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Science China(Technological Sciences) 2015年第7期58卷 1280-1288页

作者： DING Yun XIAO Yang zhong deyu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Water Conservancy and Hydropower Engineering Hohai University State Key Laboratory of Hydroscience and Engineering Tsinghua University

Resuspension of bed materials absorbing pollutants potentially poses unpredictable challenges to water management in alluvial rivers and its mechanism of transport has not been widely *** this study,a transport equation that defines the movement of pollutants adsorbed on the bed materials in the active bed layer is established,on the basis of mass conservation law and continuum *** transport equation is coupled into the 1-D mathematical model to numerically investigate water pollution process due to the scour of the bed sediment adsorbing *** with the situation in which the dynamics of the active bed layer is not considered indicate that the periodical evolution of the bed layer plays an innegligible role in the pollution process due to sediment ***,comparisons of the results with available experimental observations are presented,and fairly good agreement is obtained.

关键词： resuspension pollutants alluvial rivers active bed layer

A new mixing equation for bed material composition in bed form dominant conditions

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International Journal of Sediment Research 2022年第4期37卷 435-446页

作者： Baozhen Jia deyu zhong State Key Laboratory of Hydroscience and Engineering Tsinghua University Joint-Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai University

Vertical mixing beneath the bed surface and its effect on sediment composition has long been underestimated. This paper proposes a mixing equation to illustrate the temporal and spatial variations of bed material composition for bed form dominant rivers. A continuous mass conservation equation for elevation-specific nonuniform bed material composition is initially presented. A vertical mixing equation is finally derived as a diffusion-type partial differential equation with a source term characterized by a vertical diffusion coefficient and the geometric dimensions of bed forms. Coupled with boundary conditions, this equation is further developed in a vertical mixing model at the scale of bed forms, in which the variations of bed material composition are clearly illustrated. The equation accounts for vertical exchange fluxes driven by bed form migration and their effect on bed material composition, which helps elucidate the mixing mechanism. In application to riverbed degradation, the proposed equation is capable to describe armoring development in consideration of the interior mixing, which provides more satisfying predictions for bed surface materials. The new mixing equation helps gain insight into predicting the variations of bed material composition during morphological changes.

关键词： Mixing equation Active layer Bed forms Grain size distribution

Analytical solution to one-dimensional mathematical model of flow and morphological evolution in open channels

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Science China(Technological Sciences) 2020年第12期63卷 2606-2616页

作者： DING Yun LI ZuiSen SHI Yongzhong zhong deyu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310008China Zhejiang Provincial Key Laboratory of Hydraulic Disaster Prevention and Mitigation Hangzhou 310008China Joint-Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai UniversityXining 810016China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

The evolution of open-channel flow and morphology can be simulated by one-dimensional(1D) mathematical models. These models are typically solved by numerical or analytical methods. Because the behavior of variables can be explained by explicit mathematical determinations,compared to numerical solutions,analytical solutions provide fundamental and physical insights into flow and sediment transport mechanisms. The singular perturbation technique derives a hierarchical equation of waves and describes the evolutionary nature of disturbances in hyperbolic systems. The wave hierarchy consists of dynamic,diffusion,and kinetic waves. These three types of waves interact with each other in the process of propagation. Moreover,the Laplace transform is implemented to transform partial differential equations into ordinary differential equations. Analytical expressions in the wave front are subtracted by the approximation of kinetic and diffusion models. Moreover,an analytical solution consists of a linear combination of the kinetic wave front and the diffusion wave front expressions,pursuing to describe the physical mechanism of motion in open channels as completely as possible. Analytical solutions are presented as a combination of exponential functions,hyperbolic functions,and infinite series. The obtained analytical solution was further applied to the simulation of flood path and morphological evolution in the Lower Yellow River. The phenomenon of increased peak discharge in the downstream reach was successfully simulated. It was encouraging that the results were in good agreement with the observed data.

关键词： open channel mathematical model analytical solution Laplace transform morphological evolution

Particle inertia effect on sediment dispersion in turbulent open-channel flows

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Science China(Technological Sciences) 2014年第10期57卷 1977-1987页

作者： ZHANG Lei zhong deyu WU BaoSheng State Key Laboratory of Hydroscience and Engineering Tsinghua University

Particle inertia effect plays a significant role in sediment dispersion which has not been fully *** this paper,the profound effect of particle inertia on the sediment dispersion was *** theoretical expression for the drift velocity based on the two-phase mixture theory in turbulent open channels is firstly *** influence of particle inertia on sediment dispersion was investigated through three different aspects including vertical dispersion,motion,and flux properties based on the drift *** show that the dispersion of suspended sediment in turbulent open-channel flows is affected by three major processes including turbulence of water sediment mixtures,particle random motion,and collisions among particles,of which the contributions of particle turbulence and collisions to the sediment dispersion are remarkable for particles of high *** respect to the vertical mean velocity and sediment flux,it shows that the predictive results agree well with the measurements when the term of particle inertia is *** a result,particle inertia considerably affects the behavior of suspended *** particular,the influence of inertia must be accounted for in circumstances of flows laden with high-inertia particles.

