The present work gives a contribution to the experimental and numerical characterization of complex flows around bluff bodies and to the set-up of strategies for their control. The research activity is twofold: (i) the development and improvement of a passive method for delaying the flow separation in bluff bodies with vortex shedding thanks to the introduction of contoured transverse grooves and (ii) the study of the high-Reynolds number flow around a rectangular cylinder having a 5:1 section (object of the international benchmark BARC). Both activities are carried out through a synergic use of experiments and simulations.