Transition in flow over a swept cylinder: Correlation with experimental data

Linear stability analysis, which includes the effects of nonparallelism and body curvature, is used to calculate the N factors of stationary and traveling disturbances for the same experimental conditions measured by Poll for flow over a long swept cylinder. The correlating N factors for traveling disturbances have less scatter than the correlating N factors of stationary disturbances. The mean value of the correlating N factor for traveling disturbances is 14.9 and 7.4 for stationary disturbances. Therefore, for an initial amplitude of a stationary disturbance that is 100 times larger than that of a traveling disturbance, the amplitude of the traveling disturbance is 18 times larger than the amplitude of a stationary disturbance at the location of transition onset. The calculations indicate that transition is due to traveling disturbances; this result is in agreement with the experimental observations.