Dear CFD users,

I have a conjugate heat transfer problem in a complex internal flow geometry. The analysis procedure I have used is to keep the convection study separated from the conduction study, due to limitations in computational resources, and also due to the fact that mechanical integrity analysis will anyway be performed separately (with a different code) for this problem.

For the post processing of the convection study I have up till now used T_ref = Tbulk = a global temperature, which I know will not work if the fluid heat is entering and exiting the solid at the same time (at different locations) due to negative HTC's. The benefit of this approach is however that the grid dependence of the HTC is eliminated and the solution is roughly independent of the wall boundary condition (I use an "average" constant temperature at the wall). The other way would be to use the approach that is standard in most CFD codes; the near wall node temperature as a reference temperature (T_ref = T_nwn). But then the solution is probably grid dependent and surely strongly dependent on the wall boundary condition (i.e. specified temperature level in my case). What would You prefer?

regards Andreas

Just a question,

What do you mean by "fluid heat is entering and exiting the solid at the same time (at different locations)"?. I thought you were computing the the htc locally, that is, you will have values of heat flux, metal temperature and bulk temperature at each location at the flow. Usually, the only problem should come up when metal and bulk temperatures are closer.

Regards

Peter

Hi again Peter,

the problem is in my case to calculate local bulk temperatures because of the complex geometry. Therefore I have used the inlet temperature as a bulk temperature so far. The inlet temperature is basically the only thing that is well known in my case.

The conduction calculation result is dependent on the HTC's and reference temperature from the convection calculation (for boundary surfaces of the solid not connecting to the fluid I have also specified "well known" HTC and T_ref).

Please look in the main discussion forum for additional question to you!

regards Andreas