Fully nonlinear numerical wave tank (NWT) simulations and wave run-up prediction around 3-D structures     

J. -C. Park  M. -H. Kim  H. Miyata  H. -H. Chun 《Ocean Engineering》2003,30(15):1969-1996

A finite-difference scheme and a modified marker-and-cell (MAC) algorithm have been developed to investigate the interactions of fully nonlinear waves with two- or three-dimensional structures of arbitrary shape. The Navier–Stokes (NS) and continuity equations are solved in the computational domain and the boundary values are updated at each time step by the finite-difference time-marching scheme in the framework of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique developed for two fluid layers.To demonstrate the capability and accuracy of the present method, the numerical simulation of backstep flows with free-surface, and the numerical tests of the MDF technique with limit functions are conducted. The 3D program was then applied to nonlinear wave interactions with conical gravity platforms of circular and octagonal cross-sections. The numerical prediction of maximum wave run-up on arctic structures is compared with the prediction of the Shore Protection Manual (SPM) method and those of linear and second-order diffraction analyses based on potential theory and boundary element method (BEM). Through this comparison, the effects of non-linearity and viscosity on wave loading and run-up are discussed.  相似文献   

Outer wave number spectrum and statistical distribution of apparent wave number vector     

J. -B. Song  K. -J. Wu  Y. -H. Wu 《Ocean Engineering》2003,30(3):401-412

Based on the ray theory and Longuet-Higgins’s linear model of sea waves, the joint distribution of wave envelope and apparent wave number vector is established. From the joint distribution, we define a new concept, namely the outer wave number spectrum, to describe the outer characteristics of ocean waves. The analytical form of the outer wave number spectrum, the probability distributions of the apparent wave number vector and its components are then derived. The outer wave number spectrum is compared with the inner wave number spectrum for the average status of wind-wave development corresponding to a peakness factor P = 3. Discussions on the similarity and difference between the outer wave number spectrum and inner one are also presented in the paper.  相似文献   

Aspects of Deep Ocean Mixing     

Chris Garrett  Louis St. Laurent 《Journal of Oceanography》2002,58(1):11-24

The turbulent motions responsible for ocean mixing occur on scales much smaller than those resolved in numerical simulations of oceanic flows. Great progress has been made in understanding the sources of energy for mixing, the mechanisms, and the rates. On the other hand, we still do not have adequate answers to first order questions such as the extent to which the thermohaline circulation of the ocean, and hence the earth's climate, is sensitive to the present mixing rates in the ocean interior. Internal waves, generated by either wind or flow over topography, appear to be the principle cause of mixing. Mean and eddy flows over topography generate internal lee waves, while tidal flows over topography generate internal tides. The relative importance of these different internal wave sources is unknown. There are also great uncertainties about the spatial and temporal variation of mixing. Calculations of internal tide generation are becoming increasingly robust, but we do not know enough about the subsequent behavior of internal tides and their eventual breakdown into turbulence. It does seem, however, that most internal tide energy flux is radiated away from generation sites as low modes that propagate over basin scales. The mechanisms of wave-wave interaction and topographic scattering both act to transfer wave energy from low modes to smaller dissipative scales. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Statistics of wave forces on large horizontal cylinders     

Felice Arena   《Ocean Engineering》2002,29(4):359-372

To the first order in a Stokes expansion, the pressure force exerted by a sea state on a large horizontal cylinder represents a stationary random Gaussian process. A relationship is obtained between the spectrum of this process and the wave spectrum. As a consequence, the basic statistical properties of the height and period of the individual waves of the force-process are also obtained. It is proven that these statistical properties agree very well with the data from a small scale field experiment.  相似文献   

波浪作用下海床动力反应的数值分析   总被引：2，自引：3，他引：2  

栾茂田  王栋 《海洋工程》2001,19(4):40-45

近海和离岸建筑物的基通常处于连续不断的小风浪作用之下，可将其变形视为弹性。基于二维广义Biot理论，提出了线性或非线性波浪作用下饱和弹性海床动力应应的时域有限元数值解法。静力平衡条件和Biot方程组成的边值方程可视为其特例，在比较算例中，数值计算得到的孔压和有效应力幅值沿海床深度的分布与解析解十分吻合。土骨架和孔隙流体的加速度对海床动力反应的影响很小。具体算例表明，线性波沿缓坡海床传播时，土层中超静孔压和有效应力幅值随之增大，有可能发生滑动坡坏。所提出的数值解法能够灵活地处理非线性波浪荷载，海底复杂地质条件和波浪沿缓坡传播等复杂情况。  相似文献   

