[Gmsh] 3D volume grid fails using stl file

[Vadivelan C]

Hi,

I found the problem was in Salome. i have checked with stl file which
created using other packages in gmsh. It works well.

BTW, i have one more problem. I converted the created mesh into openfoam
format. I got failed mesh error during checkMesh operation


Checking geometry...
    Domain bounding box: (-50 -50 -50) (50 50 50)
    Boundary openness (4.14122e-19 3.54948e-19 -5.92713e-20) OK.
 ***High aspect ratio cells found, Max aspect ratio: 30829.5, number of
cells 55
  <<Writing 55 cells with high aspect ratio to set highAspectRatioCells
    Minumum face area = 0.000356307. Maximum face area = 124.208.  Face area
magnitudes OK.
    Min volume = 5.21946e-10. Max volume = 442.292.  Total volume = 999996.
Cell volumes OK.
    Mesh non-orthogonality Max: 89.9711 average: 26.9608
   *Number of severely non-orthogonal faces: 4211.
    Non-orthogonality check OK.
  <<Writing 4211 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
    Max skewness = 3.86163 OK.
    All angles in faces OK.
    Face flatness (1 = flat, 0 = butterfly) : average = 1  min = 1
    All face flatness OK.

Failed 1 mesh checks.

End



here i have seen non-orthogonal faces error. Can you tell me how to neglect
those errors ?.

 - Ranjith

On Wed, Jun 24, 2009 at 10:14 AM, Vadivelan C <vc at tetrahedrix.com> wrote:

> Dear Christophe,
>
> Apologize for tardy reply.
>
>
> Info    : Mesh 3D complete (8.23975 s)
>>> Info    : 140728 vertices 283242 elements
>>> Error   : ------------------------------
>>> Error   : Mesh generation error summary
>>> Error   :     0 warnings
>>> Error   :    12 errors
>>> Error   : Check the full log for details
>>> Error   : ------------------------------
>>>
>>> Can you tell me what mistake i am doing ?. I attached geo file and stl
>>> file which i used.
>>>
>>
>> does it work with the default algorithm (delaunay) ?
>>
>
> Yes it works with delaunay algorithm. But i got error message during the
> meshing process
>
> Warning:  Polygon 1 has two identical verts in facet 1588.
> Warning:  Polygon 1 has two identical verts in facet 1628.
> Warning:  Polygon 1 has two identical verts in facet 1713.
>
>
> I created a simple sphere geometry in salome and tried meshing with and
> without extrusion layer.
> Without extrusion layer i got the above error and with extrusion layer i
> got the below error and meshing failed. I attached the stl file which i
> used.
>
>
>
>  Constraining facets.
> Error:  Invalid PLC.
>   Two subfaces (478, 9566, 9553) and (8000, 5173, 9583)
>   are found intersecting each other.
>   Hint:  Use -d switch to find all intersecting facets.
> Error   : Self intersecting surface mesh, computing intersections (this
> could take a while)
> Constructing Delaunay tetrahedralization.
>   Creating initial tetrahedralization.
>   Incrementally inserting points.
>   58044 Flips (T23 31220, T32 24157, T22 2666, T44 1)
> Delaunay seconds:  0.3
> Creating surface mesh.
>   Constructing mapping from indices to points.
>   Constructing mapping from points to tetrahedra.
> Warning:  Polygon 1 has two identical verts in facet 1588.
> Warning:  Polygon 1 has two identical verts in facet 1628.
> Warning:  Polygon 1 has two identical verts in facet 1713.
> Warning:  Polygon 1 has two identical verts in facet 1738.
> Warning:  Polygon 1 has two identical verts in facet 2724.
> Warning:  Polygon 1 has two identical verts in facet 4176.
> Warning:  Polygon 1 has two identical verts in facet 4632.
> Warning:  Polygon 1 has two identical verts in facet 7172.
>   Unifying segments.
>   Constructing mapping from points to subfaces.
>   Merging coplanar facets.
> Detecting intersecting facets.
>   Facet #1996 intersects facet #3361 at triangles:
>     (2794, 1761, 2795) and (3083, 2794, 2453)
>   Facet #1996 intersects facet #5520 at triangles:
>     (2794, 1761, 2795) and (2452, 3083, 2453)
>
>
>   Thanks
>  - Ranjith
>
>
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