This invention relates to an element (11) for generating a fluid dynamic force, the element (11) comprising first (13) and second (15) surfaces extending in opposite directions from a leading edge (17) of the element (11) and meeting at a trailing edge (18) thereof to define a three dimensional body that is shaped to generate a fluid dynamic force when immersed at an angle of attack .alpha. to a fluid flow over the element (11) in a flow direction U, the first surface (13) comprising an array of fluid inlets (19) and the second surface (15) comprising a corresponding array of fluid outlets (21), each said inlet (19) being fluidly coupled to a said outlet (21) by means of a fluid duct (23) at least part of which is pitched at an angle .theta. to a tangent plane (Y-Y) to said second surface (15) in the vicinity of said outlet (21) and skewed at an angle .phi. to said fluid flow direction U, the arrangement being such that the element (11) is operable in use to generate a relatively high fluid pressure region downstream of said leading edge (17) proximate said first surface (13) and a relatively low fluid pressure region downstream of said leading edge (17) proximate said second surface (15), and fluid from said relatively high fluid pressure region is enabled to flow into said fluid inlets (19) through said fluid ducts (23) and out of said fluid outlets (21) into said relatively low pressure region to generate fluid vortices which reenergise said low pressure region and delay boundary layer separation from said second surface (15).