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1 .IntroductionTomeasurethereflectionofincidentwavesproducedbyaphysicalmodelinawaveflumeisacommonproblemwithphysicaltestsofwaveactiononcoastalstructures .Wavesgeneratedbythewave makerpropagateforwardinthewaveflumeandarereflectedbythephysicalmodel,andthe… 相似文献
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Presented here is a compact explicit difference scheme of high accuracy for solving the extended Boussinesq equations.For time discretization,a three-stage explicit Runge-Kutta method with TVD property is used at predicting stage,a cubic spline function is adopted at correcting stage,which made the time discretization accuracy up to fourth order;For spatial discretization,a three-point explicit compact difference scheme with arbitrary order accuracy is employed.The extended Boussinesq equations derived by Beji and Nadaoka are solved by the proposed scheme.The numerical results agree well with the experimental data.At the same time,the comparisons of the two numerical results between the present scheme and low accuracy difference method are made,which further show the necessity of using high accuracy scheme to solve the extended Boussinesq equations.As a valid sample,the wave propagation on the rectangular step is formulated by the present scheme,the modelled results are in better agreement with the experimental data than those of Kittitanasuan. 相似文献
54.
A new three-dimensional, non-hydrostatic free surface flow model is presented. For simulating water wave motions over uneven bottoms, the model employs an explicit project method on a Cartesian the staggered gird system to solve the complete three-dimensional Navier–Stokes equations. A bi-conjugated gradient method with a pre-conditioning procedure is used to solve the resulting matrix system. The model is capable of resolving non-hydrostatic pressure by incorporating the integral method of the top-layer pressure treatment, and predicting wave propagation and interaction over irregular bottom by including a partial bottom-cell treatment. Four examples of surface wave propagation are used to demonstrate the capability of the model. Using a small of vertical layers (e.g. 2–3 layers), it is shown that the model could effectively and accurately resolve wave shoaling, non-linearity, dispersion, fission, refraction, and diffraction phenomena. 相似文献
55.
Geochemical and hydrodynamic constraints on the distribution of trace metal concentrations in the lagoon of Nouméa, New Caledonia 总被引:1,自引:0,他引:1
Christophe Migon Sylvain Ouillon Xavier Mari Emmanuel Nicolas 《Estuarine, Coastal and Shelf Science》2007,74(4):756
Seawater samples were collected in the lagoon of Nouméa (southwest New Caledonia) along two transects from eutrophic coastal bays to the oligotrophic barrier reef. Land-based emissions to the lagoon were measured with dissolved and particulate concentrations of chromium (Cr) and nickel (Ni), used as tracers of both terrigenous and industrial (Ni ore treatment) activities, as well as dissolved and particulate concentrations of zinc (Zn), used as a tracer of urban effluents. The spatial variability of metal concentrations was related to geochemical and hydrodynamic conditions, i.e., respectively: (1) natural and anthropogenic emission sources, and chemical processes occurring in the water column; and (2) water residence times. The parameter used to describe the residence time of water masses was the local e-flushing time, i.e. the time required for a tracer mass contained within a given station to be reduced by a factor 1/e. High metal concentrations were found in coastal areas (up to 9000 ng dissolved Ni L−1), and steeply decreased with distance from the coast (down to 101 ng dissolved Ni L−1 near the barrier reef) to reach levels similar to those found in remote Pacific waters, suggesting a rapid renewal of waters close to the barrier. Distributions of metals in the lagoon are controlled upstream by land-based emission sources and later chemical processes. Then hydrodynamics constrain metal distributions, as shown by the observed relationship between local e-flushing times and the spatial variability of metal concentrations. In addition, a change in the direction of prevailing winds yielded a decrease of dissolved metal concentrations at the same site by a factor of 2.5 (Cr and Ni) and 2.9 (Zn). It is suggested that the residence time is a key parameter in the control of elemental concentrations in the lagoon waters, as much as land-based emission sources. 相似文献
56.
Sloshing in a two-dimensional rectangular tank in horizontal motion is analysed based on the velocity potential theory. It is found that even when the first-order excitation is away from all the natural frequencies of the tank, second-order resonance can still occur when the sum-frequency or the difference-frequency is equal to one of the natural frequencies corresponding to the even mode. However, such resonance is not excited when the sum or difference frequency is equal to the natural frequency of an odd mode. 相似文献
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泥河湾盆地东部的洞沟剖面出露一套以湖相为主的地层,其顶部覆盖了末次间冰期古土壤与末次冰期黄土。测量了该剖面的光谱光度和磁化率,结果显示,亮度(L*)随深度的变化趋势基本与色度a*、色度b*相反,即低亮度值对应高色度值。砂层的亮度值相对低,而质量磁化率高。亮度记录可以与洛川黄土剖面的磁化率记录对比,即亮度低值段可与磁化率高值段对比,这可能源于两者都受东亚季风的控制。对比后获得了30个时间控制点,在此基础上,建立了洞沟剖面测量参数的时间序列。谱分析表明,各参数的时间序列显示了主要的米兰科维奇周期,这显示泥河湾古湖沉积物对古气候的周期性变化敏感。 相似文献
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近海工程环境应用中各种风资料的平均时间分析 总被引:5,自引:0,他引:5
本文从近海工程设计应用的需要出发,对于通常使用的不同来源的测风资料平均时间进行了分析,这些资料来源包括:岸边及近海探查与生产设施上的气象台站、天气观测船、浮标、商船气象报、从受灾情况估计出的极大风速以及动力诊断模型估计出的海面风速。 相似文献
60.
长江口区风浪要素计算的探讨 总被引:2,自引:0,他引:2
本文以长江口区波浪实测资料为依据,对目前国内外常用的风浪要素计算方法进行了比较分析,认为就目前资料条件下,最适用于长江口区的、能满足工程设计等要求的风浪要素计算方法为莆田试验站方法(莆田公式)。 相似文献