TRANSITION TO TURBULENCE IN 2-DIMENSIONAL POISEUILLE FLOW

The transition of strictly two-dimensional Poiseuille flow from laminar to chaotic behaviour is studied through full numerical simulation of spatially periodic channels with fairly large longitudinal aspect ratios. The successive bifurcations are studied in detail and their physical mechanism is elucidated. The Liapunov exponents of the flow are measured and shown to be positive at large Reynolds numbers. Isolated, permanent patches of unsteady behaviour, resembling the turbulent ‘puffs’observed in circular pipes, are found at low Reynolds numbers and shown to be important for the transition to chaos. The flow exhibits several other phenomena present in natural three-dimensional flows, including wall sweeps, ejections, and intermittency. © 1990, Cambridge University Press. All rights reserved.