control volume thought experiments. (Video and image credit: S. Mould)
#chaos #elasticity #fluidDynamics #physics #science #solidMechanics
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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.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)
#flowVisualization #fluidDynamics #instability #physics #pipeFlow #science #softMatter #solidMechanics #stress
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Soft materials tend to be sticky, and once they’re adhered to a surface, they’re often harder to remove than they were to attach — think of Scotch tape stuck to a desk. This difficulty separating sticky things — known as adhesion hysteresis — has been attributed to various causes, like energy lost to viscoelasticity or age-related chemical bonding. But a new study shows that both those explanations are unnecessary.
Instead, the difficult removal comes from the way two surfaces separate in fits and starts. No two surfaces are perfectly smooth, and soft surfaces are able to conform to all the nooks and crannies of their partner surface. That molding results in a lot of surface contact, all of which must break for the materials to detach. That peeling doesn’t take place smoothly. Instead, the two surfaces part a little at a time in discrete jumps, as shown in the image above. The colors in the illustration show how much energy is dissipated in each jump, with darker colors indicating higher energy. The team found that this stick-slip mechanism is enough to account for the struggles we have un-sticking objects. They’re now looking at how water affects these narrow meeting places between sticky surfaces. (Image and research credit: A. Sanner et al.; via Physics World)
https://fyfluiddynamics.com/2024/05/unsticking-in-jumps/
#adhesion #fluidDynamics #physics #science #solidMechanics #stickSlip #surfaceRoughness
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To fly stably, parachutes need to deform and allow some air to pass through their canopy. In this video, researchers investigate kirigimi parachutes, inspired by a form of paper art that uses cuts to create three-dimensional shapes. After laser-cutting, these disks are dropped — or placed in a wind tunnel — to observe how they “fly” at different speeds. Sometimes they flutter or bend; other shapes elongate in the flow. (Video and image credit: D. Lamoureux et al.; via GoSM)
https://fyfluiddynamics.com/2024/05/kirigami-parachutes/
#2024gosm #drag #fluidDynamics #parachutes #physics #science #solidMechanics
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Oil-Slicked Bubble Bursts
When bubbles at the surface of the ocean pop, they can send up a spray of tiny droplets that carry salt, biomass, microplastics, and other contaminants into the atmosphere. Teratons of such materials enter the atmosphere from the ocean each year. To better understand how contaminants can cross from the ocean to the atmosphere, researchers studied what happens when a oil-coated water bubble pops.
The team looked at bubbles about 2 millimeters across, coated in varying amounts of oil, and observed their demise via high-speed video. When the bubble pops, capillary waves ripple down into its crater-like cavity and meet at the bottom. That collision creates a rebounding Worthington jet, like the one above, which can eject droplets from its tip.
The team found that the oil layer’s thickness affected the capillary waves and changed the width of the resulting jet. They were able to build a mathematical model that predicts how wide a jet will be, though a prediction of the jet’s velocity is still a work-in-progress. (Image credit: Р. Морозов; research credit: Z. Yang et al.; via APS)
#bubbles #capillaryWaves #contamination #fluidDynamics #physics #science #WorthingtonJet
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"In the paper, the researchers suggest they have figured out how to unify three physical theories that explain the motion of fluids. [...] This breakthrough won’t change the theories themselves, but it mathematically justifies them and strengthens our confidence that the equations work in the way we think they do."