How do I apply two periodic boundary conditions?

[dokken]

Combine them into once, as for instance shown in:

3D Periodic Boundary Conditions with Gmsh

I am trying to make a 3D simulation that has periodic boundaries on the x and y direction. The geometry on one side is a polygon, so I have been using gmsh to create the meshes. The issue I am running into is that fenics is not correctly applying periodic boundary conditions to the mesh. Some of the points are not correctly mapped from the slave side to the master side. A simple working example uses a square mesh using pygmsh, a python interface to gmsh. import dolfin as d import pygmsh as pg …