The life-cycle of tripoles in two-dimensional incompressible flows
The life-cycle of tripoles in two-dimensional incompressible flows
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二维不可压缩流中三极子的生命周期
DOI：
10.1017/s0022112094001114
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发表时间：
1994
影响因子：
3.7
通讯作者：
B. Legras
中科院分区：
文献类型：
--
作者：
X. Carton;B. Legras
本文在二维不可压缩流动的背景下分析了不稳定屏蔽圆涡相干三极形成的机制。在转换过程中，确定了三个阶段：初始简正模扰动的线性增长，其非线性放大和有限振幅饱和下的三极形式。我们给出了一个几何讨论的相互影响的核心涡和卫星产生的屏蔽。角动量在确定有限振幅饱和度的作用证明了使用一个简单的椭圆模型的核心涡与两个点涡卫星。长时间的不对称打破成偶极子和偶极子的三极被证明是由核心涡的剥离和扩散的侵蚀。最后考虑了海底地形对三极形成的影响，给出了地形高度变化时的丰富现象。
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.