An aerodynamic base drag reduction apparatus and method for bluff bodies, such
as tractor-trailer trucks, utilizing a pair of lift surfaces extending to lift
surface tips and located alongside the bluff body such as on opposing left and
right side surfaces. In a flowstream substantially parallel to the longitudinal
centerline of the bluff body, the pair of lift surfaces generate a pair of counter-rotating
trailing vortices which confluence together in the wake of the bluff body in a
direction orthogonal to the flowstream. The confluence draws or otherwise turns
the flowstream, such as the flowstream passing over a top surface of the bluff
body, in and around behind a trailing end of the bluff body to raise the pressure
on a base surface at the trailing end and thereby reduce the aerodynamic base drag.
