海岸动力学-精品
《海岸动力学》课件
实验结果与分析
01 02 03
结果分析
分析潮汐和波浪对海岸的影响机制 。
研究海岸物质的迁移模式与潮汐、 波浪的相互关系。
06
海岸动力学的未来发展
海岸动力学的前沿问题
极端气候和海平面上升的影响
研究极端气候事件对海岸带的影响，以及海平面上升对海岸动力过程、海滩演变和沿海工 程设施的影响。
海洋酸化的影响
实验方法与步骤
• 重复进行多次实验，以获得可靠的实验结果。
实验方法与步骤
使用专业软件进行数据处 理和分析。
对采集的数据进行整理和 筛选。
数据分析
01
03 02
实验结果与分析
潮汐对海岸的影响
潮汐周期与海岸物质的迁移模式之间的关系。
波浪能量耗散
波浪在传递过程中能量损失的规律。
实验结果与分析
• 近岸流速分布：潮汐和波浪共同作用下近岸流速的分布情 况。
数值求解方法
数值求解是解决偏微分方程的重要手段，通过数值方法可以将偏微分方程 转化为离散点上的数值计算。
常见的数值求解方法包括有限差分法、有限元法、谱方法等，每种方法都 有其适用范围和优缺点。
选择合适的数值求解方法需要考虑模型的复杂性和计算精度要求，以及计 算资源的限制。
模型验证与比较
01
模型验证是确保模型准确性的重要步骤，通过与实际观测数据 进行比较，可以评估模型的可靠性和精度。
研究海洋酸化对海岸带生态系统、沉积物化学和矿物学的影响，以及这些变化如何影响海 岸动力过程。
海洋垃圾和塑料污染
关注海洋垃圾和塑料污染对海岸带生态系统和环境的影响，以及如何通过减少垃圾排放和 加强废弃物管理来减轻这些影响。
海岸动力学的研究趋势
海岸动力学课件 4.2
The pressure gradient of the sloping water
surface balances the change of the incoming
momentum. There is therefore a change in
mean water surface slope whenever there
3. Applications Radiation stress has been proved to be a very
powerful tool in the study of a variety of
oceanographic phenomena. In the context of
littoral processes, it has been used to predict
4/33
Chapter 4
The radiation stress across the plane x=constant in the direction of wave advance is
The radiation stress of y-momentum across the plane y=constant
This was prompted by the agreement between
two seemingly independent estimates of the
change of wave momentum by breaking across
the shoreline.
16/33
Chapter 4
The maximum value of wave set-up at the shoreline is
海岸动力学——精选推荐
海岸动⼒学第⼀章1.2.按波浪破碎与否波浪可分为：破碎波，未破碎波和破后波3.★根据波浪传播海域的⽔深分类：①h/L=0.5深⽔波与有限⽔深波界限②h/L=0.05有限⽔深波和浅⽔波的界限，0.5>h/L>0.05为有限⽔深；h/L≤0.05为浅⽔波。
4.波浪运动描述⽅法：欧拉法和拉格朗⽇法；描述理论：微幅波理论和斯托克斯理论5.微幅波理论的假设：①假设运动是缓慢的u远⼩于0，w远⼩于0②波动的振幅a远⼩于波长L或⽔深h，即H或a远⼩于L和h。
6.(1)基本参数：①空间尺度参数：波⾼H:波⾕底⾄波峰顶的垂直距离；振幅a:波浪中⼼⾄波峰顶的垂直距离；波⾯η=η(x,t):波⾯⾄静⽔⾯的垂直位移；波长L:两个相邻波峰顶之间的⽔平距离；⽔深h:静⽔⾯⾄海底的垂直距离②时间尺度参数：波周期T：波浪推进⼀个波长所需的时间；波频率f：单位时间波动次数f=1/T；波速c：波浪传播速度c=L/T(2)复合参数：①波动⾓(圆)频率?=2π/T②波数k=2π/L③波陡δ=H/L④相对⽔深h/L或kh7.(1)势波运动的控制⽅程（拉普拉斯⽅程）：(2)伯努利⽅程：8.定解条件（边界条件）：①在海底表⾯⽔质点垂直速度为零，②在波⾯z=η处，应满⾜两个边界条件：动⼒边界条件：⾃由⽔⾯⽔压⼒为0；运动边界条件：波⾯的上升速度与⽔质点上升速度相同。
⾃由⽔⾯运动边界条件：③波场上、下两端⾯边界条件：对于简单波动，常认为它在空间和时间上呈周期性。
9.①⾃由⽔⾯的波⾯曲线：η=cos(kx-?t)*H/2②弥散⽅程：?2=gktanh(kh)③弥散⽅程推得的2/(2π), c= tanh(kh)*gT/(2π), c2= tanh(kh)*g/k长的波在传播过程中逐渐分离。
这种不同波长（或周期）的波以不同速度进⾏传播最后导致波的分散现象称为波的弥散（或⾊散）现象。
11.①深⽔波时：波长L0=gT2/(2π)；波速c0=gT/(2π)②浅⽔波时：波长L s=T；波速c s=12.微幅波⽔质点的轨迹为⼀个封闭椭圆，但不是⼀直为椭圆，在深⽔情况下，⽔质点运动轨迹为⼀个圆，随着质点距⽔⾯深度增⼤，轨迹圆的半径以指数函数形式迅速减⼩。
海岸动力学
海岸动力学第一章1.海岸带宽度按从海岸线向内陆扩展10km，向外海延伸到-15~-20m水深计算。
2.海岸的类型：基岩海岸，砂质海岸，淤泥质海岸，生物海岸（包括红树林海岸和珊瑚礁海岸）。
3.海岸的组成部分：海滩，滩肩，后滩，前滩，外滩，离岸区，溅浪带，破波带，近岸区，海岸带（图见p5）4.淤泥质海岸由陆到海：潮上带，潮间带，潮下带。
5.海岸地貌特征：海岸地貌是由波浪、潮汐、海流、风和生物等作用，在地壳运动，构造岩性等因素影响下的海岸水底地表形态。
6.海岸地貌的平面形态：沙嘴，连岛沙洲，泻湖，岬角，韵律海岸，沙脊，障壁岛，淤泥海岸地貌7.淤泥海岸地貌：侵蚀地貌：潮水沟，潮汐通道淤积地貌：潮汐三角洲，潮间浅滩，湿地（然后成为海积平原）8.海岸动力因素：波浪的作用，海岸波生流，潮流的作用，径流的作用，海流的作用，风暴潮和海啸，风的作用，海平面上升。
9.本节课的研究方法：1）理论分析方法2）实验室试验方法3）数学模型4）现场调查研究（P25优缺点要会编）第二章10.波浪的分类按波浪形态分类：规则波（涌浪），不规则波（风浪和混合浪）按波浪传播海域的水深分类：深水波，h/L=1/2，有限水深，h/L=1/20，浅水波按波浪运动状态分类：振荡波（立波），推进波（推移波）按波浪破碎与否分冷：破碎波，未破波，破后波根据波浪运动的运动学和动力学处理方法：微幅波（线性波），有限振幅波（非线性波）11.波浪运动的描述方法：微幅波理论，有限振幅波理论，椭圆余弦波理论，流函数波理论（p29）12.波浪运动控制方程：拉普拉斯方程（实质不可压缩流体的连续性方程）定解条件：1）海底表面设为固壁，因此水质点垂直速度应为零。
2）在波面z=-η处应满足动力学边界条件和运动学边界条件3）流场左、右两端的边界条件可根据简单波动在空间和时间上呈周期性来判断13.微幅波的质点运动轨迹：封闭椭圆（水面处b=A，即为波浪的振幅；水底处b=0，说明水质点沿水底只作水平运动）14.弥散方程——计算P3415.波能：E K=1/4ρgA2E P=1/4ρgA2E= E K + E P =1/2ρgA2波能传播速度：c g=cn16.波群：不同周期不同波高的许多波叠加在一起，不规则波波群速度同波能传播速度：c g=cn17.驻波的特点：1）存在腹点和节点2）势能及动能均为行进波的两倍，总能量不变18.斯托克斯波（p45）19.浅水非线性波理论：椭圆余弦波，孤立波习题：2-9,2-10,2-11,2-12,2-14第三章20.波浪的浅水损失：1）摩阻损失2）渗透损失3）泥面波阻力损失21.波浪浅水变形：底摩阻引起波高损失22.波浪折射：1）引起波向线变化2）引起波高变化23.水流对波浪运动的影响：教材P7724.波浪破碎的原因：1）运动学原因（水质点速度大于波峰移动速度，溢破波）2）动力学原因（质点离心力大于重力加速度，溢破波）25.破碎波的类型：崩破波、卷破波、激破波26.极限波陡和破碎指标27.破碎带：外破波区，内破波区，爬坡区习题：3-1,3-2,3-3,3-9第四章28.潮波运动（看PPT）习题：4-1（本章无计算）第五章29.破碎波引起的动量转移（PPT）30.第二~第四节看看（有可能计算）31.第五节，PPT，简答+填空第六章32.粘性泥沙沉降和固结的四个阶段1）絮凝沉降：当含沙量较低时，由于絮凝作用使泥沙颗粒连接成絮团而加速沉降，随沉距和和含沙量等因素的变化而变化。
《海岸动力学》课件
海岸工程：如港口建 设、防波堤设计等
海洋资源开发：如潮 汐能、波浪能等
环境保护：如海岸侵 蚀、海平面上升等
自然灾害防治：如台 风、海啸等
军事应用：如潜艇隐 蔽、导弹发射等
学科背景：海岸动力学是研究海岸线、海岸带和海岸生态系统的动力学过程和规律的科学。 发展历程：海岸动力学起源于19世纪末，随着海洋科学的发展而逐渐形成。 学科发展：20世纪初，海岸动力学开始受到重视，并逐渐成为一门独立的学科。 当代研究：现代海岸动力学研究涵盖了海岸线变化、海岸带生态系统、海岸工程等多个领域。
数值模拟技术的发展趋 势：随着计算机技术的 不断发展，数值模拟技 术在海岸动力学中的应 用将会越来越广泛，精
度也会越来越高。
验证方法：对比实验结果与理 论预测
精度评估指标：误差、偏差、 方差等
影响因素：模型参数、初始条 件、边界条件等
提高精度的方法：改进模型、 优化算法、增加计算资源等
敏感性分析：研究模型参数变化对结果 影响的程度
国际合作：加强与其他国家的合作，共同研究海岸动力学问题 学术交流：举办国际学术会议，促进学术交流与合作 技术共享：共享研究成果和技术，提高海岸动力学的研究水平 人才培养：加强国际人才培养，提高海岸动力学的研究能力
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海岸动力学PPT课件 大纲
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目录
添加目录标题
海岸动力学概述
海岸动力学的基本原 理
海岸动力学的数学模 型与数值模拟
海岸动力学的实际应 用案例
海岸动力学的未来发 展趋势与挑战
添加章节标题
海岸动力学概述
海岸动力学1-2-PPT精品
一、椭圆余弦波理论简介
椭圆余弦波1阶近似解的波面方程为
zs h
水底至波面的距离
zszt H2 c2n K()L xT t,
水底至波谷底距离
zthH 1 3L h 2 6 3K ()K ()E ()
cn 为雅可比椭圆余弦函数，以2K(κ)为周期
K(κ)，E(κ) 为第1类和第2类完全椭圆积分
不同模数κ决定着不同的波面曲线形状, κ与波要素之间有如下
H 2 c k o x t s 8 H H L c k o s . c 3 i h s k 2 n k o h h 2 h s h c 2 ( k o t x s )
HHcoskhh.co2skh2
8 L
sin3hkh
H
2
当 kh0
三、斯托克斯波二阶解的质点速度、质点轨迹和质量输移 二阶斯托克斯波水质点速度
孤立波的 波长和波周周期都趋于无这穷大
二、孤立波理论简介
孤立波理论是一种在传播过程中波形保持不变的推移波 理论，它的波面全部在静水面以上
德(De，1955) 曾指出，斯托克斯波理论不能用于h/L
＜0.125的情况.
勒·
(Le Mehaute) 认为斯托克斯波不能
用于h/L＜0.1的情况。h/L的最小限值还与波陡δ＝H/L
有关。波陡越大，限值也越大，即适用水深范围越窄。
波浪非线性的主要特征有哪些? 波面 水质点速度 水质点的运动轨迹
第四节 浅水非线性波理论
水深很浅(例如h＜0.125L)时，斯托克斯波的高阶 项可能变得很大，因而不能适用，这时就应作为浅水 非线性波来研究。 椭圆余弦波理论是最主要浅水非线 性波理论之一。
在这一理论中波浪的各特性均以雅可比椭圆函数形 式给出，因此命名为椭圆余弦波理论。椭圆余弦波的 一个极限情况是当波长无穷大时，趋近于孤立波。当 振幅很小或 h/H很大时，得到另一个椭圆余弦波的极
海岸动力学课件 3.2
