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Numerical Simulation of Nonlinear Radiation Water Surface Wave Caused by Large-Amplitude Oscillation of A Cylinder

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Communications in Nonlinear Science and Numerical Simulation 1999年第1期4卷 24-28页

作者： Wuzhou HE (department of hydraulic Engineering, Tsinghua University, Beijing 100084, China) department of hydraulic Engineering Tsinghua University Beijing 100084 China

The BEM combined with the time-stepping scheme is employed in the nonlinear numerical simulation of the development process of radiation wave profile and hydrodynamic force caused by large amplitude oscillating cylinder. To ensure stability and accuracy of the simulation, special consideration is paid on a series of difficulties in numerical modeling, such as the compatibility of free surface and body surface conditions at the intersection point and the open boundary condition problem. Numerical calculation is carried out for some study cases of different shaped cylinders undergoing large amplitude oscillating motions with distinct modes, the results show. some nonlinear phenomena and indicate the feasibility of the numerical approach.

关键词： 2-D water surface wave boundary element method time-stepping scheme

Properties of Leakage Corrosion of Concrete and Its Durability

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Journal of Wuhan University of Technology(Materials Science) 2008年第6期23卷 946-949页

作者：戈雪良 department of Materials and Structural Engineering Nanjing Hydraulic Research Institute

The properties and mechanism of concrete under water leakage corrosion were studied in terms of the dissolution of calcium oxide and silicon oxide from concrete and the variation of pH value of permeate *** experimental results show that the amount of calcium oxide and silicon oxide dissolved from per cubic meter of concrete gradually decrease with penetration time and ultimately stabilize at a certain *** pH value of permeate water descend along with penetration *** durability of concrete under leakage corrosion was analyzed by a formula fitted on the dissolved amount of calcium oxide.

关键词： concrete leakage corrosion properties durability

The physical simulation of wave groups and their variations in a wave flume

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Acta Oceanologica Sinica 2013年第11期32卷 68-73页

作者： LIU Si ZHANG Yongliang LIU Shuxue LI Jinxuan XIA Zhisheng State Key Laboratory of Hydroscience and hydraulic Engineering Department of Hydraulic EngineeringTsinghua University State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

The physical simulation method of wave groups in a wave flume is proposed and verified by the exper- iments. The experimental results demonstrate that random waves with desired wave groupiness, which simultaneously includes the wave group height and length, can be generated satisfactorily at the specified position in a wave flume using the proposed method. Furthermore, the transformation properties of the wave groupiness along the fiat-bottomed wave flume are investigated based on the physically simulated waves. Associated proposals with the physical simulation of wave groups are given.

关键词： wave groups wave groupiness physical simulation wave flume

A Target Tracking System for Applications in hydraulic Engineering

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Tsinghua Science and Technology 2008年第S1期13卷 343-347页

作者：沈乔楠安雪晖 department of hydraulic and Hydropower Engineering Tsinghua University

A new type of digital video monitoring system (DVMS) named user defined target tracking system (UDTTS), was developed based on the digital image processing (DIP) technology and the practice demands of construction site management in hydraulic engineering. The position, speed, and track of moving targets such as humans and vehicles, which could be calculated by their locations at anytime in images basically, were required for management. The proposed algorithm, dependent on the context-sensitive moving information of image sequences which was much more than one or two images provided, compared the blobs’ properties in current frame to the trajectories of targets in the previous frames and then corresponded them. The processing frame rate is about 10fps with the image 240-by-120 pixels. Experimental results show that position, direction, and speed measurements have an accuracy level compatible with the manual work. The user-define process makes the UDTTS available to the public whenever appropriate.

关键词： target tracking system digital image processing user-defined consecutive trajectory

A 2D Mathematical Model for Sediment Transport by Waves and Tidal Currents

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China Ocean Engineering 2005年第4期19卷 571-586页

作者：陆永军左利钦邵学军王红川李浩麟 Nanjing hydraulic Research Institute State's Key Laboratory of HydrologyWater Resourcesand Hydraulic Engineering Science Nanjing210029China department of hydraulic Engineering Tsinghua University Beijing100084China

In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed.

关键词： wave tidal current mathematical model suspended load bed load mud back silting waterway

3D mathematical model for suspended load transport by turbulent flows and its applications

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Science China(Technological Sciences) 2004年第2期47卷 237-256页

作者： LU Yongjun1,DOU Guoren1,HAN Longxi2,SHAO Xuejun3 & YANG Xianghua1,3 1.Nanjing hydraulic Research Institute,Nanjing 210029,China 2.College of Environmental Engineering of Hohai University,Nanjing 210098,China 3.department of hydraulic Engineering,Tsinghua University,Beijing 100084,China Nanjing hydraulic Research Institute Nanjing China College of Environmental Engineering of Hohai University Nanjing China department of hydraulic Engineering Tsinghua University Beijing China

This paper presents a 3D mathematical model for suspended load transport in turbulent flows. Based on Dous stochastic theory of turbulent flow, numerical schemes of Reynolds stresses for anisotropic turbulent flows were obtained. A refined wall function was employed to treat solid wall boundaries. The equations for 2D suspended load motion and sorting of bed material have been expanded into 3D cases. Numerical results are validated by the measured data of the Gezhouba Project, and proved to be in good agreement with the experimental. The present method has been employed to simulate sediment erosion and deposition in the dam area of Three Gorges Project, and for the operation of the project, siltation process and deposition pattern in the near-dam area of the reservoir, size distribution of the deposits and bed material, and flow fields and sediment concentration fields at different time and elevations are predicted. The predicted results are close to the experimental observations in physical model studies. Thus, a new method is established for 3D simulation of sediment motion in dam areas of multi-purpose water projects.

