The importance of accurately representing submerged vegetation morphology in the numerical prediction of complex river flow
The importance of accurately representing submerged vegetation morphology in the numerical prediction of complex river flow
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DOI：
10.1002/esp.3871
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发表时间：
2016-03-30
影响因子：
3.3
通讯作者：
Marjoribanks, Timothy I.
中科院分区：
文献类型：
--
作者：
Boothroyd, Richard J.;Hardy, Richard J.;Marjoribanks, Timothy I.
本文报告了一种将复杂植物形态纳入计算流体动力学 (CFD) 模型的新方法，从而可以对单个植物周围的流动进行数值预测。通过地面激光扫描（TLS）捕获形态复杂性，包括各个枝叶的垂直和横向分布，并在流场的数值预测中得到保留。这是通过质量通量缩放算法 (MFSA) 将后处理的体素化植物表示合并到 CFD 方案中来实现的。在去除叶子后，在叶状和落叶状态下模拟了月桂周围的流动。研究表明，复杂的植物形态会产生空间异质的下游速度场，其速度分布明显偏离理想的变形形状。植物尾流中高速自由流区域和低速区域之间的快速过渡表明存在剪切流，重新附着点向下游延伸长达七个植物长度。树叶的存在显着改变了流场响应，在茂密的树叶周围形成了第二个更明显的尾流结构。这种方法提供了压力场的全流程数值描述，从而能够量化植物阻力。对于此处给出的示例，叶状状态的阻力要大一个数量级。这里概述的方法证明了在水力模型中准确表示复杂植物形态的重要性，并允许计算特定植物物种的阻力和系数。版权所有 (c) 2015 约翰·威利父子有限公司
This paper reports a novel method for the incorporation of complex plant morphologies into a computational fluid dynamics (CFD) model, allowing the numerical prediction of flows around individual plants. The morphological complexity, which comprises the vertical and lateral distribution of individual branches and leaves is captured through terrestrial laser scanning (TLS) and is maintained in the numerical prediction of flow fields. This is achieved where the post-processed, voxelized plant representation is incorporated into a CFD scheme through a mass flux scaling algorithm (MFSA). Flow around Prunus laurocerasus has been modelled under foliated and defoliated states following the removal of leaves. The complex plant morphologies are shown to produce spatially heterogeneous downstream velocity fields, with velocity profiles that deviate significantly from the idealized inflected shape. Rapid transition between the high velocity free stream zone and the zone of reduced velocity in the plant wake indicate shearing of flow, with the point of reattachment extending up to seven plant lengths downstream. The presence of leaves significantly modifies the flow field response, with development of a second, more pronounced wake structure around the dense foliage. This approach provides a full flow numerical description of the pressure field, enabling the vegetative drag force to be quantified. For the example given here, drag force is an order of magnitude greater for the foliated state. The methodology outlined here demonstrates the importance of accurately representing complex plant morphology in hydraulic models, and allows drag forces and coefficients to be calculated for specific plant species. Copyright (c) 2015 John Wiley & Sons, Ltd.