I'm trying to determine how much heat my heat sink is convecting to the air. I want to measure the heat flux through a particular cross section of space, obviously without affecting the flow in that cross section. I have created a body in that region, and defined a surface goal on desired surface for heat flux. I then disabled the component in "Component Control." When I run the analysis, my surface goals say "Invalid."
I can specify other goals on that surface, such as mass flow rate or temperature of fluid, and I get results as anticipated. It's just heat transfer rate and heat flux that return as "Invalid."