alt Hacker NewsWith all the technological advances, why are wind tunnels still widely in use today (instead of pure computational approaches)?
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CFD is actually really difficult to get "right". Really tiny changes to simulation setup (mesh sizing, boundary conditions, solver choice, etc) can make big changes to the final results, it's honestly more of an art than a science for very complex simulations. The simulation will converge on any number of setups, but that doesn't guarantee your setup is a valid estimation of reality. So scale model testing is still a great validation of your CFD.
Because it's not enough to just simulate things.
https://spaceflightnow.com/2020/02/28/boeing-says-thorough-t...
> Both errors could have been caught before launch if Boeing had performed more thorough software testing on the ground, according to John Mulholland, vice president and manager of Boeing’s CST-100 Starliner program.
> Mulholland said Boeing engineers performed testing of Starliner’s software in chunks, with each test focused on a specific segment of the mission. Boeing did not perform an end-to-end test of the entire software suite, and in some cases used stand-ins, or emulators, for flight computers.
Cheaping out cost billions and nearly two astronauts.
There are lots of things to test besides basic aerodynamics. And even for that sometimes you want real data to validate models before building the full size thing.
Things that are tested/validated in wind tunnels nowadays: effect of different paint and coatings, engine inlet flow, noise, tunned mass dampers, effect of placement of sensors, control surface flutter.
Simply because theory (computational) only gets you so far. As much as we'd like to think we have perfectly modeled everything, most of our models are just very good approximations
Probably for insurance purposes.
In addition to the other comments, I just want to point out that we _do_ do a tremendous amount of CFD. The Pleiades supercomputer [0] sits in a building just down the street from the large wind tunnel at Ames Research Center, is generally ranked somewhere in the top 150 supercomputers in the world, and is largely used for CFD work to complement the wind tunnel work.
0: https://en.wikipedia.org/wiki/Pleiades_(supercomputer)