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Journal of Hydrodynamics 2018年第4期30卷 564-572页

作者： Mohammad Mahdi Jalali alistair g.l.borthwick Institute for Energy Systems School of Engineering The University of Edinburgh

A model is presented of particle advection near groynes in an open channel. Open channel hydrodynamics is modelled using the shallow water equations, obtained as the depth-averaged form of Reynolds-averaged continuity and Navier-Stokes momentum equations. A lagrangian particle-tracking model is used to predict trajectories of tracer particles advected by the flow field, with bilinear interpolation representing the continuous flow field. The particle-tracking model is verified for chaotic advection in an alternating flow field of a pair of blinking vortices. The combined shallow flow and lagrangian particle-tracking model is applied to the simulation of tracer advection in flow past a pair of side-wall cavities separated by a groyne, and in an open rectangular channel containing a pair of parallel groynes oriented normal to the channel wall. The study is potentially useful in understanding mixing processes in shallow flow fields near hydraulic structures in wide rivers.

关键词： Shallow water equations lagrangian particle tracking chaotic advection blinking vortices side-wall cavities groynes

Tracer advection in an idealised river bend with groynes

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Journal of Hydrodynamics 2018年第5期30卷 780-790页

作者： Mohammad Mahdi Jalali alistair g.l.borthwick Institute for Energy Systems School of Engineering The University of Edinburgh

This paper presents numerical simulations of particle advection in the bend of an open channel containing groynes, which is an idealised form of a shallow river bend in a wide river. The flow field is computed using a boundary-fitted solver of the non-orthogonal, curvilinear shallow water equations. The computational grid is generated by solving Poisson-type elliptic partial differential equations using an iterative multi-grid scheme for prescribed boundary coordinates. The shallow water equations are discretised with finite differences in space, and 4 t h order Runge-Kutta integration in time. Tracers introduced at specific initial locations have their trajectories computed using lagrangian particle tracking. The numerical shallow flow model is verified by comparison to the analytical solution of fully developed flow in an open channel. The combined shallow flow and lagrangian particle-tracking model is then used to simulate the advection of tracer particles in a rectangular channel containing a pair of parallel groynes, and tracer particles in a curved open channel containing groynes, of dimensions roughly equivalent to a Danube River bend.

关键词： Shallow water equations tracer advection lagrangian particle curvilinear coordinates system river bend groynes

Flow and magnetic structures in a kinematic ABC-dynamo

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Science China(Physics,Mechanics & Astronomy) 2020年第8期63卷 95-100页

作者： Tao Zhang Zhiliang lin ChenYang Huang alistair g.l.borthwick State Key laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China School of Engineering The University of EdinburghEdinburgh EH93JLUK

Dynamo theory describes the magnetic field induced by the rotating,convecting and electrically conducting fluid in a celestial *** classical ABC-flow model represents fast dynamo action,required to sustain such a magnetic *** this letter,lagrangian coherent structures(lCSs)in the ABC-flow are detected through Finite-time lyapunov exponents(FTlE).The flow skeleton is identified by extracting intersections between repelling and attracting *** the case A=B=C=1,the skeleton structures are made up from lines connecting two different types of stagnation points in the *** corresponding kinematic ABC-dynamo problem is solved using a spectral method,and the distribution of cigar-like magnetic structures *** links are found to exist between lCSs in the ABC-flow and induced magnetic structures,which provides insight into the mechanism behind the ABC-dynamo.

关键词： kinematic dynamo theory ABC-flow lagrangian coherent structure

Numerical analysis of the performance of a three-bladed vertical-axis turbine with active pitch control using a coupled unsteady Reynolds-averaged Navier-Stokes and actuator line model

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Journal of Hydrodynamics 2023年第3期35卷 516-532页

作者： Rui-wen Zhao Angus C.W.Creech Ye li Vengatesan Venugopal alistair g.l.borthwick laboratory of Multi-function Towing Tank State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China School of Engineering and Physical Sciences Heriot-Watt UniversityEdinburghUK School of Engineering The University of EdinburghEdinburghUK School of Engineering Computing and MathematicsUniversity of PlymouthPlymouthUK

In this paper,we present a numerical model of a vertical-axis turbine(VAT)with active-pitch torque *** model is based upon the Wind and Tidal Turbine Embedded Simulator(WATTES)and WATTES-V turbine realisations in conjunction with the actuator line method(AlM),and uses OpenFOAM to solve the unsteady Reynolds-averaged Navier-Stokes(URANS)equations with two-equation k-εturbulence *** novel pitch-controlled system is based on an even pressure drop across the entire rotor to mitigate against dynamic stall at low tip speed *** numerical model is validated against experimental measurements and alternative numerical predictions of the hydrodynamic performance of a 1:6 scale UNH-RM2 hydrokinetic *** deploying the variable pitch mechanism exhibit improved turbine performance compared to measured data and fixed zero-pitch model ***-wake characteristics are investigated by examining the vorticity distribution near the *** pitch-controlled system is demonstrated to theoretically decrease turbulence generated by turbine rotations,mitigate the intensity of vortex shedding and size of detached vortices,and significantly enhance the performance of a vertical-axis hydrokinetic turbine for rated tip-speed ratios.

