[Gmsh] R: Integer flag to .msh elements

Thu Oct 24 16:54:13 CEST 2013

On 24/10/13 16:52, Umberto Iemma wrote:
> 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} ;

Yes, indeed.

Dave

>
>
> 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
>>>> *****************************************************************
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
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>>
>>
>