Kutta Condition

The Kutta condition is a principle in steady flow fluid dynamics, especially aerodynamics, that is applicable to solid bodies which have sharp corners such as the trailing edges of airfoils. It is named for German mathematician and aerodynamicist Martin Wilhelm Kutta.

Kuethe and Schetzer state the Kutta condition as follows:

A body with a sharp trailing edge which is moving through a fluid will create about itself a circulation of sufficient strength to hold the rear stagnation point at the trailing edge.

In fluid flow around a body with a sharp corner the Kutta condition refers to the flow pattern in which fluid approaches the corner from both directions, meets at the corner and then flows away from the body. None of the fluid flows around the corner remaining attached to the body.

The Kutta condition is significant when using the Kutta–Joukowski theorem to calculate the lift generated by an airfoil. The value of circulation of the flow around the airfoil must be that value which would cause the Kutta condition to exist.