Quote:
Originally Posted by Cd
Much to my surprise, vortex generators on cars do not improve drag either - even when you can see an actuall difference using tuft testing.
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They can reduce drag. It just takes a serious under standing of whats going on. Extensive skills with CFD modeling and a wind tunnel don't hurt either.
The only article I have seen was on autospeed.com in which their experiment failed. In the papers I have read on vortex generators, they need to be only about as tall as the boundary layer other wise they create excessive drag. Unfortunately most people don't have the ability to measure the height of the boundary layer so they are shooting in the dark when applying vortex generators. Another problem is that these improvements are quite small and it takes very sophisticated instrumentation and very controlled experiments to determine if it is an improvement (a road test isn't sufficient).