Periodic Boundary Conditions with OCC and a Rotational Transformation

Hello NGSolve folks,

I have following code:

---

from netgen.occ import *
from ngsolve import *
from netgen.meshing import IdentificationType
b = Box((-1.0, -0.5, 0), (0.0, 0.5, 1.0))
a = Box((0.0, -0.5, 0), (1.0, 0.5, 1.0))
a.faces.Max(Z).col = (1, 0, 0)
b.faces.Max(Z).col = (0, 0, 1)
trafo = Rotation(Axis((0, 0, 0), Y), 180)
a.faces.Max(Z).Identify(b.faces.Max(Z), "periodic", IdentificationType.PERIODIC, trafo)
geo_objects = Glue([a, b])
geo = OCCGeometry(geo_objects)
mesh = Mesh(geo.GenerateMesh(maxh=0.4))
Draw(mesh)

---

where I would like to specify rotational periodicity between the red and blue face.
Unfortunately it seems that the identifcation is not successful
(no  Map face 1 -> 2 output; no identified points). 

I have tried different configurations, e.g., a block between so that there is no shared
edge - but this did not help.

Any suggestions ? Thank you.

(likely related with  ngsolve.org/forum/ngspy-forum/1683-openc...-boundary-conditions  ?)


 

Hi Phil,

I don't know if you check the forum regularly so I am writing to you in case you get a notification.

Professor Schöberl answered to the other post with the solution to this problem:
ngsolve.org/forum/ngspy-forum/1683-openc...dary-conditions#4737

We were not giving the correct transformation.

Best,
Alessio