9 events
when toggle format what by license comment
Jan 6, 2022 at 9:32 vote accept user207141
Nov 27, 2021 at 23:18 comment added Jpe61 I'm pretty sure stall behaviour of airfoils can be reliably modelled with CFD. How the flow acts after separation can be modelled to a satisfactory level.
Nov 27, 2021 at 20:46 comment added Carl Berger as for accuracy - there would be some use cases. Something i could think of, right now - boundary layer separation and detached flows over airfoils (leading to stall), especially to determine the stall and margin in axial compressors. To my knowledge, current CFD isn't really up to the task.
Nov 27, 2021 at 2:23 comment added jamesqf @Jurgen M: Assuming a glass of water contains one US cup, there are (per Google) 8.3569904e+24 molecules in that glass. Even if you could somehow get every one of those molecules going in EXACTLY the same random direction & speed in both glasses (which you can't: see the Heisenberg uncertainty principle), there are 3 atoms in each molecule, vibrating and spinning in various modes, some of which are only approximately real (because of quantum :-)), and our friend Chaos (AKA sensitive dependence on initial conditions) will amplify even the tiniest difference.
Nov 26, 2021 at 22:43 comment added Will @JurgenM No matter how calm it looks, any two bodies of liquid water are never the same. Each and every one of its molecules is in a different energy state, moving and bouncing with a different angle and velocity. Brownian motion giving rise to an unending number of unpredictable convective flows, and that's even if both those bodies have the same overall temperature. Then when you factor in all the boundary layer interactions, things get much much crazier still...
Nov 26, 2021 at 18:56 history edited Jpe61 CC BY-SA 4.0
deleted 3 characters in body
Nov 26, 2021 at 18:52 comment added Jpe61 Exactly. If, and only if you could make every single variable the same, the fluid dynamics of the event might be the same. But even if you do everything the same, the universe will not. On the smallest scale you will have virtual particles that randomly interfere with the experiment, altering the results ever so slightly.
Nov 26, 2021 at 18:33 comment added user207141 So if throw same stone in glass of calm water from same height,water movement in microscopic level will never be the same?
Nov 25, 2021 at 22:47 history answered Jpe61 CC BY-SA 4.0