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mesh quality requirement

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Old   February 9, 2016, 08:59
Default mesh quality requirement
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stefano zinna
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Hi All,

Do you know if there is a general guidlines for quality reuirement in openfoam. Something like: mesh should have orthogonality less than..., aspect ratio less than ... etc..

I know that it is case dependent but i am looking for a "first guess" guidlines.

regards,
Stefano
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Old   February 9, 2016, 10:34
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taygun gungor
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I also wonder how accurate the checkMesh of OF.
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Old   March 19, 2016, 15:43
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Vinícius da Costa Ávila
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Hi, I am no expert, but as you said, it depends HIGHLY on the solvers you use.
Also, OF has a standard limiting values for mesh quality with checkMesh (these standard values are mostly for reference, since they can be changed by the user).

Standar values used in OF ($WM_PROJECT_DIR/src/OpenFOAM/meshes/primitiveMesh/
primitiveMeshCheck/primitiveMeshCheck.C)
• Foam::scalar Foam:rimitiveMesh::closedThreshold_ = 1.0e-6;
• Foam::scalar Foam:rimitiveMesh::aspectThreshold_ = 1000;
• Foam::scalar Foam:rimitiveMesh::nonOrthThreshold_ = 70; // deg
• Foam::scalar Foam:rimitiveMesh::skewThreshold_ = 4;
• Foam::scalar Foam:rimitiveMesh:lanarCosAngle_ = 1.0e-6;

For example, for a case I'm used running: tutorial bubbleColumn with RAS turbulence models, I am able to run big meshes (more than a million cells) with the standard numerical solvers (fvSchemes and fvSolution) and Co=1.0 even with not very good meshes (but still within checkMesh quality limits) and I get accurate results.

In my (brief) experience I would recommend as a start point:
Aspect ratio: max 5-10
nonOrtho.: max 50-60
skewness: max 1-2.5

Then, I recommend mesh convergence studies to be made. So it will ensure your solution is mesh independent.
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