Drag reduction of a square-back bluff body under constant cross-wind conditions using asymmetric shear layer forcing

•Highly resolved computations using Delayed Detached Eddy Simulations (DDES) of a canonical Windsor body are carried out. The flow around the car model, which is investigated imposing different yaw angles (up to 10 degrees), is perturbed via a small square cylinder.•It is found that the flow mechanisms by which the drag reduction occur are twofold: (i) the flow is deviated inwards by the in-wash induced by the flow reattachment at the trailing-edge, thus acting as an inward-oriented flap, and (ii) the windward shear layer is forced by the turbulent field developing along the separated region of the perturbing cylinder.•This study shows that any modification of the turbulent state of the side boundary layer, for example if rear wheels or wheel houses are modified, will impact the balance of the wake and may result in significant yaw dependent base drag variations.