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El Capitan: New supercomputer is the fastest

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Re: El Capitan: New supercomputer is the fastest

#61

Post by p_l »

Jabbles wrote: post #60
p_l wrote: post #58

Earlier quoted context omitted.

Subatomic scale is the perfect option, but we tend to not have time for that, so we sample and average and do other things. At least that's the situation within aerospace's hunger for CFD, I figure nuclear has similar approaches.

I would like a citation for anyone in aerospace using (or even realistically proposing) subatomic fluid dynamics.

Ok, that misreading is on me - in aerospace generally you care to level of molecules, and I've met many people who would love to be just able to brute force it this way. Hypersonics do however end up dealing with simulating subatomic particle behaviours (because of things like air turning into plasma)

Re: El Capitan: New supercomputer is the fastest

#62

Post by Jabbles »

p_l wrote: post #61
Jabbles wrote: post #60

Earlier quoted context omitted.

I would like a citation for anyone in aerospace using (or even realistically proposing) subatomic fluid dynamics.

Ok, that misreading is on me - in aerospace generally you care to level of molecules, and I've met many people who would love to be just able to brute force it this way. Hypersonics do however end up dealing with simulating subatomic particle behaviours (because of things like air turning into plasma)

> in aerospace generally you care to level of molecules

I would like a citation for this.

> Hypersonics do however end up dealing with simulating subatomic particle behaviours

And this.

---

For example, you could choose to cite "A Study on Plasma Formation on Hypersonic Vehicles using Computational Fluid Dynamics" DOI: 10.13009/EUCASS2023-492 Aerospace Europe Conference 2023 – 10ᵀᴴ EUCASS – 9ᵀᴴ CEAS

At sub-orbital altitudes, air can be modelled as a continuous flow governed by the Navier-Stokes equations for a multicomponent gas mixture. At hypersonic speeds, however, this physical model must account for various non-equilibrium phenomena, including vibrational and electronic energy relaxation, dissociation and ionization.

https://www.eucass.eu/doi/EUCASS2023-492.pdf

Re: El Capitan: New supercomputer is the fastest

#63

Post by cameron_b »

balia wrote: post #42

Some may not want to hear this, but these “fastest supercomputer” list is now meaningless because all the Chinese labs have started obfuscating their progress. A while ago there were a few labs in China in top 10 and they all attracted sanctions / bad attention. Now no Chinese lab report any data now

They are in good company, with X, Meta, Microsoft and others not reporting theirs either.

The basis for the ranking was a cumulative tracking of benchmark results that were required as part of commissioning bespoke computers. A contract would be written to buy a computer that could achieve a certain performance in operations per second, and in order to satisfy that the benchmarks were agreed to and codified in the contracts. Government contracts are to a certain extent public information so the goals and clout of successive performance were tracked in this way.

If you don’t need to satisfy a government contract, or don’t need the clout to attract engineers or funding, submitting results draws unwanted attention to what you’re cooking up.

Re: El Capitan: New supercomputer is the fastest

#64

Post by dekhn »

colonCapitalDee wrote: post #55
pkaye wrote: post #27

Earlier quoted context omitted.

Are they always designing new nuclear bombs? Why the ongoing work to simulate?

Basically yes, we are always designing new nuclear bombs. This isn't done to increase yield, we've actually been moving towards lower yield nuclear bombs ever since the mid Cold War. In the 60s the US deployed the B41 bomb with a maximum yield of 25 megatons, making it the most powerful bomb ever deployed by the US. When the B41 was retired in the late 70s, the most powerful bomb in the US arsenal was the B53 with a…

Great comment- I have only one thing to add. Many people will enjoy reading "Command and Control" which covers the history of nuclear weapons accidents in the US and how they were managed/mitigated. It's always interesting to learn that a missile silo can explode, popping the warhead up and out (but without it exploding due to fission/fusion), that from the perspective of the nuclear warhead, the safety controls worked.

Re: El Capitan: New supercomputer is the fastest

#65

Post by p_l »

Jabbles wrote: post #62
p_l wrote: post #61

Earlier quoted context omitted.

