Riparian vegetation does not only affect the channel flow carrying capacity, but also plays significant roles in water management, stream restoration, and river rehabilitation. This study numerically investigates the flow characteristics through longitudinally discontinuous rigid vegetation occupying half width of the channel, with the help of three‐dimensional software FLUENT in which a Reynolds stress turbulence model was adopted. Three varying conditions of vegetation were considered comprising of vertically double‐layered vegetation (DLV), submerged vegetation (SV), and emergent vegetation (EV) while keeping the same vegetation density, as well as a varying discharge condition against DLV was also tested. The results indicated that the flow distribution becomes more complex through DLV and SV followed by multiple layers with an inflectional instability in the vertical velocity profile around submerged canopy top, as compared to the flow through EV where the uniform distribution of flow over the canopy column was observed. The velocity in the canopy zone decreased considerably because of the resistance due to vegetation, which influenced the channel carrying capacity, in comparison to that in the non‐vegetated zone. The flow velocities through the obstructed part of the channel, that is, canopy zone, in DLV arrangement reduced by a percentage difference of approximately 42 and 37% compared to that of SV and EV arrangements, respectively; whereas it was reduced by approximately 55% when the discharge was twice while keeping the same configuration of DLV. The inflectional instabilities and estimated mixing layer over the interfacial zone suggested a stronger lateral exchange of momentum for DLV configuration in comparison to that of SV and EV. Within the gaps between the patch zones, the flow velocity, turbulent kinetic energy, and turbulent intensity reduced significantly due to blockage effect and sheltering offered by the vegetation patches, signifying a positive flow response towards aquatic life and sediment deposition.

中文翻译：

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通过明渠中部分分布的不连续刚性植被研究湍流行为

河岸植被不仅影响河道的通流能力，而且在水管理，河流恢复和河流修复中也起着重要作用。本研究借助三维软件FLUENT（其中采用了雷诺应力湍流模型），对沿纵向不连续刚性植被占据河道一半宽度的水流特性进行了数值研究。考虑了三种不同的植被状况，包括垂直双层植被（DLV），水下植被（SV）和紧急植被（EV），同时保持了相同的植被密度，并测试了针对DLV的变化排放条件。结果表明，与通过EV的流量相比，通过EV的流量均匀分布在冠层柱上，通过DLV和SV的流动分布变得更加复杂，随后是在淹没的冠层周围的垂直速度剖面中具有拐点不稳定的多层。观测到的。与非植被区相比，由于植被的阻力，冠层区的速度大大降低，这影响了河道的承载能力。与SV和EV布置相比，DLV布置中通过通道阻塞部分（即顶篷区）的流速分别降低了约42％和37％的百分比差；而当放电两次时，在保持DLV相同配置的情况下，降低了约55％。与SV和EV相比，界面区域上的拐点不稳定性和估计的混合层表明DLV配置的动量横向交换更强。在斑块区域之间的间隙内，由于植被斑块提供的阻挡效应和遮挡作用，流速，湍流动能和湍流强度显着降低，表明对水生生物和沉积物的正向流动响应。