This chapter is focused on the roughness effect to evaluate the flow in order to examine the flow dynamics around airfoil for better aerodynamic efficiency. CFD analysis is done on the airfoil with circular roughness placed at two different positions, 25% and 65% chord length with two different Reynolds number. In this case, the boundary layer increased significantly due to decrease in velocity of flow resulting in increment of pressure gradient. From the computational and experimental investigation from many researchers, it is evident that adverse pressure gradient even becomes so large that the flow is forced back against the actual flow direction. In the current chapter, at 15 degrees angle of attack there was an effective increase of 65% in the aerodynamic efficiency due to roughness. There was an increase in stall angle, which refers to sudden increment of drag resulting from the aerodynamic and geometric variations over the infinite wing. With increase in Reynolds number, there is an increase in the effect of roughness at higher angles of attack.