Question

According to the reasoning given by Prandtl for his lifting line theory, finite wing is like a ________

(a) Bound vortex

(b) Horseshoe vortex

(c) Free vortex

(d) Trailing vortex

This question was posed to me in an interview.

I want to ask this question from Prandtl’s Classical Lifting-Line Theory in portion Flow over Airfoils over Finite Wing of Aerodynamics

Answer 1

Right answer is (a) Bound vortex

Explanation: Prandtl reasoned that the finite wing can be thought like a bound vortex, which is opposite to the free vortex. Since a vortex filament cannot end in the fluid, it is assumed that there are two trailing vortices which gives the appearance like that of a horseshoe vortex.