Statistical Measures and Selective Decay Principle for Generalized Euler Dynamics: Formulation and Application to the Formation of Strong Fronts
Statistical Measures and Selective Decay Principle for Generalized Euler Dynamics: Formulation and Application to the Formation of Strong Fronts
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广义欧拉动力学的统计测量和选择性衰变原理：强锋面形成的公式和应用
DOI：
10.1007/s10955-019-02472-4
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发表时间：
2020
影响因子：
1.6
通讯作者：
G. Badin
中科院分区：
文献类型：
--
作者：
G. Conti;G. Badin
在这项工作中，我们研究了一类二维（2D）流体流动的统计力学，由广义欧拉方程或模型描述。这些模型既描述了非局部动力学，也描述了局部动力学，其中地表拟地堑（SQG）模型给出了后者的一个例子，其中奇点的存在性仍在讨论中。此外，SQG还与大气和海洋动力学相关，特别是与浮力水平梯度相关的海洋亚中尺度结构，锋面和细丝。我们讨论了统计理论在什么条件下对整个湍流模型族提出了选择性衰减原理，然后我们从对应于双曲鞍的初始条件（i.c.s）开始，用数值方法探讨了选择性衰减原理、向平衡的过渡和奇点的形成。我们研究了由细丝断裂引起的流动构型的拓扑跃迁。并将理论平衡状态、广义涡度与相应流函数的函数关系与模拟结果进行了比较。对于所研究的特定i.c.s和用于模拟的域，我们没有注意到从tanh-like函数关系到sinh-like函数关系的转变，这是由相干结构的出现所期望的，然而，被用于计算平均场的时间平均值过滤。
In this work we investigate the statistical mechanics of a family of two dimensional (2D) fluid flows, described by the generalized Euler equations, or-models. These models describe both nonlocal and local dynamics, with one example of the latter given by the surface quasi geostrophy (SQG) model for which the existence of singularities is still under discussion. Furthermore, SQG is relevant both for atmosphere and ocean dynamics, and in particular, it is proposed to understand the oceanic submesoscale structures, front and filaments, associated with horizontal gradients of buoyancy. We discuss under which conditions the statistical theory suggests a principle of selective decay for the whole family of turbulent models, and then we explore the selective decay principle numerically, the transition to equilibrium and the formation of singularities, starting from initial conditions (i.c.s) corresponding to a hyperbolic saddle. We study the topological transitions in the flow configuration induced by filaments breaking. Furthermore we compare the theoretical equilibrium states, and the functional relation between the generalized vorticityqand its correspondent stream function, with the results of the simulations. For the particular i.c.s investigated, and domain used for the simulations, we have not noticed transition from tanh-like to sinh-likefunctional relation, which would be expected by the emergence of coherent structures that are, however, filtered by the time averages used to compute the mean fields.
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海洋对流模型中耦合表面/内部 QG 和传播 Heton 簇的点涡动力学
影响因子：
1.3
作者：
C. Lim;A. Majda
通讯作者：
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影响因子：
1.3
作者：
D. Chapman
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D. Chapman
三个表面准地转点涡的动力学和传输特性。
影响因子：
2.9
作者：
C. K. Taylor;Stefan G. Llewellyn Smith
通讯作者：
Stefan G. Llewellyn Smith
影响因子：
4
作者：
Tran, CV;Shepherd, TG
通讯作者：
Shepherd, TG
DOI：
10.1016/0167-2789(96)00114-5
发表时间：
1996-11
期刊：
Physica D: Nonlinear Phenomena
影响因子：
--
作者：
A. Majda;E. Tabak
通讯作者：
A. Majda;E. Tabak