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Swimming behavior of juvenile silver carp near the separation zone of a channel confluence

International Journal of Sediment Research 2022年第1期37卷 122-127页

作者： Saiyu Yuan Lei Xu Hongwu Tang Yang Xiao Colin Whittaker State Key Laboratory of hydrology-water resources and Hydraulic Engineering Hohai University Yangtze Institute for Conservation and Development Department of Civil and environmental Engineering The University of Auckland

Knowledge of locomotion of fish near river confluences is important for prediction of fish distribution in a river *** flow separation zone near the confluence of a river network is a favorite habitat and feeding place for silver carp,which is one of the four major species of Chinese carp and usually provides positive rheotaxis to water *** the current study,a series of laboratory experiments were done to determine the behavioral responses of juvenile silver carp to the hydrodynamic forces near the separation zone of a channel *** locomotion and trajectory of juvenile silver carp were recorded by infrared thermal imaging,while the flow velocity field near the separation zone was measured by a Particle Image Velocimetry (PIV) system.A total of 60 juvenile silver carp were released near the separation zone among which 40 carp swam in the upstream *** them,24 carp swam to the tributary and the remaining 16 swam into the main *** all these 24 carp travelled initially along the boundary of the separation zone near the corner,where flow shear was strongest,and then swam to the *** of avoiding zones of strong vorticity,they chose and followed a trajectory along which the flow vorticity was *** encountering these vortical flows,they increased the tailbeat frequency and decreased the tail-beat amplitude to maintain body *** observations provide important knowledge on locomotion of fish near river confluences and are beneficial for the fish habitat protection.

关键词： Channel confluence Flow separation Juvenile silver carp Fish locomotion

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Incipient motion of cohesionless sediments on riverbanks with ground water injection

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International Journal of Sediment Research 2012年第1期27卷 111-119页

作者： Yan LU Yong-jun LU Yee-meng CHIEW Nanjing Hydraulic Research Institute State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering School of Civil and environmental Engineering Nanyang Technological Univ.

This study investigates the influence of ground water injection on the initial movement of non-cohesive sediment particles on a riverbank slope analytically and *** including the hydraulic gradient in the force analysis,the critical condition was derived to account for the effect of seepage flow, showing that the seepage hydraulic gradient and the riverbank slope are governing parameters in modifying the incipient motion of sediments on a riverbank *** investigations were performed in an open-channel flume for various riverbank slopes and hydraulic gradients of injection, showing that the critical shear stress increases with decreasing riverbank slopes and vise-versa,while injection reduces the critical *** experimental data agree well with the theoretical derived expression of the critical condition in the case of injection.

关键词： Incipient motion Riverbank Injection Sediment Seepage

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Non-invasive image processing method to map the spatiotemporal evolution of solute concentration in two-dimensional porous media

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Journal of Hydrodynamics 2018年第4期30卷 758-761页

作者：钱家忠王泽坤 R.M.Garrard Yong Zhang 马雷 School of resources and environmental Engineering Hefei University of Technology The 3rd Engineering Co. LTD of China Railway 16thBureau Group Department of Geological Sciences University of Alabama State Key Laboratory of hydrology-water resources and Hydraulic Engineering Hohai University

A color visualization-based image processing method is developed in this paper to quantify the concentration evolution of the Brilliant Blue FCF transport through a two-dimensional homogeneous porous medium. A series of images are recorded at known time intervals, then the spatial distribution is estimated using a calibration curve, linking the gray pixel value to the solute concentration. Using a multi-dimensional concentration distribution map extraction technique the longitudinal and transverse concentration distributions could be observed with the physical model. The image-processed concentrations are then compared directly with the measured concentrations sampled at the outlet end. The tracer breakthrough curves sampled at multiple points along the central line of the medium are also compared with the solutions from the standard advection–dispersion equation model. It is shown that the non-invasive image processing method may be used to map the spatiotemporal evolution of a solute＇s concentration without disturbing the flow or the transport dynamics, although the measured solute breakthrough curves feature some non-Fickian dynamics that cannot be efficiently captured by the standard transport model.

