Question

Circulation is referred to as _____________

(a) divergence of velocity

(b) velocity field

(c) flux of vorticity

(d) velocity

The question was posed to me in quiz.

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

Answer 1

Right answer is (a) divergence of velocity

Easiest explanation: Using Stoke’s theorem, the line integral of velocity field along a closed curve is equal to the surface integral of velocity field along a closed path normal to the area covered by the path. But we know that curl of velocity is called vorticity and hence, the circulation is called a flux of vorticity.