[Gmsh] periodic pairs of internal nodes of each edge

[Nan Li]

Dear Christophe,

Thank you for your reply. In fact at first I thought I didn't use 'periodic
surface' the right way. Now I can focus on the post-treatment.

I have checked the node ordering of triangle_6 element, point 3 is always
in the middle of point 0 and point 1, and point 4 is always in the middle
of point 1 and 2, etc. So the correspondence of middle point can be deduced
based on this relation as we have already known the the correspondence of
the principle vertices. This is my understanding of your response. Am I
right?

Nan LI





On Fri, Jul 27, 2018 at 1:34 AM, Christophe Geuzaine <cgeuzaine at uliege.be>
wrote:

>
>
> On 26 Jul 2018, at 08:24, Nan Li <linan88433189 at gmail.com> wrote:
>
> Hello everyone,
>
> I am trying to mesh a cross-cavity with high order tetrahedron element
> (tetrahedron 10) and apply periodic boundary condition in x direction and y
> direction. As the periodic boundary condition has nothing to do with the
> cavity,  you can consider the cross-cavity as a cube.
>
> I have used 'periodic surfaces' and find the mesh of the two opposite
> surface is identical. So far so good. Then when I look into the .msh file
> and try to extract the point pairs in $Periodic $EndPeriodic, I find that
> only the nodes on the vertex of triangle are listed there. The internal
> nodes for each edge are not listed.
>
> Does anyone have successfully extract the periodic pairs of internal nodes
> of each edge ?
>
>
> Indeed we only keep track of the main vertices in the Periodic section.
> Once you have those you can get the element correspondance and match the
> high-order ones.
>
> @Koen, Amaury - should we also add the high-order vertices in the
> correspondance tables ?
>
> Christophe
>
>
> Thanks.
>
> Nan LI
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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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>
>
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