Question

If the flow is irrotational everywhere within the contour of integration then the circulation is ____________

(a) 1

(b) positive

(c) negative

(d) zero

I had been asked this question in an interview for internship.

This interesting question is from Circulation topic in division Aerodynamics – Fundamental Principles and Equations of Aerodynamics

Answer 1

Right answer is (d) zero

To explain I would say: In the case of irrotational flow, the circulation about a curve is equal to the vorticity integrated over any open surface bounded by the curve. This leads to the result that if the flow is irrotational everywhere, the circulation is zero.