基于Lagrangian粒子追踪的渤海冬夏季环流及影响因素研究

基于三维非结构有限体积海洋模式（FVCOM）对渤海环流进行了数值模拟研究。数值模拟中采用三角形网格，可以更好地拟合渤海复杂的岸线边界。潮位、潮流、温盐模拟结果验证良好。通过对粒子的拉格朗日追踪研究了渤海冬夏季环流及潮、风、海气热交换和入海径流对渤海环流的影响。研究表明：粒子输移存在明显的三维结构；与渤海中部及海峡附近相比，三个湾内水体输送均较小、表底层相差不大；渤海夏季环流强度较冬季强；由风引起的拉格朗日水体输送对渤海环流影响较大；温盐环流对水体输送的影响主要在夏季，在冬季，影响可以忽略；河流只对河口附近环流结构有影响；夏季，与热盐、风相比潮流对拉格朗日水体输送贡献较小；在研究渤海的拉格朗日余流时，只考虑单分潮的作用将不能反映渤海的实际环流情况。     

中国河口海岸风暴潮及海洋动力三维数值预报模型(CHINACOAST)研究Ⅱ:模型验证与应用

简述了在我国珠江口应用实测潮位过程、海表温度以及冬、夏季盐度分布资料对模型的验证与参数率定。在此基础上应用中国河口海岸风暴潮及海洋动力三维数值预报模型(CHINACOAST),对我国沿海冬季东北季风作用下的环流进行了模拟计算,并对环流特征进行了分析。模型被进一步用来模拟在9316号台风影响下珠江口的风暴潮位、海流过程及分布结构的变化。     

取水口附近水流泥沙运动的三维数值模拟

本文利用大涡模拟紊流模型，对某取水口附近的水流和悬沙结构进行了数值模型。三维环流结构和导沙建筑物和导沙效果都得以预测。部分结果与物理模型实验进行了比较，二者符合良好。     

烟丝气力输送特性试验与仿真

采用风洞试验与数值仿真方法,研究了圆锥管和Z形风道内烟丝气力输送特性.试验获得了烟丝悬浮率随雷诺数的变化规律,以及烟丝起浮临界气流速度等.采用一种基于离散相模V的Lagrangian粒子跟踪多相流CFD方法,对该问题进行了数值仿真,数值模型中考虑了粘性、重力、粒子直径分布、粒子形函数以及粒子质量分布等参数的影响.在两种风道内流动结构及烟丝起浮临界气流速度等方面,数值模拟与试验结果吻合良好.关位词:烟丝;气力输送;悬浮速度;风洞试验;数值仿真     

黄海冷水团的季节变化特征及其形成机制研究

在普林斯顿海洋模式(POM)的基础上,利用高精度卫星遥感得到的风和海表温度(SST)数据并考虑M2分潮的作用,模拟了黄、渤海海域三维热结构和环流的时、空变化;在此基础上,系统描述了黄海冷水团水文现象;并对黄海冷水团形成机制进行了探讨。研究结果表明:温跃层、潮混合、暖流和地形对黄海冷水团起着重要作用。     

波浪对渤海近岸海冰冲击作用的数值模拟

海冰在波浪冲击作用下可能会发生断裂,通过数值模拟定量地描述波浪引起的海冰断裂对海工结构的运行安全以及分析海冰断裂处海水与大气之间的热交换有重要作用。该文利用建立的三维数值波浪水池,将海冰视为刚性平板,结合渤海冬季海冰、波浪的相关参数,研究海冰受波浪冲击的垂向冲击力、水平冲击力、弯矩和最大弯曲正应力随波高、冰长及冰厚的变化规律;并结合渤海海冰的弯曲强度,推断海冰发生断裂的极限参数,结果表明:在渤海海域某些特定条件下,海冰断裂极限波高、冰长和最小冰厚分别为0.504 m、4.273 m和0.098 m。     

用MPS方法数值分析孤立波与平板相互作用问题

表面孤立波与海洋结构物的相互作用常伴随有砰击、上浪等现象,是船舶与海洋工程领域需要研究的重要问题之一。该文采用基于无网格半隐式移动粒子MPS法开发的MLParticle-SJTU求解器,对孤立波与平板结构相互作用问题进行数值计算分析研究。模拟了二维孤立波对平板的冲击作用过程,得到的平板受力与实验结果吻合良好,验证了MLParticle-SJTU求解器在处理此类问题上的可行性。通过对孤立波与平板相互作用过程的三维模拟,观察到了有别于二维空间下的波浪在平板上表面演化过程,即呈现U型演化过程,说明对此类问题进行三维数值模拟的必要性。     

