Reynolds stresses and mean fields generated by pure waves: applications to shear flows and convection in a rotating shell
Reynolds stresses and mean fields generated by pure waves: applications to shear flows and convection in a rotating shell
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纯波产生的雷诺应力和平均场：在旋转壳中的剪切流和对流中的应用
DOI：
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发表时间：
2008
影响因子：
3.7
通讯作者：
F. Busse
中科院分区：
文献类型：
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作者：
E. Plaut;Y. Lebranchu;Radostin D Simitev;F. Busse
本文描述了二维波打破平移或旋转不变性所产生的雷诺应力的一般重新表述。这种重新表述强调了一个几何因素的重要性：波流的分界线的斜率。它的物理相关性说明了两个模型系统：波不稳定开放剪切流和热Rossby波在旋转的球壳对流。在剪切流波的情况下，得到了一个新的Schololds-Orr放大机制的表达式，并对弱非线性波产生的平均压力场和平均速度场的形式有了较好的理解。在热Rossby波的情况下，使用无滑移边界条件的三维代码的结果在非线性政权，并与二维准地转模式。一个半定量的协议上获得的流量振幅，但观察到的非线性频移的差异。在准地转模式下，我们还重新讨论了张先生提出的一个几何公式，用以解释波浪产生的纬向流的形式，并探讨了很低的Ekman数区。发现波分叉的性质发生了变化，从超临界到亚临界。
A general reformulation of the Reynolds stresses created by two-dimensional waves breaking a translational or a rotational invariance is described. This reformulation emphasizes the importance of a geometrical factor: the slope of the separatrices of the wave flow. Its physical relevance is illustrated by two model systems: waves destabilizing open shear flows; and thermal Rossby waves in spherical shell convection with rotation. In the case of shear-flow waves, a new expression of the Reynolds–Orr amplification mechanism is obtained, and a good understanding of the form of the mean pressure and velocity fields created by weakly nonlinear waves is gained. In the case of thermal Rossby waves, results of a three-dimensional code using no-slip boundary conditions are presented in the nonlinear regime, and compared with those of a two-dimensional quasi-geostrophic model. A semi-quantitative agreement is obtained on the flow amplitudes, but discrepancies are observed concerning the nonlinear frequency shifts. With the quasi-geostrophic model we also revisit a geometrical formula proposed by Zhang to interpret the form of the zonal flow created by the waves, and explore the very low Ekman-number regime. A change in the nature of the wave bifurcation, from supercritical to subcritical, is found.