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Numerical Investigation of High Tide Level Due to A Super Typhoon in A coastal Region

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China Ocean Engineering 2007年第3期21卷 471-484页

作者：黄世昌李玉成赵鑫谢亚力 State Key laboratory of coastal and Offshore Engineering Dalian University of Technology Zhejiang Institute of hydraulics and Estuary

A numerical model of the couphng between astronomical tide and storm surge based on Mike 21 is applied to the coastal regions of Zhejiang Province. The model is used to simulate high tide levels combined with storm surge during 5 typhoons, including two super typhoons, that landed in the Province. In the model, the atmospheric forcing fields are calculated with parametric wind and pressure models. The computational results, with average computed errors of 13 cm for the high astronomical tide levels and 20 cm for the high storm-tide levels, show that the model yields good simulations. Typhoon No. 5612, the most intense to land in China since 1949, is taken as the typical super typhoon for the de- sign of 5 typhoon routes, each landing at a different location along the coast. The possible extreme storm-tide levels along the coast are calculated by the model under the conditions of the 5 designed typhoon routes when they coincide with the spring tide. Results are compared with the high storm-tide levels due to the increase of the central atmospheric pressure at the base of a typical super typhoon, the change of tidal type, and the behavior of a Saomai-type typhoon. The results have practical significance for forecasting and minimization of damage during super typhoons.

关键词： storm surge storm-tide super typhoon coastal region Zhejiang Province

Meshless Method for Analysis of Permeable Breakwaters in the Proximity of A Vertical Wall

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China Ocean Engineering 2019年第2期33卷 148-159页

作者： Nadji CHIOUKH Karim OUAZZANE Yal??n YüKSEL Benameur HAMOUDI Esin ?EVIK Department of hydraulics University Djillali Liabes of Sidi Bel-Abbes laboratory of Naval Aero-Hydrodynamics USTO MB Faculty of Life Sciences and Computing London Metropolitan University laboratory of hydraulics and coastal Engineering Yildiz Technical University

In the present work, the improved version of the meshless singular boundary method(ISBM) is developed for analyzing the performance of bottom standing submerged permeable breakwaters in regular normally incident waves and in the proximity of a vertical wall. Both single and dual prismatic breakwaters of rectangular and trapezoidal forms are examined. The physical problem is cast in terms of the Laplace equation governing an irrotational flow and incompressible fluid motion with appropriate mixed type boundary conditions, and solved numerically using the ISBM. To model the permeability of the breakwaters fully absorbing boundary conditions are assumed. Numerical results are presented in terms of hydrodynamic quantities of the reflection coefficients. These are firstly validated against the results of a multi-domain boundary element method(BEM) developed independently for a previous study. The agreement between the results of the two methods is excellent. The coefficients of reflection are then computed and discussed for a variety of structural conditions including the breakwaters height, width, spacing, and absorbing permeability. Effects of the proximity of the vertical plane wall are also investigated. The breakwater's width is found to have only marginal effects compared with its height. Permeability tends to decrease the minimum reflections. These coefficients show periodic variations with the spacing relative to the wavelength. Trapezoidal breakwaters are found to be more cost-effective than the rectangular breakwaters. Dual breakwater systems are confirmed to perform much better than single structures.

关键词： meshless improved singular boundary method regular normal waves rectangular and trapezoidal breakwaters permeability vertical wall reflection

Erosion rate of sand and mud mixtures

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International Journal of Sediment Research 2020年第6期35卷 563-575页

作者： Chamil Perera Jarrell Smith Weiming Wu David Perkey Anthony Priestas Department of Civil and Environmental Engineering Clarkson University coastal and hydraulics laboratory US Army Corps of Engineers

Erosion of mixed cohesive and noncohesive sediments is studied using the erosion test instrument *** sediment mixtures are composed of well-sorted quartz sand(0.25-0.5 mm) and one of the three used muds:kaolinite,kaolinite-bentonite and Mississippi River *** mud contents cover from 0 to 100%.The measured data of erosion rate and bed shear stress are used to examine the segmented linear,nonlinear,and exponential erosion *** parameters of each erosion model are related to the physical properties of sediment mixtures,including clay fraction,mud fraction,mixture dry density,and mud dry *** is found that the three models can fit well with the data,and their parameters have strong relations with the mud fraction and mud dry density,to a less extent with the clay fraction,but not with the mixture dry density.

关键词： Cohesive sediments Noncohesive sediments Sand and mud mixtures Segmented linear model Nonlinear model Exponential model

Numerical Investigation of Flow Motion and Performance of A Horizontal Axis Tidal Turbine Subjected to A Steady Current

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China Ocean Engineering 2015年第2期29卷 209-222页

作者：李林娟郑金海彭于轩张继生吴修广 State Key laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Harbor Coastal and Offshore Engineering Hohai University Zhejiang Institute of hydraulics and Estuary

Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-ε model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.

关键词： horizontal axis tidal turbine numerical simulation turbine performance flow motion steady current marine renewable energy

3D Numerical Simulation of Overbank Flow in Non-Orthogonal Curvilinear Coordinates

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China Ocean Engineering 2005年第3期19卷 395-407页

作者：张明亮沈永明吴修广 State Key laboratory of coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China Zhejiang Institute of hydraulics and Estuary Hangzhou 310020 China

The velocity field in meandering compound channels with overhank flow is highly three dimensional. To date, its features have been investigated experimentally and little research has been undertaken to investigate the feasibility of reproducing these velocity fields with computer models. If computer modeling were to prove successful in this context, it could become a useful prediction technique and research tool to enhance our understanding of natural river dynamics. A 3-D k-E turbulence hydrodynamic model in curvilinear coordinates is established to simulate the overhank flow. The bodyfitted coordinate is adopted in the horizontal plane, the part grid is adopted in the vertical direction, and the wall-function method is employed to simulate the bed resistance. The model is applied to the simulation of the meandering channel with straight flood plain banks, and the main velocities and secondary velocities for both the longitudinal and cross sections are presented. Comparison and analysis show that the results of simulation are fit to reflect the results of experiment. These results show the application value of the model to 3D overhank flow.