海上溢油漂移扩散的数值模拟

该文基于三维自由水面垂向分层动网格的Euler-Lagrangian模式,采用VC方式(Vertex-Centered)的非结构化有限体积方法离散三维浅水方程,模拟渤海的潮汐水流运动过程。以此为水动力背景场,采用油、水分离的Lagrangian粒子追踪模型,对渤海海域发生的溢油漂移扩散问题进行模拟。其油品的蒸发、乳化和溶解等风化作用以引入综合衰减系数的方式考虑。模型对油膜的漂移路径、厚度和面积进行了实时模拟和预测,用多个测站的同步连续实测值对水动力模式进行了参数率定与模型验证,油膜输运扩散的计算结果也与相关报告数据进行了对比,均吻合良好,说明模型具有较高的可靠性与重现性。     

某拦河闸式渠首闸门调度及运行方式的数值模拟研究

采用数值模拟的方法,对新疆某渠首工程的闸门调度及运行方式进行了三维数值模拟,并对不同工况下典型断面的流量、水位及流速进行分析。研究表明数值模拟与物理试验得出的结果吻合情况较好,不同工况下的渠首运行方式均可达到较优的泄洪、引水效果,三维数值模拟的方法能够弥补物理试验费时费力,并且对流场内部特性难以掌握的缺点,可用于类似渠首工程运行方式的数值模拟研究,并为实际工程的运行控制提供参考。     

三峡工程导截流数值实验室的建立及数值模拟(Ⅱ)

介绍了三峡工程导截流水流特性数值实验室的数值模拟技术及其应用情况.采用水深平均二维数学模型模拟坝址区大范围水域在导截流过程中水深平均的流场演变过程,利用二、三维耦合数学模型的概念,由二维数模成果给定三维模拟所需的初值条件及边界条件,使三维数值计算具有良好的精度和收敛速度.利用导截流数值实验室的实时数值试验,给出导截流过程关键部位的三维流速分布及水位分布,并与实测值吻合良好.这表明导截流水流特性数值实验室所采用的数值模拟技术合理可靠.     

潮流对黄河入海泥沙在渤海中输运的贡献

基于ECOMSED模型研究分析单纯潮流作用下黄河入海泥沙在渤海中的输运特征。研究表明,渤海海域陆架坡度远小于内波特征参量,因此除黄河入海口附近以及其他近岸极浅海域之外,单纯潮流作用下渤海大部分海域的表层悬沙含量较低,但与实际水动力条件的空间分布格局基本一致。悬沙含量垂向分布特征明显,底边界层内因为较大的垂向湍流粘性系数,因此悬沙含量可以维持较高的水平,而底边界层之外悬沙含量迅速降低2～3个数量级;同时悬沙含量呈现出比较明显的潮周期(M2)变化特征。潮流作用下,绝大部分黄河入海泥沙沉积在黄河三角洲附近,只有少量悬沙可以发生长距离输送。黄河入海泥沙输运通量在口门外呈现一对涡状结构,成为水下三角洲南北两侧泥质沉积区形成的主要机制。     

NUMERICAL SIMULATION OF SUMMER CIRCULATION IN THE EAST CHINA SEA AND ITS APPLICATION IN ESTIMATING THE SOURCES OF RED TIDES IN THE YANGTZE RIVER ESTUARY AND ADJACENT SEA AREAS

Based on the COHERENS (a Coupled Hydrodynamical Ecological model for Regional Shelf seas), a three-dimensional baroclinic model for the summer of East China Sea (ECS) was established with the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. The circulation patterns of the Kuroshio Current, the Taiwan Warm Current (TWC), the Tsushima Current and the Yangtze Diluted Water (YDW) were successfully simulated with this model. The calculated results are fairly consistent with previous observations and studies. Based on this baroclinic current field, the Lagranian particles tracking was simulated to estimate the possible origins of the red tides frequently occurring in the Yangtze River estuary and its adjacent sea areas. If there are “seeds” (cysts) of the red tide algae at the seabed of the Taiwan Strait, the offshore of Fujian and Zhejiang Provinces and the northeast Taiwan Island, those are extremely possible sources of the red tides in the Yangtze River estuary and its adjacent sea areas. Field data are needed to confirm it. Numerical simulation to estimate the source of the red tides is a new application of the Lagrangian transport in the marine ecology.     

An ocean circulation model based on Eulerian forward-backward difference scheme and three-dimensional,primitive equations and its application in regional simulations简

A two-time-level, three-dimensional numerical ocean circulation model is established with a two-level, single-step Eulerian time-difference scheme. The mathematical model of the large-scale oceanic motions is based on the terrain-following coo-rdinated, Boussinesq, Reynolds-averaged primitive equations of ocean dynamics. A simple but very practical Eulerian forward-back-ward method is adopted to replace the most preferred leapfrog scheme as the time-difference method for both barotropic and barocli-nic modes. The forward-backward method is of the second order of accuracy, requires only once of the function evaluation per time step, and is free of the computational mode inherent in the three-level schemes. It is superior in many respects to the original leapfrog and Asselin-filtered leapfrog schemes in the practical use. The performance of the newly-built circulation model is tested by simula-ting a barotropic （tides in marginal seas of China） and a baroclinic phenomenon （seasonal evolution of the Yellow Sea Cold Water Mass）, respectively. The three-year time histories of four prognostic variables obtained by the POM model and the two-time-level model are compared in a regional simulation experiment for the northwest Pacific to further show the reliability of the two-level scheme circulation model.     