“Bilingual Course”精品课程Coastal Hydrodynamics C t l H d d iHOHAI UNIVERSITYMarch 20132013 Aifeng March Jinhai/ TAOZHENGZHENG Jinhai/ TAO AifengChapter 3 WA VE TRANSFORMATIONS Stating ocean wave characteristicsStating transformations of wavesStating transformations of wavesentering shallow water31Ocean Wave Characteristics 1S i i l h i i f§3.13.1 Ocean Wave CharacteristicsOcean Wave Characteristics1.Statistical characteristics of oceanwaves2Wave height distribution and wave2. 2. Wave height distribution and waveWave height distribution and waveperiod distribution3. 3. Ocean wave energy spectraOcean wave energy spectra4. 4. DeepDeep--water wave propagationp p p g5/39What are statistically representative waves?What are statistically representative waves?11/39Rayleigh distribution curveJONSWAP spectrumT 2RT 1Example: a separate wave group movesfrom the generation area to the coastline. 6/38If R is the distance from the leading edge of the If is the distance from the leading edge of the storm fetch to point A on the coast, then timeisduration for wave period T1, the time duration is For a short wave period T2Then we can get a warning time:ransformations in shallow water3.2 Wave transformations in shallow water §3.2 Wave tWave shoaling 1.Wave conservation 2. 2. Wave shoalingWave reflection Wave refraction 4. 4. Wave reflection 3Wave refraction4Wave reflection 3. 3. Wave refractionWave breaking Wave diffraction 6. 6. Wave breaking 5. 5. Wave diffraction5Wave diffraction6Wave breakingSeveral changes occur as a train of waves S l h t i f propagates into shallow water. One of the propagates into shallow water One of the most obvious is the change in height as the most obvious is the change in height as the wave shoals. Other changes such as the wave shoals Other changes such as the decrease in wave length with shallower decrease in wave length with shallower depths and the changes in wave direction depths and the changes in wave direction are clearly observable from the air.are clearly observable from the air.1 Conservation of wave equations The conservation of wave equation can be1.1. Conservation of wave equationsConservation of wave equations expressed asThis equation states that any temporal variation q y pof the wave number vector must be balanced by spatial changes of the wave angularf frequency.If the wave field is constant in time, the wave If th fi ld i t t i ti thperiod does not change with space, even as period does not change with space even asp gthe water depth changes.This feature is very important because it is not only of convenience for the analysis of wave motions but also provides the theoretical basis for the experimental simulationsof water waves.of water wavesWave transformation in shoaling water 2. Wave transformation in shoaling water 2 W W t f ti i h li t 2.Assuming that the energy flux is conserved in Assuming that the energy flux is conserved in the process of wave propagation, the wave the process of wave propagation,the wave height at a given water depth can beg g pdetermined by:is named the shoaling coefficient（浅水变ks形系数）Using the linear theory and recalling the dispersion l ti hi hrelationship, we haveg pIt is seen that the wave length at the water depth is determined from the water depth and deep water wave length, the latter easily calculated from the wave period.f h i dWave properties in shallow waterIt is seen that L and c decrease but n increases It is seen that and decrease but nwith decreasing depth.It can be found that there should be a small decrease in the wave height in the intermediate water depths to a value below the deep water water depths to a value below the deep water gwave height.The decrease is then followed by a rapid increase in H as shallower depths are reached.Upon entering shallow water waves are3.3. Wave refractionWave refraction Upon entering shallow water, waves aresubject to in which subject to refraction（折射折射））, in whichthe direction of wave travel changes with the direction of wave travel changes withdecreasing depth of water in such a way decreasing depth of water in such a way that the crest tend to parallel the depthp pcontours.Change of wave rayg yThe horizontal line along which waves travel波向线）），which isis called a wave ray（波向线defined as a line along which the wave number vector is always tangent.As energy travels in the direction of the wave, A t l i th di ti f ththe wave energy associated with the wave the wave energy associated with the waveg ytravels along the wave ray also.It b th tIt can be seen thatas the wavecelerity decreasesas the shore ish d thapproached, theangleαwill alsogdecrease from its Wave refraction in shallow waterdeepdeep--water value.The refraction of water wave is analogous to The refraction of water wave is analogous tog g y,gthe bending of light rays, and the change in direction is related to the change in the wave celerity through the same Snell’s law.For straight coasts with parallel contours,Change of wave heightIn the treatment of wave refraction, it is I th t t t f f ti it i assumed that no energy flows laterally assumed that no energy flows laterally along the wave crests. Therefore, the along the wave crests.Therefore,thegytransmitted wave energy is conserved between two rays as waves pass over the changing topography.Conservation of wave energy flux between two raysRecognizing that there is no energy flux across the wave rays, the energy flux across bis the th th fl i th0 same as across b.same as across.Finally we have the relationship between deep and intermediate or shallow depth water:In water with straight and parallel offshore I t ith t i ht d ll l ff h contours, it is possible for us to determine contours it is possible for us to determine the refraction coefficient（折射系数）k the refraction coefficientr directly.d ect y.g gWave convergence or divergence幅聚））refers to a Wave convergence（幅聚phenomenon that waves refract and bend toward headlands so that the wave energy isd h dl d h h i therefore concentrated.therefore concentratedgWave divergence（幅散）refers to a phenomenon that waves refract and diverge over the deep water so that the waves are reduced in