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
by Dr. Mark Stremler
Department of Theoretical and Applied Mechanics,
University of Illinois at Urbana-Champaign, USA
Wednesday March 01, 2000, 15.15 h
at MIDIT, MAT, Bldg. 303, Room 026, DTU,
Abstract: A new approach to regular and chaotic fluid advection will be presented that utilizes the Thurston-Nielsen classification theorem. The prototypical 2D problem of stirring by a finite number of stirrers confined to a disk of fluid will be considered. The theory shows that for particular 'stirring protocols' a significant increase in complexity of the stirred motion -- known as topological chaos -- occurs when three or more stirrers are present and are moved about in certain ways. The basic theory will be set out without proofs, and the applicability of several topological concepts to fluid stirring will be demonstrated. A simple experiment in which a viscous liquid is stirred by three stirrers has been conducted and will be used to illustrate the theory.