Publication Date:
1991-08-01
Description:
Results from laboratory experiments on oscillatory flows over topography in a rapidly rotating cylinder of homogeneous liquid are presented and compared with weakly nonlinear and low-order theories. With periodic forcing, the motion can be either periodic or chaotic. In the periodic regime, linear Rossby waves excited by the sloshing flow over shallow bottom topography become resonant at forcing frequencies that are integer multiples of the natural free Rossby wave frequency. As the topographic effect or the forcing amplitude is increased, the maximum response is shifted away from the linearly resonant frequency to higher periods for azimuthal topographic wavenumbers of 1 and to lower periods for topographic zonal wavenumbers exceeding 1, in agreement with theory. The simple theories which use slippery sidewalls do not describe the observed chaotic flows. These complex states are associated with the development of small-scale vortices in the sidewall boundary layer that are shed into the interior. For both periodic and chaotic flows, long-time particle paths can contain significant chaotic components which are revealed in direct Poincare sections constructed from observations of surface floats. © 1991, Cambridge University Press. All rights reserved.
Print ISSN:
0022-1120
Electronic ISSN:
1469-7645
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
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