Periodic Boundary
 

I have generated a geometry in which I will simulate a fully turbulent flow. I have four inflows and four outflows in the geometry. I want to connect the outflows which represent the inflows of the next Modul of my geometrie. So I tried to create periodic boundary layers by linking the outlet faces to the matching inlet faces. Is this the right way to do it? The problem is, that I have no pressure drop in my geometry?