关键词： inertia effect suspended sediment dispersion

Coupling mechanism of mathematical models for sediment transport based on characteristic theory

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Science China(Technological Sciences) 2016年第11期59卷 1696-1706页

作者： DING Yun LI ZuiSen zhong deyu KANG YanPing State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310008 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Jiangsu Hydraulic Research Institute Nanjing 210017 China

This paper aims to explore the coupling mechanism between flow movement, sediment transport and riverbed evolution in currently widely used mathematical models for sediment transport. Based on characteristic theory, analytic forms of eigenvalues,eigenvectors and characteristic relationships of total-sediment transport model, bed-load transport model and suspenedload transport model were derived, respectively. The singular perturbation technology was implemented to obtain the asymptotic solutions to different families of eigenvalues. The results indicate that, interactions between motion variables were explicitly coupled in the characteristics of total-sediment transport model and bed-load transport model. Further qualitative and quantitative analysis demonstrates that high sediment transport intensity and significant riverbed change will inevitably affect the property of flow movement. In the process of deposition, sediment-laden flow will move faster when sediment transport intensity becomes stronger. In contrast, the wave of flow will propagate at slower speed as erosion intensity becomes *** most existing suspended-load transport models, however, the characteristics are decoupled as the interactions between motion variables cannot be integrally illustrated in eigenvalues, eigenvectors and characteristic relationship.

关键词： coupling mechanism mathematical models sediment transport characteristics eigenvalues

Effect of sediment particles on the velocity profile of sediment-water mixtures in open-channel flow

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International Journal of Sediment Research 2023年第3期38卷 361-373页

作者： Lei Zhang Jianzhao Guan deyu zhong Yousheng Wang State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Joint Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai University State Key Laboratory of Hydroscience and Engineering Tsinghua University

The presence of sediment particles in open-channel flow has an important effect on turbulence; thus, an empirical, turbulent eddy viscosity formula was established for application in the limit for low concentrations. The current study establishes a theoretical relation for the mixture viscosity based on the two-phase mixture model. The percentage contribution of the three mechanisms of mixture viscosity,namely, fluid turbulence(FT), particle turbulence(PT), and inter-particle collisions(IPCs), was calculated under different conditions. The study results indicate that the contribution of FT is dominant, whereas those of PT and IPCs are not significant when the particle inertia(PI) is small, suggesting that the movement of sediment-laden flows is mainly controlled by the fluid properties. The effects of PT and IPCs increase with increases in sediment concentration and PI. Specifically, the effect of collisions among particles generally becomes dominant near the bed surface. A good agreement between the calculated velocity profile of the mixture and available experimental data for large particle sizes and high concentrations proves that the proposed relation for mixture viscosity is more reasonable than the previous empirical relation owing to the consideration of the effects of PT and IPCs, and, thus, can be applied to both dilute and dense suspensions.

关键词： Velocity profile Sediment particles Viscosity Collisions Turbulence

Simulating cross-sectional geometry of the main channel in response to changes in water and sediment in Lower Yellow River

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Journal of Geographical Sciences 2020年第12期30卷 2033-2052页

作者： WANG Yanjun WU Baosheng zhong deyu Key Laboratory of River Regulation and Flood Control of Ministry of Water Resources Yangtze River Scientific Research InstituteWuhan 430010China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

To understand the non-equilibrium morphological adjustment of a river in response to environmental changes,it is essential to(i)accurately identify how past conditions of water and sediment have impacted current morphological adjustment of the river,and(ii)establish a corresponding simulation for non-equilibrium *** on discharge and suspended sediment concentration(SSC)as well as 82 cross-sectional data items for the Huayuankou-Lijin reach of the Lower Yellow River in the period 1965-2015,the process of adjustment of the geometry of the main channel(area,width,depth,and geomorphic coefficient),and its responses to changes in discharge and SSC for different reaches are statistically *** this,a delayed response model(DRM)of the geometry of the main channel subjected to variations in discharge and SSC is established using a multi-step analytical model,with the discharge and SSC as the main controlling *** results show that the area,width,and depth of the main channel decreased initially,then increased,decreased again,and finally increased *** features of the geometry of the channel were positively correlated with the 4-year moving average discharge and negatively with the 4-year moving average *** geomorphic coefficient for the Huayuankou-Sunkou reach exhibited a trend of decrease,whereas that of the Sunkou-Lijin reach decreased initially,then increased,decreased again,and finally increased *** for the Huayuankou-Gaocun reach in 1965-1999,the coefficient was negatively correlated with the 4-year moving average discharge and positively with *** simulated values of the morphological parameters of the main channel for all sub-reaches obtained using the DRM agreed well with the measured *** indicates that the DRM can be used to simulate the process of response of the cross-sectional geometry of the main channel to variations in the water and *** results of the model show that the adjustment of th

