Aerodynamic properties of ground vehicles

A ground vehicle having a body with an outer surface comprising a general front surface, a main upper surface, a bottom surface, two side surfaces and a rear surface, the vehicle having at least one airflow control system comprising:

• at least one air modulator having an array of openings including a number of openings which are arranged next to one another along an essentially straight line, the air modulator of each of the at least one system is arranged on the vehicle with the array of openings having an orientation relative to the outer surface such that when the vehicle travels at a particular speed an amount of vortex shedding behind the rear surface is lower than if the vehicle had traveled at this speed without the at least one system;
• and
• a control unit adapted to control the air modulator to output oscillating air from each opening such that air vortices are created outside the opening where the air vortices have spin axes that are essentially parallel to the essentially straight line,
• wherein the vehicle comprises at least one flow amplification surface which is arranged on the vehicle downstream of the at least one air modulator relative to the air flow, and the at least one flow amplification surface is adapted to augment the air vortices, the flow amplification surface extending a distance, Λ, relative to the rear surface and the air modulator is arranged relative to the flow amplification surface such that the array of openings of the air modulator is positioned a distance, Λc, downstream of a flow separation line adjacent to the rear surface where flow separation would have occurred if no air vortices had been generated, resulting in that a surface over which air vortices from the air modulator may be amplified extends a distance, XTE, from the array of openings, where XTE=Λ−Λc.