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.
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.
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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.
"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.