Experimental analysis of wave attenuation and drag forces in a realistic fringe Rhizophora mangrove forest
Experimental analysis of wave attenuation and drag forces in a realistic fringe Rhizophora mangrove forest
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DOI：
10.1016/j.advwatres.2019.07.006
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发表时间：
2019-09-01
影响因子：
4.7
通讯作者：
Losada, Inigo J.
中科院分区：
文献类型：
--
作者：
Maza, Maria;Lara, Javier L.;Losada, Inigo J.
为了更好地理解和参数化水流与红树林相互作用的物理过程，对1：6比例尺的红树林边缘红树林进行了波浪衰减和阻力沿着实验研究。26 m长的长林由135个模型组成，模型复制了24个支柱根的成熟Rhizophora红树林。水动力条件的缩放使用弗劳德相似性的基础上收集的值在自然界中。规则和随机波进行了测试，并考虑了三个水深的影响，可变红树林正面面积沿着垂直。波浪衰减分析突出了考虑水槽底部和壁摩擦影响的重要性。忽略这种额外的阻尼可能会导致过高估计的红树林耗散能力。它被证明，水深，和相关的红树林锋面面积，和波高是主导变量驱动波衰减的短波。森林向海的坡度引起波浪变浅，导致波陡增加。因此，施加在红树林上的力也沿着森林的前沿着3-4米增加。更小的力量被记录到森林中，在那里波衰减公式很好地适应记录的波高。在一般情况下，分析阻力通过使用红树林树木诱导阻尼系数比较以及森林内测量的力量。然而，在某些情况下，分析阻力可能导致高估高达两倍。这方面是非常重要的，当实验结果被用于饲料的数值或分析模型的基础上引入的阻力的动量方程。这些模型应尽可能使用直接力测量进行校准。
With the aim of better understand and parameterize the physical processes involved in flow-mangrove interaction, wave attenuation and drag forces along a 1:6 scale fringe Rhizophora mangrove forest are studied experimentally. The 26 m long forest is composed by 135 models built reproducing mature Rhizophora mangrove trees with 24 prop roots. Hydrodynamic conditions are scaled using Froude similarity based on values collected in nature. Regular and random waves are tested and three water depths are considered to account for the influence of variable mangroves frontal area along the vertical. Wave decay analysis highlights the importance of considering the effect of flume bottom and walls friction. Neglecting this additional damping can result in a high overestimation of the mangrove dissipation capacity. It is proven that water depth, and the associated mangroves frontal area, and wave height are the dominant variables driving wave attenuation for short waves. The slope seaward the forest induces wave shoaling leading to an increase of wave steepness. Accordingly, the exerted forces on the mangroves also increase along the first 3-4 m of the forest. Smaller forces are recorded further into the forest where wave decay formulations fit well to the recorded wave heights. In general, analytical drag forces obtained by using mangrove trees induced damping coefficients compare well to the forces measured within the forest. However, analytical drag forces can lead to overestimations of up to double in some cases. This aspect is very important when experimental results are used to feed numerical or analytical models based on the introduction of a drag force in the momentum equation. These models should be calibrated using, whenever possible, direct force measurements.