Question

How starting vortex is formed?

(a) As the airfoil begins to move vortex are formed

(b) As the airflows on the airfoil vortex are formed

(c) As the airfoil moves against the relative wind vortex are formed

(d) As the airflows on the circular body vortex are formed

The question was posed to me in unit test.

This intriguing question comes from The Kutta Condition topic in section Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Correct option is (a) As the airfoil begins to move vortex are formed

Explanation: As the airfoil begins to move it carries this vortex, known as the starting vortex along with it, pioneering aerodynamicists were able to photograph starting vortices in liquids to confirm their existence. The vorticity in the starting vortex is matched by the vorticity in the bound vortex in the airfoil.