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-   -   wall functions for RAS models (http://www.cfd-online.com/Forums/openfoam-pre-processing/74723-wall-functions-ras-models.html)

Epf April 7, 2010 07:43

wall functions for RAS models
 
Hi everyone,

is there a way to turn off the wall functions for the turbulent quantities in OpenFOAM 1.6? I'm a bit confused about this. I know that the RAS-models should be used with wall functions. But i want to compare the result with and without them to see the difference. Together with refining of my mesh.

Thank you in advance, Eric

farbfilm April 8, 2010 03:48

Hi,

maybe you can use "calculated" instead of (for example) "nutWallFunction" in the nut-file of your 0-directory!
But I'm not sure...

farbfilm April 8, 2010 04:00

Hi,

I tested it in the pitzDaily-tutorial and it worked (but I didn't checked the results)!
I think you also have to change the boundary conditions for k and epsilon in 0-directory! I used zeroGradient instead of kqRWallFunction and epsilonWallFunction!

cboss April 8, 2010 11:14

Hi,

you can use several provided RANS turbulence models without (log-law) wall functions. At least on can use the k-omega and k-omega-SST models. There is also a modified k-epsilon model for that purpose, the launder sharma KE.

If you are using the k-omega-SST model, I can tell you my setup for low-Re wall-treatment.
For boundary conditions at the wall, k=0, mut=0, omega=omegaWallFunction.

Note, that there is a new omegaWallFunction (very nice!) for low-Re wall-treatment. Therefore have a look at this thread.
http://www.cfd-online.com/Forums/ope...megasst-2.html


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