Advances in our understanding of vortex dynamics in bluff body wakes

There has been a strong impetus over the last decade to understand vortex dynamics in wake flows, which are important not only for our understanding of fundamental flow physics, but also for the many applications of bluff body flows in technology. A particular emphasis of the recent surge of activity concerns three-dimensional aspects of wake flows behind bodies which are nominally two-dimensional. Such effects are important when one considers the integrated unsteady forces on a structure, especially in the context of vortex-induced vibrations, which itself is experiencing an upsurge of activity at this time. In this short and selected review, we shall discuss briefly many of the new vortex dynamics phenomena which have been recently discovered, over a wide range of Reynolds numbers, but with some focus on low Reynolds number regimes. It is particularly exciting presently that direct numerical simulations are contributing immensely to our careful understanding of these wake flows, and are being combined with stability analysis and experiment. Another fruitful area of research concerns the analysis of wake patterns using amplitude equations, which has proven exceedingly rich in phemonena, and models the experimental patterns surprisingly well. Finally, amid the general excitement of recent work, we return briefly in this paper to selected early experiments of Gerrard, Hama, Roshko, Berger and others, who provided several of the key pieces of the “jigsaw” that makes up our modern understanding of wake vortex dynamics.