FWIW,
there are four possible ways airflow around a airfoil "produces" drag (at
least when slower than mach 1 <g> ).
* laminar airflow - lowest
* turbulent * "middle"
* _laminar_ separation, socalled "bubble" * high!
* turbulent separation - max, but here usually flying has ended ;-)
So, IF you have a bubble at a certain location, you might kill it with
dimple, or vortex gen, or zigzag tape or whatever, and reduce drag.
But, it is a tricky business, as the chordwise location of the bubble
varies, depending of the aoa. So, you might end with lower drag for a
certain condition, but much more drag at another....
Just my .02
Karl
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