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| 1 | The structure of turbulent flow through submerged flexible vegetation显示文摘The hydrodynamics of turbulent flow through submerged flexible vegetation is investigated in a flume using acoustic Doppler velocimetery(ADV)measurements.The flow characteristics such as the energetics and momentum transfer derived from convcntional spectral and quadrant analyses are considered as the flow encounters a finite vegetation patch.Consistent with numerous canopy flow experiments,a shear layer and coherent vortex structures near the canopy top emerge caused by Kelvin-Helmholtz instabilities after the flow equilibrates with the vegetated layer.These in stabilities are commonly attributed to velocity differences between non-vegetated and vegetated canopy layers in agreement with numerous experiments and simulations conducted on dense rigid canopies.The power-spectral density function for vertical velocity turbulent fluctuations at different downstream positions starting from the edge of the vegetation layer are also computed.For a preset water depth,the dominant dimensionless frequency is found to be surprisingly invariant around 0.027 despite large differences in vegetation densities.The ejection and sweep events significantly contribute to the Reynolds stresses near the top of the vegetation.The momentum flux carried by ejections is larger than its counterpart carried by the sweeps above the canopy top.However,the momentum flux carried by sweeps is larger below the top of the canopy. | Wen-xin Huai Jiao Zhang Gabriel G.Katul Yong-guang Cheng Xue Tang Wei-jie Wang | 2019 | Journal of Hydrodynamics2019，31，2： | 26 |
| 2 | Flow dynamics and sediment transport in vegetated rivers:A review显示文摘The significance of riparian vegetation on river flow and material transport is not in dispute.Conveyance laws,sediment erosion and deposition,and element cycling must all be adjusted from their canonical rough-wall boundary layer to accommodate the presence of aquatic plants.In turn,the growth and colonization of riparian vegetation are affected by fluvial processes and river morphology on longer time scales.These interactions and feedbacks at multiple time scales are now drawing significant attention within the research community given their relevance to river restoration.For this reason,a review summarizing methods,general laws,qualitative cognition,and quantitative models regarding the interplay between aquatic plants,flow dynamics,and sediment transport in vegetated rivers is in order.Shortcomings,pitfalls,knowledge gaps,and daunting challenges to the current state of knowledge are also covered.As a multidisciplinary research topic,a future research agenda and opportunities pertinent to river management and enhancement of ecosystem services are also highlighted. | Wen-xin Huai Shuolin Li Gabriel G.Katul Meng-yang Liu Zhong-hua Yang | 2021 | Journal of Hydrodynamics2021，33，3： | 20 |
| 3 | 植物对明渠流速分布影响的试验研究显示文摘采用圆柱铝棒模拟刚性植物进行水槽试验,利用激光流速仪LDV对含非淹没、淹没植物明渠流场进行了测量,对模拟植物淹没度、密度对流速分布的影响进行了研究.分析表明,植物非淹没条件下的平均流速可以表示为流量、渠宽、水深和植物密度的函数;植物淹没条件下,很难用统一的函数描述平均流速沿水深的分布,植物层上部和内部与顶部处的流速偏离有随淹没度、密度的增大而增大的规律,相同宽深比条件下,含淹没植物明渠和无植物明渠相比,最大流速位置前者高于后者,植物'抬高床面'或是减小了有效宽深比的作用. | 闫静 唐洪武 田志军 何晔 | 2011 | 水利水运工程学报2011，，4： | 18 |
| 4 | Interactions between vegetation, water flow and sediment transport: A review显示文摘The vegetation, as one of the most important components, plays a key role in the aquatic environment. This paper reviews recent progress on the complex interaction between the vegetation and the water flow. Meanwhile, the relationships between the vegetation and the sediment transport are discussed. The vegetation characteristics, such as the shape, the flexibility and the height, have significant effects on the flow structures. The density and the arrangement of the vegetation influence the flow velocity in varying degrees and the flow resistance increases with the increase of the plant density. In turns, the growth of aquatic plants is influenced by the water flow via the direct effect(stretching, breakage, uprooting, etc.) and the indirect effect(changes in gas exchange, bed material distribution, sediment resuspension etc.). Numerical models were developed and widely used for the flow through vegetated