Scales on butterfly wing
Close up of one scale
What's the purpose? They seem like rows of Gurney flaps, but with those tiny ridges in front. The "teeth" on top of each ridge have even tinier ridges on each one.
How do they work? Any theories?
What would do to a Gurney flap those little ridges? Is this an "idea" that can be used in a racing wing?
Please, don't explain what a vortex generator is, we already know.
My best guess is that the "holes" in front of the "Gurney" somehow interact with the laminar flow to keep it attached to the wing. That's not a vortex generator, if true.
This seems more complicated. Notice the shape of the little ridges: they are twisted with all ridges pointing in the same direction.