[fuad]

I have created a model of a fuel pin in chtMultiRegionFoam which is consisted of three concentric cylinders: the innermost and the middle one contains two different solids and the outermost one contains fluid that receives heat from the inner cylinders. But in the actual situation, this thing is repeating. So I need an appropriate boundary condition for the outermost surface. I think it should be cyclic. Is it right? If it is, how should I implement it?

The complete reactor and what I am modeling are attached here. Here I am modeling the central red rod as the my_domain.png file looks like.