[ibrahim.mohamed]

Here is a description of a modelling problem I am currently working on.
A hot cable is installed concentric to a circular tunnel. Air at 25oC is blown at 15m/s (x-direction) through the tunnel for cooling. Please see the image attached.

The objective is to find the variation of temperature from the cable surface to the tunnel wall and find the rate of heat transfer from the cable to the surrounding air and tunnel wall.

Problem: Currently the tunnel is 10m long. This is to allow the incoming flow to develop a fully developed profile. The issue is the tunnel may be not long enough.

Proposed Solution: Apply periodic boundary conditions such that the outlet flow is the inlet flow

How do I do this? How to I apply a periodic boundary condition in this case?

I am relatively new to CFX and I am using version 11.0. Any help you can offer would be highly appreciated.