This paper presents the numerical investigation of the flow field of triangular and square ribbed surfaces under a 7x3 rectangular array of circular impinging air jets. The effect of Re number, jet-to-plate distance (H/d) and rib geometry on fluid flow characteristics was examined. Firstly, the mathematical formulation and boundary conditions were presented and afterwards the numerical model was verified with experimental results from the literature. Velocity contours were shown and axial and radial velocity distributions were presented. Additionally, the turbulence kinetic energy distribution was shown. A separation of the jet flow occurs for square ribbed surfaces before impingement. For square ribbed surfaces the separation of the jet occurs at a higher location with increasing inlet velocity. Wall jets interact more effectively for the case of H/d=2. The velocity values of the wall jets for the case of triangular ribbed surface is therefore higher.