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March 29, 2001, 19:10 |
Convergence.......
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#1 |
Guest
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Hello all,
I am modeling the nose section and cooling ducts of a racing car. The solution converges well in laminar flow, however when i run turbulence in the model (standard k-e) the turbulence terms (k and e) ossilate and diverge. I tried adjusting under-relaxation factors but to no avail. In fluent I get the following message before each iteration: "Turbulence viscosity is limited to viscosity ratio of 1x10^5 in 1000 [example] cells". What does this message mean? How can I overcome this problem? Could my mesh be at fault? Thanks for your help. Oliver |
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March 30, 2001, 02:37 |
Re: Convergence.......
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#2 |
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Increase to 10^6 the turbulence viscosity. There is a panel where there are maximum value for differents variables.
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March 30, 2001, 07:00 |
Re: Convergence.......
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#3 |
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First of all, try to see where the turbulent viscosity ratio is limited to 1e5 (Surface/Iso-surface/Turb Viscosity Ratio=1e5). Maybe the cells are not good quality in that region. Check the mesh.
Anyway, increasing the turbulent viscosity ratio to 1e6 will not help the residuals convergence. I suggest you try another initialization instead. What I mean is that you can specify other values for k and epsilon when you initialize the domain. I sometimes get the warning message about the turbulent viscosity ratio. The number of cells concerned usually increases, and then decreases until no cell reaches the ratio limit. |
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