[HiddenStars]

Hello, everyone! I recently learned the chtMultiRegionFoam and tried to do some redevelopment of models in this solver. I notice that in most cases, the iteration was non-existent, and the fluid regions and solid regions are solved one by one.

In openfoam-2206

       
        for (int oCorr=0; oCorr<nOuterCorr; ++oCorr)
        {
            const bool finalIter = (oCorr == nOuterCorr-1);

            forAll(fluidRegions, i)
            {
                #include "setRegionFluidFields.H"
                #include "readFluidMultiRegionPIMPLEControls.H"
                #include "solveFluid.H"
            }

            forAll(solidRegions, i)
            {
                #include "setRegionSolidFields.H"
                #include "readSolidMultiRegionPIMPLEControls.H"
                #include "solveSolid.H"
            }
        ····
        }

notice that the nOuterCorr is 1 in most tutorial cases.
Besides, checking in boundary condition code showed different interface temperature:

A case with two regions, the initial temperatures were 300 K and 400 K, output interface temperature with code "Info <<····"

deltaT = 0.1
Region: fluid Courant Number mean: 0 max: 0
Region: metal Diffusion Number mean: 0.00411523 max: 0.0164609
deltaT = 0.11999
Time = 0.11999

Solving for fluid region fluid
···
interface temp: 400
···
···
Solving for solid region metal
···
interface temp: 300

In face, the interface temperatures in a single step never equal to the other.
I understand how the interface temperature was solved, and the results showed good conservation on energy. But discussion above bring the final question:
*In theory or real world, a interface temperature should only have a single value at any time. How could the solver remains good conservation on energy with two temperature value on interface?
In other words, the chtMultiRegionFoam could have good conservation on energy without iteration of interface temperature, which makes me confuse.
Any opinion or suggestion would be helpful, any more details could be upload if needed.