Ok, that misreading is on me - in aerospace generally you care to level of molecules, and I've met many people who would love to be just able to brute force it this way. Hypersonics do however end up dealing with simulating subatomic particle behaviours (because of things like air turning into plasma)

> in aerospace generally you care to level of molecules I would like a citation for this. > Hypersonics do however end up dealing with simulating subatomic particle behaviours And this. --- For example, you could choose to cite "A Study on Plasma Formation on Hypersonic Vehicles using Computational Fluid Dynamics" DOI: 10.13009/EUCASS2023-492 Aerospace Europe Conference 2023 – 10ᵀᴴ EUCASS – 9ᵀᴴ CEAS At sub-orbital al…

"I wish I could give the finger to Navier-Stokes and brute force every molecules kinematics" does not make for a paper that will get to publication if not accompanied with actually doing that at speed and scale that makes it usable, no matter how many tenured professors dream of it. So instead they just ramp up resolution whenever you give them access to more compute

(younger generations are worse at it, because the problems that forced elder ones into more complex approaches can now be an overnight job on their laptop in ANSYS CFX)

So unfortunately my only source on that is bitching of post-docs and professors, with and without tenure (or rather its equivalent here), at premier such institutions in Poland.

Re: El Capitan: New supercomputer is the fastest

#66

Post by rcxdude »

olao99 wrote: post #7

I fail to understand how these nuclear bomb simulations require so much compute power. Are they trying to model every single atom? Is this a case where the physicists in charge get away with programming the most inefficient models possible and then the administration simply replies "oh I guess we'll need a bigger supercomputer"

>Are they trying to model every single atom?

Modelling a single nucleus, even one much lighter weight than uranium, is a captital-H Hard Problem involving many subject matter experts and a lot of optimisation work far beyond 'just throw it on a GPU'. Quantum systems get non-tractable without very clever approximations and a lot of compute very quickly, and quantum chromodynamics is by far the worst at this. Look up lattice QCD for a relevant keyword.

Re: El Capitan: New supercomputer is the fastest

#67

Post by grapesodaaaaa »

leptons wrote: post #57
balia wrote: post #42

Some may not want to hear this, but these “fastest supercomputer” list is now meaningless because all the Chinese labs have started obfuscating their progress. A while ago there were a few labs in China in top 10 and they all attracted sanctions / bad attention. Now no Chinese lab report any data now

I doubt the US Government is telling everyone about their fastest computer.

The DOE has entered the chat.

(after the nuclear test ban treaty, they run a LOT of simulations)

Re: El Capitan: New supercomputer is the fastest

#68

Post by piombisallow »

olao99 wrote: post #7

I fail to understand how these nuclear bomb simulations require so much compute power. Are they trying to model every single atom? Is this a case where the physicists in charge get away with programming the most inefficient models possible and then the administration simply replies "oh I guess we'll need a bigger supercomputer"

These usually get split into nodes and scientists can access some nodes at a time. The whole thing isn't working on a single problem.

Re: El Capitan: New supercomputer is the fastest

#69

Post by buildbot »

leptons wrote: post #57
balia wrote: post #42

Some may not want to hear this, but these “fastest supercomputer” list is now meaningless because all the Chinese labs have started obfuscating their progress. A while ago there were a few labs in China in top 10 and they all attracted sanctions / bad attention. Now no Chinese lab report any data now

I doubt the US Government is telling everyone about their fastest computer.

Unless it's like, air gapped powered by a naval nuclear reactor, I feel like someone would question why a random US gov building is drawing 20-30MW of power, and exhausting most of that as heat...

Re: El Capitan: New supercomputer is the fastest

#70

Post by buildbot »

grapesodaaaaa wrote: post #67
leptons wrote: post #57

Earlier quoted context omitted.

I doubt the US Government is telling everyone about their fastest computer.

The DOE has entered the chat. (after the nuclear test ban treaty, they run a LOT of simulations)

Isn't that the open secret for El Cap? "Classified workloads" aka weapons sims.
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