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Max Courant Number exploded

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Old   January 18, 2017, 05:54
Default Max Courant Number exploded
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Hi all,

I am trying a simulation of venturi meter type geometry. For this, i am using pimpleFoam, after few time step there is tremendous increase of max courant Number and then program get stop.
For futher reference i am attaching geometry, error, blockMeshDict and ControlDict files.

Any suggestion is highly appreciated.

Thanks in advance
Attached Images
File Type: png Geometry.PNG (17.1 KB, 17 views)
Attached Files
File Type: txt Error.txt (1.1 KB, 8 views)
File Type: txt CheckMesh.txt (1.9 KB, 11 views)
File Type: txt blockMeshDict.txt (2.9 KB, 5 views)
File Type: txt controlDict.txt (1.2 KB, 3 views)
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Old   January 18, 2017, 13:12
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Hi,

It seems that your mesh isn't good enough : 85 max non-orthogonality is quite high.
Try to improve your mesh, and it should be better.

Regards,
Sati
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Old   January 18, 2017, 13:56
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Hello.
As sati said, You have high non-orthogonality in Your mesh.
Also... Is Your case really 54m^3? Or maybe You forgot to transform units from [mm] to [m]?
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Old   January 20, 2017, 02:36
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Thanks sati and sheaker for you response.

As i change the solver from pimpleFoam to icoFoam, simulation run well with this mesh. For this, i tried different schemes in fvSchemes file in icoFoam. I am attaching file for which my simulation going well.

Moreover, yes Sheaker, i forget to transform my geometry into mm.

Again my question, is non-orthogonality affect my simulation in pimpleFoam.

How to improve the non-orthogonality? Is different blocking strategy will improve the non-orthogonality?

Thanks
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Old   January 20, 2017, 04:19
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You can indeed improve your mesh with a different blocking.
You are using a single block to mesh a cylinder. This is not optimal : the cells situated at the corner of your block are very distorted. To improve that, you can use a blocking similar to the one used in the following picture :

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Old   January 20, 2017, 05:20
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thank you sati!

I got your point.
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