共查询到19条相似文献，搜索用时 121 毫秒
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本文在作者另文数值模拟得到的三维海浪基础上 ,进一步分析给出了三维波峰长度、高度及方向角度等特征量的统计分布。发现考虑海浪的方向性质后波峰分布不再是均匀连续的 ;波峰的长度分布受方向函数影响 ,方向分布越宽 ,波峰的平均长度越短 ,波峰的方向角分布越宽 ;波峰高度和长度在波峰高度较小时有很大的相关性 ,而在波峰高度很大时无关 相似文献
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三维随机海浪的数值模拟 总被引：1，自引：0，他引：1
本文首先分析了三维随机海浪的方向谱函数和三维随机海浪的数学模型,然后在ＭＡＴＬＡＢ环境下设计了数值模拟程序,并模拟出三维随机海浪的方向谱和三维随机海浪的三维空间模型。 相似文献
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用WAVEWATCHIII海浪模拟了5个不同风场结构的热带气旋下海浪平均要素和海浪方向谱来研究其对风场非对称性的响应。结果表明热带气旋诱发的海浪场对风场的非对称性很敏感。随着风场非对称性加强,有效波高除了左前象限增加以外在其他所有象限内都减小,且有效波高场的非对称性增强,并且非对称轴逆时针旋转,同时,有效波高最大值的位置向前移动。风场的非对称性对其他平均要素也有影响,尤其在左后象限最明显,例如平均波长,平均波向,波峰方向等。风场的非对称性对海浪谱的多峰性以及主导波的频率和传播方向都有很重要的影响。 相似文献
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多向不规则波浪生成的数值方法 总被引：4，自引：3，他引：4
实际的海浪是三维(多方向)的,海浪的方向分布对于海浪折射、绕射及泥沙运动等的研究具有重要的意义,因而人们利用多向不规则造波机对它进行物理模型试验研究.同时,基于合适的数学模型,可在计算机上产生长时段的多向不规则波浪,用于研究海浪的基本特性及其对工程建筑物的作用,也是一种方便经济有效的手段,这也是制作多向不规则波造波机控制信号的基础.因此,如何由数模有效地合成多向不规则波浪,日益受到人们的重视.常用的一种方法是把海浪看作由无数不同频率和不同方向的组成波线性叠加而成,因而将模拟二维波浪的方法[1]直接推广应用于三维波浪的模拟.但是这样模拟所得的波浪往往是空间上不均匀,时间上会重复出现,需要进一步研究改进.本文首先给出了多向不规则波的三种模拟方法,并对其模拟结果进行了分析检验,给出了较理想的海浪模式.在此基础上,研究了模拟所得波浪的基本特征和模拟参数的确定. 相似文献
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多向随机波的实验室模拟 总被引：3，自引：2，他引：3
海浪是一种多向随机波。本文首先对常用的多向随机波的数值模拟方法——双迭加法进行改进,建议了频率方向对应法,并给出了合适的模拟参数。此法能产生比较符合实际的波浪。在此基础上论述了三维随机波的物理模拟方法,并对多向随机波试验中的几个重要问题进行了探讨。 相似文献
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于定勇 《中国海洋大学学报(自然科学版)》1999,(2)
从随机海浪群因子的定义出发,分别研究将海浪视作正态过程和非正态过程时海浪的群性。研究结果发现按正态过程描述海浪时其群因子的值为常值,而按非正态过程描述海浪时其群因子的值不再是常值,它与海浪的非线性因子及谱宽度参数有关,并随这两个因子变化而变化。文中并给出了海上实测资料的验证结果 相似文献
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The statistical distribution of wave crest characteristics such as crest length, crest height, joint crest height and length are analyzed based on numerical simulation of 3-D random waves. The effects of directional functions and wave crest defining methods on crest characteristics are also studied.The results show that wave crests are no longer uniform and continuous in directional wave field; the distribution of crest length is obviously influenced by the directional function; the statistics of crest characteristics obtained by the two different methods are almost the same. 相似文献
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波浪聚焦被认为是产生极限波浪的重要机理之一,近年来受到普遍重视。通过高阶谱方法,引入造波边界建立数值计算模型,模拟聚焦波浪在不同方向分布时的产生和聚焦过程,研究波浪的方向分布对聚焦波浪的波面、波峰最大值、聚焦点的偏移、波面参数及频谱的影响。研究结果表明波浪方向分布越窄,波浪的非线性影响越强、波面越陡,波峰值、聚焦点的偏移和波面特征参数都越大;同时方向分布对波浪聚焦前后的能量具有很大的影响。 相似文献
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《Coastal Engineering》1999,36(2):147-163
Observations of waves as a time series from a fixed or moored sensor are shown to underestimate the extreme waves occurring in the vicinity. The underestimate arises because of the difference in phase and envelope propagation of surface water waves so that the highest crest, for example, is recorded only when the crest coincides with the envelope maximum at the location of the wave recorder. In addition, the dispersive nature of water waves can lead to the coalescence of groups of waves as longer waves catch up to shorter slower waves, so that the group shape changes markedly as the waves propagate. Moored accelerometer buoys introduce another error that exacerbates the underestimate of the highest crest—the quasi-Lagrangian motion of the buoy leads to flattening of the crests and sharpening of the troughs so that apparent mean water level is raised and thus the height of crests above it is reduced. An analysis approach to correct these underestimates is outlined and tested with observed data against the predictions of extreme values based on narrow-banded random wave theory. 相似文献
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Kern E. Kenyon 《Journal of Oceanography》1997,53(1):89-92
The effects of the gravity torques acting on the angular momentum of surface gravity waves are calculated theoretically. For
short crested waves the gravity torque is caused by the force of gravity on the orbiting fluid particles acting down the slopes
of the crests and troughs and in the direction parallel to the crests and troughs. The gravity torque tries to rotate the
angular momentum vectors, and thus the waves themselves, counterclockwise in the horizontal plane, as viewed from above, in
both hemispheres. The amount of rotation per unit time is computed to be significant assuming reasonable values for the along-crest
and trough slopes for waves in a storm area. The gravity torque has a frequency which is double the frequency of the waves.
