Prediction of near-field shear dispersion in an emergent canopy with heterogeneous morphology
Prediction of near-field shear dispersion in an emergent canopy with heterogeneous morphology
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DOI：
10.1007/s10652-006-9002-7
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发表时间：
2006-08
影响因子：
2.2
通讯作者：
A. Lightbody;H. Nepf
中科院分区：
文献类型：
--
作者：
A. Lightbody;H. Nepf
在水生林冠层纵向扩散的评估是必要的，以预测沼泽和湿地系统中溶解的物种和悬浮颗粒的行为。在这里，我们考虑冠层形态的影响，纵向分散，重点运输前的成分混合深度。在林冠密度垂直变化的模型林冠中测量了速度和纵向弥散。在树冠形态的垂直变化产生的平均速度分布，这反过来又创建平均剪切分散的垂直变化。我们开发并验证了一个模型，预测平均剪切分散在近场的冠层的形态特征，如茎直径和锋面面积。靠近源，纵向分散是由速度不均匀性在单个干尺度。然而，在大约1米的距离内，与深度上的速度不均匀性相关的剪切频散增加，并掩盖了这一小规模的过程。
The evaluation of longitudinal dispersion in aquatic canopies is necessary to predict the behavior of dissolved species and suspended particles in marsh and wetland systems. Here we consider the influence of canopy morphology on longitudinal dispersion, focusing on transport before constituents have mixed over depth. Velocity and longitudinal dispersion were measured in a model canopy with vertically varying canopy density. The vertical variation in canopy morphology generates vertical variation in the mean velocity profile, which in turn creates mean-shear dispersion. We develop and verify a model that predicts the mean-shear dispersion in the near field from morphological characteristics of the canopy, such as stem diameter and frontal area. Close to the source, longitudinal dispersion is dominated by velocity heterogeneity at the scale of individual stems. However, within a distance of approximately 1 m, the shear dispersion associated with velocity heterogeneity over depth increases and eclipses this smaller-scale process.