3 ms·

> It literally requires simulating each subatomic particle, individually. Citation needed. 1 gram of Uranium 235 contains 2e21 atoms, which would take 15 minu

> It literally requires simulating each subatomic particle, individually. Citation needed. 1 gram of Uranium 235 contains 2e21 atoms, which would take 15 minutes for this supercomputer to count. "nuclear bomb simulations" do not need to simulate every atom. I speculate that there will be some simulations at the subatomic scale, and they will be used to inform other simulations of larger quantities at lower resolutions. https://www.wolframalpha.com/input?i=atoms+in+1+gram+of+uranium https://www.wolframalpha.com/input?i=atoms+in+1+gram+of+uran...

p_l 2y ago
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.
- Jabbles 2y ago
  I would like a citation for anyone in aerospace using (or even realistically proposing) subatomic fluid dynamics.
  - p_l 2y ago
    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)
    - Jabbles 2y ago
      > 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 https://www.eucass.eu/doi/EUCASS2023-492.pdf
      - p_l 2y ago
        "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.

p_l 2y ago

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.

Jabbles 2y ago
I would like a citation for anyone in aerospace using (or even realistically proposing) subatomic fluid dynamics.
- p_l 2y ago
  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)
  - Jabbles 2y ago
    > 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 https://www.eucass.eu/doi/EUCASS2023-492.pdf
    - p_l 2y ago
      "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.