||August 28, 1998 02:38
Re: dimples/bumps on transportation vehicles
Dimples can be used to trigger boundary layer transition and thereby delay separation. For a blunt body this will give a smaller wake and often less drag due to a large low-pressure wake. A turbulent boundary layer is better than a laminar boundary layer at following a curved surface because the turbulent motions help to transport away low-velocity fluid close to the surface. This low-velocity fluid would otherwise build up and cause separation (very simple explanaition).