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blockMesh generates under determinants cell

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Old   February 23, 2017, 13:07
Default blockMesh generates under determinants cell
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Hello everyone,

I'm trying to simulate an external incompressible flow but the blockMeshDict in attached generates thousands of under determinant cells.

Someone can resolve this issue?

thank you in advance

Andrea
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File Type: txt blockMeshDict.txt (6.1 KB, 9 views)
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Old   February 24, 2017, 12:23
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it is extremely difficult to point where the error comes from. Can you attach a figure of what your trying to model?
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Old   February 25, 2017, 15:29
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Quote:
Originally Posted by Saideep View Post
it is extremely difficult to point where the error comes from. Can you attach a figure of what your trying to model?
Hi Saideep,

thank you for your reply,

I'm trying to simulate a flow around a magnetometer in order to evaluate it's drag.

It's an incompressible turbulent steadystate simulation and I'm using simpleFoam but during SHM's quality evaluation I saw that the under determinant cells number was every time constant, so I tryed a checkmesh (all topology -all geometry) immediately after Blockmesh and I noted that the problem was due to blockMesh.

I don't know why blockMesh generates so many under determinant cells, any idea?

thank you
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Old   February 27, 2017, 13:17
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someone who can help me?
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Old   February 28, 2017, 04:20
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Hello fluxent,

I am not very familiar with blockMesh. Can you share a picture of your mesh with the bad cells highlighted for example in paraView.

Best regards,

Kate
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Old   February 28, 2017, 05:55
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Quote:
Originally Posted by KateEisenhower View Post
Hello fluxent,

I am not very familiar with blockMesh. Can you share a picture of your mesh with the bad cells highlighted for example in paraView.

Best regards,

Kate
Hello kate,

I tried to highlight those cells with paraview but no one of them was visible, like if they don't exist.

Flux
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Old   February 28, 2017, 06:05
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You tried with
Code:
foamToVTK -cellSet underdeterminedCells
?
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Old   February 28, 2017, 06:41
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Yes but no result
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Old   February 28, 2017, 09:02
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Do you get the corresponding underdeterminedCells file in the postProcessing folder after executing the command?
If not, do you get a error message?
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Old   February 28, 2017, 21:09
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Hi,

Have you tried running your simulation and see if it runs without diverging? While underdeterminedCells might crop up, it doesn't necessarily mean that it will interfere with your simulation run/results.

Cheers,
Antimony
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Old   March 3, 2017, 17:08
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Quote:
Originally Posted by Antimony View Post
Hi,

Have you tried running your simulation and see if it runs without diverging? While underdeterminedCells might crop up, it doesn't necessarily mean that it will interfere with your simulation run/results.

Cheers,
Antimony
Hi Antimony,

I follow yours suggestion, the simulation converge, but the reason for why blockmesh generates those underdeterminant cells remains unknown.

kind regards
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Old   March 5, 2017, 22:58
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Hi,

I took a look at your blockMeshDict and noticed that the grading ratios that you had, among others, were 0.01 and 100. So it is quite possible in your mesh that there are regions which have extremely small cells and regions were there are large cells leading to underdetermined cells.

Cheers,
Antimony
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Old   March 10, 2017, 04:15
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Thank you antimony I will try as soon as possible then write the results here.
Kind regards
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