Vegetation flow is commonly studied for subcritical flow motions, while in supercritical flow, the presence of vegetation often leads to enhancement of flow self-aeration, which would in turn alter the flow hydraulics and water-plant interaction. This paper presents an experimental investigation of aerated water flow cascading down a vegetated stepped chute. The 21.8° sloping chute is equipped with a 12-m-long uniformly stepped invert section. The 0.12-m-high steps have grate-shaped rough top surface covered by 0.07-m-high flexible artificial plants, and three vegetation densities are tested in skimming flows, in addition to the reference cases of smooth steps and rough steps covered by bare grate only. The air-water flow properties and free-surface fluctuations are systematically measured from the upstream clear-water region to the downstream fully developed aerated region. The experiment results demonstrate that, compared to a man-made concrete stepped chute, the presence of vegetation cover on the steps reduces the overall self-aeration and unsteady fluctuating motions of the flow, while it enhances the dissipation of the flow kinetic energy. The present finding also suggests that the modification to flow aeration and energy loss in the vegetated flow over macrostep-shaped roughness is dependent on the flow regime which is primarily determined by the flow rate for a given slope and step-induced macroroughness height.

中文翻译：

---

超临界水流冲下人工植被阶梯溜槽的自曝气

植被流动通常被研究用于亚临界流动运动，而在超临界流动中，植被的存在通常会导致流动自曝气增强，这反过来会改变流动水力学和水厂相互作用。本文介绍了曝气水流从植被阶梯式溜槽中倾泻而下的实验研究。21.8° 斜槽配有 12 米长的均匀阶梯倒置部分。0.12米高的台阶有篦形粗糙的顶面被0.07米高的柔性人造植物覆盖，除了光滑台阶和粗糙台阶被裸露覆盖的参考案例外，在撇流中测试了三种植被密度只有炉排。系统地测量了从上游清水区到下游充分发育的充气区的气水流动特性和自由表面波动。实验结果表明，与人造混凝土阶梯溜槽相比，阶梯上植被覆盖的存在减少了整体的自曝气和流动的不稳定波动，同时增强了流动动能的耗散。目前的发现还表明，在宏观台阶形粗糙度上对植被流中流动曝气和能量损失的修改取决于流态，这主要由给定坡度的流速和台阶引起的宏观粗糙度高度决定。台阶上植被覆盖的存在减少了水流的整体自曝气和不稳定的波动运动，同时增强了水流动能的耗散。目前的发现还表明，在宏观台阶形粗糙度上对植被流中流动曝气和能量损失的修改取决于流态，这主要由给定坡度的流速和台阶引起的宏观粗糙度高度决定。台阶上植被覆盖的存在减少了水流的整体自曝气和不稳定的波动运动，同时增强了水流动能的耗散。目前的发现还表明，在宏观台阶形粗糙度上对植被流中的流动曝气和能量损失的修改取决于流动状态，这主要由给定坡度的流速和台阶引起的宏观粗糙度高度决定。