Karman Vortex Shedding and the Effect of Body Motion

Abstract

'The unsteady aerodynamic characteristics of a circular cylinder in incompressible crossflow have been studied to obtain a better understanding of the coupling between body motion and Karman vortex shedding. It is found that the coupling is taking place through the effect of body motion on the boundary-layer development between stagnation and flow separation points. Using a moving wall/wall jet analogy, the experimentally observed effects of lateral and longitudinal oscillations on the Karman vortex shedding at subcritical Reynolds numbers can be explained. This permits an assessment to be made of the potential for self-excited oscillations in the different flow regimes. Where experimental results are available, they agree with this assessment. Basic flow similarity indicates that the unsteady flow concepts developed for prediction of dynamic stall of airfoils could be modified and applied to predict the observed effects of body motion on the Karman vortex shedding as well as the measured cylinder response. a c d