Review of research on cars wake flow control methods to reduce aerodynamic drag

The reduction of aerodynamic drag is a primordial element to reduce the energy consumption for ground vehicles, thus reducing greenhouse gases. This paper reviews on methods of controlling the wake flow of bluff body to reduce its aerodynamic drag. The study is limited to methods that allow a significant drag reduction greater than 3%, studied on generic cars, in the last eight years (2010-2018). There are two main methods of controlling the wake flow: passive control (vortex generator, underbody device, deflector, tail plate ...) which is based on the installation of a device on the car to modify the vortices and active control (steady blowing, pulsed jets, suction, fluid oscillators.) witch modifies the wake of a car by setting up an additional energy. In addition, other methods allow coupling between different techniques. There is a wide variation in the drag reduction obtained for all these methods. Some of them can be industrialized and others are limited by design and habitability constraints.