Turbulence-driven reverse lift on two-dimensional and three-dimensional structures

Using laboratory experiments and simplified theoretical arguments, we show that the level of turbulence may reverse the direction of the mean lift on two- and three-dimensional structures with relatively short, deflected splitters. Planar particle image velocimetry and a high-resolution load cell were used to characterize the near wake region and the instantaneous lift of the structures for various geometric configurations, deflection angles and turbulence levels at Reynolds number Re=2×104 based on the body width. The possibility of reverse lift may occur within a critical deflection angle, which depends on the splitter length and turbulence level. This particular phenomenon is explained quantitatively with a simple formulation that accounts for the effects of the body geometry and turbulence. The distinctive role of turbulence in structures with splitters provides insight to control hydrodynamic force in various environments.