[Gmsh] meshing multiple objects

[Christophe Geuzaine]

Felix Wolfheimer wrote:
> Dear Christophe,
> 
> thank you for the quick reply. The two (or more) solids model objects with
> different material properties. Thus, I want to create a mesh that is
> conformal to the material interface, such that a tetrahedron of the
> generated mesh is located entirely in solid 1 or in solid 2 and,
> additionally, the tetrahedrons at the interface region (the face where the
> two solids touch) should share a common face. That is, the material
> interface should be handled somehow as a single face shared by both solids. 
> However, in the file generated by the solid modeler the two solids are two
> independent objects and, thus, the mesh is created independently for each of
> the objects. It would be nice to know, if there is any easy way to modify
> the step or iges file, such that a mesh with the properties described above
> is created. Is there any option in gmsh which would allow the creation of
> such a mesh directly from the step or iges file?
> 
> Please find the file test.stp, which contains a very simple model of two
> bricks where the one brick has been trimmed by the other.
> 

The boundary of the first cube has not been correctly subdivided, which 
results in partially overlapping surfaces... which causes the 3D mesh to 
fail.



> Thanks and best regards
> 
> Felix 
> 
> -----Ursprüngliche Nachricht-----
> Von: Christophe Geuzaine [mailto:cgeuzaine at ulg.ac.be] 
> Gesendet: Mittwoch, 12. November 2008 20:00
> An: Felix Wolfheimer
> Cc: gmsh at geuz.org
> Betreff: Re: [Gmsh] meshing multiple objects
> 
> Felix Wolfheimer wrote:
>> Hi Gmsh Experts,
>>
>>  
>>
>> I would like to create a tetrahedral mesh from iges or step models. The 
>> models contain parts which touch each other (result of Boolean 
>> operations). However, when I read the model with gmsh the interface 
>> region where the solids touch is meshed twice (once for the first object 
>> and once for the second). Additionally, the tetrahedrons at the 
>> interface overlap arbitrarily. Is there any way to read a CAD model and 
>> mesh it with gmsh such that the surface of the interface region of the 
>> two solids is meshed only once?
>>
> 
> You have to make sure that the solid modeler creates the correct 
> geometry for the intersecting objects (intersection curves, etc.)
> 
> Can you send the step file?
> 
> 
> 
>>  
>>
>> Best regards
>>
>>  
>>
>> Felix
>>
>>  
>>
>> PS: The screenshot enclosed to this mail may show you the result I get 
>> when I try to mesh two cylinders, where the first cylinder was trimmed 
>> by the second one.
>>
>>  
>>
>>
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>>
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> 
> 
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine