海浪方向谱的现场观测与分析

方向谱是海浪的基本性质之一。本文在国内首次采用测波仪阵列法在渤海采油平台上成功地观测到海浪方向谱，给出了当地随波浪成长而变化的方向谱表达式。观测前采用数模和模型试验方法，对阵列的布置型式、测波仪间距和平台等对观测结果的影响，以及现有各种方向谱分析方法的精度等进行了对比分析，为提高观测精度，保证方向谱分析的质量提供了依据。     

海浪方向谱的阵列测量

本文在系统分析国内外有关方向谱测量工作的基础上,根据实验室模型试验结果,采用由五个测波仪组成的“T”形阵列,于1991年6～7月同在渤海8号采油平台上首次进行了方向谱阵列测量,获得了宝贵的阵列测量资料。测量实施表明,选择最佳测量方案及性能稳定的测波仪器,对测量结果是至关重要的。     

Physical Investigation of Directional Wave Focusing and Breaking Waves in Wave Basin

An experimental scheme for the generation of directional focusing waves in a wave basin is established in this paper. The effects of the directional range, frequency width and center frequency on the wave focusing are studied. The distrihution of maximum amplitude and the evolution of time series and spectra during wave packet propagation and the variation of water surface parameters are extensively investigated. The results reveal that the characteristics of focusing waves are significantly influenced hy wave directionality and that that breaking criteria for directional waves are distinctly different from those for unidirectional waves.     

风浪方向分布模式的比较

本文对目前常用的几种风浪方向分布模式进行了分析对比，进而根据由浪高仪阵列和ＥＮＤＥＣＯ９５６测波浮标在我国各海区测得的风浪方向谱，从波能方向分布、方向累积分布、方向分布的峰值和标准差四个方面，与光易恒、Ｈａｓｓｅｌｍａｎｎ和Ｄｏｎｅｌａｎ等分别由观测得到的经验方向分布以及文圣常等由解析方法得到的风浪方向谱进行了比较，结果表明：Ｄｏｎｅｌａｎ分布与实测结果比较一致，文圣常谱也较接近。此外，笔者在渤海由仪器阵列实测方向谱拟合得到的方向分布（改进的光易模式）与各地实测资料也比较符合。     

海浪方向谱阵列资料实例分析

根据傅氏级数展开法和贝叶斯方法,对现场获得的阵列资料进行了方向谱实例分析。结果表明,实测风浪方向谱能量的相对分布与相应的波场类型密切相关。涌浪和由稳定风场引起的风浪方向谱各组成波能量相对于方向呈单峰对称分布。大风引起的风浪方向谱能量的相对分布,虽也近似为单峰,但对称性差。不同波场类型的风浪方向谱各组成波的谱密度极值方向不同,表明不同频率的组成波有不同的主方向。     

Refraction-Diffraction Model for Irregular Wave and Directional Spectrum Considering Current

- A mild-slope equation for combined refraction and diffraction of random waves in the independent time current is derived using Kirby equation(1984). In the derivation, the frequency of random waves is represented based on the time series concept, by a typical frequency and its deviation part. Numerical results, compared with those of laboratory experiments, demonstrate that new set of irregular mild slope equation with current is of good adaptability.     

Bandwidth Scale for Frequency Spectrum of Sea Waves

It is well known that energy spectrum bandwidth should be able to reflect the degree of energyconcentration.However.the commonly used bandwidth factors defined by Longuet-Higgins could not fitthe concept satisfactorily.A new kind of spectrum bandwidth scale factor with a clear physical meaning isgiven in the present paper and a constant is obtained which reveals the intrinsic characteristics of seawaves.Thereby a universal relationship between significant wave height of sea waves and spectrumbandwidth is established.     

Analysis of Directional Spectra and Reflection Coefficients in Incident and Reflected Wave Field

In this paper, the modified Bayesian method for the analysis of directional wave spectra and reflection coefficients is verified by numerical and physical simulation of waves. The results show that the method can basically separate the incident and reflected directional spectra. In addition, the effect of the type of wave gage arrays, the number of measured wave properties, and the distance between the wave gage array and the reflection line on the resolution of the method are investigated. Some suggestions are proposed for practical application.     

Directional spread parameter at intermediate water depth

The characteristics of directional spread parameters at intermediate water depth are investigated based on a cosine power ‘2s' directional spreading model. This is based on wave measurements carried out using a Datawell directional waverider buoy in 23 m water depth. An empirical equation for the frequency dependent directional spreading parameter is presented. Directional spreading function estimated based on the Maximum Entropy Method is compared with those obtained using a cosine power ‘2s' parameter model. A set of empirical equations relating the directional spreading parameter corresponding to the peak of wave spectrum to other wave parameters like significant wave height and period are obtained. It shows that the wave directional spreading at peak wave frequency can be related to the non-linearity parameter, which allows estimation of directional spreading without reference to wind information.     

