Different heights and patterns of vegetation can be seen in river channels and other bodies of water. It is also common to see a mix of emergent and submerged vegetation. The present study considers the flow past homogeneous and heterogeneous vegetation height in a controlled laboratory setting. Four primary cases were considered each for two density arrangements: fully submerged homogeneous, fully submerged heterogeneous, partially emergent heterogeneous, and fully emergent homogeneous. The vegetation occupies half of the channel width. Although the average frontal area of both submerged cases is equal, flow characteristics differ in the main channel because of the variation in height in the fully submerged heterogeneous case. As the vegetation emergence and density increases, the flow characteristics near the interaction zone between the floodplain and the main channel undergo significant enhancements. In fully emergent cases, a dip phenomenon is noticeable near the water surface within the main channel. This dip phenomenon is characterized by the presence of positive velocity gradients near the wall and negative velocity gradients near the surface. Furthermore, negative streamwise Reynolds shear stress is observed near the surface, indicating the prevalence of outward and inward interactions in fully emergent cases. The quadrant analysis for different vegetation distribution cases showed dominance of sweep and ejection events near the channel bed of main channel. The study outcomes highlight the importance of considering vegetation height variations and distribution patterns when evaluating flow characteristics in natural systems.

中文翻译：

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部分植被覆盖的河道中的水动力：研究同质和异质垂直植被分布的影响

在河道和其他水体中可以看到不同高度和图案的植被。挺水植被和沉水植被混合存在的情况也很常见。本研究考虑了在受控实验室环境中流经同质和异质植被高度的流量。两种密度排列分别考虑了四种主要情况：完全浸没的均质、完全浸没的异质、部分浮出的异质和完全浮出的均质。植被占据河道宽度的一半。尽管两种浸没情况的平均迎面面积相等，但由于完全浸没的异质情况中高度的变化，主通道中的流动特性有所不同。随着植被出现和密度的增加，洪泛区和主河道之间相互作用区附近的水流特征显着增强。在完全紧急的情况下，主航道内水面附近会出现明显的倾角现象。这种倾角现象的特征是在壁附近存在正速度梯度而在表面附近存在负速度梯度。此外，在表面附近观察到负流向雷诺剪应力，表明在完全紧急情况下普遍存在向外和向内相互作用。对不同植被分布情况的象限分析表明，主航道河床附近的扫掠和喷射事件占主导地位。研究结果强调了在评估自然系统中的流动特征时考虑植被高度变化和分布模式的重要性。