Virtual experiments on drag reduction

This paper presents numerical simulations of external flow over a flat porous surface with blowing-cross-flow that result in significant drag reduction at the interface between the boundary layer and the solid wall. Through parametric. numerical experiments it is demonstrated that it is fundamentally possible to achieve a. reduction in the shear force on the wall, if in the blowing (injection) process the velocity of the flow is controlled in conjunction with the free stream velocity and the nature of surface porosity. The results presented here demonstrate that the blowing flow uniformity is very critical to the drag reduction magnitude and even appearance. Non-uniformity is possible due to interaction of cross flow and free-stream flow. Further based on the analysis of the parametric results, the authors offer an explanation of the mechanism that apparently leads to the drag reduction phenomenon.