When simulating heat transfer between the wall-solid phase and the wall-gas phase, the heat transfer coefficient is usually correlated with operating conditions. However, I have found that in the MFIX-TFM GUI, the transfer coefficient can only be set as a constant. Therefore, we want to know if it is possible for us to replace it with a correlation and which subroutine we should modify.

I apologize for my delayed response. I appreciate your prompt reply. However, I have been unable to log in to the forum these past few days. Thank you for pointing out the areas that need modification and for your kind reminder.

After studying the code, I have observed that BC_HW_PHI in the code represents the heat transfer coefficient. It appears that in the code, the heat transfer coefficient is considered a constant, indexed by the boundary item number, as displayed in the software GUI. Therefore, it seems necessary for me to define an additional function to retrieve the heat transfer coefficient.

Moreover, I would like to know if an error would occur in the GUI when attempting to calculate this coefficient using an expression, given that the GUI only allows for a constant input.

Yes, you will need to define a function to compute a local heat transfer coefficient. The GUI can convert simple arithmetic expressions, but it is still considered a constant value once it is passed to the solver. This is not meant to have a local or transient value.