Abrasive flow finishing

[Terry Martin]

Dan wrote:

> The dimples have to be in a random pattern, else you increase
> drag.  The theory is that random dimples (or chevrons) reduce
> bursting near an aerodynamic surface.  Busting is caused by
> low speed air streaks near the wall and is believed to be
> responsible for creating intense turbulence.
> 
> Comments?
> 
> Dan L

Bang on. A perfectly smooth surface will produce a laminar flow, which
will "pull" away from the surface in small areas, disrupting the laminar
flow, and causing turbulence. The "bumps" or "dimples" increase the
surface area over which the airflow occurs, reducing the "pull" on the
specific point that will break away into the laminar flow.