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setup K,E parameters in CFX 13

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Old   May 15, 2011, 04:10
Default setup K,E parameters in CFX 13
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HE ALL ;
I want to pass parameters for sigma k and e in k-Epsilon Model with CEl Function ; it seem that it's not permit in CFX 13. wich accept only constants . is there any file or env varaiable to edit and change to make CFX 13 accpet CEL function .
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Old   May 15, 2011, 18:59
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You may be able to do this by editting the <CFX_ROOT>/etc/VARIABLES file. But no guarantees, and remember that the reason you cannot define it as a variable is because it is not properly implemented in the solver and all the cross terms which arise from this are not accounted for. In other words - "At your own risk!"
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Old   May 18, 2011, 04:55
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it's not possible to pass with Cel function , also changing to version 12.1 same result , for this closure parameter CFX accept only constant perhaps it's a limitation of CFX ?
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Old   May 18, 2011, 06:06
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Quote:
perhaps it's a limitation of CFX ?
Yes, precisely. When you allow numbers like this to vary it introduces lots of yukky cross terms and these can be fiendishly complex and frequently numerically unstable.

Why do you want them to vary anyway? It means you will not be using the k-e turbulence model. What is different about your model to require it?
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Old   May 19, 2011, 11:21
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Hi ghorrocks;
I use K-Eps model , but i wan't to pass values for sigma_E ( dissipation) with CEL function as follow:
sigma_E = if( z< seuil, 0.5, 1.3) that means the value is 0.5 or 1.3.
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Old   May 19, 2011, 18:49
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Why do you want to do this?
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Old   May 20, 2011, 14:55
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to check the possibility of enhancement of concentration prediction
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Old   May 21, 2011, 07:54
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I see.

Have you tried editting the VARIABLES file as suggested?
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Old   May 21, 2011, 18:01
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Yes I edited the VARIABLES file but there is no ligne pointing to this parameters to change it.
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