[Gmsh] Fragment + addSurfaceLoop

[Bruno]

Dear Christophe,


Thank you, I am going to try that.

I also found that using removeAllDuplicates() before creating the 
physical group also solved the issue, but your approach seems cleaner.


Best regards

Bruno


On 04.11.20 09:57, Christophe Geuzaine wrote:
>
>> On 20 Oct 2020, at 15:40, Bruno <bruno.agostini at gmail.com> wrote:
>>
>> Dear Gmsh Community:
>>
>> In the code below I import a 3D cooling fin CAD in Brep format. I want to modify the model to insert a heating area smaller than the base area and have a conformal meshing. I then tag the heating area for further use to apply boundary conditions. To this end I used the python code below:
>>
>> ```python
>>
>> # New heating area
>>
>> qa.append((2, factory.addRectangle(0, 0, 0, dz, -dy)))
>> factory.rotate([qa], 0, 0, 0, 0, 1, 0, pi/2)
>> tx = -Hd/2 - HEV
>> ty = ( dy - ( Wd + CH0 ) / 2 ) / 2
>> tz = Ld/2 + zq
>> factory.translate([qa], tx, ty, tz)
>> factory.synchronize()
>>
>> s = model.getEntitiesInBoundingBox(-Hd/2-HEV-tol, -Wd/2-CH0/2-tol, -Ld/2-tol, -Hd/2-HEV+tol, Wd/2+CH0/2+tol, Ld/2+tol, dim = 2) # Get fin bottom surface
>> sc = list(set(s) - set(qa)) # Remove heating area (duplicates)
>> sf = factory.fragment(sc, qa, removeObject = True, removeTool = False)[0]
>> factory.synchronize()
>> s = model.getEntities(2)
>> s = list(set(s) - set(sc)) # Remove original base area (duplicates)
>>
>> sl = factory.addSurfaceLoop([s[i][1] for i in range(len(s))], sewing = True)
>> factory.synchronize()
>>
>> vol = factory.addVolume([sl])
>> factory.synchronize()
>>
>> p = model.addPhysicalGroup(2, [qa[i][1] for i in range(len(qa))])
>> model.setPhysicalName(2, p, "base")
>>
>> p = model.addPhysicalGroup(3, [vol])
>> model.setPhysicalName(3, p, "fin")
>>
>> model.mesh.generate(3)
>>
>> ```
>>
>> If I use `sewing=True` then I get the results in the attached picture (superimposed_mesh.png): the heating area and the volume seem to have superimposed meshes even though I used fragment to cut-out the heating area.
>>
> I would fragment the whole model, which will ensure that everything is conforming; then extract the parts needed for boundary conditions.
>
> Christophe
>
>
>
>> If I use `sewing=False` then I get facet intersection errors (fin_NOK.png).
>>
>> Any idea what I am doing wrong here?
>>
>>
>> Best regards
>>
>>
>> Bruno
>>
>>
>>
>>
>> <superimposed_mesh.png><fin_NOK.png>_______________________________________________
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> —
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> http://people.montefiore.ulg.ac.be/geuzaine
>
>
>
>