Change of 180 degrees in the direction of a uniform current of air
A 1926 NASA technical report, drawn from the NASA Technical Reports Server, on reversing a uniform airstream by 180 degrees around a body, written for aerodynamicists. Its pictures are plain line diagrams of streamlines in black ink: curved stream paths wrapping around hook-shaped and bulbous profiles, labelled with psi stream-function values and axes. A designer could take from them the clean rhythm of nested parallel curves turning back on themselves, useful for flow-based linework or abstract pattern.
