FOUR-EQUATION TURBULENCE MODEL FOR PREDICTION OF THE TURBULENT BOUNDARY LAYER AFFECTED BY BUOYANCY FORCE OVER A FLAT PLATE.

Turbulent convective heat transfer with appreciable buoyancy effect over a heated or cooled horizontal flat plate is numerically analyzed by solving four equations for mean square temperature variance. For both highly stable and highly unstable conditions, the 'four-equation' model yields better results for mean temperature profile and surface heat flux than the two-equation model. It is also found that the magnitude of thermal von Karman constant is not a universal constant but it depends on the thermal stratification of the boundary layer.