Kutta–Joukowski theorem.

About Kutta–Joukowski theorem

The Kutta–Joukowski theorem is a fundamental theorem in aerodynamics that relates the lift per unit span of an airfoil translating in a uniform fluid at constant speed to the circulation of the velocity field, under conditions where the flow in the body-fixed frame is steady and unseparated. The theorem relates the lift generated by an airfoil to the speed of the airfoil through the fluid, the density of the fluid and the circulation around the airfoil. The circulation is defined as the line integral around a closed loop enclosing the airfoil of the component of the velocity of the fluid tangent to the loop. It is named after Martin Kutta and Nikolai Zhukovsky who first developed its key ideas in the early 20th century. Kutta–Joukowski theorem is an inviscid theory, but it is a good approximation for real viscous flow in typical aerodynamic applications.