The self-sustained formation of synchronized ring vortices in hot subsonic jets is investigated
by direct numerical simulation of the axisymmetric equations of motion. The onset of global
instability and the global frequency of synchronized oscillations are examined as functions
of the ambient-to-jet temperature ratio and the initial jet shear layer thickness. The numerical
results are found to follow the predictions from nonlinear global instability theory; global
instability sets in as the unperturbed flow is absolutely unstable over a region of finite …