一种推广的缓坡方程

从流体力学基本方程出发，假定水流的涡量和垂向流速分量小量，推导出考虑非均匀水流的推广的缓坡方程，该方程中包含了△h^2h项和（△hh)^2项。在方程中引入底摩擦项、风能输入项和非线性项，其中风能输入项的推导考虑了风浪与涌浪的区别，风流情况依据青岛海洋大学的风浪成长经验关系，涌浪情况依据Snyder等人的观测结果。经过上述推广后，得到综合考虑折射、绕射、反射、非均匀水流、底摩擦损耗、风能输入及波浪非线性的推广的缓坡方程。     

An extended time-dependent numerical model of the mild-slope equation with weakly nonlinear amplitude dispersion

In the present paper, by introducing the effective wave elevation, we transform the extended ellip- tic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simplest time-dependent hyperbolic equation. Based on this equation and the empirical nonlinear amplitude dispersion relation proposed by Li et al. (2003), the numerical scheme is established. Error analysis by Taylor expansion method shows that the numerical stability of the present model succeeds the merits in Song et al. (2007)’s model because of the introduced dissipation terms. For the purpose of verifying its performance on wave nonlinearity, rapidly vary- ing topography and wave breaking, the present model is applied to study: (1) wave refraction and diffraction over a submerged elliptic shoal on a slope (Berkhoff et al., 1982); (2) Bragg reflection of monochromatic waves from the sinusoidal ripples (Davies and Heathershaw, 1985); (3) wave transformation near a shore attached breakwater (Watanabe and Maruyama, 1986). Comparisons of the numerical solutions with the experimental or theoretical ones or with those of other models (REF/DIF model and FUNWAVE model) show good results, which indicate that the present model is capable of giving favorably predictions of wave refraction, diffraction, reflection, shoaling, bottom friction, breaking energy dissipation and weak nonlinearity in the near shore zone.     

结合椭圆型缓坡方程模拟近岸波流场

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.     

抛物型缓坡方程的变分及数值模拟

对线性水波的折射一绕射问题应用变分原理,对非等深、具有缓坡和不连续的底被导出了一种修改的抛物型缓坡方程近似模型,可预测三维地形上波浪的折射一绕射。同抛物型缓坡方程的线性方程进行了对比。通过数值模拟方法进行数值求解,表明本方法可用于地形条件下的波浪折射一绕射问题。     

利用网格划分软件和缓坡方程计算港内波浪场

提出了一套可方便应用于波浪场计算的方法。该方法包含了准确的边界输入输出技术,简便的地形输入技术,高质量的计算网格生成以及加速查寻、排序的数据结构。应用双曲型缓坡方程计算了港湾内的波浪场,数值计算时提出了处理建筑物表面部分反射边界条件的方法。将计算结果与边界元方法的结果和实验值进行了比较,证明该方法应用于波浪场可得到较理想的结果。对大连港区内的波浪折射绕射进行了计算,表明本方法可以应用于实际港口的波浪场计算中。     

Numerical simulation of wave-induced currents combined with parabolic mild-slope equation in curvilinear coordinates

Researches on breaking-induced currents by waves are summarized firstly in this paper. Then, a combined numerical model in orthogonal curvilinear coordinates is presented to simulate wave-induced current in areas with curved boundary or irregular coastline. The proposed wave-induced current model includes a nearshore current module established through orthogonal curvilinear transformation form of shallow water equations and a wave module based on the curvilinear parabolic approximation wave equation. The wave module actually serves as the driving force to provide the current module with required radiation stresses. The Crank-Nicolson finite difference scheme and the alternating directions implicit method are used to solve the wave and current module, respectively. The established surf zone currents model is validated by two numerical experiments about longshore currents and rip currents in basins with rip channel and breakwater. The numerical results are compared with the measured data and published numerical results.     

