Periodic boundary conditions on Gmsh mesh

General Discussion
1

Hello,

I am trying to solve a problem with periodic BCs on a pair of opposite faces. The 3D mesh is built with Gmsh. I was careful to have identical 2D meshes on the two faces when building the mesh (using the Gmsh command Periodic Surface {...} = {...} Translate {...};).

Everything works fine if I don’t try to impose periodic BCs, but I get an error message that looks like this if I define a FE space with periodic BCs:

Exec error : Periodic 3d:  the both number of face is not the same
   -- number :1
 err code 8 ,  mpirank 3
 vertex : 9 31.1703 0 0 214  Abscisses: s = 31.1703 0  2 0
 missing Border element : 555  105 107 194
 vertex : 282 -17.8123 13.1265 0 312  Abscisses: s = -17.8123 13.1265  23 141
 Exec error : periodic: Sorry one vertex of face is losted

Here is something close to a MWE:

load "msh3"
load "PETSc"        
load "gmsh"
int[int] n2oSaved;
int[int] n2oLoaded;
macro dimension()3// EOM            
include "macro_ddm.idp"             
macro def(i)[i, i#B, i#C, i#D]//   
macro init(i)[i, i, i, i]// EOM    
func Pk = [P1b,P1b,P1b,P1];
mesh3 Th = readmesh3("mesh.mesh");

Mat A;
macro ThN2O()n2oSaved//
createMat(Th, A, Pk); 
fespace Wh(Th, Pk); // works 
fespace Wh(Th, Pk, periodic=[[6,x,y],[7,x,y]]); // does not work

I can send the mesh if needed.

Has anyone faced the same problem or, conversely, managed to use periodic BCs with a Gmsh mesh?

Thank you.

2

Indeed, we need the mesh.

3

Here it is: mesh.mesh (243.5 KB).
I modified it slightly in the meantime, so the specific numbers (labels, coordinates etc) in the error message are different, but qualitatively it is the same idea.

Thanks.

4

Hi,
Did you prj (or someone else) had the chance to have a look? Thank you.