[elios]

Hi everyone!
I'm a new member, even if I already read some topics, usually very usefull!

I'm working with Ansys Fluent 14.5 on a circular pipe, with high temperature gas and a thermocouple inside, to measure temperature.

I want to consider the heat transfer through the pipe wall, due to convection and conduction, to account the heat losses. So I set, on the wall boundary condition, thermal form, convection method.
It ask me the Heat transfer coefficient, and I read the user's guide to understand what precisely it means, but the guide is actually not very clear about that.
I calculated the Nusselt number inside the pipe using Gnielinski correlation:



My question is if I have to combine this result with the Heat transfer coefficient outside the pipe, and with the Heat transfer coefficient of pipe wall:



and so apply this formula to combine the 3 heat transfer coefficient I get:



So, which h I have to combine to have the value fluent want me to give?

The same problem is on the thermocouple surface.
I set the mixed method, to account also the radiation, and I calculated the h value with the Churchill and Bernstein formula:



Is this the number Fluent want from me? Or I have to combine it with the h on the thermocouple surface?

I hope that my problem is clear, and I'm sorry if I said some banalities...
Thanks for everyone who could help me.

[edoan]

for the convective heat transfer BC (the one you chose) you need to specify the heat transfer coefficient from the outside of the pipe to the ambient air it assumes the pipe wall is zero thickness. Read through the heat transfer calculations at wall boundaries section in the user guide and pay attention to the delta T in the equations, this gives you a hint as to where the heat transfer coefficient is being applied.