Nonlinear standing waves in Couette-Taylor flow

A nonlinear stability analysis by Demay and Iooss of flow between concentric rotating cylinders (the Couette-Taylor system) predicted a transition from the basic flow to a state with ribbons, which are traveling waves in the azimuthal direction but standing waves in the axial direction. We have observed the transition to ribbons in laboratory experiments and numerical simulations, and the measured wave speeds are in accord with those obtained numerically.