Precessional flows in cylinders: Resonance, instabilities, and mixing

Precessing flows in cylinders are highly effective for mixing a passive scalar, as illustrated here with the thin streaks of fluorescent dye. The stretching and folding of these streaks results from chaotic advection by the flow which becomes resonant at specific cylinder heights. This paper reviews theoretical, experimental, and numerical studies of the resonances and the instabilities of a precessional flow, as well as their implications for efficient mixing.