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Wingtip vortices are circular patterns of rotating air left behind a wing as it generates lift. [1]: 5.14 The name is a misnomer because the cores of the vortices are slightly inboard of the wing tips. [2]: 369 Wingtip vortices are sometimes named trailing or lift-induced vortices because they also occur at points other than at the wing tips.
When the vortices of larger aircraft sink close to the ground — within 100–200 ft (30–61 m) — they tend to move laterally over the ground at a speed of 2–3 kn (3.7–5.6 km/h; 2.3–3.5 mph). A crosswind decreases the lateral movement of the upwind vortex and increases the movement of the downwind vortex. [4]
A wing tip (or wingtip) is the part of the wing that is most distant from the fuselage of a fixed-wing aircraft. Because the wing tip shape influences the size and drag of the wingtip vortices , tip design has produced a diversity of shapes, including:
Wingtip devices help prevent the flow around the wingtip of higher pressure air under the wing flowing to the lower pressure surface on top at the wingtip, which results in a vortex caused by the forward motion of the aircraft. Winglets also reduce the lift-induced drag caused by wingtip vortices and improve lift-to-drag ratio.
These vortices are known as wingtip vortices and are formed by fluid flowing around the wingtips from the high-pressure region that is the bottom of the wing to the low-pressure region that is the top of the wing. The flow becomes separated from the airfoil and rotates about a low pressure wake that forms the core of the vortex.
Lifting line theory for wings, wing-tip vortices and induced drag A wing has a finite span, and the circulation at any section of the wing varies with the spanwise direction. This variation is compensated by the release of streamwise vortices, called trailing vortices, due to conservation of vorticity or Kelvin Theorem of Circulation ...
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Wingtip vortices form a major component of wake turbulence and are associated with induced drag, which is a significant contributor to total drag in most regimes. A closed wing avoids the need for wingtips and thus might be expected to reduce wingtip drag effects.