Question

The component of vorticity normal to dS is equal to __________

(a) circulation per unit area

(b) negative of circulation per unit area

(c) zero

(d) circulation

I have been asked this question at a job interview.

The origin of the question is Circulation in section Aerodynamics – Fundamental Principles and Equations of Aerodynamics

Answer 1

The correct option is (b) negative of circulation per unit area

For explanation I would say: The relation between circulation and vorticity can be given by-

                        (∇*V).n = -dΓ/dS

Where dS – infinitesimal area enclosed

            C – Infinitesimal curve.