I've only seen 'bucket' used in the context of lift/drag curves for a limited series of airfoils,based on their angle of attack.
Serious 'flow-turning' has been demonstrated since the 1920s but VGs won't get it done.Typically,blown,or suctioned slots are required.
Georgia Tech continues research in this field.As of last look,the effect still required more energy than it saved.
Based on Cornish's work/report,Alex Tremulis thought we'd have cars of Cd 0.10 by now,using this technology.
