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Old   March 3, 2014, 11:56
Default Experiment - CFD Result Differences
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Hello everyone,

I have been trying to verify some results I gained for a 2D simulation of an airfoil.
To do this, I compared the plots of the lift coefficient over angle of attack of experiment and CFD results. For low angles of attack, everything is fine. At higher angles the results differ quite a bit though.
Do u have suggestions how to solve this problem ?
I already tried

using different turbulence models (currently using SST)
using more/less refined grids

I attached the lift coefficient over angle of attack plot.
If u need any additional information please tell me.


My final goal is to run simulations with a much higher Reynolds number. There do not seem to be any experimental results for those.
Do you have suggestions how to ensure my results will be valid ?

I would perform a mesh refinement study and also use an appropriate turbulence model. Are there any other things i could take into account?

Best regards,

Leif
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Old   March 3, 2014, 17:30
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Glenn Horrocks
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RANS is often not suitable for modelling in the stalled region of flow. You probably need a turbulence model from the LES family, such as SAS, DES or full LES to model it properly.
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Old   March 5, 2014, 11:35
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Hi,

thanks a lot for the fast reply !
Do you think the results I attained are comparable to what other people gained from RANS ?

Also do you have any suggestions as to how to change my simulation setup for the usage of higher velocities ?

Best Regards,

Leif
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Old   March 5, 2014, 17:34
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Your results look pretty typical for RANS simulations - pretty good in the attached flow region, but a bit off in the stalled region and the stall point is not quite right either.
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