Joukowski airfoil

In 1910 Nikolai Zhukovsky published the map z = ζ + 1/ζ. Applied to a circle through ζ = 1 that encloses -1, it gives a closed curve with a cusp, shaped like a wing in section. The map is conformal, so the flow of air around the wing can be worked out from the flow around the circle.

z = ζ + 1/ζ

On mathcurve.com as Courbe de Joukowski