VELOCITY PROFILE OF SEDIMENT-LADEN OPEN CHANNEL FLOW     

LEE Hong Yuan  YU Wei Sheng Associate Professor  Dept. of Civil Engineering  National Taiwan University  Taipei  Taiwan  China  Graduate Research Assistant  Dept. of Civil Engineering  National Taiwan University  Taipei  Taiwan  China 《国际泥沙研究》1991,(1)

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Wave Attenuation and Friction Coefficient on the Coral-Reef Flat     

朱良生黎满球  张洪生隋世峰 《中国海洋工程》2004,18(1):129-136

Several sets of S4 direction-wave-current-tide meters have been deployed on the coral-reef fiat of Yongshu Reef in the sea area of Nansha Islands. Based on the observational sea wave data, the attenuation characteristics of the waves propagating on the coral reef flat, the bottom friction coefficients and the transfer of wave energy are discussed in the paper. The results show that, in the relative depths of 0. 0613- 0.0867, the wave height attenuation per unit distance of wave propagation is 22.09 %-46.56%, with an average of 31.35 % ; the wave energy, attenuation coefficient, 33.74 %- 53.22%, with an average of 43.61%. The average of the bettom friction coefficients on the coral-reef flat is 0. 1346,which is about 10 times thai on the sand or silt bottom. In the couse of propagation on the reef flat, the waves sustain more loss in high frequency than in low frequency and the spectral energy transfers to the low frequency. These results may be used for reference in island and reef engineering.  相似文献   

Simulation of Fully Nonlinear 3-D Numerical Wave Tank   总被引：6，自引：0，他引：6  

张晓兔滕斌  宁德志 《中国海洋工程》2004,18(1):59-68

A fully nonlinear numerical wave tank (NWT) has been simulated by use of a three-dimensional higher order bouodary element method (HOBEM) in the time domain. Within the frame of potential flow and the adoption of simply Rankine source, the resulting boundary integral equation is repeatedly solved at each time step and the fully nonlinear free surface boundary conditions are integrated with time to update its position and boundary values. A smooth technique is also adopted in order to eliminate the possible saw-tooth numerical instabilities. The incident wave at the uptank is given as theoretical wave in this paper. The outgoing waves are absorbed inside a damping zone by spatially varying artificial damping on the free surface at the wave tank end. The numerical results show that the NWT developed by these approaches has a high accuracy and good numerical stability.  相似文献   

Active Absorption Wave Maker System for Irregular Waves   总被引：2，自引：0，他引：2  

柳淑学  王先涛  李木国  郭美谊 《中国海洋工程》2003,17(2)

1 .IntroductionThephysicalmodeltestisoneofthemainmethodstostudyvariousproblemsassociatedwiththedesignofcoastalstructures .Thecommonlyusedwavemakeristhepiston typewavemaker .Becausethewavemakerishighlyreflective ,akeyproblemisthewavemultiplereflectionsbetweenthewavemakerandthetestedstructuresinthewaveflume .There reflectedwavesfromthewavemakerarespuriouswavesrelativetotheincidentwavestothestructures .Howtopreventthere reflectedwavesfromthewavemakerbecomesacriticalproblemforaccurateexperimental…  相似文献   

An Improved Nearshore Wave Breaking Model Based on the Fully Nonlinear Boussinesq Equations   总被引：1，自引：2，他引：1  

李绍武  李春颖时钟 谷汉斌 《中国海洋工程》2005,19(1):61-71

This paper aims to propose an improved numerical model for wave breaking in the nearshore region based on the fully nonlinear form of Boussinesq equations. The model uses the k equation turbulence scheme to determine the eddy viscosity in the Boussinesq equations. To calculate the turbulence production term in the equation, a new formula is derived based on the concept of surface roller. By use of this formula, the turbulence production in the one-equation turbulence scheme is directly related to the difference between the water portide velocity and the wave celerity. The model is verified by Hansen and Svendsen‘s experimental data (1979) in terms of wave height and setup and sctdown. The comparison between the model and experimental results of wave height and setup and setdown shows satisfactory agreement. The modeled turbulence energy decreases as waves attenuate in the surf zone. The modeled production term peaks at the breaking point and decreases as waves propagate shoreward. It is also suggested that both convection and diffusion play their important roles in the transport of turbulence energy immediately after wave breaking. When waves approach to the shoreline, the production and dissipation of turbulence energy are almost balanced. By use of the slot technique for the simulation of the movable shoreline boundary, wave ranup in the swash zone is well simulated by the present model.  相似文献   

