[Ghoomanjan]

Hello dear friends. I am hopeful you are doing well every time in you life. I am dealing hard with a simulation in ANSYS-FLUENT. I created the model in DM of ANSYS. The model consists of two co-axis cylinders. The internal cylinder is rotating and the outer cylinder is fixed. The internal body is a little bit more complex to be called a cylinder. The volume that I need to study it is just between these two bodies. When I subtract the internal body from the outer cylinder; just a single zone is remained and for defining MRF in FLUENT I can not define interfaces. The geometry of the model is attached to this question. I do know where I should define the interfaces, too. Exactly on the internal body?
in summary:
How can I create two different fluid zone?
Where should I define the interface?

Your help is appreciated

Alireza Kiyani