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Issue with mesh running thermal simulation

  • Simon O'Reilly
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10 years 8 months ago - 10 years 8 months ago #7747 by Simon O'Reilly
Issue with mesh running thermal simulation was created by Simon O'Reilly
Hi all,

I'm new to Code Aster and Salome, I've managed to run a few simulations though and successfully get results. However I'm now trying to run a thermal model and am running into difficulties. I'll describe the problem as best I can:

* I've imported in an .STL mesh of a sealed surface. I was then able to create a solid mesh based on this surface mesh by going to Edit Mesh/Sub-Mesh and selecting to make Tetrahedral mesh type using the Netgen algorithm.
* I now want to run a simple thermal test case where I apply a fixed temperature to some tet elements and a different temperature to some other tet elements so I can see what sort of temperature distribution results in the entire mesh from doing this.

However, when I set up this model and run it I always get the same error which I have been unable to find much information about online:

   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   ! <S> Exception utilisateur levee mais pas interceptee.         !
   ! Les bases sont fermees.                                       !
   ! Type de l'exception : error                                   !
   !                                                               !
   !  Vous avez demandé l'affectation d'un modèle sur un GROUP_NO, !
   !  or le maillage tet_mesh n'en contient aucun.                 !
   !  L'affectation du modèle n'est donc pas possible.             !
   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


Can anyone shed any light on what is causing this error? Below is the command file I've been using for the analysis:
DEBUT();

tet_mesh = LIRE_MAILLAGE(FORMAT = 'MED');

SIM_TYPE = AFFE_MODELE(MAILLAGE = tet_mesh, AFFE = _F(TOUT = 'OUI', PHENOMENE = 'THERMIQUE', MODELISATION = '3D'));

MAT = DEFI_MATERIAU(THER=_F(LAMBDA=1e3, RHO_CP=1200.0,),);

PROP = AFFE_MATERIAU(MAILLAGE = tet_mesh, AFFE = _F(TOUT = 'OUI', MATER = MAT,),);

LOADS = AFFE_CHAR_THER(MODELE = SIM_TYPE, TEMP_IMPO=(_F(GROUP_NO='BC_elms', TEMP = 310,),_F(GROUP_NO='hot_elms', 
	TEMP = 400,),),);
	
RESU = THER_LINEAIRE(MODELE=SIM_TYPE, CHAM_MATER=PROP, EXCIT=_F(CHARGE=LOADS,),);


IMPR_RESU(FORMAT = 'MED', RESU = _F(MAILLAGE=tet_mesh, RESULTAT = RESU, NOM_CHAM  = ('SIGM_ELNO','DEPL') ),);

FIN();

Where "hot_elms" and "BC_elms" are Groups of Volumes which I've created from the mesh "tet_mesh".

My French isn't the best but I figure that the error is telling me that there is nothing in tet_mesh? Yet if click "Mesh Information" I can see that there are over 60,000 tetrahedron elements present, so it doesn't appear to be empty. In the attached image I have deleted some of the original 2D elements (in blue) so that the generated tets (in pink) are visible. It doesn't appear that the mesh is empty and I used this command file to run the thermal example from www.code-aster.org/V2/spip.php?action=dw2_out&id=1738 successfully so I really don't understand why it isn't working for this model, if anyone can shed some light on this I'd really appreciate it! Hope I've given enough information here.

*update* I'm thinking the values I've given for NOM_CHAM in IMPR_RESU might be the problem? Are these keywords ('SIGM_ELNO','DEPL') reserved ones that only are usable with mech analyses? I copied them from existing .comm files so don't fully understand them, if they are for mech analyses only what values should I be using for thermal analyses?

[attachment:1]Screenshot from 2014-08-26 12:07:27.png[/attachment]
Last edit: 10 years 8 months ago by Simon O'Reilly.
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10 years 8 months ago - 10 years 8 months ago #7748 by kwou
Replied by kwou on topic Re: Issue with mesh running thermal simulation
hoi oreillsi,
LOADS = AFFE_CHAR_THER(MODELE = SIM_TYPE, TEMP_IMPO=(_F(GROUP_NO='BC_elms', TEMP = 310,),_F(GROUP_NO='hot_elms', 
	TEMP = 400,),),);
Where "hot_elms" and "BC_elms" are Groups of Volumes which I've created from the mesh "tet_mesh".

GROUP_NO requires nodes as parameters, not groups of volumes.
Either change GROUP_NO to GROUP_MA or select nodes in the ''hot_elms''.
In the *.mess file you can see the groups available in your mesh (directly after reading the mesh).
Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
Last edit: 10 years 8 months ago by kwou.
The following user(s) said Thank You: Simon O'Reilly
  • Simon O'Reilly
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10 years 8 months ago #7752 by Simon O'Reilly
Replied by Simon O'Reilly on topic Re: Issue with mesh running thermal simulation
Brilliant! Thank you very much keeswouters! I changed GROUP_NO to GROUP_MA as you suggested and now the analysis runs successfully.

Thanks again!
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10 years 8 months ago - 10 years 8 months ago #7755 by kwou
Replied by kwou on topic Re: Issue with mesh running thermal simulation
hoi oreillsi,

Oeps.
Brilliant and 'some experience' may be the same.
I most cases it is not.
Thanks for the complement anyway.

Code-Asters learning curve may be steep, but afters a time your on the top of the hill, or mountain.
Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
Last edit: 10 years 8 months ago by kwou.
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