height.d d i h i htWave convergence and/or divergenceWave convergenceWave convergenceor divergence dueto wave refractionis important indeciding wheredeciding whereto construct apier or otherstructure onCase study of wave refractioncoasts.Wave reflection4. Wave reflection4.At the locations of coastal structures or at places where the bottom configuration suddenly changes, a part of wave energy dd l h fis reflected and the reflected wave isis reflected and the reflected wave isggenerated.The reflected wave has the same wave period and wave length as the incident wave, but the wave height is different.b t th h i ht i diff tThe reflection coefficient is defined aswhich varies with the angle of the slope which varies with the angle of the slope,pthe incident wave steepness and the characteristics of the slope.The reflection coefficient based on the smallamplitude wave theory can be determined by lit d th b d t i d bmeasuring the amplitudes at the antinode and measuring the amplitudes at the antinode and node of the composite wave train.node of the composite wave trainoweve,t e dete at o o t e e ect o However, the determination of the reflectionp y coefficient should be conducted experimentally for a concrete engineering.Wave diffraction5.5. Wave diffractionWhen incoming waves are interrupted by a barrier such as a breakwater or an island,the waves curve around the barrier and penetrate into the sheltered area, meanwhile the wave energy is transferred laterally along a wave crest. This phenomenon l t ll l t Thi h波浪绕射））.is called wave diffraction （波浪绕射is called wave diffractionWave diffractioniff ioccurs on theoccurs on thesheltered side ofthe breakwatersuch that a waveh th tdisturbance isdisturbance istransmitted intothe “geometricshadow zone”. Wave diffraction h d”Wave diffraction绕射系数））is The diffraction coefficient（绕射系数The diffraction coefficientdefined as the ratio between the diffracted defined as the ratio between the diffracted and incident wave heights.and incident wave heights.It is clear that a quantitative understanding of the diffraction coefficient is relevant to theplanning and evaluation of harbor layouts.Numerical Modeling of Wave DiffractionW Wave Action Balance Equation with Diffraction effect 016000.25200400-0.500.1200400-0.5005200400600800100012001400200400600800100012001400“Coastal Hydrodynamics”——chapter 3ZHENG ZHENG Jinhai Jinhai / TAO / TAO Aifeng AifengMar Mar 20132013THANK YOU。
海岸动力学11-文档资料
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1、按波浪所受的干扰力和周期分类
表面张力波: 其波长小于1.7cm，最大波高为1至2mm 重力波: 周期1～30s的波浪，其主要干扰力是风， 重力是它的恢复力。 长周期波: 风暴潮；海啸。 潮波: 其周期最长。
海岸动力学课件0
海岸动力学绪论第一章波浪理论第二章波浪的传播变形和破碎第三章近岸波浪流第四章海岸带潮波运动第五章沙质海岸的泥沙运动第六章岸滩演变第七章淤泥质海岸的泥沙运动一、课程性质：1、流体力学的分支学科（海岸流体动力学），以流体力学为力学背景。
2、海岸工程的基础学科，以海岸工程（包括海港工程）为工程应用背景。
3、海洋学的分支。
4、港口航道与海岸工程的专业基础课。
5、理论性与实用性兼有。
海岸带是陆地和海洋的交界地带，沿海岸滩与大潮平均高潮面的交线称为海岸线。
我国海岸线漫长，共长3万余公里(包括大陆海岸线1.8万公里，岛屿海岸线1.4万公里)。
二海岸带特征(研究的区域和对象)海岸线:大潮平均高潮面与陆岸的交线。
海岸带:是陆地与海洋相互作用、相互交界的一个地带(包括潮上带，潮间带，潮下带)。
潮间带:高潮时海岸线与低潮时海岸线之间的带状区域。
潮上带:海岸线向陆扩展10km 。
潮下带:向海到-10m ～-15m等深线。
海岸动力学的研究区域：下界在波浪对海底开始起作用的地方，上界在最高潮位激浪还能作用到的上限。
海岸类型:基岩海岸、砂砾质海岸、淤泥质海岸、红树林海岸和珊瑚礁海岸等五种类型基岩海岸海岸类型:沙质海岸海岸类型:砾石海岸海岸类型:淤泥质海岸海岸类型:红树林海岸海岸类型:珊瑚礁海岸三海岸动力因素:波浪、潮汐及潮流、近岸流、台风、风暴潮、海啸、异重流；以及河流影响.海岸动力学的任务就是要研究上述自然动力因素，主要是波浪、潮汐、潮流对于海岸与海岸建筑物的作用。
海啸潮汐波浪四海岸动力学的研究内容:海岸动力因素(主要是波浪、潮波)的基本理论海岸动力因素与岸滩、海岸建筑物相互作用的规律。
岸滩(海岸)演变问题以泥沙运动为中介地质学海岸地貌学海岸动力学海岸动力因素泥沙运动岸滩演变与动力相适应的平衡岸滩海岸建筑物改变岸滩边界条件第1,2,3,4,章第5章第6章课程内容结构体系海岸动力学对于利用与开发海岸带、保护海岸的事业是必不可少的，特别是对于海港的建设尤为重要。
海岸动力学课件 Coastal Dynamics_1
“Bilingual Course”海岸动力学 Coastal DynamicsZHENG JinhaiHOHAI UNIVERSITYFeb. 2013Harbour EngineeringWaterway Engineering分流口鱼咀南导堤北导堤 航道疏浚丁坝群Coastal Engineering石城南 工程点 日岛0m 4000m 8000mWave theoryWave transformationNearshore circulationsSediment movementsCoastaline changesWavestructure interactionsPROLOGUE1 Self-introduction 2 Teaching assumptions 3 Textbook & references1. SELF-INTRODUCTIONName: ZHENG JinhaiEducation: Ph.D. 1998Coastal Engineering, Hohai UniversityEmployment: ProfessorCollege of Harbor Coastal and Offshore Engineering Hohai UniversityResearch interest (a):) Numerical modeling of coastal and estuarine hydrodynamics16001400 3 2.51200 21000 1.5 1800 0.5600 0.25 0400 -0.5200200400600800100012001400A phase averaging prediction model for multi-directional random waves considering ambient currentsResearch interest (a):) Numerical modeling of coastal and estuarine hydrodynamicsV (cm/s)50Visser (1991, case 4)ExperimentsComputations 140Computations 2Computations 4Computations 53020100-10012345678x (m)Incorporating surface rollers into a quasi three dimensional neashore current model to explain the spatial lag between wave breaking point and location of maximum wave-induced currentResearch interest (b):) Experimental study on interactions of waves and structuresFloating Mat Breakwater in Daishan Central Fishery HarborR h i t t ()Research interest (c):Numerical Wave Flume)Numerical Wave FlumeDevelopmentofnumericalwaveflumeusingusing improvedsmoothedparticleparticle hydrodynamicsC t t t hiContact teaching group:R 503/506B ildi SKL)Room 503/506, Building SKL,14:30 to 17:30 pm, Every Wednesday.)Email: Email: jhzheng@ jhzheng@aifeng tao@gmail comaifeng.tao@ jszhang@zhangchi@gangwang@)Phone: 83786821837879142. TEACHING ASSUMPTIONS What is it ?Wh i i?Why is it important ?How to learn it ?How to learn it?What ?a t o credit biling al co rseWhat ?2months:from Feb25to Apr18a twoa two--credit bilingual course )2 months:from Feb. 25 to Apr. 18 bili l)bilingual:2languages—Chinese&English2 languages Chinese & English)bilingual teaching:bilingual teaching:3 types3 types ——immersion programmaintenance programtransitional programp gWhat ?a t o credit biling al co rse What ? a twoa two--credit bilingual course)main topics:wave theorywave