waterways, and the results could be applied to solve engineering problems in practice. The sediment is essential for the survival of most vegetation. The existence of the vegetation helps to resist the deformation and the erosion of the bed sediment, to maintain the bed stability and to improve the water quality by removing suspended particles. Additionally, the effects of the sediment transport on the growth of the vegetation mainly consist of the reduction of their photosynthetic capacity by decreasing the water transparency and hindering the exchange of gas and nutrients between plants and water by attaching particles to plant leaves. Therefore, the interaction between the vegetation and the sediment transport is great and complicated. In order to establish a healthy aquatic ecosystem, it is important to study the relationships between the vegetation, the water flow and the sediment transport. | 王超 郑莎莎 王沛芳 侯俊 | 2015 | Journal of Hydrodynamics2015，27，1： | 17 |
| 5 | A random walk simulation of scalar mixing in flows through submerged vegetations显示文摘The scalar transport phenomena in vertical two-dimensional flows are studied using the random walk method. The established Lagrangian model is first applied to study the idealized longitudinal dispersion in open channels, before being used to investigate the scalar mixing characteristics of the flows through submerged vegetations. The longitudinal dispersion coefficients of the fully-developed boundary layer flows, with and without vegetations, are calculated based on the positions of the particles. A convenient way of incorporating the effects of vegetations is proposed, where all the flow parameters are regarded to be continually distributed over the depth. The simulation results show high accuracy of the developed random walk method, and indicate that the new method of accounting for the vegetation effects is appropriate for all the test cases considered. The predicted longitudinal dispersion coefficients agree well with the measurements. The merit of the new method is highlighted by its simplicity and efficiency in comparison with the conventional method that assumes the discontinuous distribution of the flow parameters over the depth. | 梁东方 WU Xuefei | 2014 | Journal of Hydrodynamics2014，26，3： | 12 |
| 6 | NUMERICAL MODEL FOR FLOW THROUGH SUBMERGED VEGETATION REGIONS IN A SHALLOW LAKE显示文摘Aquatic vegetation has a significant impact on water currents. To evaluate the effects of changes in the aquatic vegetation on water currents of different velocity, a 3-D hydrodynamic model was then developed by taking into consideration of the additional hydraulic resistance of the aquatic plants. The Navier-Stokes equations were then solved using the SIMPLE method and the k-ε turbulence model. Calculations using the established models were used to forecast the vertical distribution of the horizontal velocity and horizontal flow under the transmission conditions of the South-North Water Diversion in the Nansi Lake. And comparative calculation for the flow velocity was also performed using the simplified method of assigning a high roughness coefficient to the lake bed in the same area. Results suggest that adding additional hydraulic resistance of the aquatic plants is feasible. The calculation errors between simulation result and the field observed data are smaller than 15%, while, those errors are up to 35% if the influence of aquatic vegetation is dealt with the simplified method. | WANG Pei-fang WANG Chao | 2011 | Journal of Hydrodynamics2011，23，2： | 11 |
| 7 | FLOW STRUCTURE IN PARTIALLY VEGETATED RECTANGULAR CHANNELS显示文摘This article discusses the transverse distributions of the depth averaged velocity and the Reynolds stress in a steady uniform flow in partially vegetated rectangular channels.The momentum equation is expressed in dimensionless form and solved to obtain the depth averaged velocity.The analytical solution of the velocity in dimensionless form shows that the depth-averaged velocity is determined by gravity and its distribution is mainly determined by the frictions due to water or vegetations.The analytical solution of the Reynolds stress is also obtained.A relationship between the second flow and the inertia is established and it is assumed that the former is proportional to the square of the depth averaged velocity.The Acoustic Doppler Velocimeter(Micro ADV) was used to measure the steady uniform flow with emergent artificial rigid vegetation.Comparisons between the measured data and the computed results show that our method does well in predicting the transverse distributions of the stream-wise velocity and the Reynolds stress in rectangular channels with partially vegetations. | CHEN Gang HUAI Wen-xin HAN Jie ZHAO Ming-deng | 2010 | Journal of Hydrodynamics2010，22，4： | 11 |
