[obiscolly50]

I'm performing a simple steady-state simulation with one inlet and one outlet using chtMultiRegionFoam. The geometry has a wide aspect ratio with a height of 9ft and width of 200ft. Fluid at a higher temperature of 313K flows in through a 4-inch diameter inlet and leaves through another 4-inch diameter pipe at the outlet. The initial temperature of the domain is 289K and all walls are adiabatic.

The problem I'm having is that after 3000 iterations, the fields don't seem to change anymore which should mean that I've attained convergence, but the solution does not make sense to me. I would expect that the steady-state solution in the case with hot fluid constantly flowing into the domain is a domain with almost uniform temperature of 313K due to mixing and exit of the colder fluid. But from my solution, the heat is concentrated at the inlet part of the domain and the other parts including the exit temperature is still almost 289K.

Can anyone tell me what's wrong or what i could be missing? I believe this could have to do with the length and time scale of my geometry. From my calculation the residence time of fluid in the domain is around 26 hours. How can i quickly approach convergence in this scenario?