LOCAL AND GLOBAL DISPERSION EFFECTS IN COUETTE-TAYLOR FLOW .1. DESCRIPTION AND MODELING OF THE DISPERSION EFFECTS

The Couette-Taylor flow (CTF) is a periodic flow with zero mean axial velocity. Its local and global dispersion behaviour has been investiga ted by recording the rate of tracer dispersion at the injection point. This allowed the demonstration of the existence of a strong inter-vor tex Bur, thereby refuting the generally accepted concept of non-interm ixing vortex units. The tracer responses depended strongly upon which specific part of the vortex was marked with tracer. This shows that th e axial dispersion cannot be described by the single-parameter models presently used in the literature. A first principles two-parameter mod el, based upon the newly obtained insights, is proposed. It offers a u nifying framework for all observations and resolves the contradictions encountered in the literature. The response dynamics of the model hav e been investigated to identify the possible parameter estimation stra tegies and in order to predict the long time limit behaviour.