Mixing in a meandering jet: A Markovian approximation
Mixing in a meandering jet: A Markovian approximation
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DOI：
10.1175/1520-0485(1999)029
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发表时间：
1999-10-01
影响因子：
3.5
通讯作者：
Zambianchi, E
中科院分区：
文献类型：
--
作者：
Cencini, M;Lacorata, G;Zambianchi, E
研究了与蜿蜒射流相对应的混合和传输。所保持的大尺度流量是运动学指定的流函数。分别和组合考虑两种基本混合机制：由流动的时间依赖性引起的确定性混沌平流，以及通过粒子运动的随机模型描述的湍流扩散。不是查看粒子轨迹的细节，而是根据马尔可夫近似来研究流体交换。流体粒子可访问的二维物理空间被细分为具有不同拉格朗日行为特征的区域。从观察到的区域之间的转变，可以得出许多表征所研究流态中的传输和混合的相关量，例如停留时间、子午混合和相关函数。将这些估计的数量与实际模拟产生的相应数量进行比较。比较的结果表明，通过一阶马尔可夫近似的非常简化的方法，可以以令人满意的方式描述系统的至少一些混合特性，而其他特性则表现出更高阶的记忆模式。
Mixing and transport in correspondence of a meandering jet are investigated. The large-scale flow held is a kinematically assigned streamfunction. Two basic mixing mechanisms are considered separately and in combination: deterministic chaotic advection induced by a time dependence of the flow, and turbulent diffusion described by means of a stochastic model for particle motion.Rather than looking at the details of particle trajectories, fluid exchange is studied in terms of Markovian approximations. The 2D physical space accessible to fluid particles is subdivided into regions characterized by different Lagrangian behavior. From the observed transitions between regions it is possible to derive a number of relevant quantities characterizing transport and mixing in the studied flow regime, such as residence times, meridional mixing, and correlation functions. These estimated quantities are compared to the corresponding ones resulting from the actual simulations. The outcome of the comparison suggests the possibility of describing in a satisfactory way at least some of the mixing properties of the system through the very simplified approach of a first-order Markovian approximation, whereas other properties exhibit memory patterns of higher order.