Meandering streams in a shallow fluid layerA. R. Cieślik, L. P. J. Kamp, H. J. H. Clercx and G. J. F. van Heijst
Fluid Dynamics Laboratory, Department of Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, EU
received 29 May 2008; accepted in final form 11 February 2009; published March 2009
published online 17 March 2009
Decaying turbulence in a shallow flow is shown to be characterized by the emergence of long-lived meandering currents, which are closely related to pronounced vertical flows inside the shallow layer. These vertical flows are concentrated in regions that are dominated either by vorticity or by strain of the flow field. Upwelling of fluid is observed in patch-like domains near elliptic points. Downward flow takes place close to hyperbolic points where the hyperbolic nature of the streamlines leads to thin, elongated regions of intense downwelling. The latter results in long, contracting regions in the free-surface flow. Particles that float on the liquid surface will congregate in these strain-dominated regions, thus lining out the large-scale meandering streams.
47.27.De - Coherent structures.
47.32.C- - Vortex dynamics.
47.27.-i - Turbulent flows.
© EPLA 2009