关键词： Solute transport color tracer porous media image processing method

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Back analysis of mechanical parameters of roller compacted concrete dam

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Science China(Technological Sciences) 2010年第3期53卷 848-853页

作者： GU ChongShi 1,2,3,LI Bo 1,XU GuangLei 4 &YU Hong 1,2,3 1 State Key Laboratory of hydrology-water resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China 2College of water Conservancy Hydropower,Hohai University,Nanjing 210098,China 3National Engineering Research Center of water resources Engineering Safety,Efficient Utilization and Nanjing 210098,China 4 Nanjing Hydraulic Research Institute,Nanjing 210029,China State Key Laboratory of hydrology-water resources and Hydraulic Engineering Hohai University College of water Conservancy Hydropower Hohai University National Engineering Research Center of water resources Engineering Safety Nanjing Hydraulic Researc

In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam *** the process of back analysis,the initial samples of parameters were designed with uniform design ***,a transversely isotropic model of RCCD was established by *** *** this model,training samples of LSSVM model could be *** then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was ***,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using *** inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be *** example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.

关键词： roller compacted concrete dam mechanical parameters back analysis

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Speciation and potential remobilization of heavy metals in sediments of the Taihu Lake, China

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Chinese Journal Of Geochemistry 2007年第4期26卷 384-393页

作者： YUAN Xuyin DENG Xu SHEN Zhiyong GAO Yun State Key Laboratory of hydrology-water resources and Hydraulic Engineering Nanjing 210098 China College of environmental Sciences and Engineering Hohai University Nanjing 210098 China

The species of Cu, Pb, Zn, Cd and Cr in sediments of the Taihu Lake, China, have been analyzed using the sequential chemical extraction method. Variations in the chemical fractions of these metals and their geographic distributions have also been studied. For all five metals, the residual fraction is highest but the exchangeable fraction is lowest among all the fractions. Compared to other metals, Cd has the highest percentage in the exchangeable fraction, and Cr is associated mainly with the residual fraction. Cu in the organic fraction and Pb in the Fe-Mn fraction are the important species, whereas the lowest percentages are found for Cd in the organic fraction, Cu in the Fe-Mn oxide fraction and Pb in the carbonate fraction. With respect to spatial differences, the total contents in the non-residual fractions of the metals in bay sediments are found to be higher than those in other sediments. The fractions of Cd, Cu and Cr showed significant variations in different regions. The fractions of Pb and Zn, however, did not show significant variations in spatial distribution, suggesting different amounts and different paths of anthropogenic input for the metals. Comparisons of the metal speciation indicated that Cd might be the most bioavailable metal, followed by Pb.

关键词：重金属沉积物物种形成太湖中国

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Application of Hausdorff fractal derivative to the determination of the vertical sediment concentration distribution

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International Journal of Sediment Research 2023年第1期38卷 12-23页

作者： Hongguang Sun Shiqian Nie Aaron I.Packman Yong Zhang Dong Chen Chengpeng Lu Chunmiao Zheng State Key Laboratory of hydrology-water resources and Hydraulic Engineering Hohai University College of Mechanics and Materials Hohai University College of Mathematics and Systems Science Shandong University of Science and Technology Department of Civil and environmental Engineering Northwestern University Department of Geological Sciences University of Alabama Institute of Geographic Sciences and Natural resources Research Chinese Academy of Sciences College of hydrology and water resources Hohai University School of environmental Science and Engineering Southern University of Science and Technology