transformationswave transformationsnearshore circulationssediment movementscoastal processesWhat ?a state pri e a arded co rse What ?h//l hh d/k2007a statea state--prize awarded course /jpkc2007 /jpkc2007/ h i d li/C/I d ht haiandonglixue/Course/Index.htm http://202.119.113.100:4505/ http://20211911282/scr2006 http://202.119.112.82/scr2006Why ?Students who are going to become engineersand scientists in the field of harbor, waterwayand coastal engineering should master thebasic knowledge of coastal hydrodynamics basic knowledge of coastal hydrodynamics,p ywhich will help you to avoid undesirable effectin the plan and design of coastal engineering.)technical abilities technical abilitieslanguagecultural awarenessinnovativeMaster the results of derivations How ?Master the results of derivations& their physical meanings. Regularly, Carefully, Actively, Diligentlytermterm--time performance, 10% Finapal Sc homework, 30%corefi l i ti60%final examination, 60%3. TEXTBOOK & REFERENCES 3TEXTBOOK&REFERENCES Zou Zhili(2009). Coastal Dynamics, 4th eds. Press of People’s Communication. .Press of People’s Communication2 periods for introduction10 periods for wave theory6 periods for wave transformations6i d f t f tip4 periods for nearshore circulations6 periods sediment movements4 periods for coastal processes4i d f lReferences:Yen Kai(2002)“Coastal Engineering”)Yen Kai (2002). “Coastal Engineering”.China Ocean Press.Dalrymple R. A. (2004).y p() Dean R. G. & Dalrymple)Dean R. G. &“Water Wave Mechanics for Engineers andScientists. Prentice--Hall, Inc.. PrenticePrenticeScientists”Prentice-Hall Inc)Horikawa K. (1998). “Nearshore Dynamics Horikawa K(1998)“Nearshore Dynamics and Coastal Process”. University of TokyoPress.References:海岸带环境资源与海岸工程海岸带开发利用简史海岸动力因素海岸泥沙运动与海岸演变波浪对海岸工程建筑物的作用海岸防护工程围海工程海港工程河口治理工程潮汐发电工程海岸带采油工程海岸工程现场测验海岸工程水工模型试验海岸工程数值模拟海岸工程施工References:绪论海岸动力因素海岸泥沙运动与岸滩演变波浪与海工建筑物的相互作用海岸防护工程海港工程河口治理工程海岸工程现场测验海岸工程水工模型试验海岸工程数值模拟References:References:引言海岸水动力学海岸泥沙运动海岸地质学海岸工程规划设计海岸工程结构设计海岸工程术语表ManualEngineer Manual免费版本Engineer ManualEngineer Manual免费版本免费版本/引言引言:: 手册简介、海岸分类、海岸工程史及全书概貌海岸水动力学海岸水动力学:: 波浪力学、气象与波况、近岸海浪推算、破波带水动力学、水位与长波、潮汐通道水动力学、港湾水动力学、cem026.html或水动力分析及设计条件海岸泥沙运动：海岸泥沙性质、沿岸输沙、横向输沙、风输沙、粘性沙冲刷输移及沉积、破波带外泥沙输移海岸地质学：海岸术语与地质环境、海岸地貌分类、海岸动力地貌海岸工程规划设计：规划和设计过程、航道工程、潮汐通道港湾回淤管理、/inet/ususaceace--docs/engdocs/eng--manuals 海岸环境改善工程、联邦政府的减灾工作海岸工程结构设计：海岸结构及其功能、现场特殊设计条件、工程材料与施工管理、设计原理、可行度设计、Chapter 1 INTRODUCTION Introducing characteristic features ofcoast of ChinaIntroducing development of coastal zoneresources in Chinai ChiIntroducing background information Introducing background informationof coastal engineeringIntroducing methods to study coastalhydrodynamicshydrodynamicsCharacteristic Features of1. Characteristic Features of1.1Characteristic Features ofCoast of China()y ypI)Variety of Coast Types and InnumerableIslands(II)Innumerable Rivers Emptying into thepSea and Complicated Coastal Processes (III)Vigorous Dynamic Action along the Coast (IV)Prominent Climatic Influence(I) Coast typesIn its basic sense the coastline represents the What is the coast?In its basic sense, the coastline represents the boundary between marine and terrestrial iThe coast is a dynamic environment in which environments.The coast is a dynamic environment in which land and sea are constantly interacting int t l f tresponse to external factors.“The beach is the battleground of “The real conflict is between mand S ithe shore.”____William Beebe and nature. ”____SoucieAs the beaches become even more intenselyAs the beaches become e en more intenselg p p,utilized because of increasing population,we must establish priorities in the possibleuses of the coast.(I) Coast typesFor the continental part of China, the length of tli i b t18000k d h i l di coastline is about 18000 km, and when including the coastline of 6500 islands, an overall length ofgeomorAccording to geomor--32000km may be counted.According to geomorphological features, thecoast of China may becoast of China may beclassified mainly intoil dsilty coast, sandy coast,rocky coast and coralcoast.Silty coast(淤泥质海岸)is formed chiefly due tothe supply of huge amount of fine sediment bylarge rivers. The material composing such coast large rivers.The material composing such coastis very fine, generally with grain diameter <0.06mm. The beach profile presents a very gentleslope, varying from 1/500 to 1/2000.l i f1/500t1/2000Sandy coast(沙质海岸)is formed most nearthe mouths of rivers carrying coarse sediment; the mouths of rivers carrying coarse sediment;or where wave action is so strong that finesediment is easily carried away and difficultto deposit. The grain diameter of the material to deposit The grain diameter of the material generally ranges from 0.06 to 2.0mm, with beach profile usually > 1/100.(I) Coast typesRocky coast(基岩海岸)presents irregular configuration, with numerous bays, straits and capes. n mero s ba s straits and capesOwing to the presence of great Owing to the presence of greatdepth of water and good shelteringcondition, favorable sites for port construction could be found alongsuch coast.such coast(I) Coast typesCoral coast (珊瑚礁海岸) prevails along the coastline south of the Tropic of Cancer. south of the Tropic of CancerCoral reefs are usually found around islands, such as aroundthe Hainandao, on the east and th H i d th t dsouth coast of Taiwan and atthe archipelagoes of the South China Sea.Chi S(II) Rivers emptying into the sea ()p y gAnnual di t Sediment t ti Tidal range t i th Length Name f sediment load (million t)concentration (kg/m 3)at river mouth (m)(km)of riverYangtze River6300486 0.47 2.66Yellow RiverPearl River 546422101120 83 25.200.23 1.001.26The huge amount of sediment deposited near g pthe mouths of the rivers under the action of waves and currents causes significant changes of the coastline.changes of the coastline.