Aquatic vegetation plays an important role in natural water environments by interacting with the flow and generating turbulence that affects the air-water and sediment-water interfacial transfer. Regular and staggered arrays are often set as simplified layouts for vegetation canopy to study both mean flow and turbulence statistics in vegetated flows, which creates uniform spacing between vegetation elements, resulting in preferential flow paths within the array. Such preferential paths can produce local high velocity and strong turbulence, which do not necessarily happen in natural environments where vegetation is randomly distributed. How the randomness of the canopy affects interfacial processes by altering spatial turbulence distribution, which can potentially lead to different turbulence feedback on the interfacial transfer process, remains an open question. This study conducted a series of laboratory experiments in a race-track flume using rigid cylinders as plant surrogates. Mean and turbulent flow statistics were characterized by horizontal- and vertical-sliced PIV. Based on the measured flow characteristics under different stem diameters and array configurations, we propose a method to quantify the randomness of the vegetation array and update a sediment-water-air interfacial gas transfer model with the randomness parameter to improve its accuracy. The updated model agrees well with the dissolved oxygen experimental data from our study and data from existing literature at various scales. The study provides critical insight into water quality management in vegetated channels with improved dissolved oxygen predictions considering vegetation layout as part of the interfacial transfer model.

中文翻译：

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冠层随机性、尺度和茎尺寸对植被流界面传递过程的影响

水生植被通过与水流相互作用并产生影响空气-水和沉积物-水界面转移的湍流，在自然水环境中发挥着重要作用。规则和交错阵列通常被设置为植被冠层的简化布局，以研究植被流中的平均流量和湍流统计数据，这在植被元素之间形成均匀的间距，从而导致阵列内的优先流动路径。这种优先路径会产生局部高速和强湍流，而这在植被随机分布的自然环境中不一定会发生。冠层的随机性如何通过改变空间湍流分布来影响界面过程，这可能导致界面传递过程中不同的湍流反馈，仍然是一个悬而未决的问题。本研究使用刚性圆柱体作为植物替代物，在跑道水槽中进行了一系列实验室实验。平均流和湍流统计数据通过水平和垂直切片 PIV 进行表征。基于不同茎直径和阵列配置下测量的流动特性，我们提出了一种量化植被阵列随机性的方法，并用随机性参数更新沉积物-水-空气界面气体传输模型以提高其准确性。更新后的模型与我们研究中的溶解氧实验数据以及现有文献中不同尺度的数据非常吻合。该研究为植被河道的水质管理提供了重要的见解，并考虑植被布局作为界面传输模型的一部分，改进了溶解氧预测。