[BastianNK]

Hello,


Supposing the structured mesh is enough fine, convergence goes to residual = 10^-5, turbulence modeling SST, is CFD (using CFX) accurate (less than 5% error) for conventional airfoil pitching moment (Cm) estimation?

[ghorrocks]

That depends on what you want to do with it.

If you are just testing a few concept designs then high accuracy is not required. If you are trying to work out why a specific failure mode occurs at some precise condition then high accuracy is required. If you are a jet engine design and you intend to improve the efficiency of your engine by 1%, then extreme accuracy is required.

[BastianNK]

Originally Posted by ghorrocks

That depends on what you want to do with it.

If you are just testing a few concept designs then high accuracy is not required. If you are trying to work out why a specific failure mode occurs at some precise condition then high accuracy is required. If you are a jet engine design and you intend to improve the efficiency of your engine by 1%, then extreme accuracy is required.

I'm doing CFD modeling for an aircraft wing, but I see CFD's prediction on pitching moment Cm is more 20% larger than the wind tunnel test data. So I'm trying to figure out whether it is typical to have result like this (that means CFD not accurate for pitching moment calculation) or I made an error somewhere.

[ghorrocks]

I am not a specialist in airfoil modelling, but I know getting the lift accurate is much easier than the drag. Many researchers get the lift accurate to within a few percent, but getting drag accurate to within a few percent is very challenging. I cannot say for pitching moment as I have no experience for that one.