涌潮分析与波速计算

本文首先在理论上对涌潮现象进行了分析，指出通常使用的涌潮波速计算公式，尽管得建立在连续方程和动量方程基础之上，但对于近岸浅水涌潮的传播问题并不适用。为此，文中根据连续方程和能量方程推导出新的涌潮流速公式，并与现场实测资料进行了比较，两者十分接近，说明新公式可以用来计算近岸浅水涌潮的传播速度，或用于研究与此相关的其它问题。     

钱塘江涌潮压力的分析与研究

对钱塘江涌潮的形成过程作了简单介绍，然后利用波浪力经验公式对涌潮压力进行计算并与实测的涌潮压力进行对比和分析，得出如下结论：（1）浅水长波理论和驻波理论可用于涌潮压力的初估；（2）实际的涌潮压力在以波面为零点的静水压力值附近波动；（3）涌潮动压力在低潮位偏下的位置达到最大值，然后逐渐减小。     

高阶涌潮方程的一种数值方法

涌潮潮头处,水位骤涨,相应地,流速的铅垂分量必有一定大小.考虑这个分量以后,压力不再符合静水压力分布律,据此可以得到高阶浅水流动方程.采用龙格库塔法求该方程的数值解.结果表明,强度较小时,涌潮是表面光滑,波幅渐次减小的波列,强度大到一定程度,表面破碎,进而发展成为溯源推进的水滚.     

波状水跃和波状涌潮的分析

推导了涌潮中尺度方程，并利用此方程，分析水跃和涌潮的性质，对于水跃和涌潮，色散与耗散两种效应强弱的价值依赖于Ｆｒｏｕｄｅ数的函数，存在着两个临界值，当跃前Ｆｒｏｕｄｅ数大于第一个临界值时，水跃和涌潮从单调形态转化为波动形态，随后，波陡随Ｆｒｏｕｄｅ数增大，当Ｆｒｏｕｄｅ数大于第二个临界值时，自由表面破碎，波状涌潮转化为强涌潮，对于涌潮，绝对流速，即落潮流速，对色散波的周期，波长与振幅也有影响。数值     

涌潮的形成和传播

在潮汐河口，流量峰值出现时间早于潮位峰值，潮位波中的高潮痊传播速度快于低潮位，结果使得天传播方向上，波阵面自高潮位向低潮位的比降不断增大，而低潮位向高潮位则不断减小，这种比降差使得落潮期潮流受阻，而潮流受阻反过来又抬或了低潮位，导致低潮位相位滞后，而相位滞后又使得从落潮转到涨潮时涨潮流量始于某一初值，大潮期间，相位滞后角以及由此而引起的落潮转到涨潮时涨潮流量初值增大，并形成涌浪。这种出现在落潮转互     

涌潮的水槽模拟及验证

在涌潮玻璃水槽中,通过调节水槽两端变频器的频率控制潮前水深的稳定,使水体具有一定的潮前落潮流速,并以此为工况,增加下游变频器不同的运行频率模拟各种强度的涌潮,测试涌潮的传播速度、涌潮高度、流速垂向分布等水动力学特征参数,捕捉涌潮形态.在此基础上,选用2010年10月钱塘江河口盐官河段的现场实测资料对试验结果进行比较分析,结果表明涌潮水槽试验结果与盐官河段实地观测资料匹配良好.这说明涌潮玻璃水槽物理模型能成功模拟涌潮,适用于涌潮的测试研究.     

钱塘江鱼鳞石塘涌潮作用力动态测试与分析

动态测试了钱塘江北岸海宁段鱼鳞石塘在涌潮作用过程中受到的作用力,初步探索了涌潮与鱼鳞石塘相互作用的特性,得到了鱼鳞石塘迎潮面条石所受作用力随时间和空间的分布特征.在分析涌潮入射方向和潮头高度影响涌潮压力的同时,还观测并初步分析了台风与大潮共同作用时的涌潮压力.分析表明,涌潮冲击对鱼鳞石塘迎潮面结构物具有一定破坏作用.此次分析研究结果可为保护设计钱塘江临江一线古海塘提供可靠的参考依据.     

土层剪切波速相关因素分析与探讨

土层剪切波速是对土层动力特性和场地类别评判以及结构抗震所需要的重要参数。很多地区基于已有统计资料,取得了剪切波速与深度之间及标准贯入值之间的统计关系。但标准贯入值、钻孔深度对剪切波速估值的具体影响程度和主次关系如何仍未得知。本文尝试引入系统的理论方法——灰色关联分析方法分析钻孔深度、标准贯入值对剪切波速的影响的主次关系,得出土层标贯击数与相应土层剪切波速之间具有很好的关联性,而土层深度对剪切波速影响的关联度一般,因而应该用土层标贯数据进行剪切波速估值公式的拟合的结论。     

涌波的基本性质

分析了溃坝波和涌潮等波动的基本特征。水流穿越涌波时，水流流量、动量虽保持守恒，但机械能大量损耗，因此通常所用的Saint Venant方程并不能描述涌波附近的流动。从微观角度看，考虑铅垂流速分量及水平速度不均匀性所引起的色、耗散效应后，涌波波后将产生衰减的高频波，波陡大为增加，因此表面失稳，进而形成漩滚。分析说明，Froude数也是色、耗散效应的比值，决定了涌波的局部形态。数值计算结果与试验值极为接近。由于天然河道形态复杂，进行涌波数值计算时，需对控制方程的源项进行处理，方能对涌波有深入的了解。     