| 8 | LARGE EDDY SIMULATION OF OPEN CHANNEL FLOWS WITH NONSUBMERGED VEGETATION显示文摘Results of several Large Eddy Simulations (LES) of open channel flows with non-submerged vegetation are presented in this article. It is shown that the vegetation can make the flow structure in the mainstream direction uniform for both supercritical and subcritical flows. For subcritical flows, the LES results of the ensemble-average of time-averaged velocity distributions at four vertical sections around a single plant are in good agreement with measurements. The velocity sees double peaks at the upper and lower positions of flows. For supercritical flows, the ensemble-average velocities see some discrepancy between LES and measurement results. Some secondary flow eddies appear near the single plant, and they just locate in the positions of the double peaks in stream-wise velocity profiles. It is also found that the vegetation drag coefficient deceases as the Froude number increases. | HUAI Wen-xin WU Zhen-lei QIAN Zhong-dong GENG Chuan | 2011 | Journal of Hydrodynamics2011，23，2： | 11 |
| 9 | FACTORS INFLUENCING THERMAL STRUCTURE IN A TRIBUTARY BAY OF THREE GORGES RESERVOIR显示文摘To better understand the factors influencing the thermal structure of tributaries in the Three Gorges Reservoir(TGR),a well validated three-dimensional hydrodynamic and water temperature model was proposed to simulate the water temperature distribution in the Xiangxi Bay, a representative tributary of TGR.The numerical results show that water temperature stratification seasonally occurred in the Xiangxi Bay, with stable vertical temperature profiles.It is found from the numerical experiments that three key factors are responsible for the formation of water temperature structure:(1) very often,the locations of thermocline are mainly determined by wind speeds, and the higher the wind speed is, the deeper the thermocline is located beneath the water surface,which could be expressed by a fitted exponential function,(2) the thermal structure is affected by static stability of water column, and the thermocline becomes closer to the water surface and its thickness increases with the increase of temperature, (3) due to the effect of the thermal density inflow, the water temperature of the hypolimnion tends to be uniform, however, even under the condition of larger inflow discharge,the influence of the inflow on the epilimnion and the thermocline is not significant. | YU Zhen-zhen WANG Ling-ling | 2011 | Journal of Hydrodynamics2011，23，4： | 9 |
| 10 | Effects of vegetation patch density on flow velocity characteristics in an open channel显示文摘The aquatic plants are often found in natural rivers,and they affect the channel flow structure significantly.To study the effects of the vegetation density a(the frontal area per volume)on the flow velocity characteristics,rigid bamboo circular cylinders are chosen as the model emergent vegetation.In the experiments,the density of the vegetation takes various values while all other flow parameters are kept constant.A 3-D acoustic Doppler velocimeter(ADV)is used to measure the local flow velocities for different vegetation densities.The results show that the existence of the vegetation patch leads to an increase of the depth-averaged velocity on the right and left sides behind the vegetation patch,and it increases monotonically with the vegetation density.For different vegetation densities,the lateral distribution of the stream-wise velocity behind the vegetation patch follows approximately an S-shaped profile when a≤60 m-1,and a logarithmic profile if a>60 m-1.The vertical distribution of the stream-wise velocity along the channel varies with the vegetation density and also follows an S-shaped distribution in a certain range,with the locations and the ranges being affected by the vegetation density. | Wen-qi Li Dan Wang Jun-li Jiao Ke-jun Yang | 2019 | Journal of Hydrodynamics2019，31，5： | 8 |