()y(III) Dynamic action Diversified coast types and innumerable Diversified coast types and innumerable,g griver outlets, together with scattering islands around the coast, give rise to complicated bed forms, which in turn affects the dynamic features along the coast of China.W V S NTIDE WAVE SEDIMENT()(IV) Climatic influence ¾China is a country stronglyaffected by monsoons.ff t d bIn China typhoon is of¾In China typhoon is offrequent occurrence duringsummer and autumn,p cu y o g e co sparticularly along the coastof southeastern provinces.¾China is often hit by coldwave.wave.Development of Coastal Zone2. Development of Coastal Zone2Development of Coastal Zone2.Resources in China ()Ⅰ) Coastal Resources of China(Ⅱ) Port Construction along the Coast )Port Construction along the Coast (Ⅲ) Reclamation and Land Use)R l ti d L d U(Ⅳ) Rational Utilization and Development of Coastal Resources(I) Coastal resourcesIn 1980 the State Council decided to conduct a wide Comprehensive Assessment of NationNation--wide Comprehensive Assessment of Coastal Resources along our coastline.reclaimable landreclaimable landsalt fieldstidal power oil resourcestidal powerChapter 1 aquatic breeding<IEA-OES report 2009>Chapter 1(II) Port construction(III) Land reclamation In the past 60 years, about 1.2 million ha of id l fl h b l dtidal flat have been enclosed.NEW STAGE:l i d l¾multi multi--purpose developmentf t lof coastal zone resourcesmore complicated technical ¾more complicated technicalproblems to meet withproblems to meet with(IV) Rational developmentIn the comprehensive utilization anddevelopment of coastal resources, itd l t f t l itis necessary to consider the specificcircumstances of the coastal regionconcerned, making full use of itsconcerned,making full use of itsadvantageous conditions.Meanwhile, special care should be takenof the maintenance of ecologic balanceof the maintenance of ecologic balanceand protection against pollution.ANY IGNORANCE THEREOF WILL BE PUNISHED BY NATURE3. Background Information ofCoastal Engineering Coastal engineering is a branch of civil Coastal engineering is a branch of civilengineering, which was established by the closecooperation between civil engineers andscientists in other fields such as geography scientists in other fields such as geography, oceanography and geology, etc.The term“coastal engineering”was first(I) Historical backgroundThe term coastal engineering was first introduced in Oct. 1950 at the First Conference on Coastal Engineering held at Long Beach, California, U.S.A. The early research was limited in the area of early research was limited in the area of wave prediction, wave transformation in the shallow water zone especially for ilimilitary purpose.(II) Recent trendsCoastal engineering arose from aCoastal engineering arose from astrong interest in harbor constructionand coastal protection measures.In resent years, the subjects involvedin coastal engineering have expandedto the environmental preservation oft th i t l ti fnearshore zones.the coastal and nearshorethe coastal and zones.the coastal and。
海岸动力学第一章知识点整理和答案
海岸动力学第一章第一章概论1-1分析世界上大部分海岸处于侵蚀状态的原因。
◆海平面上升◆滩涂围垦、海岸植被破坏（珊瑚礁、红树林等）、拦河坝的建造、不合理的海岸工程建设Note：海岸侵蚀原因从自然因素和人为因素两个角度作答。
1-2分析海岸地貌特征（沙坝、沙嘴、潟湖和岬角等）对海岸侵蚀和淤积的影响。
◆沙坝是由波浪将海岸泥沙通过海底回流在破碎点附近沉积形成，所以沙坝的形成是海岸被侵蚀的结果。
另外，沙坝使近岸波浪破碎更为严重，使更多岸线附近的泥沙启动，并被波浪携带入海，进一步加剧海岸侵蚀。
◆沙嘴和潟湖可以使削减波浪作用强度，有利于泥沙沉降形成海岸淤积。
◆岬角处由于波浪辐聚的作用，受到的波浪作用强度较大，海岸容易遭受侵蚀。
1-3海岸环境动力因素（风、波浪和潮流等）对海岸变形的影响是什么？◆波浪：波浪是引起海岸变化的主要作用，波浪作用较强时，容易导致海岸后退。
◆风：风对海岸变形的影响是间接的，风将能量传递给波浪，波浪再影响海岸变形。
不同的风向和风力强度，对海岸地貌发育有着重要影响。
向岸表面吹流引起相当的向海底部回流，造成向海输沙。
风对沙丘的应力，造成海滩细沙的向岸搬移和陆上沙丘的向海输送，使海岸发生向岸和向海的迁移变化。
◆潮流：潮汐影响海岸带波浪的作用强度和范围，影响海岸带地貌类型的发育，另外潮流流速也会影响海岸带的侵蚀和淤积。
◆径流：径流淡水和潮流盐水出界面形成楔形面，楔面处有絮凝作用，造成泥沙集中沉降，形成水底隆起的河口拦门沙。
◆波生流：对沿岸输沙和岸线演变具有重要影响。
◆海流：海流是海洋的大尺度流动，离岸线相对较远，影响一般较小。
◆风暴潮和海啸：海岸极端气象。
水位异常升高且波浪具有极大的破坏性。
短时间改变海岸的冲淤平衡。
◆海平面上升：海平面上升导致海岸后退。
海岸环境动力要素主要是自然要素，包括：波浪、风、潮流、径流、波生流、海流、风暴潮和海啸、海平面上升。
1-4海洋水平面升高对海岸变形会产生哪些影响？◆海平面上升：海平面上升导致海岸后退，沿海平原低地别淹没和沼泽化，河口和地下盐水入侵，海洋动力增强。
海岸动力学.doc
海岸动力学.doc海岸动力学复习提纲初始章概论1、基本概念海岸动力学动力因素：风、浪、流泥沙运动岸线变化、潮汐海滩剖面变化岸线变形海岸带：以海岸线为准，向陆地10公里，向海到-10m或-15m 等深线范畴内为海岸带。
海岸带又分为①潮上带②潮间带③潮下带海岸线：沿海岸滩与平均大潮高潮面交线称为海岸线。
潮上带：平均高潮以上潮间带：平均高潮与平均低潮之间潮下带：平均低潮以下2、海岸类型①基岩海岸基岩海岸主要由岩石组成，地质条件比较好，是建港的良好地点。
②沙质海岸组成的泥沙粒径0.06mm<d1：1000。
</d波浪对它的作用主要是迁移。
主要功能为旅游业。
③淤泥质海岸淤泥质海岸由淤泥构成，泥沙粒径<0.06mm。
潮间带比较发育，剖面坡度很缓，坡度1:500~1:2000。
主要用途为围垦和养殖。
④生物海岸生物海岸包括 1.红树林海岸和 2.珊瑚礁海岸1.红树林海岸：红树林是公认的“天然海岸卫士”。
我国的红树林海岸主要分布在海南，福建，台湾沿海。
红树林海岸的作用主要有消浪、滞流、促淤、保滩。
2.珊瑚礁海岸：是由珊瑚礁组成的海岸，是海防前哨。
可用于潜水及海底观光。
3、海岸动力因素长期因素：风、波浪、潮汐、波浪流、海平面变化短期因素：台风、海啸、风暴潮长期因素具有周期性，相对确定性；短期因素具有偶然性。
4、海岸开发现况①海岸港口建设②围垦，建海堤③海岸资源开发利用1.土地资源2.盐资源3.渔场4.油气资源④海岸环境保护5、海岸动力学研究方法①理论分析②实验室试验研究③现场原型观测研究④数学模拟研究第一章波浪理论第一节波浪的分类1、按波浪所受干扰力和周期分类：（1）表面张力波：周期最短，风是干扰力，恢复力是表面张力。
（2）重力波：周期1~30s，风是干扰力，恢复力是重力。
风浪涌浪（3）长周期波：周期5min~12h，由风暴或地震生成。
（4）潮波：周期10h或24h，由天体运功生成。
风浪：风浪直接受风力作用，是一种强制波。
海岸动力学课件 2.4
