[sasanghomi]

Dear friends,

I wonder which reference temperature is used for calculating convective heat transfer coefficient?

I tried to calculate HTC by using wall adjacent temperature, wall temperature and wall heat flux; however, it does not match the values calculated in CFD post as wall heat transfer coefficient.
Do you have any ideas?

[urosgrivc]

If you want the HTC to be based on some fixed farfield temperature
you can change the Tbulk temperature under expert parameters, in [K]

it is well described here:

https://www.cfd-online.com/Wiki/Ansys_FAQ search->Calculating the Heat Transfer Coefficient in CFX

[sasanghomi]

I know that reference temperature can be changed by expert parameters. However, my question is that what the reference temperature is when nothing is changed in expert parameters. What is the reference temperature by default?

[urosgrivc]

it is all described in the link (only a few sentences)

Wall Heat Transfer Coefficient = Wall Heat Flux / (Wall Temperature - Wall Adjacent Temperature)

Wall Adjacent Temperature, which is the fluid temperature of the first fluid node off the wall this is
why the default result is near wall mesh dependant

[sasanghomi]

I see what you are saying; however, the problem is that in my case, the wall adjacent temperatures equal almost the wall temperatures. In fact, I am simulating the fluid flow inside a duct which has a constant heat flux on its walls. So, there must be differences between wall temperatures and wall adjacent temperatures. It should be noted that I export wall temperature and wall adjacent temperatures in CFD Post software program.

Any ideas?

[ghorrocks]

This just suggests that heat transfer is faster than the fluid flow in your case, so the wall temperature is bringing the temperature of the flow to close to the wall temperature (or at least the section near the wall).