Theoretical Studies of the Kinematics, Dynamics, Stability and Control of Unsteady/Vortical Flows.

摘要

(1) Several unsteady vortical flows have been computed with success. A free vortex might be trapped by an oscillating airfoil for lift augmentation. (2) Numerical simulations of streaklines have shown some pitfalls that might be encountered when interpreting photographs of unsteady vortical flows. (3) Traveling acoustic waves are found to have the effect of either re-orienting a cluster of vortices or destabilizing the otherwise stable Karman vortex street. (4) The onset of instability of boundary layers along semi-infinite circular cylinders is analyzed, including the effects of transverse curvature and spin motion of the cylinders. Some important mechanisms that are responsible for vorticity generation and flow separation on bodies in unsteady motion have been identified.