Quote:
Originally Posted by aerohead
*Any dimple would actually degrade performance of a smooth panel (Hoerner is a good source for this info).
*Adding any type of VG would betray a poor design to begin with.
*And a dimple is never chosen,other than in golf balls,as a VG.There are at least a half-dozen VG designs which would out perform the dimple.
*A specific vehicle,of which it's styling and major tooling had been locked in,if found to have trouble when assembled,could be 'tuned' in a wind tunnel,and a low cost gimmick could be added to mitigate design flaws discovered.But they would just be a Bandaid.
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Do you know a good place to read on the reynolds numbers? My knowledge with aero so far is pretty existential. There's a lot of guessing by feel and checking the results if you don't have CFD and don't know the math. I thought the boundary layer would thicken and continue to drag along a surface until it had to contend with a change in direction. Is the the turbulence you're talking about from the boundary layer slowing to a crawl and falling apart?
As far as the bandaid thing, a lot of engineering is bandaids but I see where you're going with elegant design. An afterthought shouldn't be praised as a breakthrough. I was referring to the Audi photos posted earlier with significant dimples 2-4" across that have a clear defined shape. I haven't posted enough here quite yet to link the photos, I believe they were page 1. But they seem concentrated around boundaries. It looks like the interest is around the edges of the floorpan, and the gap for the exhaust and transmission.
In an application where you can't be scraping every speed bump with nice ducting and diffusers, using vortex generators to fence airflow boundaries without impacting ground clearance is pretty elegant engineering. I'd really like to know if that's their real game with those large dimples on the undertray. On a golf ball, dimples trip up the boundary layer to keep it moving, if you created turbulent, faster airflow in the right places it should do a good job dividing different areas so you don't have unwanted spill over different pressure boundaries