The impact of fluidic actuation on the wake and drag of a 3D blunt body is experimentally investigated. The wake is forced by jets pulsed tangentially to the main flow with variable frequency and velocity. Depending on the forcing conditions, two flow regimes can be identified. First, for a broadband range of frequencies comprising the natural wake instabilities, the convection of the jet structures enhances wake entrainment, shortening the recirculating flow length with an augmentation of the bluff body drag. Further increase of the actuation frequency induces a wake fluidic boat-tailing by shear-layer deviation. It additionally lowers turbulent intensity and entrainment of high momentum fluid in the shear layer, leading to an overall reduction of the wake fluctuating kinetic energy. The association of both mechanisms is responsible for a raise of base pressure and decrease of the model's drag. The physical features of such regimes are discussed on the basis of drag, pressure and velocity measurements at several upstream conditions and control parameters. By adding curved surfaces at the jet outlets to take advantage of the so-called Coanda effect, periodic actuation can be further reinforced leading to drag reductions of about 20 % in unsteady regime. In general, the unsteady Coanda blowing not only intensifies the base pressure recovery but also preserves the effect of unsteady high frequency forcing on the turbulent field. The present results encourage the development of fluidic control in road vehicles' aerodynamics as well as provide a complement to our current understanding of bluff body drag and its manipulation.Comment: 47 pages, 35 figures, extended versio

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