Primary and secondary Hopf bifurcations in stratified Taylor-Couette flow

Experimental and theoretical results for the axially, stably stratified Tay lor-Couette flow are presented. The primary instability is a direct Hopf bi furcation. It leads the system into an oscillatory state of confined intern al waves, in good agreement with linear stability analysis. The secondary b ifurcation, which leads the system to a pattern of drifting nonaxisymmetric vortices, is a subcritical Hopf bifurcation. This first experimental evide nce of a global bifurcation is thought to be generic to dynamical systems w ith one destabilizing and one stabilizing control parameter. [S0031-9007(99 )09248-0].