关键词： Vertical-axis turbine pitch control hydrodynamic performance unsteady Reynolds-averaged Navier-Stokes(URANS) numerical simulation

Marine Renewable Energy Seascape

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Engineering 2016年第1期2卷 69-78页

作者： alistair g.l.borthwick School of Engineering The University of Edinburgh

Energy production based on fossil fuel reserves is largely responsible for carbon emissions, and hence global warming. The planet needs concerted action to reduce fossil fuel usage and to implement carbon mitigation measures. Ocean energy has huge potential, but there are major interdisciplinary problems to be overcome regarding technology, cost reduction, investment, environmental impact, governance, and so forth. This article briefly reviews ocean energy production from offshore wind, tidal stream, ocean current, tidal range, wave, thermal, salinity gradients, and biomass sources. Future areas of research and development are outlined that could make exploitation of the marine renewable energy （MRE） seascape a viable proposition; these areas include energy storage, advanced materials, robotics, and informatics. The article concludes with a sustainability perspective on the MRE seascape encompassing ethics, leg- islation, the regulatory environment, governance and consenting, economic, social, and environmental constraints. A new generation of engineers is needed with the ingenuity and spirit of adventure to meet the global challenge posed by MRE.

关键词： Marine renewable energy Offshore wind Tidal stream Ocean current Tidal range Wave energy Ocean thermal energyBioenergySustainability

Erosion-deposition patterns and depo-center movements in branching channels at the near-estuary reach of the Yangtze River

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Frontiers of Earth Science 2020年第3期14卷 537-552页

作者： Boyuan Zhu Jinyun Deng Jinwu Tang Wenjun Yu alistair g.l.borthwick Yuanfang Chai Zhaohua Sun Yitian li School of Hydraulic Engineering Changsha University of Science&TechnologyChangsha410114China Key laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province Changsha410114China State Key laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Changjiang Institute of Survey PlanningDesign and ResearchWuhan430010China Changjiang Waterway Institute of Planning Design&ResearchWuhan430040China School of Engineering The University of EdinburghThe King’s BuildingsEdinburghEH93JLUK Department of Earth Sciences Vrije Universiteit AmsterdamBoelelaan 10851081 HVAmsterdamThe Netherlands

Channel evolution and depo-center migrations in braided reaches are significantly influenced by variations in *** study examines the effect of runoff variations on the erosion-deposition patterns and depocenter movements within branching channels of the near-estuary reach of the Yangtze *** assume that variations in annual mean duration days of runoff discharges,ebb partition ratios in branching channels,and the erosional/depositional rates of entire channels and sub-reaches are representative of variations in runoff intensity,flow dynamics in branching channels,and morphological features in the *** results show that the north region of Fujiangsha Waterway,the liuhaisha branch of Rugaosha Waterway,the west branch of Tongzhousha Waterway,and the west branch of langshansha Waterway experience deposition or reduced erosion under low runoff intensity,and erosion or reduced deposition under high runoff intensity,with the depocenters moving upstream and downstream,*** waterway branches undergo opposite trends in erosion-deposition patterns and depo-center movements as the runoff *** morphological changes may be associated with trends in ebb partition ratio as the runoff discharge rises and *** flattening the intra-annual distribution of runoff discharge,dam construction in the Yangtze Basin has altered the ebb partition ratios in waterway branches,affecting their erosion-deposition patterns and depo-center *** trends are likely to continue into the future due to the succession of large cascade dams under construction along the upper Yangtze and ongoing climate change.

关键词： near-estuary reach Yangtze River runoff discharge ebb partition ratio erosion-deposition pattern depo-center movement

Solving the mystery of vanishing rivers in China

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National Science Review 2019年第6期6卷 1239-1246页

作者： Yichu Wang Jinren Ni Yao Yue Jiaye li alistair g.l.borthwick Ximing Cai An Xue li li guangqian Wang The Key laboratory of Water and Sediment Sciences Ministry of EducationCollege of Environmental Sciences and Engineering Peking University Beijing Innovation Center for Engineering Science and Advanced Technology Peking University State Key laboratory of Plateau Ecology and Agriculture Qinghai University School of Water Resources and Hydropower Engineering Wuhan University State Key laboratory of Hydroscience and Engineering Tsinghua University School of Engineering The University of Edinburgh Ven Te Chow Hydrosystems lab Department of Civil and Environmental EngineeringUniversity of Illinois

A major controversy was sparked worldwide by a recent national water census claiming that the number of Chinese rivers with watersheds ≥100 km2was less than half the previous estimate of 50 000 rivers, which also stimulates debates on the potential causes and consequences. Here, we estimated the number of rivers in terms of stream-segmentation characteristics described by Horton, Strahler and Shreve stream-order rules, as well as their mixed mode for named rivers recorded in the Encyclopedia of Rivers and lakes in *** a result, the number of ‘vanishing rivers’ has been found to be highly relevant to statistical specifications in addition to the erroneous inclusion of pseudo-rivers primarily generated in arid or frost-thaw areas. The modified Horton stream-order scheme reasonably depicts the configuration of complete natural streams from headwater to destination, while the Strahler largely projects the fragmentation of the named river networks associated with human aggregation to the hierarchical river systems.