波浪作用下潜标拖缆动力学分析     

朱刚  杜月中 《海洋工程》2007,25(4):15-20

对三维潜标拖缆在规则波作用下的动力响应进行了研究,首先基于集中质量法给出了缆绳在规则波作用下的控制方程,然后提出了两种不同类型的自由端边界条件:质点型和艇型自由端边界条件,前者把拖体视为作三个自由度线运动的质点,而后者把拖体视为作六自由度运动的艇体,最后用有限差分法进行了数值研究。数值计算结果表明潜标拖缆在规则波的作用下,不仅作近似的简谐振动,还会在横向、垂向产生一个偏移量,该偏移量的大小随浪向角的变化而变化,另外受遭遇频率的影响,振动的幅值也随浪向角的变化而呈现不同的特征。  相似文献   

Modified mild slope equation and open boundary conditions     

M. C. Khellaf  M. Bouhadef 《Ocean Engineering》2004,31(13):1713-1723

A numerical model to compute wave field is developed. It is based on the Berkhoff diffraction-refraction equation, in which an energy dissipation term is added, to take into account the breaking and the bottom friction phenomena. The energy dissipation function, by breaking and by bottom friction, is introduced in the Berkhoff equation to obtain a new equation of propagation.The resolution is done with the hybrid finite element method, where lagrangians elements are used.  相似文献   

太平洋波高分布及变化规律研究   总被引：4，自引：0，他引：4  

韩树宗  朱大勇  郭佩芳 《中国海洋大学学报(自然科学版)》2003,33(6):825-832

使用 Topex/ Poseidon卫星高度计 1 992年 1 0月～ 1 998年 1 2月连续 75个月 ,2 30个重复周期的有效波高资料对南北太平洋的有效波高进行了统计 ,分析了太平洋有效波高的多年平均、多年各月平均和多年各季平均的空间分布特征和时间变化规律。结果表明 ,太平洋波高分布具有明显季节变化的规律 ,与太平洋的风速分布特征具有良好的对应关系  相似文献   

Hydrodynamic Forces on Smooth Inclined Cyh''''nders in Oscillatory Flow     

Kang Haigui Asscociate Professor 《中国海洋工程》1994,(3)

-The hydrodynamic forces on a smooth inclined circular cylinder exposed to oscillating flow were experimentally investigated at Reynolds number (Re) in the range 40000-200000 and Keulegan-Capenter number (KC) in the interval from 5-40. In the test, Re number and KC number were varied systematically. The inertia force coefficient (Cu) and the drag force coefficient (CD) in Morison equation were determined from the measured loads and the water particle kinematics. In this analysis a modified form of Morison equation was used since it uses the normal velocity and acceleration. Thus, the applicability of the Cross Flow Principle was assumed. This principle, simply stated, is as follows: the force acting in the direction normal to the axis of a cylinder placed at some oblique angle with the direction of flow is expressed in terms of the normal component of flow only, and the axial component is disregarded. Both the total in-line force coefficient (CF) and transverse force (lift) coefficient (Cf) were analyzed  相似文献   

High Frequency Current Fluctuations and Cross-shelf Flows around the Pycnocline near the Shelf Break in the East China Sea     

In-Seong Han  Koichiro Kamio  Takeshi Matsuno  Atsuyoshi Manda  Atsuhiko Isobe 《Journal of Oceanography》2001,57(2):235-249

Relation between internal waves with short time scale and density distribution near the shelf break in the East China Sea is studied utilizing moored current meters, thermometers and conductivity-temperature-depth (CTD) casts. A well developed pycnocline was frequently observed around 150–200 m depth near the shelf break accompanied with the development of internal waves with short time scale. During the cruise in May 1998, the intensified internal wave motion with short time scale and the distinct offshore flow were observed just below the lower pycnocline, which shoaled and extended above the shelf area. It is suggested that vertical mixing generated by amplified internal waves would produce cross-shelf ageostophic density current around the pycnocline. During the cruise in May 1999, on the other hand, the lower pycnocline was located offshore below the shelf break, and the internal wave motion was amplified just above the lower pycnocline. In this case, the offshore flow should be generated above the lower pycnocline, but vertical profiles of current velocity were not obtained because acoustic Doppler current profiler (ADCP) data were not available around the lower pycnocline.  相似文献