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-   -   Pb in conv. k-e 3D Help (http://www.cfd-online.com/Forums/fluent/69666-pb-conv-k-e-3d-help.html)

fluser October 30, 2009 06:27

Pb in conv. k-e 3D Help
 
Hello,
I am running a 3d simulation using the standard K-E model.

after 10 iterations "sliding mesh simulation" (in steady state flow) values of k & epsilon are diverging. I have the message: "Turbulent viscosity limited to viscosity ratio of 1e5 in cells".
I used pressure based solver.

Can anyone help with this please? Thanks.

CFD_4 October 30, 2009 06:28

mesh
 
pl. check mesh quality.:)

fluser October 30, 2009 06:44

I do grid--check, everything is good!

fluser October 30, 2009 07:18

and if I make simulation in laminar flow, solution converge!

tez October 30, 2009 16:51

Try with very small under-relaxation numbers and gradually increase them to default values. That might help.

fluser November 2, 2009 07:16

Hi Tez,
I divided UR factors by 100, results are better . but there are fluctuations of the epsilon parameter. After 100 iterations the residuals of k and e parameters are about 5.e-2.
tell me plz. how to increase gradually these parameters? by stopping and restart calculation and increasing URP without initializing?

greeneye November 3, 2009 07:42

hello
 
I think it is better to give a inviscid solution and then set it as a intial condition for turbulent solution.another way is to set the "turbulent insity" and "turbulent viscousity ratio" to 1 at velocity inlet.

fluser November 4, 2009 06:26

Hi greeneye,
I apply your second proposition but k & epsilon residuals remind at too high values (about 1.e-1).
I have a simple question for you: how to use a solution as an initial condition in Fluent?
by iterating without initilize solution?
thanks


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