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首页> 外文期刊>Estuarine Coastal and Shelf Science >Effects of time dependence in unstratified tidal boundary layers: results from large eddy simulations
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Effects of time dependence in unstratified tidal boundary layers: results from large eddy simulations

机译：时间的影响在未分层的潮汐边界层中：大涡模拟的结果

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摘要

A three-dimensional Large Eddy Simulation (LES) model is used to simulate oscillating tidal boundary layers and test previous results obtained from one-dimensional boundary layer models and turbulence measurements in tidal channels. The LES model produces low-order turbulence statistics in agreement with the semi-analytic theory and observations. It shows a logarithmic layer in the mean velocity profile and a linear distribution of Reynolds stress with water depth. However, the eddy viscosity profile predicted by the LES model is not parabolic but better matches a parabolic profile modified by wake effect observed in the outer part of depth-limited steady boundary layers. Low-order turbulence statistics can be scaled by the instantaneous friction velocity at the bottom boundary. Although turbulence intensities in three directions fluctuate over a tidal cycle, their normalized values are in good agreement with those determined from laboratory experiments of steady open-channel flows. The LES model confirms that tidal turbulence is in quasi-equilibrium. However, it also demonstrates the importance of flow acceleration/deceleration term in the depth-integrated momentum balance for the mean flow. Phase differences are found between flows at different heights above the bottom boundary.
机译：使用三维大涡模拟（LES）模型来模拟潮汐边界层的振荡，并测试从一维边界层模型和潮汐通道中的湍流测量获得的先前结果。 LES模型与半解析理论和观测结果一致，产生了低阶湍流统计数据。它在平均速度曲线中显示了对数层，并且雷诺应力与水深呈线性分布。但是，LES模型预测的涡流粘度曲线不是抛物线形的，而是更好地匹配了受深度限制的稳定边界层外部观察到的尾流效应影响的抛物线形。低阶湍流统计可以通过底部边界处的瞬时摩擦速度来缩放。尽管三个方向的湍流强度会在一个潮汐周期内波动，但其归一化值与稳定的明渠水流实验室实验确定的值一致。 LES模型证实潮汐湍流处于准平衡状态。但是，它也证明了在加速流/加速项对深度平均动量的深度积分动量平衡中的重要性。在底部边界上方不同高度的流之间发现了相位差。

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