Yuji Hattori (Institute of Fluid Science, Tohoku University, Japan)

Instability and Dynamics of Vortex Rings, Helical Vortices and Hub Vortices

Strong vortices are generated from wingtips of aircrafts, wind turbines and many other devices which possess wings. They often affect the performance of these devices. These vortices are subject to various types of instability induced by the interaction with themselves and/or other vortices. There have been a number of attempts to break down vortices by exciting instabilities to achieve better performance of the devices, for which understanding of the mechanisms of the instabilities and the subsequent nonlinear dynamics are essential. In this seminar, we present our recent results on the instability and nonlinear dynamics of vortex rings, helical vortices and hub vortices. We discuss the mechanisms and characteristics of the curvature, elliptic, and triangular instabilities and the process leading to turbulent transition.