Effects and Mitigation
Wingtip vortices are associated to induced drag, an unavoidable consequence of three-dimensional lift generation. The rotary motion of the air within the shed wingtip vortices (sometimes described as a "leakage") reduces the effective angle of attack of the air on the wing.
The lifting-line theory describes the shedding of trailing vortices as span-wise changes in lift distribution. For a given wing span and surface, minimal induced drag is obtained with an elliptical lift distribution. For a given lift distribution and surface, induced drag is reduced with increasing aspect ratio.
As a consequence, aircraft for which a high lift-to-drag ratio is desirable, such as gliders or long-range airliners, typically have high aspect ratio wings. Such wings however have disadvantages with respect to structural constraints and manoeuvrability, as evidenced by combat and aerobatic planes which usually feature short, stubby wings despite the efficiency losses.
Another method of reducing induced drag is the use of winglets, as seen on most modern airliners. Winglets increase the effective aspect ratio of the wing, changing the pattern and magnitude of the vorticity in the vortex pattern. A reduction is achieved in the kinetic energy in the circular air flow, which reduces the amount of fuel expended to perform work upon the spinning air.
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