Abstarct: Recently, a passive method has gained more attention to control the flow separation which is known as swelling of the angle of attack. The idea behind this method was baxsed on the studies of huge humped flipper humpback that was considered by biologists. In the mentioned study they investigated the effects of making airfoil wavy on the aerodynamic characteristics in the lab. In the current study, for validity first, the Standard airfoil S809 was made and its results were recorded Then wavy airfoil S809 was made and its result is compared with Standard airfoil at domain Reynolds Numbers of (2×〖10〗^5-6/5×〖10〗^5). The surface pressure distribution and the flow structure over wavy airfoil with regard to standard airfoil has a considerably different. For angles below the stall angle, for standard airfoil in comparison with wavy airfoil less lift coefficient and more drag coefficient is observed. On the other hand, at angle higher than stall angle for wavy airfoil in comparison with standard airfoil, airfoil more lift coefficient and less drag coefficient is observed. As a conclusion, in the case of wavy airfoils for after stall angle, the airfoil’s performance is noticeably improved.