> On 23 Oct 2018, at 21:37, Koen Hillewaert (Cenaero)
> <[email protected]> wrote:
>
> Hi,
>
> the issue is that the periodic connection for high order nodes uses the
> transformation, which is not computed anymore. This computation is not
> univocal (even your case has infinite possibilities for transforming line 2
> into 4).
>
> The approach used for meshing the non-high order vertices assumes the
> parametric representation of periodic counterparts is fully compatible and
> then finds the node counterparts simply by using the same parametric
> coordinates on the other line/surface. Although this assumption is not
> generally true, we could also make it for the high order nodes in case no
> transformation is specified. However only by using the transformation to
> position periodic vertices we can guarantee watertight meshes, in particular
> since some high order node optimisations may position high order nodes
> slightly off the surface/edge. I would even be in favour of also using the
> transformation to position principal vertices instead of assuming the same
> parametrisation.
>
> Christophe, what is your opinion ?
If no transformation is given, I would use the parametrization. This would
provide backward compatibility with Gmsh 3, and will work on many simple (but
common) cases, e.g. straight lines created with the build-in CAD engine, which
are always parametrized in [0,1].
>
> Best,
>
> Koen
>
>
> On 10/23/18 7:57 PM, Christophe Geuzaine wrote:
>> Dear Martien,
>>
>> It's indeed one more side effect of the changes for correctly handling
>> periodicity for high-order meshes. As a workaround you should currently
>> specify the transformation explicitly, i.e. specify
>>
>> Periodic Line {2} = {4} Translate{lx,0,0};
>>
>> instead of
>>
>> Periodic Line {2} = {-4};
>>
>> @Koen - do you see an easy fix?
>>
>> Christophe
>>
>>
>>> On 23 Oct 2018, at 18:19, Hulsen, M.A. <[email protected]> wrote:
>>>
>>> Hi,
>>>
>>> The following geo file does not work correctly for gmsh4.0.4 when running
>>> with ‘gmsh -2 -order 2’. It does work for ‘gsmh -2’. Also gmsh3.0.6 is fine.
>>>
>>> ox = -1.00000000000000;
>>> oy = -0.50000000000000;
>>> lx = 2.00000000000000;
>>> ly = 1.00000000000000;
>>> dx_box = 0.10000000000000;
>>> // Create domain vertices
>>> Point(1) = {ox, oy, 0.0, dx_box};
>>> Point(2) = {ox+lx, oy, 0.0, dx_box};
>>> Point(3) = {ox+lx, oy+ly, 0.0, dx_box};
>>> Point(4) = {ox, oy+ly, 0.0, dx_box};
>>> For i In {1:4}
>>> Physical Point(i) = i;
>>> EndFor
>>> // Create domain sides
>>> Line(1) = {1, 2};
>>> Line(2) = {2, 3};
>>> Line(3) = {3, 4};
>>> Line(4) = {4, 1};
>>> For i In {1:4}
>>> Physical Line(i) = i;
>>> EndFor
>>> // Create outer boundary
>>> lin_loop[0] = newll;
>>> Line Loop(lin_loop[0]) = { 1, 2, 3, 4 };
>>> // Make lines periodic
>>> Periodic Line {2} = {-4};
>>> // Create surface mesh
>>> Plane Surface(1) = {lin_loop[]};
>>> Physical Surface(1) = {1};
>>>
>>>
>>> Martien
>>> _______________________________________________
>>> gmsh mailing list
>>> [email protected]
>>> 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
>>
>>
>>
>
> --
> Koen Hillewaert
> Fluid Dynamics Technology Leader
>
> https://www.researchgate.net/profile/Koen_Hillewaert
>
> Cenaero
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>
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> <koen_hillewaert.vcf>
—
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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