I would make the 4 m/s ring like 2 m thick.
I think the problem will be determining the values for: solar absorptivity, surface emissivity, and what the ambient temperature that you are radiating to. You are not flying so you will get heaps of solar reflection and radiation off the runway surface.
For aviation analysis you should use the appropriate agency requirements for example...
Thanks for your comment. I'm actually using the 1% hot day configuration accordingly with MIL...810.
But can you explain why the thickness of the disk for 2m?
Do you think I should do a rectangular box around my tube, and do an internal study ?
The outside of the tube is cooled by forced convection so the air-flow with eddies, convection layer, etc will need a lot of room to develop.
I would definitely include the ground in the model. Note that the air velocity at the ground will be 0 and increases with elevation - so I would add this detail in (the atmospheric boundary layer).
Is this a transient or static simulation?
Thanks. Good point will add the ground.
It's a static.