Experimental hydrodynamic study of the Qiantang River tidal bore

To study the hydrodynamics of tidal bore, a physical modeling study is carried out in a rectangular flume with considerations of the tidal bore heights, the propagation speeds, the tidal current velocities, the front steepness, and the bore shapes. After the validation with the field observations, the experimental results are analyzed, and it is shown that: (1) the greater initial ebb velocity or the larger initial water depth impedes the tidal bore propagation, (2) the maximum bore height appears at an initial ebb velocity in the range of 0.5 m/s-1.5 m/s, (3) when the Froude number exceeds 1.2, an undular bore appears, after it exceeds 1.3, a breaking bore occurs, and after it exceeds 1.7, the bore is broken.     

A computationally efficient model for determining sound speed in shallow tropical freshwater systems,with field validation

The optimum performance of any underwater system depends on the propagation characteristics of the acoustic signals in the local water medium. Shallow tropical freshwater systems suffer from sub‐optimal performance of sonar systems deployed for any acoustic sensing because of random fluctuations of the water medium. The propagation characteristics depend largely on the sound speed variations defined by the site‐specific physical parameters such as water temperature, salinity and depth. The present study focuses on analysing the sound speed profile of a typical shallow freshwater system (Khadakwasla Lake; 18.43°N, 73.76°E), using regression models with the goal of deriving a computationally efficient model. To this end, a linear and polynomial regression model was developed, and their performance compared with the results of the model of Chen and Millero ( 1977 ), based on root mean square error (RMSE). In situ measurements of electrical conductivity, temperature and density (CTD) were carried out using a Valeport 602 CTD meter. Approximately 125 CTD samples were obtained during a 2‐day experimental study conducted at Khadakwasla Lake from 11 October 2017 to 12 October 2017. The data collection was undertaken throughout the day at multiple locations in the lake over a spatial distance of ~16 km. The Valeport 602 CTD meter uses the Chen and Millero ( 1977 ) formula, considered the most conventional sound speed equation. The computational complexity of the proposed models was measured in terms of the number of addition and multiplication operations required. The validation of both models was carried out by varying the model input parameters within defined limits. The model inputs have been derived from an in situ experimental data collection process in a typical shallow tropical freshwater system. The linear regression model exhibited an RMSE of 4.15 m/s, while the polynomial regression model exhibited a good agreement with an RMSE of 0.5 m/s.     

Wave propagation speeds and source term influences in single and integral porosity shallow water equations

In urban flood modeling, so-called porosity shallow water equations (PSWEs), which conceptually account for unresolved structures, e.g., buildings, are a promising approach to addressing high CPU times associated with state-of-the-art explicit numerical methods. The PSWE can be formulated with a single porosity term, referred to as the single porosity shallow water model (SP model), which accounts for both the reduced storage in the cell and the reduced conveyance, or with two porosity terms: one accounting for the reduced storage in the cell and another accounting for the reduced conveyance. The latter form is referred to as an integral or anisotropic porosity shallow water model (AP model). The aim of this study was to analyze the differences in wave propagation speeds of the SP model and the AP model and the implications of numerical model results. First, augmented Roe-type solutions were used to assess the influence of the source terms appearing in both models. It is shown that different source terms have different influences on the stability of the models. Second, four computational test cases were presented and the numerical models were compared. It is observed in the eigenvalue-based analysis as well as in the computational test cases that the models converge if the conveyance porosity in the AP model is close to the storage porosity. If the porosity values differ significantly, the AP model yields different wave propagation speeds and numerical fluxes from those of the BP model. In this study, the ratio between the conveyance and storage porosities was determined to be the most significant parameter.     

生态用水量计算分析

针对我国目前的水资源问题及用水计算问题,提出生态用水包括工业、农业、生活用水和自然环境用水两部分的思想,同时,从这4个方面进行生态用水量计算分析,得出可以实现的结论。     

建桥对钱塘江涌潮高度影响的试验研究

采用潮浪水槽和定床模型进行建桥对钱塘江涌潮高度影响的试验,结果表明涌潮高度的减小幅度与桥墩的阻水率成正比,因此为了保护涌潮的景观,在满足桥梁结构强度和安全的前提下,应尽量减小桥墩的阻水率.     

球面-Rossby波的波谱分析和计算

用正压涡度方程分析了球面-Rossby波的波谱特征,给出了连续谱出现的条件和范围,计算出了球面-Rossby波的特征结构。结果表明:球面-Rossby波在基流角速度存在切变时可出现连续谱,其波谱是由离散谱和连续谱共同组成,连续谱和离散谱的谱函数不同,离散谱的谱函数表现为在子午圈上不同节点的波动,而连续谱的谱的谱函数表现为在子午圈上的某个纬度上出现了跳跃。     

大汶河水环境承载能力的分析与计算

利用实地调查、勘察和监测数据资料，根据流域可持续发展和南水北调东线工程实施的要求，应用系统分析方法及物质循环和能量平衡原理，借助数学模型对大汶河水环境承载能力进行了分析计算，其计算结果可为流域排污总量控制规划和生态环境的综合治理以及南水北调东线工程的实施提供科学依据。