Quote:
Originally Posted by garys_1k
Nice job, they sure LOOK like they'd make a significant, positive difference in FE. The improvement in flow is so obvious that the lack of a clear, positive FE test result is very surprising.
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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.