结合抛物型缓坡方程计算波浪辐射应力

将波浪辐射应力与抛物型缓坡方程中的待求变量联系起来,提出了一种计算辐射应力的新方法,并用有限差分法对控制方程进行了数值求解。数值结果表明这种方法精度高、编程简单、求解快速,可用于实际大区域波浪辐射应力的计算。     

带有侧摩擦和底摩擦的绕岛理论

绕岛理论来自于Sverdrup理论,被广泛用于估计和分析通过岛屿之间海峡的输运情况。以往的研究得到了带有侧摩擦或底摩擦的单岛理论或多岛理论。本文在线性情况下考虑了风驱动环流下的解析模型。在同时考虑侧摩擦和底摩擦的情况下,推导出了岛屿周围输运流函数的解析解,并给出了通过岛屿之间通道的流量输运。其结果与Wajsowicz相似,但摩擦常数表示不同的值。从解析解上看,摩擦常数与侧摩擦和底摩擦之间的关系比较复杂,为了推导出它们之间的相互作用原理,本文在正压β平面上随机选取了一些侧摩擦和底摩擦的值。结果表明,在构成摩擦常数方面,侧摩擦和底摩擦近似呈线性关系。我们研究了宽度对通道输运值的影响,结果表明摩擦在一定宽度内提高了流量,这种现象和只考虑侧摩擦时比较相似。本文也比较了在不同深度下的流量,发现当水平涡粘性系数和底部拖曳系数固定时,水深越大,输运减少率越小。为了进一步揭示侧摩擦和底摩擦耗散的联合作用,在两个岛屿的情况下,本文在不同宽度的通道中与Wajsowicz的只考虑底摩擦或侧摩擦的模型进行了比较。结果表明,当通道比较窄,尤其是在小于Munk边界层厚度时,侧摩擦的作用大于底摩擦。当通道宽度远大于Munk边界层厚度时,底摩擦的作用大于侧摩擦。将模型应用到印尼贯穿流,得到大约20%的输运减少量。     

东大港与豆腐渣腰门交汇区潮流动力特征分析

对江苏省辐射沙洲海域东大港与豆腐渣水道交汇处5号站位连续两个潮次流速测量资料进行分析,对该交汇区域的潮流特征和潮流过程有了近一步认识,拟合给出了潮汐过程流速垂线分布表达式。     

苏北辐射沙洲区间流系分布格局及对大气强迫力的响应

苏北辐射沙洲海域由10余条主沙脊和10余条主水道组成,其沙脊群间水动力的消长决定了沙洲的生成、发展及消亡,形成了滩槽相间、水道交错的独特地貌。黄海旋转潮波与东海前进潮波交汇于沙洲中心弶港,在沙洲外围诸多流系如黄海沿岸流、苏北沿岸水和长江冲淡水等影响下,又受复杂地形和大气强迫对浅水作用的影响,沙洲间余环流结构呈现4种环流结构迥异的特征。本文利用2006-2012年间8次共23站一年四季、涵盖主要沙脊和水道间准同步调查数据,以及沙洲南部4站长达1个月以上连续观测的ADCP资料,结合吕四和洋口港海洋站气象水文数据,分析了沙洲间余流四季输运分布格局,并重点讨论和分析了沙洲南部余流与风应力的响应关系。     

The study on the bottom friction and the breaking coefficient for typhoon waves in radial sand ridges--the Lanshayang Channel as an example

Owing to the interactions among the complex terrain, bottom materials, and the complicate hydrodynam-ics, typhoon waves show special characteristics as big waves appeared at the high water level (HWL) ...     

基于数值模拟与统计学方法的南黄海近岸沙脊与水道稳定性评价

以南黄海江苏岸外辐射沙脊群为对象,基于已验证的该区域沉积动力学数值模型模拟近30 a(1979~2011年)的水下地形演化,计算辐射沙脊区域海底地形年际变化标准偏差,对沙脊和水道的地貌稳定性进行定量评估。研究发现,地形变化标准偏差愈小,地貌愈稳定;标准偏差愈高,地貌愈不稳定。定量地确定了南黄海辐射沙脊区域内沙脊与水道稳定性系数的时空分布,发现主要淤积区域位于沙脊周围,近岸沙洲有淤高的趋势;主要侵蚀区位于水道,沙脊间水道逐渐冲刷加深,如西洋水道和黄沙洋水道。本研究提出的基于海底地形年际变化标准偏差确定地貌稳定性评估方法,可为海岸陆架地貌稳定性研究、区域资源开发和环境保护等提供参考。     

