I have a question on the “Real wall” boundary condition:
Typically containers have both inner and outer walls because the solid material has thickness. It is reasonable to set an inner wall to be “Real”, however in addition to the Heat Transfer Coefficient, the software also asks to specify “External Fluid Temperature”. However for internal fluid, the direct inner wall bounding it has no external fluid, but only the solid material inside the wall.
So what does “External Fluid Temperature” mean for inner “Real Walls”?