[marcel_jay]

Hello Community,

I have encountered an imbalance in the heat transfer rate (q in Watts) which I cannot explain.

Following Problem, I have a solid body with a heatsource with 66W into it. There are two other solid bodies in contact as well as a fluid domain (air).
I measured the imbalance in CFD-Post via an expression:

areaAve(Wall Heat Flux)@Interface1_Side1*area()@Interface1_Side1+areaAve(Wall Heat Flux)@Interface2_Side1.....

. In a converged steady state simulation (plotted Temperatures are not changing anymore), the result should be 0 Watts, right? But it is: 32W.
Is it possible that CFX defines some faces as negative? Since the part of the solid in contact with the fluid has a positive value for q. When I substract that one face I get a result of about 1W, which can be a round off error. Strangely, also the heatsource defined as 66W is only about 64.8W in CFD Post.

Any Idea?

Cheers