On 18/02/10 01:05, [email protected] wrote:
Dear Gmsh Users and Developers,
I would need to impose pseudo-periodic boundary conditions on two sets
of parallel surfaces in the attached geometry (respectively parallel to
zOx and zOy).
Originally, I was planning to use identical unstructured mesh on these
surfaces, but as far as I understood, my only options consist in using
(i) an extrusion of surfaces or (ii) the Transfinite Algo which both
lead to structured surface mesh.
I have considered these two last options:
(i) I did not manage to extrude the mesh in both directions. Thus, after
extruding one surface in one direction (say Ox) and deleting all the
middle entries (as mentioned in
http://www.geuz.org/pipermail/gmsh/2009/004416.html), I still have to
extrude it in the Oy direction, which leads me to define some points two
times (?).
(ii) I tried to use Transfinite Surfaces, like in the attached geo file.
I used MeshAdapt for the 2D part which generates proper 2D meshes.
Everything seems OK until the 3D meshing part:
- Delaunay overwrites my identical surface mesh as mentioned in some
past mail.
- Frontal leads to unexpected multiple "Error : Edge a - b multiple
times in surface mesh"
Is there any workaround?
Hello Guillaume,
Unfortunately we cannot correct the error in the Frontal algorithm: it
fails due to some internal floating point precision issue. A workaround
is to define nm=1 in your geometry, and apply a global scaling factor
(using Mesh.ScalingFactor=1.e-9) when saving the mesh...
I also think until we have actual "mesh copying" operations (work in
progress... almost done but not quite!), Extrusion would be a better way
forward. Why didn't extrusion work in your case?
Best,
Christophe
Wouldn't you use Extrude instead?
Eventually, I would like to end up with a fine mesh in the so-called
groove physical volume (n°6000), and ideally a mesh that goes
progressively coarser when reaching the top (resp. bottom) of the
physical region 5000=PML_top (resp. 1000=PML_bot). However, it seems
that Transfinite doesn't enjoy this kind of setting, e.g.
"paramaille_hol>paramaille". Would you have any solution in mind,
compatible with my early issue ?
Thank you very much for your time.
Best,
Guillaume Demésy,
Postdoc at University of Toronto.
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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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