Passive Control of Flow Around a Circular Cylinder with Different Bluff-Bodies

The paper presents steady and unsteady numerical simulations of the flow around a circular bluff-body to investigate a methodology to apply to hydraulic turbines draft tube. The linear global stability analysis (LSA) is performed to study the evolution of an infinitesimal disturbance that is introduced into the flow. The mean-flow over 20 fully developed vortex shedding is computed from the unsteady-state simulation. The sensitivity map computed using the spatial structures of the instabilities is used to reveal the most receptive zones to an external force. Different control bluff-bodies are placed in the indicated areas and their influence is analysed.