mesh quality requirement
 

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

I also wonder how accurate the checkMesh of OF.

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::primitiveMesh::closedThreshold_ = 1.0e-6;
• Foam::scalar Foam::primitiveMesh::aspectThreshold_ = 1000;
• Foam::scalar Foam::primitiveMesh::nonOrthThreshold_ = 70; // deg
• Foam::scalar Foam::primitiveMesh::skewThreshold_ = 4;
• Foam::scalar Foam::primitiveMesh::planarCosAngle_ = 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.