Hello,

I have a question on mesh generation.

I need purely quad/hex periodic meshes to test convergence properties of some methods. The domain is a simple square/cube.

The i-tutorial

https://ngsolve.org/docu/nightly/i-tutorials/unit-4.3-manualmesh/manualmeshing.html

contains a manual generated rectangular mesh.

How to modify the boundary elements/boundary conditions to have periodic boundary?

Well, in this 2D case, I can use the idea

https://ngsolve.org/docu/nightly/i-tutorials/unit-4.1-geom2d/geom2d.html

to generate a periodic geometry and use

ngmesh = geo.GenerateMesh(maxh=0.5, quad_dominated=True)

to get the mesh, so this is not really an issue right now.

But for 3D, when I do quad_dominated=True, it gives me an error like:

SYSTEM ERROR: mesh has still open quads

Caught NgException: Stop meshing since too many attempts

Best,

Guosheng