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.     

斜堤护面块体在斜向波作用下的稳定性

通过三维模型试验 ,研究了在斜向波作用下 ,扭工字块体、钩连块体、四脚空心方块和抛填块石等 4种块体在斜向波浪作用下的稳定性 ,给出了实用计算方法。     

多向不规则波作用下九桩群桩效应试验研究

小尺度群桩应用广泛,一直是学者研究的重点,小尺度有别于大尺度桩柱,由于桩柱周围存在漩涡的脱落,使得受力特性复杂。以往的研究过程中,波浪主要采用单向不规则波浪,并且试验模型多以两桩或三桩组成的群桩结构为主,桩数相对较少。多向不规则波与群桩结构的作用特点有别于单向不规则波且研究较少。通过物理模型试验,针对多向不规则波对于9桩桩排群桩结构的作用进行了研究。首先综合考虑KC1/3数和相对桩径的影响,提出以参数KCLD 1/3数来衡量群桩的效应,并分析了正向力与横向力随着参数KCLD 1/3数和相对桩距的变化关系,研究了群桩中不同桩位桩柱波浪力的变化规律和方向分布宽度对于群桩波浪力的影响。研究结果表明,群桩中各桩的正向力随着方向分布标准差的增大而减小,而横向力在相对桩距较大时随着方向分布标准差的增大而增大,同时群桩中不同位置桩上的波浪力具有较大的差异。     

印尼ADIPALA海域较长周期波浪统计特征分析

对印尼ADIPALA海岸观测的较长周期波浪数据进行了统计分析,给出了不同统计波高特征值之间的关系以及统计特征周期和相对水深的关系;并就波浪统计中的波高分布,采用威布尔分布形式进行拟合,得到波高累积分布;给出了最大波高计算公式,可为工程设计提供参考。     

多向不规则波浪的确定性模拟

波浪波动时间过程及波列的模拟,对于开展实际波浪对于工程建筑物的作用具有重要的意义。本文采用线性叠加的单叠加模型,建立了多向不规则波浪的确定性模拟方法。基于理论模拟的规则波、单向不规则波和多向不规则波,验证了波浪确定性模拟方法的有效性。定性地对比分析了模拟波列和已知波列的一致性;定量地研究了模拟波浪在空间范围rr/L_s的误差分布情况(rr表示指定位置与给定位置的空间距离,L_s为有效波长)。并且建议,采用本文方法进行波浪确定性模拟时,最佳的浪高仪间距应小于0.12L_s。     

分段式造波机生成波的方法和特性

本文叙述了分段式造波机生成波的理论和方法，通过试验确定了造波板前过渡段的长度，研究了分段式造波机生成波浪的特性，并将规则波的试验结果与理论结果进行了比较，给出了有效实验区的范围，可供实际应用时参考。     

Active Absorption Wave Maker System for Irregular Waves

1 .IntroductionThephysicalmodeltestisoneofthemainmethodstostudyvariousproblemsassociatedwiththedesignofcoastalstructures .Thecommonlyusedwavemakeristhepiston typewavemaker .Becausethewavemakerishighlyreflective ,akeyproblemisthewavemultiplereflectionsbetweenthewavemakerandthetestedstructuresinthewaveflume .There reflectedwavesfromthewavemakerarespuriouswavesrelativetotheincidentwavestothestructures .Howtopreventthere reflectedwavesfromthewavemakerbecomesacriticalproblemforaccurateexperimental…     

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.     

Numerical investigation of the effect of current on wave focusing

In the present study,a numerical wave tank is developed to simulate the nonlinear wave-current interactions based on High Order Spectral(HOS) method.The influences of current on wave focusing are investigated by use of numerical model.The current is assumed to be constant in space.Focused waves with different amplitudes and frequency spectra are simulated with and without current.The focused wave characteristics,such as surface elevation,the maximum crest and frequency spectrum,with different current are compared.The results show that the opposing current increases the maximum crest and the energy transform during wave focusing process,and vice versa for the following current.     

A Piston-Type Active Absorbing Wavemaker System with Delay Compensation

Physical model tests with highly reflective structures often encounter a problem of multiple reflections between the structures and the wavemaker. This paper presents a piston-type active absorbing wavemaker system which can absorb most of the reflections. Based on the first-order wavemaker theory, a frequency domain absorption transfer function is modeled. Its time realization can be achieved by designing an IIR digital filter, which is used to control the absorbing wavemaker system. In a real system, time delays often exist in the wave making process. Thus a delay compensation term to the transfer function is proposed. Experimental results show that the system performs well for both regular and irregular waves with periods from 0.6 s to 2.0 s, and the absorption capability is larger than 96.5% at target wave fields.