Question

Is surface is perturb the boundary layer and promote turbulence?

(a) True

(b) False

The question was asked during an interview.

I'm obligated to ask this question of Turbulent Flow in section Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Correct option is (a) True

Explanation: The surface is dimpled to perturb the boundary layer and promote a transition to turbulence. This results in higher skin friction, but moves the point of boundary layer separation further along, resulting in lower form drag and lower overall drag.