Hi, am trying to simulate a parallel plates (air to air) heat exchanger......

I had a problem with the mesh, and that's normal because the plates are too thin and the walls as well.....

the problem is when I pass the mesh and the Fluent accept my mesh, and run the program without the Divergence detected in AMG Solver problem, I can find the temperatures in my simulation are (Higher and Lower) than the input values??

can anyone help??