CFD Online Discussion Forums - [OpenFOAM-2.1.0] kklOmega RAS Turbulence Model (low Re)

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Joe ferrari,

In your thesis, you stated that nut at wall should be zeroGradient. I also noticed that internal field is initialized to "zero".

I am having a similar problem like you ( but using SimpleFoam) but I can not solve it changin nut to fixedValue.
kl at the wake of the airfoil is very high and at the end, the solution diverges.

Dear Mojtab,

Do you set the omega boundary condition at the wall the same as the komega SST turbulence model? I also made this mistake. Change it to zeroGradient, and should be fine.

Best regards
Ye

Quote:

Originally Posted by kiddmax (Post 501917)

Dear Ye,

Yes, that was the problem. :)
Thank you for your kind response.

With all the best wishes.
Mojtaba

Quote:

Originally Posted by be_inspired (Post 497227)

Hi, I was wondering if you can provide me some more information on the airfoil test case you were running referred in this post. What was the geometry?, Inlet conditions.

Thanks in advanced

After 8 years, there is a new version (or new model) of the k-kl-omega model.

There are a few problems with the k-kl-omega model in the farfield. One of them is the growth of Laminar Kinetic energy when separation occurs. Lopez and Walters have a paper (have not been published yet) correcting this issue:

Maurin Lopez. D. K. Walters. “A recommended correction to the k-kl-omega transition sensitive eddy-viscosity model”. Journal of Fluid Engineering.

This correction has to be made to the 2008 k-kl-omega model from now on.

Now, Lopez and Walters also developed a new transitional model (k-omega-v2) as an alternative to the k-kl-omega one. This new model has more capabilities (it is more reliable) than the k-kl-omega model, especially in the farfield computations. Fortunately the paper for this new model is already publish.

Maurin Lopez. D. K. Walters. “Prediction of transitional and fully turbulent free shear flows using an alternative to the laminar kinetic energy approach”. Journal of Turbulence, Vol 17, Iss. 3, 2016.

If you see the papers, you will immediately see how the k-kl-omega model is not good for free shear flows, and how the new model corrects all those issues. From now on, k-kl-omega users have to start using the new k-omega-v2 model.

Hope this helps