When an aircraft moves, it creates a wake consisting of two powerful contrarotating vortex sheets shed from the wing tips, whose intensity decreases slowly.

When another aircraft encounters this wake, it is subjected to roll and vertical movements which can be very hazardous, in particular during takeoff or landing. Aircraft must therefore comply with spacing requirements.

To reduce the intensity and effects of these wakes and thereby increase the traffic handling capacity of airports, it is essential to understand the mechanisms governing their creation and evolution. This has been the subject of much work, both experimental (wind-tunnel testing and model flight testing) and theoretical.