[Gmsh] Volume{} creates duplicate Surfaces: gmsh w/o OpenCascade

[Christophe Geuzaine]

Dear Paul,

When changing the surface and recreating the volume, the shape fixing algorithm decides that orientations must be changed to get a correctly oriented shape (finite).

You can disable this automatic fixing by setting at the beginning of your file:

Geometry.OCCAutoFix = 0;

Cheers,

Christophe'


> On 19 Jan 2018, at 16:23, Paul Fulmek <fulmek at tuwien.ac.at> wrote:
> 
> Dear gmsh-list,
> 
> I noticed a different or strange behaviour of gmsh-3.0.1/3.0.6 w/o SetFactory("OpenCASCADE") when creating a Volume{}.
> Usually I rely upon my list of surfaces, which I use in the Surface Loop{} command to create a Volume, accordingly I declare the Physical-ID Volumes/Surfaces from my private book-keeping of surfaces and volumes. If I do use SetFactory("OpenCASCADE") in my script, however, this assumption fails, at least in my simple test-case. The Volume-command creates new Surfaces, ignoring my original surface-IDs, which leads to physical volumes which are not bounded by my physical surfaces, leading to unexpected behaviour in the subsequent GetDP simulations.
> 
> I have attached a simple test-case geo-script which shows this behaviour, this script contains some more comments on what has been tried:
> 
> If using gmsh-built-in everything is OK, as expected
> 
> If using openCASCADE a strange thing happens:
>       Volume(P_Vol) = { surface_loop };
> creates some duplicate surfaces from the complete and correct surface-list!  I.e. my original surface-loop does no longer describe the boundaries of the new volume!
> gmsh-3.0.6 shows this behavior always
> gmsh-3.0.1 shows this only if my original surface-ID-list has been modified in the process!
> 
> Whats wrong with my script/assumptions?
> 
> Thank you very much,
> 
> kind regards
> 
> Paul
> 
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine

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