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-   -   Implementing special K-eps with UDF (http://www.cfd-online.com/Forums/fluent/49890-implementing-special-k-eps-udf.html)

Sergio Rossi November 25, 2008 06:23

Implementing special K-eps with UDF
 
Hi,

I would like to implement a modified K-eps model in Fluent, for subsonic/supersonic axisymmetric jet flow computations. I'd like to use either :

H. Shen, C. K. W. Tam, Numerical simulation of the generation of axisymmetric mode jet screech tones, AIAA Journal Vol. 36, No. 10, October 1998.

or :

Dash, S.M., Kenzakowski, D.C., Papp, .J.L., Progress in jet turbulence modelling for aero-acoustic application, AIAA 2002-2316.

Is it simple to do it in Fluent? The first model is basically Jones-Launder with strongly different coefficients. I have no references for the damping functions near the walls, so I'd have to use standard values: I expect the result to be strongly unstable.

The second model has slightly different coefficients, but there are some additional source terms, depending on the curl of the flow and on derivatives of rho*U*U, which again make the equations way more stiff.

Has anybody experience with this? Can you give advices/suggestions?

Cheers

deltaquattro

k.baker November 25, 2008 08:11

Re: Implementing special K-eps with UDF
 
did you want to use the low Re k-epsilon model? the Jones-Launder available is a low k-epsilon model and in the low k-e model there is no need for wall functions check it.

Cris November 26, 2008 12:44

Re: Implementing special K-eps with UDF
 
Have you done some progress? I also want to implement a modified low-Re model and I need some help


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