Help to generate periodic boundaries
 

I am trying to perform a Conjugate Heat Transfer Analysis of a NASA Mark II vane. The setup consists of a 3 vane cascade and it is simplified by analysing the central vane with periodic boundary conditions. I don't know how to generate the periodic boundary walls. Some help would be much appreciated.

I have attached 2 images - one of what I am supposed to generate (walls) and the other is my trial.