On the physics of vortex generators for flow separation control

We aim at analyzing the physical phenomena fixing the global efficiency of Vortex Generators for turbulent flow separation control. Fluidic and Mechanical Vortex Generators characteristic are considered. The vortices properties are evaluated with mean of hot wire and PIV measurements. We show that two mechanisms are likely participating in fixing the control strategy efficiency. The first one is mixing, carried out by vortices. The second one is an instability mechanism, which is responsible for the vortex system disruption. An efficient control strategy thus results from a compromise between improving vortex mixing and delaying the development of vortex instability.