The Rouse formula and its variants have been widely used to calculate the steady-state vertical concentration distribution for suspended sediment in steady sediment-laden flows, where the diffusive flux is assumed to be Fickian. Turbulent flow, however, exhibits fractal properties, leading to non-Fickian diffusive flux for sediment particles. To characterize non-Fickian dynamics of suspended sediment, the current study proposes a Hausdorff fractal derivative based advection-dispersion equation(HADE)model, where the Fickian diffusive flux in the Rouse model is replaced by a fractal derivative re-scaled using a constant diffusivity. The order of the Hausdorff fractal derivative is designed to characterize the influence of the multi-fractal turbulence structure on sediment diffusion. Applications show that the HADE model, with the analytical solution expressed using a stretched exponential function, can accurately describe the observed vertical concentration profiles for suspended sediment with different *** improvement well captures the non-exponential decay of the vertical sediment concentration in turbulent flow. Further analyses of measured sediment concentration profiles reveal that the Hausdorff fractal order decreases with the Rouse parameter, which describes the stronger impact of turbulent flow and a more uniform sediment concentration profile for smaller particles. Model comparisons also show that the HADE model provides better performance in describing the sediment concentration profiles than the improved Rouse formula and the standard fractional derivative advection-dispersion equation(FADE), which either under-or over-estimates vertical displacement of sediment particles, likely due to coherent turbulent structures.

关键词： Anomalous diffusion Hausdorff fractal derivative Vertical concentration distribution Suspended sediment Metric transform

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Initiatives to clarify mechanisms of hydrological evolution in human-influenced Yellow River Basin

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water Science and Engineering 2023年第2期16卷 117-121页

作者： Li-liang Ren Shan-shui Yuan Xiao-li Yang Shan-hu Jiang Gui-bao Li Qiu-an Zhu Xiu-qin Fang Yi Liu Yi-qi Yan State Key Laboratory of hydrology-water resources and Hydraulic Engineering Hohai UniversityNanjing 210098China College of hydrology and water resources Hohai UniversityNanjing 210098China Yangtze Institute for Conservation and Development Hohai UniversityNanjing 210098China Chinese Hydraulic Engineering Society Beijing 100053China hydrology Bureau Yellow River Conservancy CommissionMinistry of Water ResourcesZhengzhou 450003China

Significant changes in water cycle elements/processes have created serious challenges to regional sustainability and high-quality development in the Yellow River Basin in *** is necessary to investigate the impacts of climate change and human activities on hydrological evolution and disaster risk from a holistic perspective of the *** study developed initiatives to clarify the mechanisms of hydrological evolution in the human-influenced Yellow River *** proposed research method includes:(1)a tool to simulate multiple factors and a multi-scale water cycle using a grid-based spatiotemporal coupling approach,and(2)a new algorithm to separate the responses of the water cycle to climate change and human impacts,and de-couple the eco-environmental effects using artificial intelligence *** this research framework,key breakthroughs are expected to be made in the understanding of the impacts of land cover change on the water cycle and blue/green water *** outcomes of this research project are expected to provide theoretical support for ecological protection and water governance in the basin.

关键词： Climate change Human activities Hydrological evolution Runoff change Yellow River Basin

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NUMERICAL SIMULATION FOR SHALLOW FLOW AND POLLUTANT DISPERSION BASED ON QUAD-TREE MESHES

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Journal of Hydrodynamics 2006年第2期18卷 161-169页

作者： LIU Xiao-dong HUA Zu-lin State Key Laboratory of hydrology-water resources and Hydraulic Engineering Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow LakesCollege of Environmental Science and Engineering Hohai UniversityNanjing 210098 China

A 2D depth-averaged flow-pollutant coupled model based on quad-tree meshes was established to accurately simulate flows in water areas with irregular natural boundaries in this paper. The grids were generated by recursive subdivision about seeding points. A new neighbor-finding algorithm was presented. The governing equations were discrctized in collocated conservative variables by using the finite volume method, and the normal flux of mass, momentum and pollutants across the interlace between cells were computed by a Godunov-type Flux Difference Splitting （FDS） scheme. The model was applied to simulate flow fields around a groin. The computed values are in agreement with observed data. The results indicate that quad-tree meshes have fine local resolution, high efficiency and easy local refinement. It is clear that the quad-tree grid model can offer gains in efficiency when applied to complex flow domains or strong shear flows. Finally the model is applied to flow fields and concentration fields simulation in Jiangsu Haizhou Bay. The simulated polluted area is matched well with observations. Therefore, this model can be used to predict flow and concentration fields of actual water area with irregular natural land boundaries.

