dimples/bumps on transportation vehicles
 

I need help on a project that deals with the way air flows over an object with dimples or bumps as opposed to an object that is just smooth.I know pretty near nothing about fluid dynamics and would appreciate any information.

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).