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Bed-load transport rate based on the entrainment probabilities of sediment grains by rolling and lifting

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International Journal of Sediment Research 2018年第2期33卷 126-136页

作者： Jun-De Li Jian Sun binliang lin College of Engineering and Science Victoria University State Key Laboratory of Hydroscience and Engineering Tsinghua University

A function for the bed-load sediment transport rate is derived. This function is obtained by using the entrainment probabilities of the rolling and lifted sediment grains, and by introducing two travel lengths,respectively. The predictions from the new bed-load function agree well with experimental results over the entire experimental range and show significant improvement over the commonly used formula for the bed-load transport rate. The new function shows that, in terms of contributing to the bed-load transport rate, the total entrainment probability of the sediment grains is a weighted summation of those for the lifted and rolling grains, rather than a simple addition of the two. The function is also used to predict the total entrainment probability, saltation length, and the bed layer thickness at a high bed-load transport rate. These predictions all agree well with the experimental results. It is found that, on average,the travel length for the rolling sand grains is about an order of magnitude less than that of the lifted grains.

关键词： Sedimentation Bed load Entrainment probability

Processes of dike-break induced flows:A combined experimental and numerical model study

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International Journal of Sediment Research 2017年第4期32卷 465-471页

作者： Jian Sun lingwei Lu binliang lin Lu Liu State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua University Guangzhou Metro Design & Research Institute

Dike breaking is a disaster that could cause extensive damage. It could lead to flood flows outside the dike and induce water level fluctuations in the main channel. Numerical models are increasingly used to simulate flood flows due to dike-break, because direct observations from field surveys and physical models are rather limited. Existing knowledge concerning dam-break flows cannot be applied directly to dike-break flows because the effect of channel discharge cannot be neglected in the latter. In this study,physical experiments are done in a large laboratory flume to simulate the process of dike-break induced flood wave propagation in the floodplain and flow fluctuations in the main channel. The variations of water levels and velocities are measured and recorded using an array of pressure sensors and two acoustic Doppler velocimetry devices. A numerical model has been set up according to the experimental layout. The experiments have high repeatability and the numerical model predictions agree closely with the physical model data. The experimental results provide reliable information for improving the understanding of dike-break flow dynamics and for the verification of numerical models.

关键词： Dike-break flow Hydrodynamics Physical experiment Numerical model Flooding River channel

Microbial diversity accumulates in a downstream direction in the Three Gorges Reservoir

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Journal of Environmental Sciences 2021年第3期33卷 156-167页

作者： Shang Wang Weiguo Hou Hongchen Jiang Liuqin Huang Hailiang Dong Shu Chen Bin Wang Yongcan Chen binliang lin Ye Deng CAS Key Laboratory of Environmental Biotechnology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China School of Environment and Resource Southwest University of Science and TechnologySichuan 621010China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing 100083China School of Ocean Sciences China University of GeosciencesBeijing 100083China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China Department of Geology and Environmental Earth Science Miami UniversityOxfordOH 45056USA

Organic and inorganic materials migrate downstream and have important roles in regulating environmental health in the river ***,it remains unclear whether and how a mixture of materials(i.e.,microbial species)from various upstream habitats contribute to microbial community coalescence upstream of a *** we track the spatial variation in microbial abundance and diversity in the Three Gorges Reservoir based on quantitative PCR and 16 S rRNA gene high-throughput sequencing *** further quantitatively assess the relative contributions of microbial species from mainstem,its tributaries,and the surrounding riverbank soils to the area immediately upstream of the Three Gorges Dam(TGD).We found an increase of microbial diversity and the convergent microbial distribution pattern in areas immediately upstream of TGD,suggesting this area become a new confluence for microbial diversity immigrating from ***,the number of shared species increased from upstream to TGD but unique species decreased,indicating immigration of various sources of microbial species overwhelms local environmental conditions in structuring microbial community close to *** quantifying the sources of microbial species close to TGD,we found little contribution from soils as compared to tributaries,especially for sites closer to TGD,suggesting tributary microbes have greater influence on microbial diversity and environmental health in the Three Gorges ***,our results suggest that tracking microbial geographic origin and evaluating accumulating effects of microbial diversity shed light on the ecological processes in microbial communities and provide information for regulating aquatic ecological health.