黄、东海环流的数值研究Ⅱ潮及潮致环流数值模拟

该文中数值模拟了黄、东海陆架区的四大天文潮及其潮致拉格朗日环流。运用“流速分解法”将线性三维分潮波问题化为一个分潮潮位及深度平均流的二维问题和一个流速垂向剖面问题求解。其二维问题的底摩擦系数由三维模式导出 ,所导得的线性底摩擦力公式更符合物理意义 ,且避免一般二维模式中底摩擦力的经验假定。结果表明 ,三维模式完全可以通过准二维方法求解 ,以避免一般三维问题的繁重计算     

Modeling and Simulation of Supercavity with Inertial Force in the Horizontal Curvilinear Motion简

To make a curvilinear motion in the horizontal plane is one of the most contents for realizing the maneuverability of the supercavitating vehicle. It is significant to achieve the controllability and maneuverability of the vehicle in three dimensions both theoretically and practically on research. Models of angle of attack, gravity and inertial force effects on the supercavity in the horizontal curvilinear motion are established, respectively. The supercavity is simulated based on these models in combination with Logvinovich model and the unsteady gas-leakage rate model at the given ventilation rate, and the effect of the inertial force on it is analyzed numerically. Results show that the maximum deviation of the center line of the cross section of supercavity towards the outward normal direction of its trajectory increases as the cavitation number or curvature radius decrease and always occur in the tail because of the increase of inertial effects along the axis of supercavity from the cavitator when other models and flow parameters are constant for the given trajectory curvature. For the variable curvature, the supercavity sheds due to its instability caused by the time-varying angle of attack. The deviation increases along the length of supercavity if the curvature remains the same sign.     

用一维水力学方程求取泻湖水位及潮汐汊道断面流速——以海南陵水新村港为例

本文通过一维水力学运动方程及连续性方程,得出一个反映泻湖水位变化的二阶非线性有阻尼的强迫振动方程,采用龙格-库特四步格式进行求解,并以海南陵水新村港为例,计算了泻湖水位及潮汐汊道的断面流速.研究结果表明:(1)一维水力学方程可容易地求得泻湖-潮汐汊道体系中泻湖内的水位及汊道的断面流速,计算简单快捷.(2)一维水力学方程可分析潮汐汊道体系中的一些基本现象.如潮汐汊道对潮波的"过滤器"特征;由于泻湖-潮汐汊道体系的阻尼系数较大所导致的潮波自外向泻湖传播时衰减剧烈;径流对泻湖水位及汊道流速产生有利于落潮优势的影响;风可使泻湖水位抬升或下降等.(3)无论是否考虑泻湖与潮汐汊道面积随水位的变化,一维水力学方程都具有相当大的缺陷.由于其不能反映泻湖内地形的空间变化,也不能解决漫滩与归槽等过程,在外海潮波无次生波的情况下,它本身不能产生次生潮波,因而不能正确地反映潮汐汊道体系的涨落潮历时与流速不对称,从而不能分析泥沙的净输运及潮汐汊道的稳定性问题.(4)新村港泻湖-潮汐汊道体系中潮汐汊道的断面面积大小对整个体系的稳定性及演变趋势起着控制作用.     

Numerical and simplified methods for the calculation of the total horizontal wave force on a perforated caisson with a top cover

The VOF method and the k–ε model, combined with the equation of state of air at constant temperature, have been used to calculate the total horizontal wave force caused by monochromatic waves acting on a perforated caisson with a top cover. From comparison of various parameters, such as the total horizontal force, the pressure difference on the front wall, the pressure on the back wall and the pressure on the top cover, between the numerical results and test data, it can be seen that the numerical results agree well with the test data. It is concluded that the method described in this paper can be utilized to calculate wave forces acting on perforated caissons with a top cover in the case of nonovertopping, nonbreaking waves. A simplified method to calculate the total horizontal force has been developed, based on test data, using a least-squares method. A comparison between the numerical results and the values calculated from the simplified equations shows good agreement. Therefore the simplified equations can be used in engineering applications to evaluate the total horizontal force on a perforated caisson with a top cover.