Question

Which of these distributions is required in the wake region of the lifting body?

(a) Source

(b) Dipole

(c) Sink

(d) Doublet

The question was asked during a job interview.

The origin of the question is General Three Dimensional Flows-Panel Techniques topic in section Three-Dimensional Incompressible Flow of Aerodynamics

Answer 1

The correct choice is (b) Dipole

The explanation is: Lifting bodies have a trailing edge which leads to a wake region. In the wake region, there is formation of vortices due to the disturbances in the flow. In this region, a dipole or vorticity singularity is used.