[Gmsh] half of structure disappears

[Christophe Geuzaine]

> On 4 Mar 2018, at 18:46, Juan E. Sanchez <juan.e.sanchez at gmail.com> wrote:
> 
> Hi Christophe,
> 
> In my actual structure, it is unknown whether or not it will be split. There will also be many more volumes with different tags.
> 
> I also do not want "air" to contain any of "gate".
> 
> How do I get all volumes created from the BooleanDifference into the same Physical Volume?
> 

Use the list (note the "()") returned by the boolean command :

air()=BooleanDifference{Volume{air}; Delete;}{ Volume{gate};};

Recursive Delete{Volume{unit_box};}
BooleanFragments{ Volume{air()}; Volume{gate}; Delete;}{}

Physical Volume ("gate") = {gate};
Physical Volume ("air") = {air()};



> Regards,
> 
> Juan
> 
> 
> 
> On 3/4/18 11:29 AM, Christophe Geuzaine wrote:
>>> On 4 Mar 2018, at 17:46, Juan E. Sanchez <juan.e.sanchez at gmail.com <mailto:juan.e.sanchez at gmail.com>> wrote:
>>> 
>>> Using the latest Mac OS snapshot, it is the same behavior.
>>> 
>>> 3 sections appear (air, gate, air)
>>> 
>>> I go into the visibility dialog, visualize both "gate" and "air", and the last "air" disappears.
>>> 
>> I think you are misunderstanding the definition of physical groups. Your boolean operations create 3 elementary volumes : left, center and right. You put the left one in the physical group "air" and the middle one in "gate". (Note that your boolean operations are unnecessarily complicated - you could just fragment the 2 boxes instead of doing a difference followed by a fragment.)
>> So if you select the 2 physical groups, indeed you hide the right volume...
>>> If I mesh before opening the visibility dialog, all 3 sections get meshed.
>>> 
>> Normal again: by default with the MSH2 format Gmsh only saves elements that belong to physical groupe.
>>> When I save the mesh, and then open the mesh file, one of the "air" sections is missing.
>>> 
>>> 
>>> Starting over:
>>> 
>>> If I open the visibility dialog, and select both physical groups, one of the "air" sections disappear.
>>> 
>>> Looking in the Elementary entities, it appears that there are 3 volumes.  It looks like one of the "air" sections did not get assigned to the Physical Group.
>>> 
>>> How do I ensure that both "air" sections get assigned to the same Physical Group?
>>> 
>> Physical Group ("air") = {3,4};
>> Christophe
>>> Regards,
>>> 
>>> Juan
>>> 
>>> 
>>> 
>>> 
>>> On 3/4/18 1:21 AM, Christophe Geuzaine wrote:
>>>> Dear Juan,
>>>> Not sure what you observe - your file seems to behave normally with the latest version. Can you try with the latest automated snapshot ?
>>>> Christophe
>>>>> On 3 Mar 2018, at 20:40, Juan E. Sanchez <juan.e.sanchez at gmail.com <mailto:juan.e.sanchez at gmail.com> <mailto:juan.e.sanchez at gmail.com>> wrote:
>>>>> 
>>>>> Hello,
>>>>> 
>>>>> I am using the OpenCASCADE factory to create a fairly complicated structure.  In this simplified test case, I run into the issue where part of the structure disappears when the center of it is removed.
>>>>> 
>>>>> When GMSH opens the file, it looks correct.  Then when I start manipulating it in the Visibility dialog, half of the "air" volume disappears.
>>>>> 
>>>>> When 3d meshing half of the "air" volume is also missing.
>>>>> 
>>>>> When I reopen the saved mesh, half the "air" volume is also missing.
>>>>> 
>>>>> Could someone please take a look?
>>>>> 
>>>>> 
>>>>> Regards,
>>>>> 
>>>>> Juan Sanchez
>>>>> <test.geo>_______________________________________________
>>>>> gmsh mailing list
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>>>>> http://onelab.info/mailman/listinfo/gmsh
>>>> —
>>>> Prof. Christophe Geuzaine
>>>> University of Liege, Electrical Engineering and Computer Science
>>>> http://www.montefiore.ulg.ac.be/~geuzaine
>>>> Free software: http://gmsh.info | http://getdp.info | http://onelab.info
>>> 
>> —
>> Prof. Christophe Geuzaine
>> University of Liege, Electrical Engineering and Computer Science
>> http://www.montefiore.ulg.ac.be/~geuzaine
>> Free software: http://gmsh.info | http://getdp.info | http://onelab.info
> 

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

Free software: http://gmsh.info | http://getdp.info | http://onelab.info

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