MIDIT OFD CATS Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and Technical University of Denmark Building 128 Department of Chemistry Building 321 P.O. Box 49 University of Copenhagen DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø Denmark Denmark Denmark
Wolf-Gerrit Früh,
Mechanical and Chemical Engineering,
Heriot-Watt University,
Riccartion, Edinburgh, EH14 4AS, UK
Wednesday, May 16, 2001, 14.00 h
at OFD Meeting Room, Building 130, Risø National Laboratory
Abstract: The barotropic shear layer in a rotating fluid is studied in a laboratory experiment. Through the rotation of circular sections in the base and lid of a circular tank relative to a background rotation of the entire system, a vertical layer of strong horizontal shear develops, the Stewartson layer. The shear layer breaks up through inertial instability above a critical shear. The flow then develops a string of vortices along the shear zone in a wave-like (or normal mode) fashion. A series of mode transitions to successively fewer vortices is followed by transitions to more complex flows. The complex flows include modulated vortices, chaos, and highly irregular flow. The experimental techniques employed to monitor the flow will be presented, and methods used to analyse the data will be discussed. The relative merits of point measurements using LDA and flow field measurements using DigImage (particle tracking) will become apparent. The presentation will discuss some aspects of the dynamics underlying the observed flow features. This will be in the form of a stability analysis of the basic flow, and a description of the transitions in terms of dynamical systems terminology.