[Gmsh] Segmentation violation in GMSH 2.0.8 using STEP

[=?windows-1252?Q?Jean-Fran=8D=E7ois_Remacle?=]

Gaël Bressy a écrit :
>
> Dear GMSH Team !
>
>  
>
> I’ve been using GMSH v2.0.8 since July for creating geometries and 
> meshes for a CFD code. Recent improvements in our tool allow us to use 
> large meshes for industrial applications and we want to use geometries 
> imported from a commercial CAD program.
>
>  
>
> However, when importing from a STEP (203 or 214) file, we have a 
> */‘segmentation violation’/* error when meshing.
>
>  
>
> I attach to this mail the original /*.STEP/, the translated /*.geo/ 
> and the /*.gmsh-errors/ files. Note that all dimensions are in /mm/, 
> not in /m/ ! You may want to change the Characteristic Length factor 
> (‘Lc’ in geo file) accordingly… We have found that the cylinders are 
> the ones responsible for the error : when deleting them from the 
> geometry, the meshing works fine.
>
>  
>
The problem is the definition of the mesh size field. By default, GMSH 
provides
a mesh size field of the tenth of the characteristic size of the 
problem, which may be
too large. Here, I have tryed

gmsh Transfo.STEP -3 -clscale .1 -optimize

and the result is a very decent 3D mesh (see the image).

When I use STEP files, I create a .geo file (e.g. Transfo.geo) where
I add the line

Merge "Transfo.STEP";

I load Transfor.geo with gmsh and I can modify the size field using 
either the
interface or directly editing the file.


JFR


> Could you tell us what we are doing wrong, or if there is a way to 
> correct the geometry ?
>
>  
>
> If this is a known bug in GMSH v2.0.8, is there an update planned to 
> correct it in the coming weeks/months ?
>
>  
>
> Thank you for your time and for this excellent tool ! I hope you can 
> help us solve this J
>
>  
>
> Best regards,
>
>  
>
> Gaël de BRESSY
>  
> SERGI Research Department
> 186, avenue du Gal de GAULLE
> P.O. Box 90 - 78260 ACHERES - FRANCE
> Tel: 33 - 1 39 22 37 18 / Fax: 33 - 1 39 22 48 55
> =========================================
>
>  
>
> ------------------------------------------------------------------------
>
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