An Experimental Study of Mangrove‐Induced Resistance on Water Waves Considering the Impacts of Typical <i>Rhizophora</i> Roots
An Experimental Study of Mangrove‐Induced Resistance on Water Waves Considering the Impacts of Typical <i>Rhizophora</i> Roots
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考虑典型红树根系影响的红树林对水波抵抗力的实验研究
DOI：
10.1029/2022jc018653
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Yanagisawa Hideaki
中科院分区：
文献类型：
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作者：
Chang Che‐Wei;Mori Nobuhito;Tsuruta Naoki;Suzuki Kojiro;Yanagisawa Hideaki
通过室内实验研究了红树林与水波的相互作用。基于典型红树植物的扫描图像，使用1：7比例的3D打印树木，我们复制了天然红树林的根系结构并构建了模型森林。采用三种红树林模型配置，两种不同树干密度的模型林和一株孤立的单木。为研究红树林阻力与波浪的关系，采用直接测力法，在波浪水槽中测量了红树林模型上的波浪力、流体流速和自由面高程沿着的变化。测试各种条件下的规则波和孤立波，我们观察到测量力中不可忽略的惯性效应。基于直接测量，我们估计了Morison型方程中的阻力和惯性系数（Morison等人，1950，https：//doi.org/10.2118/950149-g），并建立了两个系数与雷诺数和Keulegan-Carpenter数之间的经验关系。这些阻力系数和惯性系数的关系可用于数学/数值模拟，以参数化相似尺度条件下的红树林效应。与以前的研究相比，红树林的阻力系数比刚性圆柱体更分散，特别是在较浅的水深。通过测试不同的水深，我们观察到不同的模式的阻力和惯性系数时，根系被部分或完全淹没。此外，在支柱根部附近的垂直位置处的波动的流体速度和增强的湍流动能指示了由于复杂的根部结构导致的阻塞效应和剪切诱导的湍流。这些结果表明，红树林根系对水波的影响。
This paper studied the interactions between mangroves and water waves through laboratory experiments. Using 1:7 scale 3D‐printed trees based on the scanned image of a typicalRhizophoraspecies, we replicated the root structure of natural mangroves and constructed a model forest. Three arrangements of mangrove models, two model forests of different stem densities and a single tree in isolation, were adopted. To investigate the relationships between mangrove resistance and waves, we applied the approach of direct force measurement, measuring wave forces on mangrove models, fluid velocity, and free surface elevation along the wave flume. Testing regular and solitary waves of various conditions, we observed non‐negligible inertia effects in the measured forces. Based on the direct measurements, we estimated drag and inertia coefficients in the Morison‐type equation (Morison et al., 1950, https://doi.org/10.2118/950149-g) and established empirical relationships between the two coefficients and Reynolds and Keulegan‐Carpenter numbers. These relationships of drag and inertia coefficients can be used in mathematical/numerical simulations to parameterize mangrove effects under similar scale conditions. Compared to previous studies, the drag coefficients for mangroves were more scattered than rigid cylinders, especially in shallower water depths. By testing different water depths, we observed different patterns of drag and inertia coefficients when the root system was partially or fully submerged. In addition, the fluctuating fluid velocity and enhanced turbulence kinetic energy at the vertical positions near prop roots indicated the blockage effects and the shear‐induced turbulence due to the complex root structure. These findings suggested the influence of mangrove roots on water waves.