关键词： Lower Yellow River water and sediment changes cross-sectional geometry of the main channel delayed response model

Simulations of granular flow along an inclined plane using the Savage-Hutter model

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Particuology 2012年第2期10卷 236-241页

作者： Minglong Fei Qicheng Sun deyu zhong Gordon G.D.Zhou State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

In this work a velocity-dependent friction is introduced into a depth-averaged 5avage-Hutter dynamical model for shallow granular flows. The process of granular material flowing along an inclined plane and then depositing on a horizontal plane is simulated. The surface profiles and evolution of various types of energy are investigated and compared when using the standard Coulomb-type friction versus velocity- dependent friction. Interestingly, there is a small difference between the two different types of friction.

关键词： Granular flowsDynamics frictionSavage-Flutter model

Stochastic evolution of hydraulic geometry relations in the lower Yellow River of China under environmental uncertainties

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International Journal of Sediment Research 2020年第4期35卷 328-346页

作者： Xiaolong Song deyu zhong Guangqian Wang Xiaonan Li State Key Laboratory of Hydro-science and Engineering Tsinghua University State Key Laboratory of Hydraulic Engintering Simulation and Safety Tianjin University Changjiang Survey PlanningDesign and Research Co.Ltd

Hydraulic geometry relations comprise a classic way to understand characteristics of a ***,environmental changes pose large uncertainties for the reliability of such *** the current study,on the basis of the ordinary differential equations(ODEs) formed through linear treatment of the deterministic power-law hydraulic geometry relations,a set of stochastic differential equations(SDEs)driven by Fractional white noise and Poisson noise are developed to simulate the historical dynamic probability distributions of typical hydraulic geometry variables such as slope,width,depth,and velocity with bankfull discharge variation over time in the lower Yellow River of *** group of possible stochastic average behaviors within the next 50 years are calculated under three different design incoming water-sediment conditions(including 300,600,and 800 million t of annual average sediment discharge).In each part of the lower reaches,after estimation of the SDE parameters using a nonparametric maximum likelihood estimation(MLE) method,the model is carefully examined using Monte Carlo simulation as compared with the deterministic control *** results of this comparison reveal the potential responses of hydraulic geometry characteristics to environmental disturbances,and the average trends mainly agree with the *** among the three different prediction results reveal the stochastic average solution generally is greater than the deterministic *** results also confirm the severe negative impacts that result from the condition of 300 million t of incoming sediment,thus,pointing out the need to raise the level of river evolution alert for the lower Yellow River of China in the ***,with the help of the stochastic computation,the stream power and hydraulic width/depth ratio could be representative of an effective systematic measure for river *** proposed stochastic approach is not only important to development in t

关键词： Hydraulic geometry relations Environmental uncertainties Stochastic differential equation Lower Yellow River River system

Adjustment in the main-channel geometry of the lower Yellow River before and after the operation of the Xiaolangdi Reservoir from 1986 to 2015

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Journal of Geographical Sciences 2020年第3期30卷 468-486页

作者： WANG Yanjun WU Baosheng zhong deyu State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

Based on the measured discharge,sediment load,and cross-sectional data from 1986 to 2015 for the lower Yellow River,changes in the morphological parameters(width,depth,and cross-sectional geomorphic coefficient)of the main channel are analyzed in this *** results show that before the operation of the Xiaolangdi Reservoir(XLDR)from 1986 to 1999,the main channel shrunk continually,with decreasing width and *** rate of reduction in its width decreased along the river whereas that of depth increased in the downstream *** the rate of decrease in the width of the main channel was greater than that in channel depth,the cross-sectional geomorphic coefficient decreased in the sub-reach above *** contrast,for the sub-reach below Gaocun,the rate of decrease in channel width was smaller than that in channel depth,and the cross-sectional geomorphic coefficient *** the XLDR had begun operation,the main channel eroded continually,and both its width and depth increased from 2000 to *** rate of increase in channel width decreased in the longitudinal direction,and the depth of the main channel in all sub-reaches increased by more than 2 *** the rate of increase in the depth of the main channel was clearly larger than that of its width,the cross-sectional geomorphic coefficient decreased in all *** cross-sectional geometry of the main-channel of the lower Yellow River exhibited different adjustment patterns before and after the XLDR began *** its operation,the main channel mainly narrowed in the transverse direction and silted in the vertical direction in the sub-reach above Aishan;in the sub-reach below Aishan,it primarily silted in the vertical *** the XLDR began operation,the main channel adjusted by widening in the transverse direction and deepening in the vertical direction in the sub-reach above Aishan;in the sub-reach below it,the main channel adjusted mainly by deepening in the vertical

关键词： lower Yellow River changes in water and sediment conditions Xiaolangdi Reservoir geometry of main channel