In this paper the three different simulations has been done and it is analyzed and those simulations has been compared with the literature papers. The first simulation is Air Flow within an Annulus , In this simulation the hollow pipe is simulated using the STAR -CCM and the pressure gradient , velocity parabola are analysed and compared with the literature results. The second simulation is Airflow over an airfoil , In this simulation the subsonic flow over a NACA 0012 is analyzed at different angle of attack with the Mach number of 0.5. The third simulation is Convective Heat Transfer from a Heat Source of a Radiator within an Enclosed Room. In this simulation heat convection is studied as the laminar model is assumed for the steady, Coupled and the ideal gas flow