关键词： quad-tree grid shallow flow numerical simulation dispersion Godunov-type

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Taylor Dispersion of Contaminants by Dual-peak Spectral Random Waves

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China Ocean Engineering 2019年第5期33卷 537-543页

作者： HUANG Guo-xing Adrian Wing-Keung LAW GUO Xiao-meng State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China School of Civil and environmental Engineering and environmental Process Modelling Centre Nanyang Environment and Water Resources Institute (NEWRI) Nanyang Technological University Singapore 639798 Singapore State Key Laboratory of hydrology-water resources and Hydraulic Engineering Nanjing Hydraulic Research Institute Nanjing 210029 China

Recent extensive and important studies have provided detailed information and compelling evidence on how the presence of waves influences the vertical diffusivity/dispersivity in the coastal environment, which can affect various water quality considerations such as the distribution of suspended sediments in the water column as well as the potential of eutrophication. Comparatively, how the presence of waves influences the horizontal diffusivity/dispersivity has received only scant attention in the literature. Our previous works investigated the role played by the Taylor mechanism due to the wave-induced drift profile which leads to the longitudinal dispersion of contaminants in the horizontal direction, under regular sinusoidal waves and random waves with single-peak spectra. Natural waves in the coastal environment, however, often possess dual-peak spectra, comprising both higher frequency wind waves and lower frequency swells. In this study, the Taylor dispersion of contaminants under random waves with dual-peak spectra is examined through analytical derivation and numerical calculations. The effects of various dual-peak spectral parameters on the horizontal dispersion, including the proportion of lower frequency energy, peak frequency ratio and spectral shape parameter, are investigated. The results show that the relative energy distribution between the dual peaks has the most significant effect. Compared with single-peak spectra with equivalent energy, the Taylor dispersion with dual-peak spectra is stronger when the lower frequency is close to the peak frequency of the single-peak spectrum, and weaker with the higher frequency instead. Thus, it can be concluded that with a dual-peak wave spectrum, wind-dominated seas with higher frequency lead to stronger dispersion in the horizontal direction than swell-dominated seas with lower frequency.

关键词： Taylor dispersion dual-peak spectrum random waves

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Damage and progressive failure of concrete structures using non-local peridynamic modeling

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Science China(Technological Sciences) 2011年第3期54卷 591-596页

作者： HUANG Dan1,2, ZHANG Qing1,2 & QIAO PiZhong1,3 1 State Key Laboratory of hydrology-water resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China 2 Department of Engineering Mechanics, Hohai University, Nanjing 210098, China 3 Department of Civil and environmental Engineering, Washington State University, Pullman, WA 99164-2910, USA State Key Laboratory of hydrology-water resources and Hydraulic Engineering Hohai University Department of Engineering Mechanics Hohai University

Peridynamics (PD), a recently developed theory of solid mechanics, which employs a non-local model of force interaction and makes use of integral formulation rather than the spatial partial differential equations used in the classical continuum mechanics theory, has shown effectiveness and promise in solving discontinuous problems at both macro and micro scales. In this paper, the peridynamics theory is used to analyze damage and progressive failure of concrete structures. A non-local peridynamic model for a rectangular concrete plate is developed, and a central pairwise force function is introduced to describe the interior interactions between particles within some definite distance. Damage initiation, evolution and crack propagation in the concrete model subject to in-plane uni-axial tension, in-plane uni-axial compression and out-of-plane impact load are investigated respectively. The numerical results show that discontinuities appear and grow spontaneously as part of the solution to the peridynamic equations of motion, and no special failure criteria or re-meshing techniques are required, which proves the potential of peridynamic modeling as a promising technique for analyzing the progressive failure of concrete materials and structures.

关键词： concrete damage progressive failure peridynamic model discontinuities

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