“Bilingual Course”精品课程Coastal Hydrodynamics C t l H d d iHOHAI UNIVERSITYAifeng March 2013 / TAO AifengZHENGZHENG JinhaiJinhai/ TAO2.3 Small Amplitude Wave TheorySmall Amplitude Wave Theory §2.323S A iLinearization of basic equations1. 1. Linearization of basic equations2. 2. Solution of the linearized equationsSolution of the linearized equationsDynamic & kinetic characteristics3. 3. Dynamic & kinetic characteristicsof small amplitude wavesStanding waves4. 4. Standing waves2/383. Dynamic & kinetic characteristics¾Water particle velocity components¾Water particle trajectoryPressure field¾Pressure fieldEnergy and energy propagation ¾Energy and energy propagation3/38Velocity componentsThe velocity components can be found byy psubstituting the solution of velocity potentiali t th d fi iti f t ti l f tiinto the definition of potential function.4/38Velocity components are harmonic functions of V l it t h i f ti f x and t.y pThe horizontal velocity component has the same phase as the elevation of the free surface.The horizontal and vertical components are 90 The horizontal and vertical components are 90ººout of phase.Velocity components decrease exponentially with depthwith depth.5/38Water particle trajectoryThe displacement of the water particle can bep j yfound by integrating the velocity with respect to time.to time.Squaring and adding yields the water particle path as6/38The water particles travel in an elliptical path. The water particles travel in an elliptical path. The elliptical motion becomes flatter withwater depth.water depthp,In deep water, the orbits become true circles. In shallow water, the major diameters of ellipses are constant.7/38Pressure fieldThe pressure field associated with a progressive wave is determined from the unsteady Bernoulli equation.tiThe pressure equation contains two terms:h h d ithe hydrostatic pressure (静水压强) & the dynamic pressure (动水压强)&the dynamic pressure8/38The dynamic pressure is in phase with the water Th d i i i h ith th tpsurface elevation. It is positive where the free surface is above the SWL, and is negative where the free surface is below the SWL.In deep water dynamicI d d ipressure is very smallp yat the bottom, whilein shallow water itapproaches unity.approaches unity.9/38The maximum value or the minimum one appears when wave crest or trough reaches a given point when wave crest or trough reaches a given point respectively.Hydrostatic & dynamic pressure at various phases10/38is referred to as the “pressure response The term Ki f“zfactor(压力响应系数).”The “pressure response factor” has a maximum of unity at the mean water level and a minimum at the bottom.Below the mean water surface,at the bottom. Below the mean water surface,it is always less than unity.11/38A commonly used method to measure waves in either the laboratory or field by sensing the either the laboratory or field by sensing the pressure fluctuations is stated as follows.If the dynamic pressure is isolated by subtracting out the mean hydrostatic pressure, then the free t th h d t ti th th f surface displacementη ispWave energyThe total energy consists of two kinds:the potential energy (势能), resulting from the displacement of the free surface；the kinetic energy(动能), due to the orbitalmotion of the water particles.13/38The potential energy per unit crest width over The potential energ per nit crest idth o er one wave length isThe kinetic energy per unit crest width of a wave iswave isThe total energy per wave per unit width is The total energy per wave per unit width isFor Airy waves the potential energy is equal Ai i ito the kinetic energy, which is characteristic to the kinetic energy,which is characteristic of conservative (nonof conservative (non--dissipative) systems.It is worthwhile emphasizing that neither the It is worthwhile emphasizing that neither the average potential nor kinetic energy per unit area depends on water depth or wave length, but each is simply proportional to the square b t h i i l ti l t thof the wave height.of the wave height.15/38Energy fluxThe rate at which the energy is transferred in thegydirection of wave propagation is called thefl d i i h hi h energy flux (波能流), and it is the rate at which work is being done by the fluid on one side of a work is being done by the fluid on one side of a vertical section on the fluid on the other side. The relationship for the energy flux isEnergy flux has the units of power, and for thatreason it is denoted by P; it is commonly referred it i d t d b it i l f dto as the wave power(波功率).to as the wave powerIn deep water, the energy is transmitted at onlyhalf the speed of the wave profile (n=1/2), and half the speed of the wave profile()andin the shallow water, the profile and energyin the shallow water,the profile and energytravel at the same speed (n=1).17/38Conservation of the energy flux will be used later to examine the wave height variationsgin shoaling waves and to relate the heightdeep--water wave of breaking waves to the deepconditions..conditionsThe rate of sand transport along beaches is commonly correlated with the “longshorel l t d ith th“l h component of the energy flux”component of the energy flux.18/38p y(群)Group velocity 群速If there are two trains of waves of the same height propagating in the same direction with a slightly different frequencies and wavethe resulting profile, is modulated, is modulated numbers,numbers, the resulting profileb th lti fil i d l t d by an envelop that propagates with speed of by an‘envelop’that propagates with speed of group velocity.Characteristics of a group of wavesIt is clear that no energy can propagate past a node It is clear that no energy can propagate past a nodenergy as the wave height is zero there. Therefore, theas the wave height is zero there. Therefore, the nergy must travel with the speed of the group of waves.20/38Sequence of photographs showing a planeprogressive wave system advancing intoclam waterwater..The water is darkened withdye,and the lower half of the water depthis not shownshown..The wave energy islinescontained within the heavy diagonal lines,and propagate with group velocityvelocity..Theposition of one wave crest is connected ini h t h b th li ht lisuccessive photographs by the light line,which advances with the phase velocityvelocity..Each wave crest moves with the phasevelocity,equal the twice the groupvelocityvelocity..Thus each wave crest vanishes atthe front end and,after the wave maker isturned off,arises from calm water at thebackback..The interval between successivephotographs is0.2525s s and the wave periodis0.3636s