关键词： vanishing rivers river network stream segmentation stream-order rules

Three gorges Dam: friend or foe of riverine greenhouse gases?

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National Science Review 2022年第6期9卷 81-89页

作者： Jinren Ni Haizhen Wang Tao Ma Rong Huang Philippe Ciais Zhe li Yao Yue Jinfeng Chen Bin li Yuchun Wang Maosheng Zheng Ting Wang alistair g.l.borthwick Key laboratory for Water and Sediment Sciences Ministry of Education College of Environmental Sciences and Engineering Peking University State Environmental Protection Key laboratory of All Materials Fluxes in River Ecosystems Ministry of Ecology and Environment laboratoire des Sciences du Climat et de l'Environnement Institut Pierre Simon LaplaceCommissariat à l' énergie Atomique et aux énergies AlternativesCNRS Université de Versailles Saint-Quentinen-Yvelines Key laboratory of Reservoir Environment Chongqing Institute of Green and Intelligent TechnologyChinese Academy of Sciences State Key laboratory of Water Resources and Hydropower Engineering Science Wuhan University Department of Water Environment China Institute of Water Resources and Hydropower Research MOE Key laboratory of Regional Energy Systems Optimization Resources and Environmental Research AcademyNorth China Electric Power University School of Engineering The University of Edinburgh

Dams are often regarded as greenhouse gas(gHg) emitters. However, our study indicated that the world’s largest dam, the Three gorges Dam(TgD), has caused significant drops in annual average emissions of CO2, CH4and N2O over 4300 km along the Yangtze River, accompanied by remarkable reductions in the annual export of CO2(79%), CH4(50%) and N2O(9%) to the sea. Since the commencement of its operation in 2003, the TgD has altered the carbonate equilibrium in the reservoir area, enhanced methanogenesis in the upstream, and restrained methanogenesis and denitrification via modifying anoxic habitats through long-distance scouring in the downstream. These findings suggest that ‘large-dam effects’ are far beyond our previous understanding spatiotemporally, which highlights the fundamental importance of whole-system budgeting of gHgs under the profound impacts of huge dams.

关键词： Three gorges Dam greenhouse gas spatiotemporal variation equilibrium Yangtze River whole system analysis

High-quality reconstruction of China’s natural streamflow

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Science Bulletin 2022年第5期67卷 547-556,M0004页

作者： Chiyuan Miao Jiaojiao gou Bojie Fu Qiuhong Tang Qingyun Duan Zhongsheng Chen Huimin lei Jie Chen Jiali guo alistair g.l.borthwick Wenfeng Ding Xingwu Duan Yungang li Dongxian Kong Xiaoying guo Jingwen Wu State Key laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China State Key laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Key laboratory of Water Cycle and Related land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of land and Resources China West Normal UniversityNanchong 637009China State Key laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China State Key laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China College of Hydraulic and Environmental Engineering China Three Gorges UniversityYichang 443002China Engineering Research Center of Eco-environment in Three gorges Reservoir Region Ministry of EducationChina Three Gorges UniversityYichang 443002China School of Engineering the University of Edinburghthe King’s BuildingsEdinburgh EH93JLUK Changjiang River Scientific Research Institute Wuhan 430010China Institute of International Rivers and Eco-security Yunnan UniversityKunming 650091China

Reconstruction of natural streamflow is fundamental to the sustainable management of water *** China,previous reconstructions from sparse and poor-quality gauge measurements have led to large biases in simulation of the interannual and seasonal variability of natural *** we use a well-trained and tested land surface model coupled to a routing model with flow direction correction to reconstruct the first high-quality gauge-based natural streamflow dataset for China,covering all its330 catchments during the period from 1961 to 2018.A stronger positive linear relationship holds between upstream routing cells and drainage areas,after flow direction correction to 330 *** also introduce a parameter-uncertainty analysis framework including sensitivity analysis,optimization,and regionalization,which further minimizes biases between modeled and inferred natural streamflow from natural or near-natural *** resulting behavior of the natural hydrological system is represented properly by the model which achieves high skill metric values of the monthly streamflow,with about 83%of the 330 catchments having Nash-Sutcliffe efficiency coefficient(NSE)>0.7,and about56%of the 330 catchments having Kling-gupta efficiency coefficient(KgE)>*** proposed construction scheme has important implications for similar simulation studies in other regions,and the developed low bias long-term national datasets by statistical postprocessing should be useful in supporting river management activities in China.

关键词： Natural streamflow Reconstruction land surface model Parameter uncertainty analysis

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浅水水沙耦合动力学方程的数值解法

浅水水沙耦合动力学方程的数值解法