Phenomena, dynamics and instabilities of vortex pairs

Our motivation for studying the dynamics of vortex pairs stems initially from an interest in the trailing wake vortices from aircraft and the dynamics of longitudinal vortices close to a vehicle surface. However, our motivation also comes from the fact that vortex–vortex interactions and vortex–wall interactions are fundamental to many turbulent flows. The intent of the paper is to present an overview of some of our recent work concerning the formation and structure of counter-rotating vortex pairs. We are interested in the long-wave and short-wave three-dimensional instabilities that evolve for an isolated vortex pair, but also we would like to know how vortex pairs interact with a wall, including both two-dimensional interactions, and also the influence of the surface on the three-dimensional instabilities. The emphasis of this presentation is on physical mechanisms by which vortices interact with each other and with surfaces, principally from an experimental approach, but also coupled with analytical studies.