Surface Heat Transfer Coefficient driven by a UDF, using coupled wall
 

Hi, I'm quite new in using CFD software and I have a dissertation based around simulation results but I have run into several problems as I've progressed.

My model involves a cylinder placed inside a significantly larger cylinder. The larger cylinder is simply an air fluid domain whilst the smaller cylinder is a solid. In this solid, four very thin layers exist on the outer wall, in which heat is generated in one of the layers. The solid inwards of these layers is acting adiabatically, meaning that the heat mainly conducts outwards and axially.

Whilst I've managed to do this using the shell conduction option in the wall boundary condition, my tutor advised me that the wall must also be coupled since it separates a solid zone from a fluid zone, which I understood and implemented. However, I also realised that the option to make the surface heat transfer coefficient of the wall obey a UDF I've created, vanishes with the implementation of the coupled wall.

He was sure of implementing a UDF, I guess my question is "Can this be done in the manner my tutor has advised me (i.e. using a UDF defining the heat transfer coefficient and a coupled wall at the same time) or is there a simpler method, which actually works please?"

This might be obvious for some of you but please have patience explaining it, this software is still very new to me. If anyone could help me, I would very much appreciate it.

I will attach screenshots to explain what I'm referring to.

If something is unclear, please ask me and I'll clarify ASAP.
Thanks.

I think that you should not use HTC (HTC in Fluent may be not the same as you understand). You should use coupled wall.
Try do it without shell conduction and compare the results.