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Direct Numerical Simulations of Miniature Along-Shelf Current-Supported Turbidity Currents: Conceptual Investigation of Velocity Structure and Drag Coefficient
Journal of Geophysical Research: Oceans ( IF 3.3 ) Pub Date : 2021-06-25 , DOI: 10.1029/2020jc016736
S. Haddadian 1 , C. E. Ozdemir 1, 2, 3 , B. L. Goodlow 1 , G. Xue 2, 3, 4 , S. J. Bentley 3, 5
Affiliation  

Alongshore current-supported turbidity currents (ACSTCs) are a subclass of wave- and current-supported turbidity currents. They are one of the agents responsible for the dispersal of the river-borne sediments on the continental shelf, which constitutes a major phenomenon controlling the geomorphic evolution of ocean-basin margins over geological time. Therefore, parameterization of the sediment flux associated with ACSTCs will help its implementation in operational models and quantify the sediment flux budgets on the continental shelf. The velocity structure of ACSTCs and the amount of sediments suspended by them are crucial to determine the suspended sediment flux. This study investigates the velocity structure of a simplified miniature ACSTC over an erodible bed composed of fine sediments. Direct numerical simulations are conducted for various bed erosion parameters and sediment settling velocity. The role of sediment-induced stable density stratification on the velocity structure of ACSTCs is analyzed. The simulation results indicate that density stratification and the drag coefficient are functions of the product of sediment settling velocity and sediment concentration. The velocity profile was found to deviate toward the alongshore direction with strengthening density stratification, which enhances the drag coefficient. By using the Monin-Obukhov theory, the drag coefficient associated with the cross-shelf propagation of ACSTCs is formulated as a function of the Reynolds number, sediment concentration, and sediment settling velocity.

中文翻译:

微型沿架流支持的浊流的直接数值模拟:速度结构和阻力系数的概念研究

沿岸水流支持的浊流 (ACSTC) 是波浪和水流支持的浊流的一个子类。它们是造成大陆架上河流沉积物扩散的因素之一,它构成了控制海盆边缘在地质时期内地貌演化的主要现象。因此,与 ACSTC 相关的沉积物通量的参数化将有助于其在操作模型中的实施并量化大陆架上的沉积物通量预算。ACSTCs 的速度结构及其悬浮沉积物的数量对于确定悬浮沉积物通量至关重要。本研究调查了由细粒沉积物组成的易蚀床层上的简化微型 ACSTC 的速度结构。对各种河床侵蚀参数和沉积物沉降速度进行了直接数值模拟。分析了沉积物引起的稳定密度分层对ACSTCs速度结构的作用。模拟结果表明,密度分层和阻力系数是泥沙沉降速度和泥沙浓度乘积的函数。发现随着密度分层的加强,速度剖面向岸边方向偏移,这增加了阻力系数。通过使用 Monin-Obukhov 理论,与 ACSTC 跨架传播相关的阻力系数被公式化为雷诺数、沉积物浓度和沉积物沉降速度的函数。分析了沉积物引起的稳定密度分层对ACSTCs速度结构的作用。模拟结果表明,密度分层和阻力系数是泥沙沉降速度和泥沙浓度乘积的函数。发现随着密度分层的加强,速度剖面向岸边方向偏移,这增加了阻力系数。通过使用 Monin-Obukhov 理论,与 ACSTC 跨架传播相关的阻力系数被公式化为雷诺数、沉积物浓度和沉积物沉降速度的函数。分析了沉积物引起的稳定密度分层对ACSTCs速度结构的作用。模拟结果表明,密度分层和阻力系数是泥沙沉降速度和泥沙浓度乘积的函数。发现随着密度分层的加强,速度剖面向岸边方向偏移,这增加了阻力系数。通过使用 Monin-Obukhov 理论,与 ACSTC 跨架传播相关的阻力系数被公式化为雷诺数、沉积物浓度和沉积物沉降速度的函数。模拟结果表明,密度分层和阻力系数是泥沙沉降速度和泥沙浓度乘积的函数。发现随着密度分层的加强,速度剖面向岸边方向偏移,这增加了阻力系数。通过使用 Monin-Obukhov 理论,与 ACSTC 跨架传播相关的阻力系数被公式化为雷诺数、沉积物浓度和沉积物沉降速度的函数。模拟结果表明,密度分层和阻力系数是泥沙沉降速度和泥沙浓度乘积的函数。发现随着密度分层的加强,速度剖面向岸边方向偏移,这增加了阻力系数。通过使用 Monin-Obukhov 理论,与 ACSTC 跨架传播相关的阻力系数被公式化为雷诺数、沉积物浓度和沉积物沉降速度的函数。
更新日期:2021-08-03
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