Talk:Kutta–Joukowski theorem

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"The Kutta–Joukowski theorem is a fundamental theorem of aerodynamics, for the calculation of the lift on a rotating cylinder." Is is this statement true? The theorem was developed for finite wing. Hence, it will be correct to alter the statement and say that the theorem is used in the calculation of aerodynamic forces acting on any body cutting through the fluid (say air/water). Share'n'serve (talk) 10:50, 13 April 2014 (UTC) Vasanth.G[reply]

The K-J theorem is certainly one of the fundamental theorems of fluid dynamics because it quantifies the lift generated on each unit of span of the lifting body. It is not confined to a rotating cylinder. The K-J theorem can also be used to quantify the lift generated on each unit of span of an airfoil. In its simplest form, it applies to two-dimensional flow and this implies an airfoil of infinite span or an airfoil that completely spans the width of a wind tunnel so there is no spanwise flow and no induced drag.

In the most general case of a body moving relative to a fluid, there is no circulation and so no lift. In some cases, there is circulation because the body is rotating or because the body has a sharp trailing edge of the kind described in the Kutta condition. Dolphin (t) 12:53, 13 April 2014 (UTC)[reply]

Isn't it strange that the expansion to Laurent series is used although the potential has a discontinuity starting at the trailing tip of the airfoil (see e.g. Landau, Lifshitz, volume 6, Fluid Mechanics)? Laurent series are used for functions holomorphic except for isolated singularities, but a discontinuity in form a a curve is not an isolated singularity. Perhaps the formal derivation should be corrected.

A cylinder is circular by definition. — Preceding unsigned comment added by 194.224.157.104 (talk) 12:37, 22 August 2023 (UTC)[reply]

Not true. See Cylinder which has diagrams of an elliptic cylinder and a parabolic cylinder. The article implies that a cylinder is any shape or closed figure extended, possibly to infinity, in either direction. A cylinder based on a circle is a circular cylinder, but a cylinder can be based on any shape. Dolphin (t) 12:48, 22 August 2023 (UTC)[reply]