#kelvinhelmholtzinstability — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #kelvinhelmholtzinstability, aggregated by home.social.
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Richtmyer-Meshkov Instability
If you send a shock wave through a magnetized plasma–something that happens in both supernova explosions and inertial confinement fusion–it can trigger an instability known as the Richtmyer-Meshkov instability. The image above shows a form of this, taken from a simulation. Rather than treating the plasma as a single idealized fluid, the researchers represented it as two fluids: an ion fluid and an electron fluid. This allowed them to better capture what happens when certain components of the plasma react to changes faster than others do.
The image itself shows the electron number density across the fluid, where darker colors represent higher electron number density. The interface between high and low-densities shows a roll-up instability that resembles the Kelvin-Helmholtz instability, but there are also regions of mushroom-like plumes that more closely resemble Rayleigh-Taylor instabilities.
The authors note that these structures don’t appear in simulations that represent a plasma as a single fluid; you need the two-fluid representation to see them. (Image and research credit: O. Thompson et al.)
#CFD #computationalFluidDynamics #fluidDynamics #instability #KelvinHelmholtzInstability #magnetohydrodynamics #numericalSimulation #physics #plasma #RayleighTaylorInstability #RichtmyerMeshkovInstability #science #shockwave -
“Glacial River Blues”
Glacier-fed rivers are often rich in colorful sediments. Here, photographer Jan Erik Waider shows us Iceland’s glacial rivers flowing primarily in shades of blue. While the wave action and diffraction in these videos is great, the real star is the turbulent mixing where turbid and clearer waters meet. Watch those boundaries, and you’ll see shear from flows moving at different speeds which feeds the ragged, Kelvin-Helmholtz-unstable edge between colors. (Video and image credit: J. Waider; via Laughing Squid)
#flowVisualization #fluidDynamics #fluidsAsArt #glacier #instability #KelvinHelmholtzInstability #physics #rivers #science #turbidity #turbulence #turbulentMixing -
Kelvin-Helmholtz instabilities (KHI) are a favorite among fluid dynamicists. They resemble the curls of a breaking ocean wave — not a coincidence, since KHI create those ocean waves to begin with — and show up in picturesque clouds, Martian lava coils, and Jovian cloud bands. The instability occurs when two layers of fluid move at different speeds and the friction between them causes wrinkles that grow into waves.
Scientists have long suspected that KHI could occur in solar phenomena, too, like the coronal mass ejections that drive space weather. The Parker Solar Probe, a spacecraft designed to explore the sun, caught evidence of a series of turbulent eddies during a 2021 coronal mass ejection, and a recent study of those observations shows that the series of vortices are consistent with KHI. Put simply, the team found that the features are spaced and aligned as we’d expect for KHI and, during the probe’s measurements, the features grew at the rate Kelvin-Helmholtz eddies would. Although the instability itself may be common in the sun’s corona, it’s unlikely that we’ll see it often, simply because conditions need to be just right for them to be visible. (Image credit: NASA/Johns Hopkins APL/NRL/Guillermo Stenborg and Evangelos Paouris; research credit: E. Paouris et al.; via Gizmodo)
https://fyfluiddynamics.com/2024/05/kelvin-helmholtz-and-the-sun/
#coronalMassEjection #fluidDynamics #instability #KelvinHelmholtzInstability #magnetohydrodynamics #physics #science #solarDynamics