The airflow around two-dimensional standard NACA 0015 airfoil effect was studied and analysed. The study was performed by simulating three geometrical modification airfoils (bumps NACA 0015, multi-element NACA 0015, and a backward-facing step NACA0015). Using SST (Shear Stress Transport) turbulence model and compared with standard NACA 0015 was the performed methodology. The research focuses on two cases (at different attack angles from 0 to 18 degrees with Re=1.65x106). Case I: the numerical analysis method data for the coefficient of lift of standard NACA 0015 (baseline case study) is compared to the previous experimental data. Case II: the coefficient of pressure, coefficient of lift, the contour of static pressure, and the velocity contour for standard NACA 0015(chord length c=1m) were calculated and compared with three geometrical modifications NACA 0015 airfoil. The CFD software ANSYS FLUENT version 17.1 was used for the computations in the present study. As a result, the geometrical modification influences on the aerodynamic properties of NACA 0015 was investigated. Compared to standard NACA 0015 airfoil, a significant improvement in the lift coefficient for multi-element NACA 0015 was noticed especially at the angle of attack (6°,14° and 18°) while slight improvement was noticed in the lifting coefficient for the other two models (bumps NACA 0015, and a backward-facing step NACA0015) at AOA 14 degree.