Effects of body curvature and nonparallelism on the stability of flow over a swept cylinder

Abstract

The linear stability of three-dimensional incompressible flow over an infinite swept cylinder is considered. In particular, the effects of convex body curvature and nonparallelism on both stationary and traveling disturbances are studied. Both an exact approach and a perturbation approach are used to account for the body-curvature effect and the results from both approaches agree very well. The nonparallel effects are accounted for by using a perturbation method. The influence of convex body curvature and nonparallelism with variation in the sweep angle, the unit Reynolds number, the cylinder radius, the location on the cylinder, and the disturbance spanwise wave number and frequency is studied. Both stationary and traveling disturbances are destabilized by the nonparallel effects and are stabilized by the convex body-curvature effects. This is in agreement with the results obtained by solving linear parabolized stability equations. The effect of convex body curvature is gradually less stabilizing as the disturbance frequency increases. The variation of the combined effects of convex body curvature and nonparallelism in the parameter space is controlled mainly by the variation (in the parameter space) of the convex body-curvature effects.