| 11 | The characteristics of secondary flows in compound channels with vegetated floodplains显示文摘The experiments were conducted in compound channels with vegetated floodplains for investigating the influence of vegetation types on the characteristics of secondary flows. In terms of the streamwise and transverse velocities and the depth-averaged velocity, the secondary flow coefficient, M , is proposed, with good physical meanings, and it may characterize the rotational direction and the intensity of the secondary currents. The experimental results show that, for the cases without vegetation and with grass, the rotational directions of the secondary flows are all anticlockwise while for the cases with shrubs, they are all changed to the clockwise direction in the whole cross-section. However, when trees are planted, the secondary flows rotate in the anticlockwise direction in the main channel and in the clockwise direction on the floodplain. In addition, for all cases, the intensities of the secondary currents on the floodplain are stronger than those in the main channel. | 刘超 单钰淇 杨克君 刘兴年 | 2013 | Journal of Hydrodynamics2013，25，3： | 7 |
| 12 | HYBRID SIMULATION OF THE HYDRAULIC CHARACTERISTICS AT RIVER AND LAKE CONFLUENCE显示文摘The hydraulic characteristics at the confluence reach of river and lake are influenced by multiple factors such as inflow,topography and vegetation resistance,and are very complicated.In this article,the confluence reach of Yangtze River and Dong-ting Lake is selected as a special example and a hybrid model is built to study the flow at this confluence,with the consideration of the interactions between aquatic vegetation and flow.Validation tests and calculations show that the model is effective and highly accurate.The simulations show that the separation levee at the confluence reach may change the discharge capacity in the flood plain,which would be enhanced in the upper reach of the levee,hardly changed in the middle reach and reduced at the lower place.Moreover,the separation levee also limits the water exchange between the Yangtze River and Dong-ting Lake. | LIU Shi-he CAO Bing | 2011 | Journal of Hydrodynamics2011，23，1： | 4 |
| 13 | 沉水植物对水流结构与泥沙淤积的影响显示文摘为了研究水生植物对水流结构和泥沙淤积的影响,针对不同布置的沉水植物进行33组浑水水槽试验.结果表明,矮株植物区流速冠顶下为二次多项式分布,以上为对数分布;考虑相对株距的影响,建立矮株植物区紊动强度的双高斯垂线分布公式,按该公式计算的流速和紊动强度与实测资料较吻合.高株植物区流速呈“C”型分布,紊动强度以冠顶附近最大.3种株距布置时,混合植物冠顶以下平均流速为无植物时的32.5%~72.3%.提出小弗汝德数(Fr≤0.18)条件下矮株植物区相对淤积增量与水流强度和相对株距的非线性关系.在相同水流和株距下,混合植物淤积量高达无植物时的7倍,高株植物次之,随着株距的减小促淤效果逐渐增强. | 孙志林 郑佳芸 祝丽丽 种琳 刘俊 罗居元 | 2021 | 浙江大学学报(工学版)2021，55，1： | 3 |
| 14 | An improved formula for incipient sediment motion in vegetated open channel flows显示文摘Quantifying incipient sediment motion in vegetated open channel flow is pivotal for estimating bed load transport and the aquatic ecological environment in rivers.A new formula is developed to predict the critical flow velocity for incipient sediment motion in the presence of emergent vegetation,by incorporating the influence of vegetation drag that characterizes the effects of mean flow and turbulence on sediment movement.The proposed formula is shown to agree with existing experimental data.Moreover,the proposed formula is extended to scenarios with submerged vegetation,suggesting that the vegetation drag may be the inherent impact factor for incipient sediment motion in vegetated open channel flow. | Xiang Wang Wenxin Huai Zhixian Cao | 2022 | International Journal of Sediment Research2022，37，1： | 3 |
| 15 | 基于机器学习的含植被水流流速分布研究显示文摘引入机器学习的方法,对含植被渠道断面流速分布进行预测,分析水流与植被的相互作用机理。基于变量间的物理关系,得到机器学习模型的输入、输出项,结合非淹没刚性植被模型试验数据,并利用BP神经网络、RBF神经网络、支持向量回归SVR和随机森林RF四种机器学习方法对预处理后的数据集进行学习和建模。最后,通过模糊意见集中决策方法中的Borda数,对四种模型进行综合评价。结果表明:机器学习模型可以根据具体数据进行自适应建模,具有良好的工程应用前景;机器学习模拟结果与试验测量结果吻合较好,说明机器学习方法可有效预测含植被水流流速分布结构;其中BP神经网络的整体性能最好,综合使用4种模型的计算值可提高结果精度。 | 韩宇 刘家备 穆同 刘晓东 唐良川 | 2020 | 中国农村水利水电2020，，6： | 2 |
