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Old   June 18, 2008, 13:36
Default problem in prism layer generation
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shrimp
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Hi guys,

I follow the tutorial of iCEM 11.0 to generate tetra mesh and then want to creat prism layer. But I fail again and agin with errors like these:

face at 118583 173622 230139 has one volume neighbor and no shell element vt1 loc = 15.1891 18.1678 -27.5124 3 elements at face 181849 224649 224804, not all tets PYRA_5 TETRA_4 TETRA_4 PYRA_5 PENTA_6 PENTA_6 PENTA_6 PENTA_6 PYRA_5 TETRA_4 TETRA_4 PYRA_5 TETRA_4 PYRA_5 TETRA_4 PYRA_5 PENTA_6 PENTA_6 PYRA_5 TETRA_4 TETRA_4 some tetrahedra occupy the same volume and that couldn't be fixed .... and 27 more error messages ... orientation errors! writing out prism layer 1 done initializing directions from levelset norm 5805 prism_nodes Assertion failed: has_volume_elements == 0, file compute_marching_dir.C, line 559

This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. Application is finished. Error: prism terminated prematurely

Anybody has any idea? Thanks!!
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Old   June 19, 2008, 10:51
Default Re: problem in prism layer generation
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myron
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First make sure your tetra mesh passes all errors and possible problems checks. Sounds like the tet mesh may have some problems.
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Old   June 22, 2008, 18:57
Default Re: problem in prism layer generation
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Glenn Horrocks
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Hi,

These sort of errors usually occur when the mesh is not fine enough to resolve the geometry or the underlying mesh is poor quality. The fix is finer mesh and/or better quality mesh.

Glenn Horrocks
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Old   March 26, 2010, 05:21
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Hi

I have had the exact same problem.
Unfortunately, I have not been able to resolve this situation.
My mesh contains 4 Millions tet elements so I suppose it could be fine enough.
But indeed, it works when I ask ICEM to prism only very simple surfaces, so it tends to prove Glenn Horrocks' point.

Please let me know here if any solution has been found except a perfect mesh, which usually never happens in industry

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Old   March 26, 2010, 06:03
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Glenn Horrocks
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The solution is training and experience. You can earn a good wage as a CFD engineer and the reason is because it is not easy.
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Old   March 26, 2010, 13:34
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A collegue has found a way to avoid the crash.
This crash happens after extruding the first prism layer because the quality has diminished. Therefore, an easy way to compute prism boundary layer is :
- compute only one layer
- split it (split prism option)

My collegue always used this method so that the prism are more regular and gradients better computed.

Hoping this will help,

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