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非结构化网格下近岸波生流数值模拟 总被引：5，自引：2，他引：3
波浪破碎产生的近岸流是近岸海域关键的水动力因素之一。基于近岸波浪的椭圆型缓坡方程和二维近岸波生流方程,建立了非结构化网格下近岸波浪破碎形成的近岸流数值模型。数值模型中,在空间上采用有限体积法进行数值离散,在时间上采用欧拉向前格式数值离散。数值计算结果表明,该数值模型可以有效地模拟近岸波浪破碎产生的近岸流。 相似文献
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基于非结构网格有限体积法的环流模型,建立了相位平均的波流作用模型。模型中考虑了波浪破碎效应的三维辐射应力和波流作用下的扩散系数。通过模拟试验水池中人工岛和天然岛屿周围的波生流,对岛周围波生流的运动特征进行了分析。当波浪垂直入射到均匀斜坡上的人工岛时,岛周围产生回流和对称的环流,流速沿水深分布稍有差异。在天然岛屿中,入射波浪在近岸形成沿岸流。靠近岸线岛屿周围的沿岸流比离岸较远岛屿周围的流速大。这和辐射应力在浅水区域作用有关,岸线区域波生流特征明显。近岸岛屿周围在波浪辐射应力下产生不同的波浪增水,该波浪增水形成压力梯度进而促进岛屿周围的流态变化。 相似文献
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波浪漫滩是近岸波浪的小尺度运动,在实际海域的波生流数值计算中通常被忽略。本文基于Boussinesq方程的FUNWAVE模式,分别采用波浪漫滩边界、固壁边界、海绵边界进行Haller波浪港池物理模型实验的数值模拟,比较三种边界计算结果与实验观测数据的误差,检验波浪漫滩边界对波生流数值计算的影响;然后设计了多种周期、波高的波生流数值模拟试验,分析多种波浪入射条件下波浪漫滩边界对近岸波生流数值计算的影响。结果表明,波浪漫滩对邻近区域波生流有明显影响,漫滩边界下的波生流计算结果更接近实验观测值,在近岸波生流数值模型中引入波浪漫滩边界可以提高波生流计算精度。 相似文献
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沙质海岸沿岸输沙率的数值模型 总被引：1，自引：0，他引：1
为了较为准确地计算沙质海岸沿岸输沙率,基于网格模型建立沙质海岸波浪的传播变化模型,根据求得的波高和波向分布特征,并考虑辐射应力等,计算波生流的分布.并在此基础上通过波浪最大底部轨道速度和沿岸流的分布特点,建立估算破波带内各网格单元上沿岸输沙率的分布模型. 相似文献
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任意水深变化水域非线性波数值模拟 总被引：2，自引：0，他引：2
为了较为准确地计算沙质海岸沿岸输沙率,基于网格模型建立沙质海岸波浪的传播变化模型,根据求得的波高和波向分布特征,并考虑辐射应力等,计算波生流的分布。并在此基础上通过波浪最大底部轨道速度和沿岸流的分布特点,建立估算破波带内各网格单元上沿岸输沙率的分布模型。 相似文献
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海岸湿地是近海地区重要的生态系统,由于潮流、波浪尤其是非连续水流与植被的相互作用,导致该海域的水动力环境复杂多变。本文发展了一个深度平均二维波流耦合数学模型,模拟湿地海域波浪和波生沿岸流的运动特性。水动力模型中植物拖曳力作为源项放入动量方程中,在波浪作用量平衡方程增加波能耗散项用于解释水生植物对波浪产生的阻力作用。在动态耦合模型中,波浪模型为潮流模型提供波浪辐射应力、波高、波浪周期等数据信息,潮流模型为波浪模型提供计算的水位和流速,可以达到双向动态耦合。本文发展的波流耦合模型通过三个实验室试验数据加以验证,计算结果和实验数据吻合较好,在波浪、波生流和植物迭加条件下,所建模型能够有效地模拟波浪、沿岸流等不同现象。 相似文献
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结合椭圆型缓坡方程模拟近岸波流场 总被引：6，自引：3，他引：6
波浪向近岸传播的过程中,由波浪破碎效应所产生的近岸波流场是近岸海域关键的水动力学因素之一.结合近岸波浪场的椭圆型缓坡方程和近岸波流场数学模型对近岸波浪场及由斜向入射波浪破碎后所形成的近岸波流场进行了数值模拟.计算中考虑到波浪向近岸传播中由于波浪的折射、绕射、反射等效应使局部复杂区域波向不易确定,采用结合椭圆型缓坡方程所给出的波浪辐射应力公式来计算波浪产生的辐射应力,在此基础上耦合椭圆型缓坡方程和近岸波流场数学模型对近岸波流场进行数值模拟,从而使模型综合考虑了波浪的折射、绕射、反射等效应且避免了对波向角的直接求解,可以应用于相对较复杂区域的近岸波流场模拟. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans 总被引：1，自引：0，他引：1
A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
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Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges. 相似文献