s.The wavelength is0.2323m m and thewater depth is0.1111m m.21/38“Marine Hydrodynamics”___J.N. Newman (MIT), 1977The speed at which the energy is transmitted is equal to the group velocity. .equal to the group velocityThe average rate of energy propagation per unit crest width over one wave period is seen to be the average energy per unit surface area progressing with the group velocity.22/38The group velocity is defined asThe group velocity is defined asThis derivative can be evaluated from the This derivative can be evaluated from the dispersion relationshipp p4. Standing waves4 Standing wavesStanding waves立波often occur when incoming g(波)g waves are completely reflected by vertical walls. If a progressive wave were normally incident on a vertical wall, it would be reflected backward without a change in height, thus giving a without a change in height thus giving agstanding wave in front of the wall.Standing waves are also called clapotis .g p(驻波)24/38The surface elevation of standing waves can be expressed asbe expressed asIt is seen that the height of the standing wave is twice the height of each of the twoprogressive waves forming theprogressive waves forming thegstanding wave.25/38Node( 波节) Antinode(波腹)Water surface displacementassociated with a standing waveassociated wit a sta di g wave26/38The velocity components of standingwaves arewaves areIt is of interest that the horizontal and vertical components of velocity under a standing wavet f l it d t diare in phase.are in phase.27/38The extreme values of u and w in space occurpunder the nodes and antinodes of the water surface profile, and they are equal to zero under the antinodes and nodesunder the antinodes and nodes.28/38A standing wave could exit within a basin with t ll it t d t t ti d Wh? two walls situated at two antinodes. Why? The lateral boundary condition at the vertical wall would be one of no flow through the wall. Inspection of the equation for the horizontalI ti f th ti f th h i t l velocity shows that at locations of antinodes velocity shows that at locations of antinodes the no--flow condition is satisfied.the no29/38The potential and kinetic energies of standing The potential and kinetic energies of standing waves averaged over one wave length per unit crest width areThus both the potential and kinetic energies of standing waves are twice those off t di t i th f progressive waves.progressive waves.30/38At certain times, the velocity is zero everywherein the standing wave system. It is thereforei th t di t It i th fevident that at some times all the energy is evident that at some times all the energy ispotential and at other times all the energy is potential and at other times all the energy iset c.at s to say,t e e e gy c a ges o kinetic. That is to say, the energy changes form p y p gy periodically from kinetic to potential energy, and vice versa.31/38The displacement of a The displacement of a water particle under a standing wave isThe water particlepath under astanding wavestanding a eis a straight lineis a straight line.32/38The pressure at any depth under a standing The pressure at any depth under a standing wave isNote that under the nodes the pressure is solely Note that under the nodes, the pressure is solely y y p p hydrostatic. The dynamic pressure is in phase with the water surface elevation, and as before it is a combined result of the local surface displacement and the vertical acceleration. displacement and the vertical acceleration33/38If the wave heights of the incident wave and the If th h i ht f th i id t d th,p p reflected wave are different, the superpositiona partial standing wave. .creates a partial standing wavecreatesThe surface elevation of a partial standing wave is34/38It is realized that the successive antinodes and nodes appear at the intervals of L/4.35/38The reflection coefficient(反射系数)based onth li th b d t i d b the linear wave theory can be determined bymeasuring the amplitudes at the antinode measuring the amplitudes at the antinode and node of the composite wave train.36/38position would the wall be located?position would the wall be located? 37/38“Coastal Hydrodynamics”——chapter 2ZHENGZHENG JinhaiJinhai TAOTAO AifengAifeng March 2013THANK YOU。
海岸动力学海岸动力学复习资料(全)
海岸动力学海岸动力学复习资料（全）处，应满足动力学边界条件运动学边2)在波面 z=,海岸动力学复习资料第一章界条件。
动力学边界条件为水面上压力为常数，因此取z=，并令p=0，得到自由表面动力学边界条件。
,1.海岸带宽度按从海岸线向内陆扩展10KM,向外海延伸到-15~-20m水深计算。
3)流场左右两端的边界条件可根据简单的波动在空间和2.海岸类型:基岩海岸，砂质海岸，淤泥质海岸，生物海时间上呈周期性来却确定。
在空间上看的波要素是相同岸。
的，在时间上看一个周期后的要素也应相等，故波场上下3.海岸的基本概念:海岸是海洋和陆地相互接触和相互作两端面边界条件可表示为用的地带，包括遭受波浪为主的海水动力作用的广阔范。
,(x,z,t),,(x，L,z,t),,(x,z,t，T)围，即从波浪所能作用到的海底，向陆延伸至暴风浪所能到达的地带。
5.建立简单波理论时，一般作如下规定:流体是均质和不4.海岸动力因素:波浪的作用、海岸波生流、潮流的作可压缩的，其密度为常数;流体是无粘性的理想液体;自用、径流的作用、海流的作用、风暴潮和海啸、风的作用、由水面的压力是均匀的且为常数;水流运动是无旋的;海海平面上升。
底水平、不透水;质量力仅为重力，表面张力和柯氏力可5.波浪是引起海岸变化的主要因素。
忽略不计;波浪属于平面运动，在xz平面内坐二维运动。
6.近岸波生流——波浪传至近岸地区发生变形、折射与破6.微幅波理论的控制方程和定解条件22碎，不仅其尺度改变了，同时还形成的一定水体流. ,,,, 控制方程: ，,022,x,z7.沿岸流——斜向入射的波浪进入海滨地带后，在破波带引起一股与海岸平行的平均流。
8.裂流流速很高，会带动强烈的向外海输移的泥沙运动。
,,定解条件:海底部边界条件: z=-h ,09.潮流对海岸的作用:影响海岸带波浪的作用范围及作用,t强度;影响海岸带地貌类型的发育;潮流流速影响海岸带自由水面处: 1,,的侵蚀与淤积。
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(0)max(H L00)m
1 ax0.1427
max(H L)max0.14t2 ankh)h(
max(H L)max0.142L 2h
浅水区破碎时，破碎点波高与水深之间的关系 H b 0.89
hb
用孤立波一阶近似求得海滩上的破碎指标为
b
Hb hb
0.78
柯林斯和韦尔得到的经验公式为 b0.7 25.6tg
涌浪传到滨海区以后，受海底地形、地貌、水深变 浅、沿岸水流、港口及海岸建筑物等的影响，波浪产生 变形、折射、绕射、反射等；当波浪变陡或水深减少到 一定限度后，产生破碎。
波浪在浅水中的变化对港口海岸建筑物和近岸航道 设计等是重要的。在多数情况下，波浪是构成近岸泥 沙运动的主要原因，近岸泥沙运动影响着航道和港区 的淤积，造成岸滩的侵蚀变形。
2)内碎波区，该区内的波高大致与水深相适应，波前沿 陡立，后坡平坦，这种波形称为段波(Bore)。其波高完
3)上爬区，波浪到达岸线，波浪最后一次破碎，破碎 后的水体由于剩余动能而涌上海滩，然后又由于重力 作用而沿岸滩坡面下落。
破波带波高衰减规律 破碎后任一点的波高近似地与当地水深成正比,
碎波带内波高与水深之比可写为
HhKb
γ—碎波带内波高对于水深的比值，由试验确定。通常取为0.8。
第二节 波浪在水流中的运动特性 涨潮时顺水流进入河口附近的海浪波长增大、
波高减小； 落潮时逆水流进入河口的海浪波长减小、波高
增大，从而使波陡增大，有时造成波顶破碎.
