[snappyHexMesh] SnappyHexMesh Internal Flow Example (Diesel Injector)

wyldckat · July 7, 2013, 06:25

Hi Danny,

Without an example STL file, there isn't much I can suggest

You can try using OpenFOAM's commands surfaceCheck and surfaceClean.
The other possibility is to use either Blender or Meshlab for repairing the STL file.

Best regards,
Bruno

Dmoore · July 8, 2013, 09:00

here is an example stl file

Danny

wyldckat · July 13, 2013, 16:50

Hi Danny,

I renamed the file to "test.stl" (OpenFOAM dislikes spaces and special characters) and ran:

Code:

surfaceCheck test.stl

And it gave serious indications of a bad surface mesh on this geometry. Almost 70% of the triangles have a quality lesser or equal 0.05 and the one with smallest quality has "0.000133138"!
And there seems to be problems with connections between triangles, since this is indicated:

Code:

Surface is not closed since not all edges connected to two faces:
    connected to one face : 12
    connected to >2 faces : 0
Conflicting face labels:12

But given the low quality triangles, this is only natural to occur.

If I'm not mistaken, the best procedure is to export to Step or IGES format and then use Salome to convert the surface mesh to STL. This is because SolidWorks is doing a very lousy job on converting this to STL.

The other possibility is to export the geometry to STL in binary form, so that you do not loose numerical precision. I say this because, for example from your file:

Code:

vertex 3.125293e+000 3.067232e+000 8.410000e+000

7 digits is far from enough for such bad quality triangles

Best regards,
Bruno

Dmoore · July 15, 2013, 08:45

Thank you Bruno for your help! that makes sense with the troubles I was having! I appreciate your help!

Danny

July 7, 2013, 06:25		#21
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,981 Blog Entries: 45 Rep Power: 130	Hi Danny, Without an example STL file, there isn't much I can suggest You can try using OpenFOAM's commands surfaceCheck and surfaceClean. The other possibility is to use either Blender or Meshlab for repairing the STL file. Best regards, Bruno __________________ OpenFOAM: FAQ \| Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

July 13, 2013, 16:50		#23
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,981 Blog Entries: 45 Rep Power: 130	Hi Danny, I renamed the file to "test.stl" (OpenFOAM dislikes spaces and special characters) and ran: Code: surfaceCheck test.stl And it gave serious indications of a bad surface mesh on this geometry. Almost 70% of the triangles have a quality lesser or equal 0.05 and the one with smallest quality has "0.000133138"! And there seems to be problems with connections between triangles, since this is indicated: Code: Surface is not closed since not all edges connected to two faces: connected to one face : 12 connected to >2 faces : 0 Conflicting face labels:12 But given the low quality triangles, this is only natural to occur. If I'm not mistaken, the best procedure is to export to Step or IGES format and then use Salome to convert the surface mesh to STL. This is because SolidWorks is doing a very lousy job on converting this to STL. The other possibility is to export the geometry to STL in binary form, so that you do not loose numerical precision. I say this because, for example from your file: Code: vertex 3.125293e+000 3.067232e+000 8.410000e+000 7 digits is far from enough for such bad quality triangles Best regards, Bruno __________________ OpenFOAM: FAQ \| Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

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July 15, 2013, 08:45		#24
Dmoore New Member Danny Moore Join Date: Jun 2013 Location: Vermont, USA Posts: 14 Rep Power: 14	Thank you Bruno for your help! that makes sense with the troubles I was having! I appreciate your help! Danny