[Gmsh] Re: Gmsh digest, Vol 1 #49 - 2 msgs

[Jean-Francois Remacle <remacle@scorec.rpi.edu>]

Hello,

When you save a mesh using Gmsh, the file will contain all
the vertices . Then, there are 2 options.

You can "Save All", then gmsh will save all entities of
maximal dimension (it depends if it's 2d or 3d) and all
entities that are "equally classified" which means all
edges that are on geometric edges and all faces that are on
geometric faces. This is the maximum amount of mesh entities
gmsh can save presently. If you want more mesh entities :
interior edges, interior faces, you have to build them in
your code. Note that no geometrical check has to be made for
doing that,

You can "Save". In this case, you will save vertices but
only mesh entities that you group in "Physical Entities".
You can read the tutorials for understanding this notion.

For some applications, this info is sufficient. You can build your finite
element matrix and use "Physicals" for boundart conitions. FOr other
applications (Finite Volumes, Higher Order Finite Elements), you have to
do some work. Note that a future version of gmsh (begin of 2002) will
allow you to create all entities.

If you look for a tool to read gmsh meshes and create some additional mesh
adjacencies, look into www.scorec.rpi.edu/AOMD.

Jean-Francois.



--
Jean-Francois Remacle, Research Associate
Scientific Computation Research Center     (518) 276-8045
Rensselaer Polytechnic Insitute
http://www.scorec.rpi.edu/~remacle
CII
110 8th Street
Troy, New York 12180-3590


On Wed, 7 Nov 2001 gmsh-request at geuz.org wrote:

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>    1. =?gb2312?B?UGxlYXNlIGhlbHAgbWUh?= (LFKI)
>    2. Re: Please help me! (Christophe Geuzaine)
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> Message: 1
> Date: Wed, 7 Nov 2001 11:52:00 +0800 (CST)
> From: "LFKI" <txsts1974 at 263.net>
> To: gmsh at geuz.org
> Subject: [Gmsh] =?gb2312?B?UGxlYXNlIGhlbHAgbWUh?=
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>
> --Boundary-=_eQSfGLgSTjtyjdTEOGtPuFfsOseZ
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> Dear Mr.Christophe,<br>  May I ask you a question? When I use Gmsh to mesh the example of t1.geo, I found that the output file (t1.msh) did not list all line elements information, such as those lines in the interior of the rectangle. There are only information of lines elements on the edges of the rectangle in 't1.msh'. What's the matter?<br> <br>            S.Tan<br><br><br><br><br><br><table border="1" bordercolorlight="#FFFFFF" bordercolordark="#FFFFFF"width="496">  <tr>     <td width="217">      <script language="JavaScript1.1" src="http://ad263.allyes.com/main/adfshow?user=tebie|footer|footer3&db=ad263&local=yes&js=ie"></script>    </td>    <td width="263">      <script language="JavaScript1.1" src="http://ad263.allyes.com/main/adfshow?user=tebie|footer|footer4&db=ad263&local=yes&js=ie"></script>    </td>  </tr>  <tr>    <td width="217">       <script language="JavaScript1.1" src="http://ad263.allyes.com/main/adfshow?user=tebie|footer|footer1&db=ad263&local=yes&js=ie"!
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> Dear Mr.Christophe,
>   May I ask you a question? When I use Gmsh to mesh the example of t1.geo, I found that the output file (t1.msh) did not list all line elements information, such as those lines in the interior of the rectangle. There are only information of lines elements on the edges of the rectangle in 't1.msh'. What's the matter?
>
>             S.Tan
>
>
>
>
>
>
>
> --Boundary-=_eQSfGLgSTjtyjdTEOGtPuFfsOseZ--
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> Message: 2
> Date: Wed, 07 Nov 2001 08:32:15 +0100
> From: Christophe Geuzaine <Christophe.Geuzaine at ulg.ac.be>
> Organization: =?iso-8859-1?Q?Universit=E9?= de =?iso-8859-1?Q?Li=E8ge?= - Service
> 	=?iso-8859-1?Q?d=27Electricit=E9=20Appliqu=E9e?=
> To: LFKI <txsts1974 at 263.net>
> Cc: gmsh at geuz.org
> Subject: Re: [Gmsh] Please help me!
>
> LFKI wrote:
> >
> > Dear Mr.Christophe,
> >   May I ask you a question? When I use Gmsh to mesh the example of t1.geo, I found that the output file (t1.msh) did not list all line elements information, such as those lines in the interior of the rectangle. There are only information of lines elements on the edges of the rectangle in 't1.msh'. What's the matter?
> >
>
> Of course, there are no line elements generated inside the rectangle,
> since this information can be very simply derived from the triangular
> elements. To get the information you want (I guess), simply loop on the
> triangles and generate the edges (each triangle has three nodes, and
> each edge joins two of these nodes)... For all interior edges, you will
> have to choose one out of the two possible orientations, though (i.e.
> going from node 24 to node 25, or vice versa).
>
> Christophe
>
> --
> Christophe Geuzaine
>
> Tel: 32 (0) 4 366 37 10    http://geuz.org
> Fax: 32 (0) 4 366 29 10    mailto:Christophe.Geuzaine at ulg.ac.be
>
>
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