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A vortex sheet is a term used in fluid mechanics for a surface across which there is a discontinuity in fluid velocity, such as in slippage of one layer of fluid over another. [1] While the tangential components of the flow velocity are discontinuous across the vortex sheet, the normal component of the flow velocity is continuous.
The Vortex lattice method, (VLM), is a numerical method used in computational fluid dynamics, mainly in the early stages of aircraft design and in aerodynamic education at university level. The VLM models the lifting surfaces, such as a wing , of an aircraft as an infinitely thin sheet of discrete vortices to compute lift and induced drag .
However, on a highly-swept wing leading-edge separation still occurs but instead creates a vortex sheet that rolls up above the wing producing spanwise flow beneath. Flow not entrained by the vortex passes over the top of the vortex and reattaches to the wing surface. [5] The vortex generates a high negative pressure field on the top of the wing.
Visualisation of the vortex street behind a circular cylinder in air; the flow is made visible through release of glycerol vapour in the air near the cylinder. In fluid dynamics, a Kármán vortex street (or a von Kármán vortex street) is a repeating pattern of swirling vortices, caused by a process known as vortex shedding, which is responsible for the unsteady separation of flow of a fluid ...
The combination of the wingtip vortices and the vortex sheets feeding them is called the vortex wake. In addition to the vorticity in the trailing vortex wake there is vorticity in the wing's boundary layer, called 'bound vorticity', which connects the trailing sheets from the two sides of the wing into a vortex system in the general form of a ...
The Burgers vortex sheet is shown to be unstable to small disturbances by K. N. Beronov and S. Kida [9] thereby undergoing Kelvin–Helmholtz instability initially, followed by second instabilities [10] [11] and possibly transitioning to Kerr–Dold vortices at moderately large Reynolds numbers, but becoming turbulent at large Reynolds numbers.
The Lanchester-Prandtl lifting-line theory [1] is a mathematical model in aerodynamics that predicts lift distribution over a three-dimensional wing from the wing's geometry. [2] The theory was expressed independently [3] by Frederick W. Lanchester in 1907, [4] and by Ludwig Prandtl in 1918–1919 [5] after working with Albert Betz and Max Munk ...
[3] [2]: 8.1.1 [4] Three-dimensional lift and the occurrence of wingtip vortices can be approached with the concept of horseshoe vortex and described accurately with the Lanchester–Prandtl theory. In this view, the trailing vortex is a continuation of the wing-bound vortex inherent to the lift generation.