关键词： Three Gorges Dam Microbial source tracking Microbial community coalescence Immigration Accumulating effect

Modelling Open Channel Flows with Vegetation Using a Three-Dimensional Model

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Journal of Water Resource and Protection 2011年第2期3卷 114-119页

作者： Guanghai Gao Roger A. Falconer binliang lin 不详

The effects of vegetation on the flow structure are investigated in this paper. In previous studies of modelling vegetated flows, two-equation turbulence models, such as the model, were often used. However, this approach involves a level of uncertainty since the empirical coefficients in these two equations have not yet been satisfactorily obtained for such flow conditions. In addition to this, two extra partial differential equations needing which will result in an increase in the computational cost. The main purpose of the study was therefore to try and acquire accurate velocity profiles without the more advanced two-equation turbulence models. A three-dimensional model using a simple two layer mixing length model was therefore used. The governing hydrodynamic equations were refined to include the effects of drag force induced by vegetation on the flow structure. The model was applied to an experiment flume to study the flow field with vegetations, where experiment data are available. Distributions predicted by the model were compared with laboratory measured ones, with very good agreements being obtained. The results showed that the simple mixing length model could produce accurate complex velocity profile predictions requiring fewer coefficient data and less computation.

关键词： Hydrodynamic Turbulence Model Vegetation

Numerical Modelling Sediment-Bacteria Interaction Processes in the Severn Estuary

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Journal of Water Resource and Protection 2011年第1期3卷 22-31页

作者： Guanghai Gao Roger A. Falconer binliang lin 不详

Faecal bacteria exist in both free-living and attached forms in estuarine waters. The deposition of sediments can take faecal bacteria out of the water column and to the bed. The sediments can subsequently be re-suspended to the water column, which can then lead to re-suspension of the faecal bacteria of the attached forms back to the water column. Therefore, the fate and transport of faecal bacteria is highly related to the governing sediment transport processes, particularly where these processes are significant, such as the Severn Estuary, UK. However, little attempt has been made to model such processes in terms of predicting the impact of the sediment fluxes on faecal bacteria levels. Details are given of the refinement of a numerical model of faecal bacteria transport, where the sediment transport processes are significant. After testing the sediment-bacteria interaction model favourably against known results in previous study, the model was applied to the Severn Estuary and Bristol Channel, UK, to investigate the impact of suspended sediment fluxes on the corresponding faecal bacteria transport processes. The model predictions have proved to be encouraging, with the results being compared to a traditional faecal bacteria modelling approach, where sediment bacteria interactions were not included. The new model provides improved predictions of faecal bacteria concentrations when sediment transport is included and for the Bristol Channel Severn Estuary it can be seen that the effects of the sediments on the bacterial levels in the water column can be significant.

关键词： Numerical Modelling Faecal Bacteria Sediment Transport Enterococci

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水平轴潮流发电机作用下流场的动态模拟

太阳能学报 2016年第4期37卷 1050-1056页

作者：林杰林斌良陈娅玲孙健清华大学水利水电工程系北京100084

该研究的主要目的是寻找一种新的模拟方法,尽量精细地模拟出大范围流场中潮流发电机与流场的相互作用。根据这一目标,提出一种耦合叶素模型的水平轴潮流发电机的表示方法,并将它集成到有限差分算法之中。利用集成后的模型,对实验室尺度... 详细信息

该研究的主要目的是寻找一种新的模拟方法,尽量精细地模拟出大范围流场中潮流发电机与流场的相互作用。根据这一目标,提出一种耦合叶素模型的水平轴潮流发电机的表示方法,并将它集成到有限差分算法之中。利用集成后的模型,对实验室尺度的水轮机阵列实验进行模拟,并将模拟结果与实测数据进行对比。实验结果表明,该耦合模型可较好地模拟出水轮机阵列下游5倍直径以外的流场分布。

关键词：潮流能可再生能源水平轴评估水动力学

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流量非恒定性对河道演变影响机理的研究

水力发电学报 2014年第6期33卷 111-118页

作者：况宏伟孙健林斌良长江航道规划设计研究院武汉430011 清华大学水沙科学与水利水电工程国家重点实验室北京100084

河流流量在自然条件下大多都有一定的非恒定特性,它是河道演变的重要动力因素。为了增加流量非恒定性对河道演变规律的认识,课题开展了概化的物理模型河流试验,对不同流量过程作用下河道地形的变化进行了精细测量。模型试验包括三个组次... 详细信息

