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CFX Error - Reynolds number out of range

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Old   May 10, 2012, 08:58
Default CFX Error - Reynolds number out of range
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I was trying to run a case in and I encountered the following error:

The Reynolds number is outside of the range expected based on the Option selected for the TURBULENCE MODEL

Please look into the attachment for more info. on this error

I switched into the Laminar regime later and the problem is then resolved.


Could some one please let me know how to figure out the Reynolds number even before starting the run ( The domain geometry may not be simple in all the cases).
Attached Images
File Type: jpg error.jpg (48.7 KB, 13 views)
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Last edited by saisanthoshm88; May 10, 2012 at 09:31.
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Old   May 10, 2012, 09:54
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It's a warning, not an error.

Reynolds Number Outside the Range ??
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Old   May 11, 2012, 01:42
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Could some one please explain how to know the Reynolds number for a complex geometry before starting the run. I mean if we are clear about the flow regime beforehand then it would help to plan the meshing.
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Old   May 11, 2012, 07:04
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Remember that in this case Reynolds number is simply used to determine which regime you are in. So it does not need to be calculated exactly. So just use any length, velocity and fluid property values which are representative of your geometry. If you know the transitional Reynolds number for the geometry you then know if it is laminar or turbulent and can choose a turbulence model appropriately.

Likewise for getting an appropriate y+ up-front, estimate the mesh requirements by what you expect the flow to do. The documentation has a guide of how to estimate y+.

But do not be surprised if this initial guess is wrong and requires some adjustment. It is an estimate, after all.
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