THE STUDY OF THE YELLOW SEA WARM CURRENT AND ITS SEASONAL VARIABILITY

The Yellow Sea Warm Current (YSWC) penetrates northward along the Yellow Sea Trough, and brings warm and saline water towards the Bohai Sea. The YSWC becomes much less intrusive in summer and is limited mostly in the southern trough, contrasting with a deep winter penetration well into the trough. The seasonal variability of the YSWC has prompted a debate regarding which controls the YSWC and its seasonal variability. In this article, the annual mean and seasonal variability of the YSWC was examined by using a 3-D ocean model together with several experiments. The results show that in the annual mean the YSWC is a compensating current firstly for the southward Korea Coastal Current (KCC), which is mainly caused by the Kuroshio Current (KC). The local wind-stress forcing plays an important but secondary role. However, the local monsoonal forcing plays a prominent role in modulating the seasonal variability. A deep northwestward intrusion of the YSWC in winter, for instance, is mainly due to a robustly developed China Coastal Current (CCC) which draws water along the Yellow Sea trough to feed a southward flow all the way from the Bohai Sea to the Taiwan Strait.     

Numerical analysis of impacts of 2011 Japan Tohoku tsunami on China Coast

On the 11th of March, 2011, a subduction earthquake of magnitude Mw9.0 happened at the northeast of Japan, generating a tsunami which resulted in huge damage in Japan. Okada’s elastic fault model is used to generate the deformation of the sea bottom based on USGS sources and UCSB sources respectively. The shallow water equations are solved by the adaptively refined finite volume methods so that it can compute the propagation of tsunami in the Pacific Ocean efficiently. The computed time series of the surface elevation are compared with the measured data from NOAA real-time tsunami monitoring systems for model validation, and UCSB sources derive better results than USGS sources. Furthermore, one nested domain with fine grid and higher topography resolution is combined to compute numerically this tsunami spreading in the Bohai Sea, Yellow Sea, East China Sea, and North of South China Sea. The impacts on China Coast and seas are analyzed and discussed. The results show that the tsunami has almost no impact in the Bohai Sea and Yellow Sea. It has some kind impact on the East China Sea and South China Sea. However, maximum wave height on China Coast is smaller than 0.5 m. It is thus concluded that the 2011 Tohoku tsunami did not generate a significant influence on China Coast.     

法国Gironde河口盐水入侵与泥沙输送的三维数值研究

运用可计算河口流场的全三维数值模型研究Gironde河口的河口环流与盐水入侵问题。本模型应用有限差分法求解浅水方程,同时采用模态分裂技术获取关于水位的泊松方程。而湍流计算则采用二阶K-L模型求解。模型采用Gironde河口两次不同实测数据进行率定参数与验证。通过对潮汐与径流作用的详细分析以研究该河口动力结构及影响河口环流盐水入侵的主要影响因素。     

DRUCKER-PRAGER YIELD CRITERIA IN VISCOELASTIC-PLASTIC CONSTITUTIVE MODEL FOR THE STUDY OF SEA ICE DYNAMICS

1. INTRODUCTION The motion of sea ice is an important factor that contributes to the global distribution of water, which has obvious influence on the global climatic change and the marine activities in cold regions. The sea ice dynamics mainly includes se…     

黄、渤海近海海浪环境测量与分析

利用近海海浪环境开展大尺度船模试验是一种有效的船舶性能试验技术,了解近海海浪环境特征对该试验的开展具有重要意义。文中对黄、渤海多个海域近海海浪进行实地测量,采用谱分析法得到测量海浪的有义波高、特征周期、波能谱等参数,并将实测波浪谱与大洋谱进行无因次化比较,讨论了实测波浪谱与大洋谱的相似性。分析结果表明特定风向与潮汐条件下近海海浪谱与大洋谱具有相似性。     

非线性隶属函数集对分析方法在海域水质评价中的应用

海域水环境质量评价是不确定性系统的分析问题,具有高度的非线性关系。本文建立了非线性隶属函数的集对分析综合评价方法与系统的评价步骤,提出了针对海洋水环境质量评价相应指标的非线性联系度函数构建方式。以渤海湾某工程海域的水环境质量评价为例,检验该方法的可行性,结果表明集对评价法具有简洁、易操作和高精度等优点,非线性隶属函数能更合理的量化评价指标的等级归属程度,评价结果具有更高的可信度。