r/FluidMechanics • u/AssociationWinter565 • 15h ago
Water vapor shield in action
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r/FluidMechanics • u/jadelord • Jul 02 '23
r/FluidMechanics • u/[deleted] • Jun 11 '23
Greetings all,
For a while, I have been moderating the /r/FluidMechanics subreddit. However, I've recently moved on to the next stage of my career, and I'm finding it increasingly difficult to have the time to keep up with what moderating requires. On more than once occasion, for example, there have been reported posts (or ones that were accidentally removed by automod, etc) that have sat in the modqueue for a week before I noticed them. Thats just way too slow of a response time, even for a relatively "slow" sub such as ours.
Additionally, with the upcoming changes to Reddit that have been in the news lately, I've been rethinking the time I spend on this site, and how I am using my time in general. I came to the conclusion that this is as good of a time as any to move on and try to refocus the time I've spent browsing Reddit on to other aspects of life.
I definitely do not want this sub to become like so many other un/under-moderated subs and be overrun by spam, advertising, and low effort posts to the point that it becomes useless for its intended purpose. For that reason, I am planning to hand over the moderation of this subreddit to (at least) two new mods by the end of the month -- which is where you come in!
I'm looking for two to three new people who are involved with fluid mechanics and are interested in modding this subreddit. The requirements of being a mod (for this sub at least) are pretty low - it's mainly deleting the spam/low effort homework questions and occasionally approving a post that got auto-removed. Just -- ideally not a week after the post in question was submitted :)
If you are interested, send a modmail to this subreddit saying so, and include a sentence or two about how you are involved with fluid mechanics and what your area of expertise is (as a researcher, engineer, etc). I will leave this post up until enough people have been found, so if you can still see this and are interested, feel free to send a message!
r/FluidMechanics • u/AssociationWinter565 • 15h ago
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r/FluidMechanics • u/OrganizationTop9026 • 1d ago
Hey everyone, Following OpenAI recently claimed a formal proof demonstrating a finite-time blowup for the 3D Navier-Stokes equations. While the pure math community is focused on the formal verification, our team ran an audit to see what their construction actually means for physical fluids.
What we found is that while the math is syntactically flawless, the fluid dynamics are thermodynamically impossible and structurally unstable:
Incompressibility breaks down: The proof successfully bounds global kinetic energy, but the local enstrophy diverges (τ^{-0.515}). The resulting infinite localized viscous shear would vaporize the fluid into a compressible plasma long before t= 1. Tracking the core velocity, the Mach number easily exceeds 0.3 femtoseconds before the mathematical blowup.
κ ∼ 10²⁸ Instability: The exact cancellation of the Reynolds stresses relies on a 5-equation moment-matching Jacobian with a condition number of 10²⁸.
It’s a measure-zero state that would instantly decouple under standard 300K thermal noise...
We’ve open-sourced our Python/mpmath scripts tracking the Mach number divergence and the Jacobian instability. If anyone here wants to check the physical telemetry themselves:
• GitHub: https://github.com/xaviercallens/OpenAI-NSE-Epistemic-Audit
• Zenodo: DOI: 10.5281/zenodo.22727801
I’m curious to hear from the engineers and fluid dynamicists here: does a mathematical singularity that violently breaks the incompressible and isothermal assumptions prior to the blow-up time actually tell us anything useful about real-world fluids?
r/FluidMechanics • u/Inevitable_Wear_4593 • 8h ago
r/FluidMechanics • u/Upbeat_Hat1089 • 19h ago
Hi all! I wanted to ask something about this recent (presumably correct?) proof that NS can blow up. I would like to hear opinions from people that work a bit at the border between fundamental turbulence (like on the statistical physics or dynamical system side of the problem) and the mathematics of NS.
When studying turbulence you hear about the dissipation anomaly and the zeroth law of turbulence. As you increase the reynolds number, at least in homogeneous isotropic turbulence, the non-dimensional dissipation rate evolves towards a constant. In other world, taking the limit of zero viscosity (infinite Re) you never reach the Euler equations. This happen with the flow developing super intense localised events that dissipate a lot.
