Abstract
In the mid 1980s computer speed and storage had developed to a degree that Euler methods (Model 8 in TableĀ 1.3) became a viable tool for aerodynamic design work. At that time very much discussed was the fact that at delta wings with sharp leading edges lee-sideĀ vortices resulted in the relevant angle of attack and Mach number regime. The question was, where is the apparent vorticity coming from, and accordingly the associated entropy rise.
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Notes
- 1.
See also the introductory discussion in Sect.Ā 1.4.
- 2.
Regarding the definition of the boundary-layer thickness see AppendixĀ A.5.4.
- 3.
A discussion of the flow at the trailing edges of real airfoils and wings is given in Chap.Ā 6.
- 4.
The amount of vorticity which must be canceled is small compared to the amount of vorticity of each of the involved boundary layers, usually only a few per cent.
- 5.
These properties are important, because behind a straight shock wave with constant pre-shock Mach number, a total pressure lossĀ is present, but no vorticity. See in this regard Croccoās theorem, Sect.Ā 3.5.
- 6.
Note that a discrete (Model 8) Euler solution close to a solid surface always exhibits a thin total-pressure loss layer, casually called Euler boundaryĀ layer. That is an artifact due to the finite discretization of the computation domain and the flow variables used.
- 7.
- 8.
See the examples in Chap.Ā 8.
- 9.
- 10.
Trailing edge properties as well as the Kutta condition in reality are treated in Chap.Ā 6.
- 11.
LighthillĀ calls the trailing vorticity also residual vorticity.
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Hirschel, E.H., Rizzi, A., Breitsamter, C., Staudacher, W. (2021). The Local Vorticity Content of a Shear Layer. In: Separated and Vortical Flow in Aircraft Wing Aerodynamics. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-61328-3_4
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