Question

What is the condition for rotational flow in Kutta-Joukowski theorem?

(a) Small number of unsteady flow

(b) Large number of unsteady flow

(c) Large number of steady flow

(d) Small number of steady flow

This question was addressed to me by my college director while I was bunking the class.

This interesting question is from The Kutta-Joukowski Theorem topic in chapter Inviscid & Incompressible Flow of Aerodynamics

Answer 1

Correct answer is (b) Large number of unsteady flow

For explanation I would say: When there are free vortices outside of the body as may be the case for a large number of unsteady flow, the flow is rotational. A fluid is said to be rotational if fluid particles are rotating about their own mass center, otherwise, flow is irrotational.