Large Eddy Breakup Devices as Low Reynolds Number Airfoils

Turbulent drag reduction downstream of large-eddy breakup (LEBU) devices is analyzed from the viewpoint of low-Reynolds number airfoil aerodynamics. It is argued that the variability of results between different research labs is primarily due to low Reynolds number “phenomena” associated with unsteady separation/transition of the LEBU device boundary layer. LEBU drag reduction is shown to be an extremely sensitive function of device micro-geometry at the low Reynolds numbers of all current investigations, and by analogy with conventional low-Reynolds number airfoil testing, the conclusion is drawn that the full potential for LEBU drag reduction must be explored at chord Reynolds numbers of 300,000 and above.