Moon mass approximation in algebraic form analogous to activity sphere formula     

Professor of Aerospace Engineering Irving Michelson 《Pure and Applied Geophysics》1966,63(1):105-108

Summary The concept of comet orbit activity sphere as introduced byD'Alembert and developed byLaplace is modified and applied to the Sun-Earth-Moon system, leading to a new approximate relationship between astronomical constants usually regarded as independent quantities. When Sun-Earth mass ratio, the astronomic unit, and Earth-Moon separation distance are taken as known, an elementary algebraic formula gives the Earth-Moon mass ratio in terms of these. Despite the inherently imprecise character of this type of calculation, surprisingly close numerical agreement with independently determined values is obtained. The great simplicity and directness of the result contrast with ardous orthodox inference procedures for the lunar mass, suggesting that newer methods of general dynamic analysis are required in the study of asymptotic states of the three-body problem.  相似文献   

Three Dimensional Baroclinic Numerical Model for Simulating Fresh and Salt Water Mixing in the Yangtze Estuary   总被引：1，自引：5，他引：1  

ZHENG  Jinhai 《中国海洋工程》2002,16(2):227-238

For simulating fresh and salt water mixing in estuaries, a three dimensional nonlinear baroclinic numerical model is developed, in which the gradients of horizontal pressure contain the gradient of barotropic pressure arising from the gradi-ent of tidal level and the gradient of baroclinic pressure due to the gradient of salinity. The Eulerian-Lagrangian method is employed to descretize both the momentum equations of tidal motion and the equation of salt water diffusion so as to im-prove the computational stability and accuracy. The methods to provide the boundary conditions and the initial conditions are proposed, and the criterion for computational stability of the salinity fields is presented. The present model is used for modeling fresh and salt water mixing in the Yangtze Estuary. Computations show that the salinity distribution has the characteristics of partial mixing pattern, and that the present model is suitable for simulalion of fresh and salt waler mixing in ihe Yanglze Esluary.  相似文献   

Experimental Investigation on Element Immersing Process of Immersed Tube Tunnel     

ZHOU  Yu   《中国海洋工程》2001,(4):531-540

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Finite Element Analysis of Deformed Legs of Offshore Platform Structures     

LIU  Chuntu 《中国海洋工程》2002,16(3):311-320

The element stiffness matrix of the equivalent beam or pipe element of the deformed leg of the platform is derived by the finite element method. The stresses and displacements of some damaged components are calculated, and the numeri-cal solutions agree well with those obtained by the fine mesh finite element method. Finally, as an application of this method, the stresses of some platform structures are calculated and analyzed.  相似文献   

Effect of Sample Disturbance on Unconfined Compression Strength of Natural Marine Clays   总被引：7，自引：0，他引：7  

刘汉龙  洪振舜 《中国海洋工程》2003,17(3)

1 .IntroductionCoastalstructuresoftenencountersettlementandstabilityproblemsofsoftmarinefoundation (Liuetal.,1 999;Zhouetal.,2 0 0 0 ;Liuetal.,2 0 0 3) .Manyresearchershaveillustratedthatnaturalmarineclaysaregenerallysubjectedtotheeffectsofsoilstructureduringtheirdepositionalandpost depositionalprocesses (Zhangetal.,1 995;Hongetal.,2 0 0 3a ;2 0 0 3b) .Thesoilstructureofnat uralmarineclaysiseasilydamagedduringsamplingandhandlingbecausenaturalmarineclaysgeneral lyhavehighwatercontentandlowsti…  相似文献