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Old   December 27, 2010, 16:05
Default Not stall
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Hi!
I searched in the entire forum and did not find a precisely answer so i am posting my problem (I'm new in CFX).
I'm working with 2D simulation of NACA 0012, with a mesh (unstructured) designed in ICEM. My Cl values seems very good until the stall angle.
The cl gets higher and higher while the AOA attack increases. I can see in the post that the separation occured with a streamline, but the cl remains increasing.
I used the SST isothermic model.


Thanks!
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Old   December 28, 2010, 05:05
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Getting accurate models after stall is difficult. You probably won't be able to do it using SST, you will probably need a very careful validated LES/SAS/DES model.
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Old   December 28, 2010, 19:56
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Thanks for your answer!
But, what you mean with careful validated ?
I tried to use these models and the cl values get close but they remain higher. Do you think it can be related only to my mesh quality? I checked in ICEM and the transition near the airfoil wasn't abrupt, and the quality was good.

Thanks again.
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Old   December 29, 2010, 06:44
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Validated means you have ensured the mesh, convergence, time step and other numerical parameters are correctly set to give the required level of accuracy.

The LES/SAS/DES models will require different time steps and meshes to the RANS models.
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