[Gmsh] Virtual topology problem

[Christophe Geuzaine]

> On 22 Jul 2019, at 21:47, Martin Kraska <martin.kraska at th-brandenburg.de> wrote:
> 
> Hello, 
> 
> in the attached script I try to mesh a step part using virtual topology (trying to update the example https://github.com/mkraska/CalculiX-Examples/tree/master/CAD/OnshapeTutorial )
> I see that I have to use a new syntax for virtual topology but otherwise did not make any changes compared to gmsh 3.0.3 which I tried last.
> 
> In gmsh 4.3.0 I get a boundary mesh issue.
> In 4.4.0 the virtual topology is just ignored but the part is meshed.
> in the git version of today (2019-07-22) I get a slightly different boundary mesh issue.
> 
> Did I miss some settings? Or is the part just too nasty?

You forgot to set:

Compound Surface {21};
Compound Surface {22};

With these the first order mesh looks OK.

Note that the 2nd order mesh will not work - this is currently expected with Mesh.CompoundClassify=1 (the default), as elements are reclassified across the boundaries.

We will improve this in the future. In the meantime, you can set Mesh.CompoundClassify=0; but you will need to redefine the volume in terms of the new surfaces. We haven't decided yet what the best/most  natural workflow should be in that case. Any feedback is welcome!

Christophe



> 
> Thanks for any advice, Martin Kraska
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine