i got heat transfer problems of a heat sink with very thin fins.i am trying to mesh using gridgen and simulate it in fluent. 1)the gridgen's default volumn is fluild, not solid. so it's not easy to set right BCs,it took me a long time to set it. 2)i run the fluent solve the flow first and then the energy, i can't get convergent temperature solution. pls help me out!

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the case is a forced convection problem with a blower and a heat sink.i meshed both the fluild and the solid part, there are three energy sources in the case. MFR model are used to simulate the rotation of the blower. the inlet/outlet boundary condition is pressure inlet/outlet. i solve the flow and turbulence equations fist, i got a good result of the flow, but when i solve the energy equation, i can't get convergent result of temperature.