convective cooling in channel flow
 

I am trying to model convection as air flows over a surface in FLUENT. To do this, I have made the surface a WALL boundary in gambit, and specified a negative heat flux in FLUENT (since the surface will be cooling the air). Then, also in FLUENT, I specified the inlet temperature as 300K and its velocity, ran the calculation, and displayed the temperature contour.

The solution, however, is not making sense. The entire channel temperature is now 330K, with colder temperatures very close to the cooling surface.

Would this be the right way to model convection? Or what else could be messing up my solutions?

Any help is greatly appreciated!! :D