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KOmega Turbulence model from wwwopenFOAMWikinet

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Old   July 1, 2009, 10:01
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Bernhard Gschaider
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Quote:
Originally Posted by maruthamuthu_venkatraman View Post
Could anyone give some step by step illustration of implimenting these low reynolds number K omega models in OpenFoam 1.5 as referred in link below:

http://openfoamwiki.net/index.php/Tu...e_models_files

I tried to extract the contents and complied them by typing " wmake libso " in the terminal from incompresible directory.

I got an error

kOmega/kOmega.C:111: error: no matching function for call to ‘Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh>::GeometricField(Foam::IOobject, Foam::tmp<Foam::GeometricField<Foam::SymmTensor<do uble>, Foam::fvPatchField, Foam::volMesh> >, Foam::wordList)’ ...................

Let me know the right way of implimenting the same..
The problem is probably that the last change to the page was 2007. That means that the code is for 1.4 or earlier. There were some slight changes to the interface of turbulence-models in the mean time that mean that the code won't compile with 1.5.

Why don't you use the k-omega-model that is already in OF nowadays?
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Old   July 1, 2009, 11:17
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Maruthamuthu Venkatraman
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Thanks for your quick Reply.
Presently iam using OF 1.5 version. I cannot see any K omega model which is implimented with low Reynolds number correction.

The SST k omega version is based on HRN version. May be iam wrong, but i cannot see them in src directory... Pls clarify.

Thanks,
Muthu
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Old   July 1, 2009, 11:33
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Quote:
Originally Posted by maruthamuthu_venkatraman View Post
Thanks for your quick Reply.
Presently iam using OF 1.5 version. I cannot see any K omega model which is implimented with low Reynolds number correction.

The SST k omega version is based on HRN version. May be iam wrong, but i cannot see them in src directory... Pls clarify.

Thanks,
Muthu
Don't look at me: I'm no turbulence-expert.

One way to port that turbulence-model is to have a look at (for instance) kEpsion for version 1.5 and version 1.4, compare them and apply the changes to the sources you loaded from the Wiki.

The other solution might be found at
https://openfoam-extend.svn.sourcefo...urbulence/src/

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Old   July 2, 2009, 01:24
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Maruthamuthu Venkatraman
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Thanks for the directions. I went through the link that you gave me , that SSTF version is also based on High Reynlods number model,i.e. Wall function implimentation.

I prefer the first method i.e. By comparing the changes in src files for 1.5 and 1.4 and modify the same and then shall compile in 1.5 version.

I wonder there must be somebody who might use LRN version of SST k omega models in OF 1.5. If anybody there then just give me the right directions, it will save some time...

Thanks
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Old   July 2, 2009, 05:26
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Quote:
Originally Posted by maruthamuthu_venkatraman View Post
Thanks for the directions. I went through the link that you gave me , that SSTF version is also based on High Reynlods number model,i.e. Wall function implimentation.

I prefer the first method i.e. By comparing the changes in src files for 1.5 and 1.4 and modify the same and then shall compile in 1.5 version.

I wonder there must be somebody who might use LRN version of SST k omega models in OF 1.5. If anybody there then just give me the right directions, it will save some time...

Thanks
I'm sure that if you succeed you'll either upload it to the Wiki or contact the guys from the Turbulence-SIG to include it in the repository or ask the guys from OpenCFD to include it in the release

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Old   July 6, 2009, 04:42
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Maruthamuthu Venkatraman
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Hi ,
I cannot able to find OF 1.4 version in Web to download the src files. I went this main website

http://www.opencfd.co.uk/openfoam/do....html#download

OF 1.4 is not available there. Let me know is there is anyway to download the src files of the same.


Thanks
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Old   July 6, 2009, 14:58
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Quote:
Originally Posted by maruthamuthu_venkatraman View Post
Hi ,
I cannot able to find OF 1.4 version in Web to download the src files. I went this main website

http://www.opencfd.co.uk/openfoam/do....html#download

OF 1.4 is not available there. Let me know is there is anyway to download the src files of the same.


Thanks
Have a look at
http://sourceforge.net/projects/foam/files/

Bernhard
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Old   July 26, 2009, 12:02
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Hi,

@Maruthamuthu Venkatraman,

Were you able to implement the model in OpenFoam 1.5?! If yes, can you please share it!!!
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Old   July 26, 2009, 22:51
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Quote:
Originally Posted by lakeat View Post
Also note on CFD-Online WIKI,
http://www.cfd-online.com/Wiki/Turbu...ary_conditions
\epsilon = C_\mu^\frac{3}{4} \, \frac{k^\frac{3}{2}}{l}
\omega = C_\mu^{-\frac{1}{4}} \, \frac{\sqrt{k}}{l}
I dont see \omega = \frac{\epsilon}{k}
Am I missing sth??
it seems that you have loss the betaStar..
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Old   July 27, 2009, 08:09
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Quote:
Originally Posted by barath.ezhilan View Post
Hi,

@Maruthamuthu Venkatraman,

Were you able to implement the model in OpenFoam 1.5?! If yes, can you please share it!!!
Not yet succeeded!
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Old   August 4, 2010, 10:26
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Hi, sorry that I can not find a reference about komega BSL model. Would you please give me a list or link?
Thank you.

Quote:
Originally Posted by panara View Post
Hi Philippose,

I suggest you to read the articles I used as reference for the model implementation (see the Wiki)

in short, the k-omega BSL is a mix of k-omega near the wall and k-epsilon outside the near wall region.
This is done because it is easier to give freestream condition in terms of epsilon rather than omega.

at the wall you have to specify omega using the relation

omega=10*(6*nu)/(0.075*Dy1^2)

where Dy1 is the distance from the wall at the first grid point. Dy1 should be in the laminar sublayer.

In the freestream remember that omega is
equal to epsilon/k.

The k-Omega SST is the same as the BSL but it satisfy also the Bradshaw assumption that the shear stress in a boundary layer is proportional to the turbulent kinetic energy. (see the article for details)

The k-Omega SST sas is very different. In stable flow it behaves exactly as the k-Omega SST but in 3D flows with instabilities it behaves like an LES computation. When instabilities appear the model tends to decrease the turbulent viscosity up to the LES like value. The result is analogous to a LES computation. (see articles for details)

Hope that this helps you,

have fun,
Daniele
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