河流流量在自然条件下大多都有一定的非恒定特性,它是河道演变的重要动力因素。为了增加流量非恒定性对河道演变规律的认识,课题开展了概化的物理模型河流试验,对不同流量过程作用下河道地形的变化进行了精细测量。模型试验包括三个组次:恒定流量试验、突变流量试验和渐变流量试验。突变流量试验和渐变流量试验的结果以恒定流量试验作为参考进行对比分析。试验结果表明:1在上游斜道和二次流作用下河道发展出滩槽结构,浅滩包括两个部分,滩面较高的部分起到导流的作用,使得水流主流蜿蜒向前,并保护了滩面较低的浅滩不受主流侵蚀作用;2流量的非恒定特性使得原有的滩槽结构不断破坏,岸滩变得平整,主流变浅;3具有较大流量波动强度(均方差)的流量过程具有更强的岸滩冲刷能力,使得河道展宽增加。

关键词：河流动力学河道演变,物理模型试验非恒定流量恒定流量横向摆动弯道

城市暴雨地表积水过程研究：以清华大学校园为例

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水力发电学报 2019年第8期38卷 98-109页

作者：刘璐孙健袁冰林斌良清华大学水沙科学与水利水电工程国家重点实验室

我国正处于城市化的高速发展阶段,不透水地表面积增大,导致城市内涝风险增加。本研究考虑建筑物、道路、绿地和雨水口等城市地物特征,旨在对降雨-径流过程进行精细模拟,对地面排水系统的能力进行评估。采用二维水动力学模型,以北京市清... 详细信息

我国正处于城市化的高速发展阶段,不透水地表面积增大,导致城市内涝风险增加。本研究考虑建筑物、道路、绿地和雨水口等城市地物特征,旨在对降雨-径流过程进行精细模拟,对地面排水系统的能力进行评估。采用二维水动力学模型,以北京市清华大学校园为研究区域。通过两场降雨过程中积水点的实测水深对水动力学模型进行率定和验证,结果表明该高分辨率模型能够比较准确地计算出地表积水深度。在采用压强式水位计记录降雨过程中积水点压强时,必须同时记录大气压强的变化,否则水深会有一定的误差。基于上述结果,以2012年7月21日暴雨为例,对清华大学校园进行大暴雨情景的地表积水过程模拟,结果表明雨水口总排水量随降雨过程变化较大,地表积水主要通过雨水口排走,降雨结束时雨水口排水总量约占降雨总量的70.0%,而土壤入渗量较少,仅占降雨总量的11.1%。

关键词：水动力学模型地表积水高分辨率模拟实测水深大气压强

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连续丁坝回流特性实验研究

水力发电学报 2017年第10期36卷 84-92页

作者：韩晗张曼林斌良周建军清华大学水沙科学与水利水电工程国家重点实验室北京100084

丁坝是水利工程中最为常见的水工建筑之一,丁坝区产生的回流将引起复杂的河道流速分布和泥沙输移过程,对于船舶航行和水利工程有着重要的影响。现有丁坝水沙特性研究多集中于数学模型方面,现场实测资料和模型实验等直接观察得到的数据... 详细信息

丁坝是水利工程中最为常见的水工建筑之一,丁坝区产生的回流将引起复杂的河道流速分布和泥沙输移过程,对于船舶航行和水利工程有着重要的影响。现有丁坝水沙特性研究多集中于数学模型方面,现场实测资料和模型实验等直接观察得到的数据非常有限。本文通过室内大型水槽进行的实体模型实验,模拟水流在连续丁坝区的回流形态。通过粒子跟踪测速技术对全流场的水流流速、分布进行了测量,记录流量和水深过程,并对水流回流特性进行了分析。实验结果表明:(1)采用电磁流量计量测结果准确,水深变化过程稳定;(2)丁坝区的回流存在纵向零流速线,将其沿横向划分为主流区、回流正区和回流负区,沿纵向划分为增流区和减流区,横向障碍物前存在次生回流;(3)回流流量呈现中心稳定两侧迅速增减,最大可达上游来流量的50%。实验成果可为更加深入地研究丁坝区回流和泥沙冲淤特性提供可靠的数据,为数值模拟提供详细的验证资料,进而对航道设计及河岸维护等工程实际提供科学的支撑作用。

关键词：河流动力学丁坝模型实验回流区