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Old 08-19-2008, 11:30 PM   #34 (permalink)
garys_1k
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Join Date: May 2008
Location: Motor City
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Quote:
Originally Posted by MetroMPG View Post
I'll admit my jaw dropped when I saw the obvious change in flow shown by the tufts!

But I had to keep reminding myself: vortex generators themselves create drag. If the size, style & placement isn't optimized, you can end up with a net increase in drag (or zero sum gain), even while you apparently improve downstream flow.

We could just as easily stick a wind deflector at the trailing edge of the roof to force air down the rear window and tidy up the tufts. But we'd end up with turbulence aft of the deflector negating the gain of the improved flow on the glass/trunk lid.
Thanks so much for doing the grunt work and testing these things! You answered a LOT of questions we had about them.
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