[Gmsh] Periodic Line (Curve) not working for second-order elements

[Christophe Geuzaine]

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. <M.A.Hulsen at tue.nl> 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
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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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