In aerodynamics, the Crow instability, or V.C.I. vortex crow instability, is an inviscid line-vortex instability, named after its discoverer S. C. Crow.The effect of the Crow instability can often be observed in the skies behind large aircraft, when the wingtip vortices interact with contrails from the engines, producing visible distortions in the shape of the contrail.
The Crow instability is a vortex pair instability, and typically goes through several stages:
The wings of airplanes in flight produce at least one pair of trailing vortices. These vortices are a major source of wake turbulence as they persist for a significant period of time after the airplane has passed. If the decay of trailing vortices were due solely to viscous effects in the core of each vortex, decay would be so slow that they would persist for hundreds of miles behind the airplane. In fact, these vortices only persist for tens of miles. The additional cause of the collapse of these vortices is large-scale instabilities such as Crow instability.[1]