[Gmsh] VB: SV: not multiply connected

Wern Lennart lennart.wern at smhi.se
Tue Apr 17 09:07:52 CEST 2007


Dear Prof. Christophe Geuzaine
 
I am so happy that you can help me and thank you very much for the example you sent me. 

I think it would be good to know more about C-programming than I do. I am much better with fortran.

It looks like there are cells inside the building in the mesh you sent me? I will use my mesh with CFD-software for calculating the wind around the buildings. Therefor I do not want to have a mesh inside the buildings.

>From the information you sent me I tried to make a very simple geo-fil with only 5 buildings. 4 of them are 20 m high and one building 10 m high. 3 of the buildings are connected. If I understand how to mesh this geometry I think I can mesh all geometrys I need to mesh.

How do I mesh this geometry without meshing the buildings?

Will you please help? This is very important for my work.



Regards,

Lennart Wern
SMHI
Swedish Meteorological and Hydrological Institute
SE-601 76 NORRKÖPING
Sweden

http://www.smhi.se/cfd

Visiting address: Folkborgsvägen 1
Email: lennart.wern at smhi.se
Phone: +46 11 495 81 49
Fax: +46 11 495 82 50




-----Ursprungligt meddelande-----
Från: Christophe Geuzaine [mailto:cgeuzaine at ulg.ac.be]
Skickat: den 6 april 2007 11:57
Till: Wern Lennart
Ämne: Re: SV: [Gmsh] not multiply connected

Wern Lennart wrote:
> Dear Prof. Christophe Geuzaine
> 
> I am very greatful that you want to help me.
> 
> What I really want to mesh are many buildings with different building heights, see attached geo-fil. My thoughts was to start 100 m above ground and extrude downwards to the roofs where the buildings are and extrude to the ground around the buildings. The ground are at 0 m.
> 
> I want to mesh my geometry with hexaedrals or prisms, absolutely not with tetraedrals. I only want to mesh around the buildings, not inside.
> 
> How can I best mesh around my buildings?


I would probably just extrude the surface mesh (I've created a simplified example--have a look at the attached file).





> 
> I am so happy for all help I can get.
> 
> 
> Regards,
> 
> Lennart Wern
> SMHI
> Swedish Meteorological and Hydrological Institute
> SE-601 76 NORRKÖPING
> Sweden
> 
> http://www.smhi.se/cfd
> 
> Visiting address: Folkborgsvägen 1
> Email: lennart.wern at smhi.se
> Phone: +46 11 495 81 49
> Fax: +46 11 495 82 50
> 
> 
> 
> 
> -----Ursprungligt meddelande-----
> Från: Christophe Geuzaine [mailto:cgeuzaine at ulg.ac.be]
> Skickat: den 4 april 2007 14:14
> Till: Wern Lennart
> Kopia: gmsh at geuz.org
> Ämne: Re: [Gmsh] not multiply connected
> 
> Wern Lennart wrote:
>> Dear Gmsh-user
>>
>> I am a new user of gmsh and I need some assistance.
>>
>> I have made a very simple geometry with two volumes that I can mesh 
>> without any problems, see attached file.
>>
>> I want to use my mesh in OpenFOAM and I therfor convert it. In the 
>> converting log I get text like the below:
>>
>> It seems like the two volumes are not connected. How can I connect them? 
>> Please help !!!
> 
> 
> The way you generated the volumes, they are indeed not connected (you extruded the surfaces by 2 different heights).
> 
> Attached is a version of your geometry that connects the volumes.
> 
> 
> 
> 
>> ------------------------------
>> checkCoords : points 1142 and 492 with coordinates:(250 343.75 70) 
>> and (250 343.75 70)  are relatively close to each other. This might 
>> be correct in case of e.g. baffles.
>> checkCoords : points 491 and 1141 with coordinates:(250 343.75 80) 
>> and (250 343.75 80)  are relatively close to each other. This might 
>> be correct in case of e.g. baffles.
>> checkCoords : points 490 and 1140 with coordinates:(250 343.75 90) 
>> and (250 343.75 90)  are relatively close to each other. This might 
>> be correct in case of e.g. baffles.
>> checkCoords : points 488 and 192 with coordinates:(250 375 20) and 
>> (250
>> 375 20)
>>  are relatively close to each other. This might be correct in case of 
>> e.g. baffles.
>>
>> patch9  146     156     ok (not multiply connected)
>> patch11 145     155     ok (not multiply connected)
>> patch33 146     156     ok (not multiply connected)
>> patch55 145     155     ok (not multiply connected)
>> ------------------------------
>>
>>
>> Regards,
>>
>> Lennart Wern
>> SMHI
>> Swedish Meteorological and Hydrological Institute
>> SE-601 76 NORRKÖPING
>> Sweden
>>
>> Visiting address: Folkborgsvägen 1
>> Email: lennart.wern at smhi.se
>> Phone: +46 11 495 81 49
>> Fax: +46 11 495 82 50
>>
>>
>>
>>
>> <<test_1.geo>>
>>
>>
>> ---------------------------------------------------------------------
>> -
>> --
>>
>> _______________________________________________
>> 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
> 


--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science http://www.montefiore.ulg.ac.be/~geuzaine

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