Dear rwoolhou,

Thanks for your response.

Well, I got exact results for fluid domain and my problem is just solid temperature that must not exceed 1873 but after several simulations with denser mesh I got about 1900K for maximum solid temperature, of course I did this simulation using other fluid too and didn't have any problem in solid domain and the maximum value of solid temperature was very less than 1873 but for nitrogen  the solid temperature is higher.