HELICAL MODES IN SWIRLING JETS

摘要

The spiral form of vortex breakdown observed in the numerical simulations of Ruith et al. (2003) is interpreted as the consequence of the development of a so-called nonlinear global mode originating in the convective/absolute transition of the instability in the lee of the vortex breakdown bubble. This local theory gives an excellent prediction of the precession frequency measured in the three-dimensional DNS.