ELi5 Why are CFD and wind tunnels used together for flight simulation

Question

I am wondering why there aren’t full simulations using CFD for flight.

In: 4

Answer 1

NASA Ames Research center, which has had massive wind tunnel facilities dating Back to the 50s, was also an early center for computational aerodynamics. They acquired the Illiac 4, a 70s era supercomputer, for that program. But these problems are hugely difficult.(I recall my father claiming that most airplane CFD problems could be handled ok at the second or third order, but that rotorcraft ( like the Osprey) went out to the twelfth order.)

So my point, which I failed to make, is that you can’t, yet, solve these problems computationally. That’s why Ames, in its heyday, had numerous wind tunnels ranging from hypersonic down to highway speed, as well as an active flight test program, AND high-end computers.