This paper presents an experimental and numerical investigation on the flow modification in an air intake S-shaped aggressive diffuser. The selected diffuser has an actual geometry of 45°subsection from annular cross section, with implementing flow modifiers. The S-shaped diffuser had an area ratio 3.1 and turning angle of 35°/35°. The investigation is performed with three types of passive flow control flow modifiers. 3D CFD simulation was performed through ANSYS-FLUENT 15 software. The experimental results showed a good agreement with the numerical results. The measurements were conducted inside annular subsection at inlet Reynold number 40 � 104 and turbulence intensity 4.8. The performance parameters, static pressure recovery and distortion coefficient, used for performance evaluation. Implementing flow modifiers type 2 gives maximum static pressure recovery of 0.77, 0.83 and minimum distortion coefficient of 0.086, 0.077 for experimental and numerical results, respectively. While the less improvement was produced with implementing flow modifiers type 3. © 2018 Author(s).