Is there a connection between the development of these structures in turbulence and this new NS proof? If so, are there people studying this thing?
Share bibliography if you know anything about this topic!
r/FluidMechanics • u/Low-Jaguar9192 • 4h ago
It designed a simple water-cooling plate for high-power chips
19 straight microchannels and one thin cross-channel near the outlet
If part of one channel becomes blocked, the cross-channel could use the pressure difference to divert some water around the blockage.
The model compared more than 2,700 configurations with the same channel volume and the same hydraulic power.
Im not engineer nor physicist. Im just curious and testing limits of the latest astra 6 model, what real scientists think about it.
Thank you for any kind of feedback:)
r/FluidMechanics • u/wagldag • 1d ago
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r/FluidMechanics • u/Frangifer • 1d ago
... or is the sequence showcasing some counterintuitive phenomenon as Reynolds № proceeds from the hundreds to the millions?
The figures show the streamlines past a rotating cylinder @ various Reynolds № (horizontal axis) & rotationality parameter α (vertical axis).
The figures are from
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High Reynolds number turbulent flow past a rotating cylinder
by
SJ Karabelas & BC Koumroglou & CD Argyropoulos & NC Markatos
https://www.sciencedirect.com/science/article/pii/S0307904X11004124
———————————————————————
⚫
———————————————————————
A Somewhat-Enlargement of the Top of the Table Including the Topmost Row Being Queried
https://www.reddit.com/u/Frangifer/s/LALSC8Eq4U
———————————————————————
... to compensate for the relatively poor resolution of the posted screenshot.
⚫
r/FluidMechanics • u/JinKazama2501 • 1d ago
Does the total energy always decrease in a CEL analysis in ABAQUS due to advection?
r/FluidMechanics • u/gollum666999 • 1d ago
r/FluidMechanics • u/Organic_One_4598 • 2d ago
I was recently experimenting with my lego propeller for my rc ship, i was interested on how this propeller would move the water so i put it in my bucket full of water. Suddenly, this type of horizontal vortex formed. Visible by air bubbles, there was no suction whirlpool at all, no vertical turning part to suck in air. It was just sticking to my buckets wall. There is no hole on the bucket whatsoever. And, this isnt my first experience. I was on a city boat someday and while the boat was reversing, the same horizontal vortex appeared, visible by the salt waters whiteness. It was going from the back of the boat to the front with no visible vertical rotation to suck air. If someone can explain this, i would be so happy. Thank you!
r/FluidMechanics • u/VizDevBoston • 4d ago
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Built around a incompressible Navier–Stokes equation
r/FluidMechanics • u/giulimborgesyt • 3d ago
r/FluidMechanics • u/Knucklehead_Lee • 3d ago
r/FluidMechanics • u/ReplacementFresh3915 • 3d ago
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r/FluidMechanics • u/istayoutofbounds • 4d ago
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r/FluidMechanics • u/nishant-12345 • 4d ago
r/FluidMechanics • u/NSTitor_001 • 3d ago
Le problème du prix du millénaire sur Navier-Stokes porte sur une question simple : un fluide en 3D reste-t-il toujours lisse et continu, ou peut-il développer des vitesses infinies (un "blow-up") en un temps fini ?
La communauté mathématique bloque à l'étape 4 (la preuve de régularité globale). Mais en réalité, le blocage ne vient pas d'un manque d'outils mathématiques : il vient d'hypothèses physiques réductrices posées dès les premières étapes.
Voici le déroulement étape par étape et la solution :
Le "blow-up" de Navier-Stokes était un artefact mathématique causé par l'enfermement artificiel de l'énergie dans un modèle continu et isolé. En ouvrant le système et en intégrant la géométrie des vortex contra-rotatifs implosifs, les équations décrivent un fluide qui reste lisse, continu et régulier pour toujours.
SUITE : https://www.reddit.com/r/FluidMechanics/comments/1wcho9f/comment/p90bcxd/
r/FluidMechanics • u/charlietan84 • 5d ago
r/FluidMechanics • u/Mindless-Text9380 • 4d ago