I am trying to model baffle-impeller interaction in a continuous flow stirred tank. Inlet is from bottom of the tank (a circular opening) and outlet from top of the tank (a circular opening). Impeller has 6 blades while baffles are 4 in numbers. I could simulate the whole tank using sliding mesh. Now I want to half the volume by defining periodic Boundary conditions. When I do so after few iterations a messgae: "get node on edge-face-cell" comes. Where can be the problems. The inner (sliding volume) contains part of the top and bottom walls. I define them as rotating with absolute velocity equal to zero rpm.

Do you have periodic boundary conditions? Are they set to be rotational?