Stories of vortices that do not fly away

This talk will present the stories of two special vortices that improve the performances of the body that formed them. The first one, is the vortex of the dandelion fruit, which - optimised by natural evolution - exploits the vortex to maximise its dispersal. The dandelion fruit that, despite all our efforts, grows in our garden, might have flew more than 150 km before landing there.  

The second of these vortices is the one of asymmetric spinnakers, a very efficient yacht sail. Optimised by experienced craftsmen who are unaware of the ingenuous fluid mechanics of their creations, these sails promote the formation and stability of a vortex that enhances the yacht thrust. These sails are unique wings with a very small thickness, which makes them more similar to the wings of small birds and insects than man-made aeronautical wings. It will be shown that these two vortices have a common characteristic, which is rare between vortices: they remain stably in the same position with respect to the body that formed them, without convecting downstream with the flow.

Bio: Dr Ignazio Maria Viola is Senior Lecturer (Associate Professor) at the Institute for Energy Systems of the School of Engineering, University of Edinburgh. His research is in applied fluid dynamics, and focuses on the vortical flow of immersed bodies, and how these vortices can be manipulated by fluid-structure interaction. He has more than 15 years in sail aerodynamics and has collaborated with 4 America’s Cup teams. More on his research can be found at www.ignazioviola.com.