Utilising thin walls in "Boundary Conditions"
 

I've set up my geometry using Design Modeller. I have a solid object which represents my fluid body, and I've created an external thin wall with a thickness of 0 from this object and combined these two objects as one part.

I've meshed this body, named the thin wall as a hot temperature source and named the surface of the fluid body (excluding inlet and outlet), as the cold walls. I can't select the internal sides of the thin wall as when I hide the internal body and try to select the internal sides, it just highlights the external faces.

What I want to do is utilise this thin wall as a constant temperature boundary, and run a transient simulation so the fluid flow in the internal solid object (really confusing nomenclature - that doesn't help :confused:), is heated by this thin wall over time.

My issues are, I can't create a contact between the internals of the thin wall and the edge of the fluid body. I can also not see the thin wall in the "Boundary Conditions" table when setting up the simulation calculation.

I don't understand why there is not just an option to set the wall temperature of the fluid body to a different temperature to the interior of the fluid body at the beginning of the calculation.

I'm using Ansys 18.1, and all guidance would be much appreciated.

What solver do you want to use?

I'm using a Laminar solver in fluent (microchannels being simulated, and if Mesh is fine enough it is accurate).

A quick fix that was advised to me by a colleague was to use Standard Initialisation as opposed to Hybrid Initialisation, and set the initial temperatures relative to the inlet.

I would suggest to use CFX which has more tools to handle thin surfaces, interfaces, etc. Might be new for you, but that is my experience.