Separated flow about lifting bodies and impulsive flow about cylinders.

The analogy between the impulsive flow over circular cylinders and flat plates and the separated flow about slender bodies moving at high angles of attack in the subsonic to moderately supersonic-velocity range is discussed. The cross-flow drag and normal force coefficients are determined experimentally as a function of the relative displacement of fluid in time-dependent two-dimensional flow. The evolution with time of the body-wake characteristics are determined from high-speed motion pictures. The results show that during the growth of symmetrical vortices, the laminar flow drag coefficients of the test bodies reach a value about 25% higher than their corresponding steady flow values. In the supercritical range, records for the drag show considerable disagreement, except that the drag coefficient lies between 0.25 and 0.40.