关键词： turbulent flows, Dou's stochastic theory, nonuniform suspended load, riverbed erosion and deposition, 3D mathematical model, Three Gorges Project.

A zero-flux principle for extracting secondary flows in arbitrary vertical planes of naturalrivers

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Journal of Hydrodynamics 2022年第4期34卷 744-755页

作者： De-chao Hu department of hydraulic Engineering Yangtze River Scientific Research InstituteWuhan 430010China School of Civil and hydraulic Engineering Huazhong Univ.of Science and TechnologyWuhan 430074China

The cross-sectional transverse flow field(represented by u_(con),)of rivers comprises a convective part(represented by ucon)and a circulatory part(represented by ueire),and a zero-flux principle of the ucire has been known for a long ***,it is still difficult to separate the circulatory part from the convective part quantitatively in a 3-D velocity field,for an arbitrarily vertical plane in natura ivers of iregular shape this study,a ero-flux prineiple of the uis derived,o replace th old zero-fux principle of the ueire:.Based on the new principle,an all-purpose new method is proposed for extracting the circulations in arbitrary vertical planes of natural rivers of irregular *** calculation with the new method requires only the distribution of the horizontal velocities of a single vertical line(VL),and is *** calculation can be made based on either the velocity field simulated by a 3-D hydrodynamic model or the field measurements obtained by the acacoustic Doppler velocimetry(ADV).The new method is validated by using the field data of the lower Yangtze *** extracted circulations are reasonable,while the results of the circulation extraction,respectively,based on the velocity field of a 3-D model and the field measurements of the ADV,are shown to be *** capability of the method is also demonstrated,using the typical riverbends of the Yangtze River as examples.

关键词： Real river cross-sectional secondary flow circulation extraction zero-flux principle

Risk analysis for a cascade reservoir system using the brittle risk entropy method

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Science China(Technological Sciences) 2016年第6期59卷 882-887页

作者： YANG Yin REN Qing Wen TIAN Ying XIONG Yao College of hydraulic Conservation and Hydropower Engineering Hohai University department of Engineering Mechanics Hohai University

The principal means of conserving water and utilizing hydropower in China is to exploit the use of a series of reservoirs in a cascade. This method and its inherent engineering safety problems are receiving increasing attention nowadays. In the field of engineering safety analysis, much work has focused on single reservoir projects in the past few years, but there is little research available on the safety risk analysis of cascade reservoirs, either within China or internationally. Therefore, a framework for risk analysis on the cascade reservoir system based on the theory of system engineering is constructed in this article. A cascading failure model is established and the connection degree factor discussed. In addition, the importance degree of the subsystem, which can be calculated by combining the analytical hierarchy process and the entropy weight method, is explained. According to brittleness theory of a complex system, brittle risk entropy is proposed as a performance index for measuring the collapse uncertainty of the cascade reservoir system. In addition, the brittle risk of the cascade reservoir system is predicted, which provides a reference for safety analysis in water conservation and hydropower construction projects in China.

关键词： cascading failure model safety analysis risk assessment complex system brittle risk entropy

Formation of Equilibrium Beach Profile of the Abandoned Yellow River Delta Coast in North Jiangsu

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China Ocean Engineering 2001年第1期16卷 139-146页

作者：徐敏陆培东雷智益 department of Geography Nanjing Normal University Harbour and River department Nanjing Hydraulic Research Institute

The abandoned Yellow River Delta coast is a typical erodible silty and muddy coast in China. The paper analyses the marine dynamic characteristics and the mechanism of beach erosion of this area. Analysis and calculation show that in this sea area wave and tidal current action should be considered. Based on the above analysis, an equilibrium beach profile calculation model is developed, in which the wave-current interaction is considered while sediment supply and sediment re-deposition are neglected. The model consists of four parts: (1) calculation of wave parameters, (2) calculation of velocity due to wave-current interaction at different water depth, (3) calculation of friction velocity and shear stress at different water depths, and (4) calculation of the amount of sediment erosion, erosion intensity and variation of beach profile. Calculated results are in good agreement with observed data. Finally, the evolution tendency is discussed and the equilibrium beach profile of this coast is calculated. B

关键词： equilibrium beach profile wave-current interaction silty and muddy coast abandoned Yellow River Delta