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Pb in conv. k-e 3D Help

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Old   October 30, 2009, 06:27
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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.
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Old   October 30, 2009, 06:28
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pl. check mesh quality.
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Old   October 30, 2009, 06:44
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I do grid--check, everything is good!
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Old   October 30, 2009, 07:18
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and if I make simulation in laminar flow, solution converge!
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Old   October 30, 2009, 16:51
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Try with very small under-relaxation numbers and gradually increase them to default values. That might help.
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Old   November 2, 2009, 07:16
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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?
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Old   November 3, 2009, 07:42
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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.
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Old   November 4, 2009, 06:26
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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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