SELFORGANISATION OF QUASI-2D FLOWS IN A RECTANGULAR CONTAINER

This contribution describes a combined experimental-numerical study of decaying quasi-2D turbulent flows on a rectangular domain with no-sli p boundaries. While decaying, the flow is found to organise in a domai n-filling pattern of counter-rotating cells. Advection of filaments of viscously generated wall vorticity into the interior results in a con tinuing perturbation of the cellular pattern. The time dependence thus introduced provides the essential mechanism for chaotic advection: pa ssive tracers may move from one cell to a neighbouring one, all the wa y along the array.