[AntonioDesah]

Hi all,

I am trying to analyze a turbulent flow over a NACA 0012 airfoil but I am facing 2 kinds problem.

The velocity is 100m/s and the AoA=5deg.

I am using K-eps realizable model for the turbulence.

The problems are these: I can get a quick convergence, after 130 iterations with a very inconsistent result(i.e. Cl=0.03) or I will never reach the convergence.
The quality of mesh is not that bad :

  p, li { white-space: pre-wrap; }  

 Mesh Quality:
 

 Minimum Orthogonal Quality =  5.98224e-01
 (Orthogonal Quality ranges from 0 to 1, where values close to 0 correspond to low quality.)
 

 Maximum Ortho Skew =  4.01776e-01
 (Ortho Skew ranges from 0 to 1, where values close to 1 correspond to low quality.)
 

 Maximum Aspect Ratio =  5.89780e+01

I am quite sure that everything is due to the boundary conditions which I have tried to fix but without any success.

Can anybody help me?

I am posting my project.

http://www33.zippyshare.com/v/Hp7e2oQs/file.html

I would appreciate any help

[Héctor Lodoso]

Hello

NOTE: I answer you without seeing your project, and maybe is too late for you.


Boundary conditions for such a problem use to be velocity-inlet (with the value of wind speed and the components, unless you give the orientation to the geometry itself) and pressure-outlet (nothing else here).
The quality of the mesh is actually very good. I dont know if you build an inflation layer around the airfoil, but you should. This helps to obtain better results. If you have one, try to refine it according to Y+ requirements.
Also, try another turbulence model, i suggests k-omega SST, or even spalart-allmaras works fine in 2D.

Hope my answer helps.

Good luck

[AntonioDesah]

Thanks a lot! I did need your help.

As you suggest I applied velocity inlet through components since I have the same angle but nothing changes. Also, I used K omega Sst as well but still facing the same problems.

Would you try to open my project and see what is wrong? I would very appreciate!

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[Héctor Lodoso]

OK. At this computer I cant. I will have some time tomorrow afternoon for it.

Just another idea about the inlet velocity. If you have set it through components, make sure the total speed is properly input in the reference values tab. Sometimes this is not that obvious (Fluent is weird).
Still, I think bad results in Cl and Cd may be due to a too much coarse mesh around the airfoil, specially for high reynold numbers as yours...

[AntonioDesah]

I cross checked the reference values and they are ok.I will put an inflection around the airfoil and see what happens.thanks any way. I can wait for your check!

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