[HB833]

Hello everyone, I now have a pipe with fluid A inside and fluid B wrapped around the outside for heating. Fluid B is 443.15K steam that enters from the upper inlet. Now I need to set the boundary conditions for fluid B. My choice is: temperature,443.15K. Is this reasonable?

[LJA_Koers]

It looks like you have fluid A enclosed by a solid but haven't dont so for fluid B, why?

Usually, the interface between a solid and fluid is modeled as a coupled BC. I would apply the 0 heat flux condition here as you are cooling the steam and the temperature condition is probably not adequate.

Have you thought about what condition you'd apply on the solid sections which enclose the inlet and outlet of fluid A? These are often set as a zero heat flux condition, but in reality there will be heat condition along the pipe that is out of the domain now. I usually set this as a heat flux determined by the temperature of this surface and the average temperature of the same surface offset a little along the length of the tube.