[Gmsh] Help with rewrite of mesh I/O layer

[Christophe Geuzaine]

Laurent CHAMPANEY wrote:
> 
> 
> Christophe Geuzaine a écrit :
>> Hi all - We are currently rewriting Gmsh's mesh module, including the
>> input/output layer, and I have a few questions for all of you who
>> use the UNV ("IDEAS Universal Mesh") mesh file format:
>>
>> * What should we put in the "physical property", "material" and "color"
>> fields? Right now we just put the "elementary" region everywhere, and 7
>> (!) in the color field.
>>   
> "Physical property" is a way to link an element to a  physical property 
> (beam section, plate thickness, ...)  and "material"  to material 
> property (young's modulus, density, ...) than can be defined elsewhere 
> in the  .unv file.
> Those informations will be used for the matrix construction, but they 
> can also be used for selecting the parts of the mesh to be visualized. I 
> think than you can use the same reference the two fields than would be 
> related to the "physical" definition in gmsh.

Sounds good to me. But if we do this, should we still also define the
"Groups of nodes" groups for each physical?


> 
> Color codes are just used for screen presentation. The color codes are  
> attached.
> 
>> * Should we treat the physical groups like in the native MSH file
>> format, i.e., if physical groups are defined, only save the elements
>> that belong to a physical group? Right now we always save all the 
>> elements.
>>   
> I think than you can save only the physical groups.
>> * I don't have access to any program that can read UNV files. Does
>> anyone on this list with access to such a program want to volunteer to
>> test a alpha-quality version of the new import/export code?
>>
>>   
> I will check
> 
>> Thanks,
>>
>> Christophe
>>   
> Laurent
>> PS: While we're at it, are there any mesh file formats that we should
>> implement besides MSH, UNV, MESH (INRIA) and STL? Due to changes in the
>> database, we've had to remove the P3D and the GREF formats.
>>   
> Nastran Bulk Data file format is used a lot...
> 

OK. I've implemented a first version of the I/O routines for the Nastran 
Bulk Data File format by reverse engineering some BDF files I found on 
the web.

Do you know what all the possible element types are in that format (I've
added support for CTRIA3, CTRIA6, CQUAD4, CTETRA, CHEXA and CPENTA)?

Also, do you know how the fields should be written to disk? I've seen
several different number formats in the BDF files I came across on the 
web (%f, %e, fixed width, ...).



> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> gmsh mailing list
> gmsh at geuz.org
> http://www.geuz.org/mailman/listinfo/gmsh


-- 
Christophe Geuzaine
Assistant Professor, Case Western Reserve University, Mathematics
http://www.case.edu/artsci/math/geuzaine