[Gmsh] An idea

[CEM ALBUKREK]

Hello Christophe,

I have addressed the issue a long time ago in the same way you described.
Thanks for the response anyways.

Best,

Cem

On Sun, Feb 15, 2009 at 10:14 AM, Christophe Geuzaine
<cgeuzaine at ulg.ac.be>wrote:

> CEM ALBUKREK wrote:
>
>> Hello Christophe,
>>
>> I have been using Gmsh successfully to build complex tet meshes as input
>> to OpenFOAM. To give you a sense of the complexity attached is a picture of
>> a typical surface mesh, which is an assembly of NAS and STL files combined
>> into one closed volume using some scripts I developed. You have warned on
>> your website that GMSH is not so good at large meshes from STL's; what
>> threshold (# of tets) did you have in mind? I am able to go as far as the 32
>> bit memory allows me to at this point. May be the trick is the application
>> of effective surface mesh smoothing techniques before moving onto volume
>> meshing...
>>
>> One issue with CFD is that one can march an unsteady (varying time)
>> simulation only as fast as the smallest tetrahedron allows; i.e.
>>
>> velocity * time_step <= tet size
>>
>> for each one of the tetrahedra.
>>
>> Sometimes small elements are unavoidable no matter how great a surface
>> mesh one puts together. One way around the problem is to blindly erase the
>> tetrahedra smaller than a threshold and run the flow simulation around these
>> tiny blockages, which are too small to affect the bulk flow. I would like to
>> implement a little sub-routine to do the same thing with GMSH. For instance
>> we have the mesh quality filters for beta, gamma & theta. In a similar
>> fashion I would like to put one for the size (or volume) and also be able to
>> click delete. Do you see any problem with this?
>>
>
>
> Hi Cem - You could do this interactively:
>
> 1) select a size range for the elements in Options->Mesh->Visibility
>
> 2) in the mesh menu select "Delete"
>
> 3) select all the visible elements with the mouse (Ctrl+LeftButton to
> start a rectangular selection area, LeftButton to finish)
>
>
>
>
>  May be FEM solvers could benefit from this kind of feature as well knowing
>> tiny bubbles are not uncommon in molded plastics and cast metals.
>>
>> What do you think?
>>
>> --
>> CEM M. ALBUKREK, PhD
>> Computer Aided Engineering Design Consultant
>> Tel: (857) 234-1035
>>
>> ------------------------------------------------------------------------
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> gmsh mailing list
>> gmsh at geuz.org
>> http://www.geuz.org/mailman/listinfo/gmsh
>>
>
>
> --
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> http://www.montefiore.ulg.ac.be/~geuzaine<http://www.montefiore.ulg.ac.be/%7Egeuzaine>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.geuz.org/pipermail/gmsh/attachments/20090215/67d6423f/attachment.html>