Influence of Energy Directional Spread on Wave Spectral Refraction

Pierson- Moskowitz Spectrum, JONSWAP Spectrum as well as Bretschneider- Mitsuyasu Spectrum are used in this paper for analyzing the influence of wave energy directional spread on refraction of wave spectrum due to both current and topography of sea bed. The author's calculation indicates that such kind influence on the characteristic value of wave height as well as the average direction of wave energy propagation can not be ignored.     

Directional spreading of waves in the nearshore zone

The directionality of waves inside a groin field near the German coastal zone of the island of Norderney is studied in the frequency domain. The maximum entropy method is adopted to estimate the directional spreading function. The various characteristics of the directional distribution of waves have been presented for the locations both inside and outside the groin field. The variation of directional spreading with depth and the importance of study of directional waves in coastal regions are discussed.     

非线性相互作用对高频方向谱估计的影响

海浪组成波之间的三阶非线性相互作用产生的高次谐波,不仅改变了波面的外观形状,而且使得高频域不再满足通常的线性频散关系,当ｆ＞１．７ｆｐ时,频散关系应修改为ω２＝２ｇｋ。用最大似然法（ＭＬＭ）分析方向分布的结果表明：在二倍峰频附近,方向分布再次变窄,且能量在方向上的集中程度与海浪的成长状态有关,得到的高频方向分布跟Ｃａｕｄａｌ和Ｈａｕｓｅｒ（１９９６）的微波遥感结果定性一致。     

Wave Reflection Coefficient Spectrum

1 .IntroductionWavereflectionfromstructuresisanimportantfactorforthedesignofthestructures .Therehavebeenmanyresearchesonwavereflectionwithregularwavesandmonochromaticirregularwaves .Miche( 1 951 )proposedanon dimensionalMichenumberMfornormallyincidentirregularwavesconsideringwavebreakingbecauseofthedeepeningofwavesteepnessontheslopeofbreakwaters .ThereflectioncoefficientisproportionaltoM ,i.e .,Kr ∝M =4g( 2π) 5/ 2tan5/ 2 α(Hsf2p) ( 1 )wheregisthegravitationalacceleration ,Hsthesignifican…     

Application of the four models of directional spectra in the Bohai Sea

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波浪谱形对不规则波数值模拟的影响

通过数值模拟分析了波浪谱形对不规则波浪数值模拟结果的影响.采用不同参数的JONSWAP谱模拟入射波要素,基于抛物型缓坡方程模拟不规则波浪的传播,分析了波浪谱形状对波浪数值模拟结果的影响.结果表明,采用抛物型缓坡方程模拟不规则波浪时,入射波浪谱形对模拟结果影响不明显;但由于模型中非线性项的影响,采用不规则波模拟的波高分布和采用规则波模拟的结果略有差别.     

海浪谱型对最大波高估算的影响研究

无论是对于各种涉海水工建筑物的设计还是对于它们的防护而言,最大波高的预测都是非常重要的工作。目前常用的海浪预报模式多以相位平均模型为主,其能直接给出的计算结果是海浪谱,因此基于海浪谱给出合理的最大波高估算具有重要的意义。前人对波陡、谱宽等参数对最大波高公式的影响都有了较为清楚的认知,然而相关研究大多围绕单峰谱开展,尚没有考虑包括双峰谱在内的海浪谱型最大波高公式的影响。本文首先探讨了海浪谱对最大波高的影响特性,进而提出了海浪谱谱型的参数化定义,最后给出了考虑谱型因子的最大波高公式。     

胶州湾双峰谱型波浪的统计特征

本文对胶州湾实测双峰海浪谱的资料进行了统计分析和谱分析，探讨了双峰谱型海浪的波要素概率分布及其群性特征，并与单峰谱型海浪进行了比较．最后通过双峰谱的合成波高、周期与实测值的比较，对采用能量迭加方式的式（９）和式（８）进行一些讨论，主要结果列于本文最后一节．     

海浪谱峰周期与跨零周期的一个经验关系式

从PM谱出发,推导出谱峰周期与跨零周期的谱关系式Tp=(5π/4)^1/4Tz≈1．41Tz;对海上实测海浪谱资料进行了分析,表明该式所给出的系数与统计值相当接近,较好地解决了由海浪谱直接获取谱峰周期所产生的谱稳定性问题。     

双峰谱型海浪的波高和周期分布

本文利用收集到的实测双峰谱型海浪过程资料，把这些资料以波高和周期的相关系数为参数分成５组，讨论每组双峰谱型下被高、周期的统计分布．并探讨了相关系数对波高分布和周期分布的影响。     

分段式造波机生成波浪的方向谱分析

采用声学多普勒流速仪(ADV)和多点测波仪的实验资料,对分段式造波机生成的多向随机波浪进行方向谱分析.结果表明,分段式造波机生成的多向随机波浪的时间平稳性优于空间均匀性;贝叶斯方法(BDM)适合于流速实验资料和阵列波浪资料的方向谱分析,给出的方向谱满足随机波浪的内禀性质(如光滑性、连续性等);流速资料和阵列波浪资料给出的方向谱具有相当的精度,但与测速的深度有关;三参量(如三点波浪、两个方向的速度分量和一点波浪等)可给出具有相当精度的方向谱;给出了衡量方向谱精度的初步标准.