Bodies with reduced base drag

DETAILED DESCRIPTION We claim: 1.
An article adapted to be disposed in a fluid moving downstream relative thereto, said article having a first surface extending generally downstream, and a blunt end surface immediately downstream of an adjoining said first surface and facing generally downstream, a plurality of adjacent troughs formed in said first surface extending in an axial direction, which is the direction of the streamlines of the bulk fluid flow adjacent said surface in which said troughs are disposed, and continuing to said end surface to form a plurality of adjacent trough outlets in said end surface, each of said troughs including a pair of downstream extending sidewall surfaces which intersect said end surface to form side edges of said trough outlets, wherein a portion of the area of said blunt end surface extends laterally from each of said side edges of each of said plurality of trough outlets to the side edge of an adjacent trough outlet over the full length of each of said side edges, wherein said laterally extending area portion between each pair of adjacent trough outlets is at least one-fourth (1/4) of the downstream projected area of one of said adjacent trough outlets, wherein, in cross-section perpendicular to the downstream direction, lines tangent to each sidewall of said pair of trough sidewalls at their steepest point at said trough outlet are substantially parallel, wherein each of said troughs has an inlet and gradually increases from no depth at said inlet to its maximum depth, and wherein the contour and dimensions of said troughs and the size of said laterally extending area portions of said blunt end surface are such as to ensure that each trough flows full throughout its length and causes fluid to flow into the space immediately downstream of said blunt end surface to reduce base drag.
2.
The article according to claim 1 wherein said pair of sidewall surfaces of each trough are substantially parallel to the direction of bulk fluid flow over said first surface in the vicinity of said trough over a substantial continuous portion of the length of said trough, said continuous portion including said trough outlet