| 16 | Analytical solution of velocity distribution for flow through submerged large deflection flexible vegetation显示文摘An analytical solution for predicting the vertical distribution of streamwise mean velocity in an open channel flow with submerged flexible vegetation is proposed when large bending occurs. The flow regime is separated into two horizontal layers: a vegetation layer and a free water layer. In the vegetation layer, a mechanical analysis for the flexible vegetation is conducted, and an approximately linear relationship between the drag force of bending vegetation and the streamwise mean flow velocity is observed in the case of large deflection, which differes significantly from the case of rigid upright vegetation. Based on the theoretical analysis, a linear streamwise drag force-mean flow velocity expression in the momentum equation is derived, and an analytical solution is obtained. For the free water layer, a new expression is presented, replacing the traditional logarithmic velocity distribution, to obtain a zero velocity gradient at the water surface.Finally, the analytical predictions are compared with published experimental data, and the good agreement demonstrates that this model is effective for the open channel flow through the large deflection flexible vegetation. | Wei-jie WANG Wen-xin HUAI Yu-hong ZENG Ji-fu ZHOU | 2015 | Applied Mathematics and Mechanics(English Edition)2015，36，1： | 2 |
| 17 | Impacts of ship movement on the sediment transport in shipping channel显示文摘The duration of ship-generated waves(wake waves) and accelerated currents can generate significant influences on the sediment transport. A 3-D numerical model is presented to estimate these effects. The hydrodynamic model is the 3-D Reynolds averaged Navier-Stokes(RANS) equations including the standard k-ε model while the 3-D convection-diffusion model is for the resuspended sediment transport. This hydro-sedimentary model is firstly validated with the trench experimental results, and then applied to the open channel with a moving ship. The computed results demonstrate that the resuspension generation mainly depends on ship speeds, barge number, and the relative distance away from ship. The acceleration effects of ship on the sediment transport are analyzed as well. | JI Sheng-cheng OUAHSINE Abdellatif SMAOUI Hassan SERGENT Philippe JING Guo-qing | 2014 | Journal of Hydrodynamics2014，26，5： | 1 |
| 18 | Incipient sediment motion in vegetated open-channel flows predicted by critical flow velocity显示文摘Incipient sediment motion plays a key role in scouring and bed load transport. However, the incipient sediment motion in the vegetated open-channel flows has yet to be fully understood. This study aims to quantify the critical conditions of the sediment particle movement in the presence of emergent and submerged vegetation. A new formula of the critical flow velocity was proposed to predict the incipient sediment motion based on the force balance equation of a sediment particle and the assumption that the velocity distribution in the bed roughness boundary layer fits the logarithmic law. Analysis of the derived formula revealed that the critical flow velocity for incipient sediment motion decreases with the increase in vegetation density. The proposed formula agrees well with the experimental data in the literature, thereby implying that the critical flow velocity can effectively quantify the incipient sediment motion in the vegetated open channel flows. | Xiang Wang Shuolin Li Zhong-hua Yang Wen-xin Huai | 2022 | Journal of Hydrodynamics2022，34，1： | 1 |
| 19 | 山区河流植被洲滩河段水沙运动特性试验研究显示文摘山区河流受水沙条件和河流形态影响,植被洲滩发育丰富,显著改变局部河段的水沙运动及其演变特征。基于室内洲滩模型自然生长植被的水沙试验,探讨了植被与泥沙补给对洲滩河段水流结构及冲淤变形的影响。试验结果表明:植被茎叶加大了对水流的扰动,减缓水流流速,上游补给泥沙在植被周围形成小型沙丘,以波状输移为主;大量来沙条件下,泥沙多落淤洲头及洲尾,促使洲滩快速发育;淹没植被枯萎,茎叶凋落,加剧洲头及洲滩两侧冲刷;植被与上游来沙显著影响洲滩汊道分流特性,加沙和植被茎叶促使左汊分流比降低。因此,山区河流植被与上游泥沙补给调整洲滩汊道过流能力及发育过程,对植被洲滩河段的水沙运动产生较大影响。 | 叶晨 许泽星 关见朝 方春明 王协康 | 2020 | 工程科学与技术2020，52，1： | 1 |
| 20 | 植被茎秆倾伏角变化对明渠水流结构的影响显示文摘【目的】分析植被茎秆倾伏角变化对明渠水流结构流态的影响,充分发挥河道水生植被功能以减缓河堤的侵蚀和水土流失的速率。【方法】建立明渠植被水流结构模型将水流液层在空间高度上分为植被层和自由层,在茎秆不同的变形状态下及流量范围内开展试验。【结果】①在同一茎秆倾伏角下,植被层V_(v)随水深h增加呈增加减少再增加最终趋于稳定的变化规律,自由层平均速度Vs、雷诺数Re_(s)、弗劳德数Fr_(s)随水深h的增大迅速减小后趋于稳定。②不同茎秆倾伏角下,植被层水力参数V_(v)、Re_(v)、Fr_(v)在空间上表现出各向异性,自由层V_(s)、Re_(s)、Fr_(s)随植被倾伏角θ增大而减小,植被淹没临界水深h存在“滞后”现象。【结论】自由层的水流流速V_(s)、雷诺数Re_(s)、弗劳德数Fr_(s)均大于植被层;植被层水流流态为缓紊流,自由层水流流态从急紊流迅速过渡到缓紊流。 | 刘明 张升堂 张景洲 赵庆星 孙桤汶 王磊 | 2021 | 灌溉排水学报2021，40，8： | 0 |
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