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-   -   default values of kOmega (Wilcox) different from paper (http://www.cfd-online.com/Forums/openfoam-solving/90949-default-values-komega-wilcox-different-paper.html)

romant July 26, 2011 09:04

default values of kOmega (Wilcox) different from paper
 
Hej,

does anyone know why the default values for the k omega model by Wilcox from 1988, which is implemented into OpenFOAM are different from the ones that the paper suggests.

alpha = 5/9 in the paper but 13/25 in OpenFOAM (it is also 13/25 in the 2006 version of the model, which adds a cross diffusion term and a stress delimiter)

beta = 3/40=0.075 in the paper, but 0.072 in OpenFOAM (in the 2006 model, this term is modelled by the stress delimiter modification).

The paper is http://adsabs.harvard.edu/abs/1988AIAAJ..26.1299W

daveatstyacht August 2, 2011 11:39

roman,
The beta of 0.072 is equivalent to the beta0 of the 1998 version of k-w on the NASA langley turbulence page for k-w: http://turbmodels.larc.nasa.gov/wilcox.html . This beta0 term is then multiplied by (1+70*chiomega)/(1+80*chiomega) to form beta. Note that term differs from the 2006 version as well. I have not looked at the code for the k-w model in OpenFOAM to see which formulation has been implemented but both of those cofficients match those of the 98' formulation.
Regards,
Dave

romant August 3, 2011 06:43

Quote:

Originally Posted by daveatstyacht (Post 318528)
roman,
The beta of 0.072 is equivalent to the beta0 of the 1998 version of k-w on the NASA langley turbulence page for k-w: http://turbmodels.larc.nasa.gov/wilcox.html . This beta0 term is then multiplied by (1+70*chiomega)/(1+80*chiomega) to form beta. Note that term differs from the 2006 version as well. I have not looked at the code for the k-w model in OpenFOAM to see which formulation has been implemented but both of those cofficients match those of the 98' formulation.
Regards,
Dave


Thank you, I think I will check with the NASA website and see if the terms correspond to the model as well.


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