THE LIFE-CYCLE OF TRIPOLES IN 2-DIMENSIONAL INCOMPRESSIBLE FLOWS

被引:81
作者
CARTON, X [1 ]
LEGRAS, B [1 ]
机构
[1] ECOLE NORMALE SUPER, CNRS, METEOROL DYNAM LAB, F-75231 PARIS 05, FRANCE
关键词
D O I
10.1017/S0022112094001114
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
The mechanisms of coherent tripole formation from unstable shielded circular vortices are analysed in the context of two-dimensional incompressible flows. Three stages are identified during the transformation process: the linear growth of the initial normal mode perturbation, its nonlinear amplification and the finite-amplitude saturation under the tripolar form. We give a geometrical discussion of the mutual influence of the core vortex and of the satellites generated from the shield. The role of the angular momentum in determining the finite amplitude saturation is demonstrated using a simple elliptical model of the core vortex associated with two point-vortex satellites. The long-time asymmetric breaking of the tripole into a dipole and a monopole is shown to be driven by the erosion of the core vortex by stripping and diffusion. Finally the influence of bottom topography on tripole formation is considered, providing a rich phenomenology when the height of the topography is varied.
引用
收藏
页码:53 / 82
页数:30
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