[Gmsh] R: Integer flag to .msh elements

Umberto Iemma umberto.iemma at uniroma3.it
Thu Oct 24 16:52:55 CEST 2013


David,

Thanks for the help.

Does it work also for physical entities made of more than one surface?
i.e. Something like 

> Physical Surface (5555) = {6, 7, 22} ;


I'm not at my pc and I can't check by myself now.

Thanks,
Umberto

Sent from my iPad

> On 24/ott/2013, at 15:36, "David Colignon" <David.Colignon at ulg.ac.be> wrote:
> 
> 
>> On 24/10/13 13:38, Alessandro Vicini wrote:
>> 
>> Hullo everybody,
>> 
>> the problem is (as far as I know), that when you assign a surface to a
>> physical group, you don't have control on the number of the group, which is
>> automatically assigned by Gmesh.
> 
> 
> No. See t1.geo. If you write
> 
> Physical Surface (5555) = {6} ;
> 
> in t1.geo file, mesh it and save the mesh, the elements belonging to surface 6 will be tagged with the 5555 integer.
> 
> ace35:~/gmsh/tutorial >   cat  t1.msh
> 
> $MeshFormat
> 2.2 0 8
> $EndMeshFormat
> $Nodes
> 427
> 1 0 0 0
> 2 0.1 0 0
> 3 0.1 0.3 0
> 4 0 0.3 0
> 5 0.009999999999982483 0 0
> 6 0.019999999999956 0 0
> 7 0.02999999999992728 0 0
> 8 0.03999999999989585 0 0
> ...
> ...
> ...
> 426 0.01732880869837657 0.1002635856800227 0
> 427 0.06912838083014602 0.1057967588383864 0
> $EndNodes
> $Elements
> 844
> 1 15 2 1 1 1
> 2 15 2 1 2 2
> 3 1 2 99 1 1 5
> 4 1 2 99 1 5 6
> 5 1 2 99 1 6 7
> ...
> ...
> ...
> 71 1 2 99 4 79 80
> 72 1 2 99 4 80 1
> 73 2 2 5555 6 33 308 214
>      #####
> 
> 74 2 2 5555 6 105 229 284
> 75 2 2 5555 6 106 228 285
> 76 2 2 5555 6 122 234 316
> 77 2 2 5555 6 135 238 262
> 78 2 2 5555 6 60 166 282
> 79 2 2 5555 6 84 196 170
> 80 2 2 5555 6 97 197 170
> 81 2 2 5555 6 127 245 183
> 82 2 2 5555 6 54 164 270
> 83 2 2 5555 6 174 347 154
> 84 2 2 5555 6 84 170 337
> 85 2 2 5555 6 75 76 172
> ...
> ...
> ...
> 
> Dave
> 
> 
> 
> 
> If I understand what Umberto is saying
>> (which is the same thing that would be useful in my case), it would be nice
>> to have the possibility of explicitly assigning these integer flags to
>> surfaces (or groups of surfaces), in order to specify boundary conditions.
>> 
>> Regards,
>> 
>> Alessandro
>> 
>> 
>> 
>> -----Messaggio originale-----
>> Da: gmsh-bounces at ace20.montefiore.ulg.ac.be
>> [mailto:gmsh-bounces at ace20.montefiore.ulg.ac.be] Per conto di David Colignon
>> Inviato: giovedì 24 ottobre 2013 13.02
>> A: Umberto Iemma; gmsh at geuz.org
>> Oggetto: Re: [Gmsh] Integer flag to .msh elements
>> 
>> 
>>> On 24/10/13 11:57, Umberto Iemma wrote:
>>> 
>>> First, I'd like to thank the authors for the wonderful work they are doing
>> !
>>> Gmsh is one of the most useful free technical tools ever!
>>> Thanks!
>>> 
>>> After this, I have a question.
>>> 
>>> It is possible to include in the .msh file a integer flag to each element
>> ?
>>> I need this to specify particular physical properties of the boundary.
>> 
>> 
>> Hi Umberto,
>> 
>> you should use Physical groups for that purpose, see
>> http://geuz.org/gmsh/doc/texinfo/gmsh.html#Elementary-vs-physical-entities
>> 
>> "Groups of elementary geometrical entities can also be defined and are
>> called “physical” entities.
>> These physical entities cannot be modified by geometry commands: their only
>> purpose is to assemble elementary entities into larger groups, possibly
>> modifying their orientation, so that they can be referred to by the mesh
>> module as single entities. As is the case with elementary entities, each
>> physical point, physical line, physical surface or physical volume must be
>> assigned a unique identification number. "
>> 
>> 
>> and tutorial t1.geo, http://geuz.org/gmsh/doc/texinfo/gmsh.html#t1_002egeo
>> 
>> 
>> Regards,
>> 
>> Dave
>> 
>> --
>> David Colignon, Ph.D.
>> Collaborateur Logistique du F.R.S.-FNRS
>> CÉCI - Consortium des Équipements de Calcul Intensif ACE - Applied &
>> Computational Electromagnetics Université de Liège Sart-Tilman B28 10,
>> Grande Traverse
>> 4000 Liège - BELGIQUE
>> Tél: +32 (0)4 366 37 32
>> WWW:    http://www.ceci-hpc.be/
>> 
>>> 
>>> I'm the coordinator of the open-source project AcouSTO
>>> http://acousto.sourceforge.net, a tool for acoustic simulation. I'm
>>> going to release soon version 1.6 including the possibility to read Gmsh
>> files.
>>> Everything is working fine and the release candidate could be issued
>>> now, but this additional possibility would broaden significantly the
>>> field of application.
>>> 
>>> Thanks in advance,
>>> Umberto
>>> 
>>> *****************************************************************
>>>     Prof. Umberto IEMMA
>>>     Associate Professor of Aerospace Structures and Design
>>>     Dip. di Ingegneria - Universita' Roma Tre
>>>     via Vito Volterra 62, 00146 Roma
>>>     tel. +39-0657333274 fax  +39-065593732
>>>     www   : http://acousto.sourceforge.net
>>> *****************************************************************
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> gmsh mailing list
>>> gmsh at geuz.org
>>> http://www.geuz.org/mailman/listinfo/gmsh
>> 
>> 
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> 
> 





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