Question

Is circulation remains constant around the C?

(a) True

(b) False

This question was posed to me by my school principal while I was bunking the class.

The above asked question is from Kelvin’s Circulation Theorem and the Starting Vortex in section Incompressible Flow over Airfoils of Aerodynamics

Answer 1

The correct answer is (a) True

The best I can explain: The inviscid equation of motion enter the proof only in helping to evaluate a line integral round C, so if viscous forces happened to be important elsewhere in the flow that is off the curve C, this would not affect the conclusion that the circulation remains constant round C.