Abstract The problem of turbulent Couette flow driven by a statistically steady external wind is studied in the framework of spatially filtered Navier–Stokes equations. The phenomenon of wind-driven flow of water is represented by a layer of air modeled as Poiseuille flow (air sub-domain), coupled to a layer of water modeled as Couette flow (water sub-domain). We focus on changes in the statistics in either the air or the water sub-domain, due to the coupling with the other sub-domain. We also highlight dynamic flow structures forming near the air-water interface. Simulations based on different Reynolds numbers in the air and the water sub-domains are compared to computationally less demanding simulations with equal Reynolds numbers. Results of these simulations indicate strong similarities, i.e., the flow is well approximated by simulating air and water at the same Reynolds numbers. Further analysis shows that the flow in the water domain shares important features with classical Couette flows. The horizontal turbulent mixing renders a thinner boundary layer in the water sub-domain. Moreover, an increased intermittency in the flow velocities is observed, which may be linked to so-called splat events near the air-water interface. These splats characterize the interaction of coherent structures across the interface, being stronger in the water phase. An analysis of the pressure-strain correlation near the air-water interface on the water side shows that such splats are responsible for redistributing energy from the streamwise and spanwise directions, to the vertical direction. This behavior, although qualitatively similar to wall-bounded flows, differ mainly on the fact that most of the energy drained comes from the streamwise direction: in wall-bounded the main contributor is the spanwise direction. The boundary layers near the air-water interface show inclined vortical structures. Unlike in coupled Couette–Couette flow, the peak in the Reynolds stress is displaced from the channel’s center into the buffer region of the water sub-domain.

中文翻译：

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使用大涡模拟的耦合 Couette-Poiseuille 流中的能量再分配动力学

摘要 在空间滤波 Navier-Stokes 方程的框架内研究了由统计稳定的外部风驱动的湍流 Couette 流问题。风力驱动的水流现象由建模为 Poiseuille 流（空气子域）的空气层表示，耦合到建模为 Couette 流（水子域）的水层。由于与其他子域的耦合，我们关注空气或水子域中统计数据的变化。我们还强调了在空气-水界面附近形成的动态流动结构。将基于空气和水子域中不同雷诺数的模拟与具有相同雷诺数的计算要求较低的模拟进行比较。这些模拟的结果表明有很强的相似性，即，通过模拟相同雷诺数下的空气和水，可以很好地近似流量。进一步的分析表明，水域中的流动与经典的库埃特流动具有重要的特征。水平湍流混合使水子域中的边界层变薄。此外，观察到流速的间歇性增加，这可能与空气-水界面附近所谓的喷溅事件有关。这些碎片表征了界面上相干结构的相互作用，在水相中更强。对水侧空气-水界面附近的压力-应变相关性的分析表明，这种板片负责将能量从流向和展向方向重新分配到垂直方向。这种行为，尽管在性质上与壁面流动相似，但主要区别在于大部分能量消耗来自流向：在壁面流动中，主要贡献者是展向。气水界面附近的边界层显示出倾斜的涡旋结构。与耦合 Couette-Couette 流不同，雷诺应力的峰值从通道中心转移到水子域的缓冲区中。