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Strange mesh dependent result of a pipe flow with SSG

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Old   November 8, 2017, 05:24
Default Strange mesh dependent result of a pipe flow with SSG
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Andi
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Hello everybody,

I have simulated a simple turbulent pipe flow with the SSG turbulence model. The residuals converge. Some probs are constant.
I only use linear or limitedLinear schemes in the Divergence scheme. With the Surface-normal gradient I use the Corrected schemes. However, the result shows a strong dependence on the mesh or the orientation of the mesh.
A refinement delivers the same result.
I used wall functions at yPlus = 30.
Is there any hint, what I can try.

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And I
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Old   November 9, 2017, 04:14
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Hello

has anyone some experience with the SSG Reynolds Stress Model?

Best Regards
Andi
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Old   November 9, 2017, 16:03
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Generally, every solution is mesh dependent ... maybe introducing nonOrthogonal correctors or bigger number of PISO correctors can give you better results.

Also, results usually converge when increasing mesh density. Also, using smooth transitions from one type of meshing to another improve results, those triangles may be causing the trouble ...
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Old   November 10, 2017, 00:14
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The construction of the mesh may be better:
1) The transition form the radial elements to the rectangular is far to close to the edge.
2) I would look for a construction idea where the transition is nut such abrupt
3) I would use only square/hexagonal elements an avoid abnormal triangular ones
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