Prior numerical investigations show that, if an object is placed into a turbulent boundary layer, it affects on near wall flow structure, alters heat transfer and friction coefficient of the nearby wall. To govern these flow features, a quadrilateral insert is selected as a promoter. The frontal face of the quad acts to control the size and position of the upstream stagnation point. The face parallel to the wall controls the formation and development of near wall jet and the two other faces operate in controlling the rearward circulation zone. Having these all faces set, the heat transfer optimization of the neighboring flat plate is left to examination. The quad is inserted into the boundary layer while its shape and distance from the flat plate is repeatedly modified to gain moderate forms of disruption and improvement in heat transfer coefficient. The single objective Genetic Algorithm (GA) as a tool, coupled with the modified Teach-t code was employed to optimize the shape and distance of the obstacle from the plate. When application of optimal geometry is reached, the mean heat transfer coefficient over the affected area of the flat plate was enhanced by more than 51%. The study of flow features around the quad show that; each feature makes its own contribution to the heat transfer change from the flat plate. Common to all cases under study, the frontal stagnation point formed on the quad, counts for the slight decrease in the heat transfer coefficient, while the jet underneath the obstacle followed by the developing boundary layer are responsible for the sudden increase of the heat transfer coefficient. However, the downstream circulating flow area makes the main and widespread contribution.

Keywords