For long crested waves the gravity torque acts in the vertical plane of the orbit and tries to decelerate the particles when
they rise and accelerate them when they fall. By disrupting the horizontal cyclostrophic balance of forces on the fluid particles
(centrifugal force versus pressure force) the gravity torque accounts qualitatively for the three characteristics of breaking
waves: that they break at the surface, that they break at the crest, and that the crest breaks in the direction of wave propagation. 相似文献
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本文在时域非线性数值波浪水槽中,研究了不同风速条件下极端波浪的特性。采用推板造波的方式生成非线性波浪,基于Jeffrey遮蔽理论将风压项引入自由面动力学边界条件来模拟风压作用,通过高阶边界元法和混合欧拉-拉格朗日时间步进法来求解初边值问题。通过与已发表的聚焦波群实验结果对比验证了该数值模型的准确性,并研究了风压对极端波浪的最大波高、聚焦位置的偏移和波浪谱的演变等波浪性质的影响。本文进一步在数值波浪水槽中引入均匀水流,来模拟风生流对波浪演变的影响。结果表明,风压的存在会少量增大极端波浪的最大波高,波浪的聚焦和解焦过程伴随着明显的能量传递,并且风生流进一步导致了波浪聚焦位置的偏移。 相似文献
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It is well established that the modulational instability enhances the probability of occurrence for extreme events in long crested wave fields. Recent studies, however, have shown that the coexistence of directional wave components can reduce the effects related to the modulational instability. Here, numerical simulations of the Euler equations are used to investigate whether the modulational instability may produce significant deviations from second-order statistical properties of surface gravity waves when short crestness (i.e., directionality) is accounted for. The case of a broad-banded directional wave field (i.e. wind sea) is investigated. The analysis is concentrated on the wave crest and trough distribution. For completeness a comparison with a unidirectional wave field is presented also. Results will show that the distributions based on second-order theory provide a good estimate for the simulated crest and trough height also at low probability levels. 相似文献
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Statistics of nonlinear wave crests and groups 总被引：1，自引：0，他引：1
Groups of large nonlinear waves with sharper higher crests can pose hazards to ships, induce harbor resonance and cause wave-overtopping of fixed and floating structures. Past interest in wave groups has mostly been focused on the statistics and modeling of linear wave groups. Studies on nonlinear wave groups are surprisingly few, and address deep water waves only. Here, statistics of nonlinear wave crests and wave-crest groups in deep and transitional water depths are considered, using an appropriate second-order representation for crest heights and the continuous wave-envelope approach. In particular, theoretical expressions describing the statistics of nonlinear wave crests and their groups are posed in the form of a simple second-order transformation of well-known results on linear waves. Predictions from the transformation so posed compare well with nonlinear wave data gathered in the North Sea, and demonstrate that nonlinearities do affect the statistics of large wave crests and their groups significantly. 相似文献
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用60个波高仪组成2m×2m的方阵,同步测量波面过程,用Doppler声学流速仪获得了二维正向和斜向规则波、二维正向和斜向随机波以及三维随机波浪场中不同水深处的同步Euler水质点速度各方向分量的高精度的时间过程资料.以此为出发点,讨论了分段式造波机生成波浪的周期分布特征,发现三维随机波浪周期分布的μ值与二维随机波浪比较有明显增大的趋势.分别从速度合矢量方向与波向的吻合程度(对二维波浪)、"多点波面"组合与"波面-水质点速度"组合两种方式得到方向谱的吻合程度(对三维随机波浪)等不同角度,论证了分段式造波机产生的波浪的内外部结构的一致性. 相似文献
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风浪波高和周期的联合概率密度分布 总被引：1，自引：0，他引：1
本文采用有代表性的44008美国国家浮标站2003年1～3月实测的海浪谱密度资料,选取三次大风过程进行风浪谱分析。通过对实测平均海浪谱与PM谱、JONSWAP谱及Torsethaugen谱的比较,得到PM谱拟和最好。然后用国际上最先进的随机波分析方法,根据协方差矩阵的循环嵌套技术,以实测平均谱与PM谱为靶谱,对随机波面进行模拟。得到由模拟波面统计的特征值及估计的谱与实测谱结果极为相近,谱峰及谱峰频率都基本一致。说明利用模拟波面研究海浪具有代表性,它可以反映实测海浪的特征。利用Longuet-Higgins(1983)模型计算波高-周期联合概率密度分布,得到变换高斯过程计算的波高、周期联合分布与实测情况基本相同,更好地描述了波高-周期联合概率密度分布。 相似文献