Mesh overlap message in Fluent
 

Hello,
I'm working on modeling conjugate heat transfer in a 1/12th fuel assembly of a nuclear reactor design. The fuel assembly has fuel pins in which the fuel region surrounded by a cladding. The coolant flows through a bank of these fuel pins. I use the k-omega SST model for turbulence modeling, and use inflation to resolve the viscous sublayer. I have posted an image of the mesh I generated for the fuel assembly (using ANSYS meshing). I'm able to run simulations and get some reasonable results for the fuel temperatures and bundle pressure drop, and for the baseline wall grid scheme, my y+ value is ~0.5. However, when I try to reduce the first layer thickness even further (to see how much of an impact does this have on the results), Fluent throws up a message saying "Info: Interface zones overlap for mesh interface xyz". The interface that Fluent is indicating is the interface between the solid (cladding outer surface) and the fluid. I don't clearly understand what this warning/info means (I suppose it has something to do with the inflation affecting the interface), and what I could do to fix this message. If you could help me out with some pointers on what might be the cause and what could be done to fix this issue, I would much appreciate it.