第三节
波浪进入浅水区后，从波浪“触底”时起，波浪
即开始损失能量。这些损失可能包括如下3
传播方向沿x轴 Hcosk(xt)
2
波向与x轴交角为α
H cokscx(o sksyin t)
2
波向沿x轴
kxt
波向与x轴交角为α
kcx o k s sy i n t
势函数 波向沿x轴
g 2 H cc o k o s z k s h h h h sik n x (t)
定义 r 与x轴交角为α(波向) rrer
波向单位矢量 e r ci o sj i s ( x n / r ) i ( y / r ) j
r x2 y2
rxiyj
定义波数矢量
kker
k k co i s k sij n
波浪绕射是波浪从能量高 的区域向着能量低的区域进行 重新分布的过程。
绕射区同一波峰线上的波高 不同，愈深入掩蔽区内波高愈 小，但其波周期则保持不变。
(1) 规则波绕射
研究波浪绕射时，假定流体无粘性和不可压缩， 运动是无旋的，水深为恒定，则波场中的总波势等于 入射波势和散射波势之和，取坐标系统(x, y, z)， 波浪场的总速度势应满足拉普拉斯方程
t
k 0 (波浪守恒方程)
t
波浪守恒方程的物理意义?
对于稳定的波场，波周期(T＝2π/σ)为常量，即不 随空间变化，即使水深有缓慢变化时，波周期也始终保 持恒量。
二、波能守恒和波浪浅水变形
在稳定波场中，若假定波浪在传播过程中波能是守恒的. 波 能只沿着波向传播，没有能量穿过波向线，因此，波浪正向行近 岸滩时，单位宽度内的波能流在传播中保持常数，即
波向与x轴交角为α
g 2c H c o k o z k s h s h h sh k ic n x o (k s sy i n t)
u
x
v y
w z
kcx o k s sy i n t
xiyjkxikyjk
一、波浪守恒 波浪进入浅水区后，随着水深变化，其波速、波长、
波高和波向将发生变化，但是其波周期则始终保持不变。
波浪沿x方向传播其波面方程 (x ,t) a co k s x t()
波向与x轴交角为α 的波动，波面方程如何表示?
波浪沿x方向传播时波面方程 (x ,t) a co k s x t()
对于复杂地形海域通常采用图解方法绘制折射图， 也可用数值计算方法利用计算机求解和绘出折射图。
2 折射引起的波高变化
设两相邻波向线在深水中的间距为b０，进入浅水区 后的间距变成bi。假设两波向线之间的波能没有损失， 也无能量进入，则相邻两波向线之间单位时间平均向 前传播的波能不变，亦即
E0 c b 0 n Eic b 0 n const
3 破波带 波浪破碎点至岸边这一地带称为破波带，在碎波带内
由于水深从破碎点向岸不断地减小，波浪始终处于破碎 状态，水体的紊动与漩涡非常强烈，是波能的主要消耗 区域，也是海滩上泥沙运动最剧烈的地区。
破波带大致可分为3个区
1)外碎波区，波形急剧变化，能量消耗较多，紊动和 漩涡强烈，水体大量掺气，区内的水流特性与破波的 型式关系很大，
ksi nkcos0
x
y
Hale Waihona Puke 若各变量沿y方向为恒量，即岸滩具有平直且相互平 等的等深线时，上式可化 简为
dksi n 0
dx
斯奈尔 (Snell) 定律
sin const
c
sin sin0
c
c0
0 , c0
深水处波向角和波速
sin i sin 0 c c0 sin 0tan kh h
k k co i k s si j n k x i k y j
kxkco skco s
kyksinksin
k(kx 2ky 2)12k
波向沿x轴
kxt
波向与x轴交角为α
kcx o k s sy i n t
波面
cb ghb
nb 1
Hb bhb
Hb(gb)15(H202cc0coosbs0)25
si
nb
si
n0
cb c0
2 破碎波类型
波浪破碎的形态是多种多样的，主要取决于深水中的波陡和近 岸水底的坡度，大致可分为三种类型：
1)“崩波”型破碎波：波峰开始出现白色浪花，逐渐向 波浪的前沿扩大而崩碎的波型，波的形态前后比较对称。 2)“卷波”型破碎波：波的前沿不断变陡，最后波峰向 前大量覆盖，形成向前方飞溅破碎，并伴随着空气的卷 入。 3)“激散波”型破碎波：波的前沿逐渐变陡，在行进途 中从下部开始破碎，波浪前面大部分呈非常杂乱的状态， 并沿斜坡上爬。
海 岸 动 力 学2
第二章 波浪的传播变形和破碎
第一节、波浪在浅水中的变化 第二节、波浪在水流中的特性 第三节、波浪近底边界层和底摩阻引起的波浪衰减
第一节 波浪在浅水中的变化
风浪离开风区后继续传播，传播中由于弥散和能量 损失，其频率范围和能量不断变化，风浪逐渐转化为涌 浪，涌浪的频谱范围窄，波形接近于简谐波。
关于散射波势的控制方程和边界条件 s
i s
u v w
x
y
z
速度
pgz
t
波浪力
1gt z0
Hd 2m ax绕射区内任一点波高
任一点波高与入射波高之比称为绕射系数
值得指出，天然海湾或人工港湾附近，因水底一 般都不是水平的，水深是变化的，故进入海湾或人工 港湾内的波浪受绕射作用外还将受到折射影响，这时 必须考虑折射和绕射的综合作用。
其全部或部分波能被反射而形成反射波，这种现象称为 波浪的反射。反射波具有和入射波相同的波长和周期， 但其波高的大小则随反射波能的大小而定。
波浪反射系数Krf : 反射波高Hrf与入射波高Hi之 比。其大小随岸坡或人工建筑物的坡度、透水率、糙率 及波陡而异。
1 波浪的反射
当波浪正向入射于直立不透水墙时，完全反射， 反射波高等于入射波高，反射系数为Krf＝１，其组 合波为立波。
(2)不规则波绕射
海浪是不规则波，试验表明，不规则波绕射系数 一般较规则波绕射系数为大，如按规则波绕射系统布 置防坡堤，将使港口掩护情况偏于不安全。因此，80 年代以来世界各国对不规则波绕射问题进行了广泛研 究。
五、波浪的破碎
1 极限波陡与破碎指标
深水波的极限波陡 有限水深极限波陡 浅水情况极限波陡
波向与x轴交角为α时波面
(x ,y ,t) a ck o .r st) (
( x ,y ,t ) a ck o cx s o k s (s y i n t )
(x,y,t)aco s
k x x k y y t k r t(相位函数)
波浪的浅水变形开始于波浪第一次“触底”的时候， 这时的水深约为波长的一半.随着水深的减小，波长和波速 逐渐减小，波高逐渐增大，到了波浪破碎区外不远处，波 浪的波峰尖起，波谷变坦而宽，当深度减小到一定程度时， 出现各种形式的波浪破碎。
此外，随着水深变浅，如果波向与海底等深线斜交， 波向也将发生变化，即所谓产生折射。
当波浪不完全反射或波能在反射过程中有能量损 失时，反射波高不等于入射波高，Krf＝Hrf/Hi＜1， 入射波和反射波相互叠加后形成不完全立波
2 波浪绕射 波浪在传播中遇到障碍物如防波堤、岛屿时，除可
能在障碍物前产生波浪反射外，还将绕过障碍物继续传 播，并在掩蔽区内发生波浪扩散，这种现象称为波浪绕 射。
c0 L 0
L/L 0
n1 21sin2kh2h k( h)
随着水深h的减小，波速c、波长L都逐渐减小，n却 逐渐增大。波高H在有限水深范围内随水深减小略有减 小，进入浅水区后，则随水深减小而迅速增大。波高在 有限水深范围内减小的原因与n值的增大有关。
三、波浪折射
c gTtanhk(h)
给定深水波要素,任何求破碎时的波高与水深?