Abstract: A method and apparatus for reducing the skin friction on objects in relative motion to a field of fluid. The areas of relative low speed motion are fixed to align with a series of ridges on the surface of the object. The areas of low speed motion aligned with the ridges are removed by suction from the turbulent boundary layer which results in a reduction of drag on the object. An alternative embodiment injects fluid into areas of relative high speed between the ridges to reduce the shear and the drag caused by it. Selective suction and injection are combined in one apparatus in a second alternative embodiment. A fourth embodiment injects a polymeric solution to reduce drag. A fifth embodiment heats the fluid in specified areas to reduce drag. A sixth embodiment uses a compliant material in specified areas of the surface in contact with flowing fluid to reduce drag.

Abstract: The lift generated by delta wings is due primarily to large vortices associated with the flow separation near the leading edge. The invention includes a perturbation device to control the separation shedding of those vortices and manipulate their frequency and pairing. This results in different growth rates of the vortices downstream of the device and thus the lift produced by the large bound vortices may be controlled. If the invention is applied to both leading edges, the total lift of the wing will be altered; if the perturbation is preferentially applied on only one side of the wing, the moment around the roll axis of the aircraft is controlled. A first embodiment uses a piston coupled to a cavity and slot to produce the desired perturbation. Alternative embodiments are described which achieve the results without moving parts.