[Mahe]

I want to simulate the flow of the Helium in the quartz tube which is heated by the heating equipment placed in the quartz tube and its heating exchange with the tube (the quartz tube is in the 27 oC air environment). The model was built in the Cartesian co-ordinates and PRPS was stored for conjugate heat transfer could be solved. After calculated some time, the residual of temperature lowered to a large number (10^5) quickly, and then it would not change until the end of calculation. The residual of the other variable solved could decrease to a reasonable value. However, the result of the temperature field is reasonable basically (10^0). I try hard to adjust the grid or relaxing factor but the residual of temperature good enough could not still be gained. Could anybody give me some advices?
Thank you very much.