关键词： non-orthogonal curvilinear coordinates overbank flow wall-function method k-ε turbulence model

Novel Heat Transfer Issues Associated with the Design and Safe Operation of the MEGAPIE Spallation Source Target

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Journal of Thermal Science 2007年第1期16卷 63-78页

作者： Brian L.Smith Thermal hydraulics laboratory Paul Scherrer InstituteSwitzerland

Critical heat transfer problems are discussed in the context of the operation of a spallation source target, which represents a first demonstration of the feasibility of an innovative concept for generating energy using a particle accelerator. Within the framework of the umbrella project MEGAPIE, an R＆D support group was organized to take responsibility for target cooling. This involved the use of advanced numerical methods - Computational Fluid Dynamics （CFD） and Finite Element Method （FEM） - validated against suitable experimental data, and by means of appropriate benchmarking exercises. The design studies using CFD resulted in an optimum flow configuration being defined for the coolant circulation. Flow visualization tests were undertaken using a glass/water test section, with the velocity field mapped using optical and ultrasonic measuring techniques. These were followed by heat transfer tests, using the actual target materials （lead-bismuth-eutectic coolant and steel confinement）. Further CFD/FEM work to analyze operational transients and accident sequences was also carded out, and is described in the paper.

关键词： computational fluid dynamics finite element method liquid-metal coolant spallation source target

Detailed bed topography and sediment load measurements for two stepdown flows in a laboratory flume

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International Journal of Sediment Research 2022年第3期37卷 287-298页

作者： Daniel Wren Roger Kuhnle Tate Mc Alpin David Abraham Keaton Jones United States Department of Agriculture Agricultural Research Service National Sedimentation Laboratory U.S.Army Research and Development Center Coastal and Hydraulics Laboratory

Streams and rivers, particularly smaller ones, often do not maintain steady flow rates for long enough to reach equilibrium conditions for sediment transport and bed topography. In particular, streams in small watersheds may be subject to rapidly changing hydrographs, and relict bedforms from previous high flows can cause further disequilibrium that complicates the prediction of sediment transport rates. In order to advance the understanding of how bedforms respond to rapid changes in flow rate, a series of flume experiments were performed where the flow was reduced rapidly from equilibrium *** transport rates and bed elevation data across the flume and over a 15-meter-long test section were collected during the experiments to allow detailed examination of evolving bedform dynamics. It was found that relict bedforms stopped moving completely after flow reductions, and the mode of sediment transport was shifted to small bedforms that arose rapidly over dune stoss sections throughout the test section. The changes in sediment transport with time as the sand bed adjusted to the new flow rate was found to agree with predictions based on the relations proposed in Wren et al.(2020). Wavelet analysis is used to visualize changes in length and amplitude scales during the bed transition process.

关键词： Sediment transport Bedforms Dunes Wavelets

Effects of Perforated Baffle on Reducing Sloshing in Rectangular Tank:Experimental and Numerical Study

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China Ocean Engineering 2013年第5期27卷 615-628页

作者：薛米安林鹏智郑金海马玉祥苑晓丽 Viet-Thanh NGUYENa State Key laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Harbour coastal and Offshore Engineering Hohai University State Key laboratory of hydraulics and Mountain River Engineering Sichuan University State Key laboratory of coastal and Offshore Engineering Dalian University of Technology College of Mechanics and Materials Hohai University

A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.

关键词： liquid sloshing experimental study rectangular tank perforated baffle

Meshless Method with Domain Decomposition for Submerged Porous Breakwaters in Waves

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Journal of Ocean University of China 2021年第6期20卷 1325-1340页

作者： CHIOUKH Nadji YÜKSEL Yalçın Department of hydraulics University of Sidi Bel-AbbesSidi Bel-Abbes 22000Algeria laboratory of Civil Engineering and Environment University of Sidi Bel-AbbesSidi Bel-Abbes 22000Algeria laboratory of hydraulics and coastal Engineering Yildiz Technical UniversityEsenler-Istanbul 34220Turkey

Based on the improved version of the meshless singular boundary method(ISBM)in multi domain(MD),a numerical method is proposed in this paper to study the interaction of submerged permeable breakwaters and regular waves at normal *** account for fluid flow inside the porous breakwaters,the conventional model of Sollitt and Cross for porous media is *** single and dual trapezoidal breakwaters are *** physical problem is formulated in the context of the linear potential wave *** domain decomposition method(DDM)is employed,in which the full computational domain is decomposed into separate domains,that is,the fluid domain and the domains of the ***,appropriate mixed type boundary and continuity conditions are applied for each subdomain and at the interfaces between *** solution is approximated in each subdomain by the *** discretized algebraic equations are combined,resulting in an overdetermined full system that is solved using a least-square solution *** numerical results are presented in terms of the hydrodynamic quantities of reflection,transmission,and wave-energy *** relevance of the results of the present numerical procedure is first validated against data of previous studies,and then selected computations are discussed for various structural *** proposed method is demonstrated to be highly accurate and computationally efficient.

关键词： meshless method domain decomposition regular waves breakwaters porosity reflection transmission dissipation coastal environment