Passive Drag Reduction Techniques for Modulating the Effects of Vortex Shedding

摘要

Over a wide range of Reynolds numbers, the phenomenon of vortex shedding and the associated fluctuations in drag and lift, and the possible vibration in the structure, can be a formidable problem in many applications. Attempts have been made to control, reduce, or altogether eliminate these vortex-induced fluctuations in flow properties. In this study, unsteady laminar flow around a circular cylinder is numerically simulated using the finite volume method. The passive technique of introducing simple slits at specified locations around the cylinder for the purpose of modulating the effect of vortex shedding is investigated. It was found that at a Reynolds number of 1000 the reduction in the coefficient of drag is over 14%, which decreases in Nusselt number, and thus the total heat transfer from the cylinder, of 15.5% and 4.44%, respectively. Physical insight is given to explain the source of the phenomenon, and the advantages of applying such passive techniques to control free flows are discussed.