共查询到20条相似文献，搜索用时 15 毫秒
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The hydrodynamic efficiencies of caisson-type vertical porous seawalls used for protecting coastal areas were calculated in this study. Physical models were developed to compare the wave reflection from vertical plane, semi-porous, and porous seawalls caused by both regular and random waves. Tests were carried out for a wide range of wave heights, wave periods, and different water depths (d=0.165, 0.270 and 0.375 m). The performance regarding the reflected waves from porous and semi-porous seawalls showed improvement when compared with those from the plane seawall. The reflection coefficients of the porous and semi-porous seawalls were calculated as 0.6 and 0.75, respectively, while the coefficient for the fully reflecting plane vertical wall was significantly higher (0.9). It was also observed that the reflection coefficient decreases with increase in wave steepness and relative water depth. In addition, the reduction in the reflection coefficient of porous and semi-porous seawalls, as compared to that of a plane seawall, was observed for both regular and random waves. New equations were also proposed to calculate the reflection coefficient of different types of seawalls with the aid of laboratory experiments. By verifying the developed equations using some other experimental data, it was validated that the equations could be used for practical situations. The results of the present study can be applied to optimize the design of vertical seawalls and for coastal protecting schemes. 相似文献
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Hsien-KuoCHANG Jin-ChengLIOU 《中国海洋工程》2004,18(3):371-380
This investigation examines long wave reflection and transmission induced by a sloping step. Bellman and Kalaba‘s (1959) invariant imbeddlng is introduced to find wave reflection. An alternative method matching both the surface elevation and its surface slope of each region at the junction is applied to the determination of wave reflection and transmission.The proposed methods are compared with the accurate numerical results of Porter and Porter (2000) and those of Mei (1983) for a vertical step. The wave reflection obtained for a mildly sloping step differs significantly from the result of Mei. The wave reflection is found to fluctuate owing to wave trapping for the ntild sloping step. The height and the face slope of the step are important for determining wave reflection and transmission coefficients. 相似文献
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通过数模波浪和物模实验，比较分析了估算多向不规则入射波与反射波相互叠加的锁相波浪场方向分布和反射系数方向分布的改进的贝叶斯估计法MBDM和扩展的最大似然法MMLM的性能。数模试验检验了不同波浪条件、不同波浪测量系统和结构物的不同反射特性等情况下的估算结果，同时还比较了两种分析方法的计算速度和稳定性，结果显示，对于波浪的方向分布估计，MBDM优于MMLM，对于反射系数的方向分布估计以及计算速度和稳定性，MMLM优于MBDM。 相似文献
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近岸植物带能有效削弱波浪作用,植物带消浪影响因素分析对布置护岸工程、维护岸线稳定有重要意义。在模型实验基础上,探究相对波高、模型相对宽度、模型相对高度和体积分数对透射系数的影响。设置波浪水槽试验,研究孤立波在不同水深、入射波高及植物排布方式等组合条件下对植物消浪效果的影响。采用遗传编程法得出各复杂度下的透射系数计算公式,并分析各参数在方程中的表现情况,发现遗传编程能定性给出参数的敏感度。相比于非线性回归拟合结果,遗传编程方法得到的函数关系更加精确。采用人工神经网络方法进一步分析与验证各影响因素对植物消浪效果的影响程度,结果表明人工神经网络得出的结果与遗传编程方法相近,体积分数对消浪效果起主导作用。 相似文献
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The wave transmission characteristics and wave induced pressures on twin plate breakwater are investigated experimentally in regular and random waves.A total of twenty pressure transducers are fixed on four surfaces of twin plate to measure the wave induced dynamic pressures.The spatial distribution of dynamic wave pressure is given along the surface of the twin plate.The uplift wave force obtained by integrating the hydrodynamic pressure along the structure is presented.Discussed are the influence of different incident wave parameters including the relative plate width B /L,relative wave height /i H a and relative submergence depth s /a on the non-dimensional dynamic wave pressures and total wave forces.From the investigation,it is found that the optimum transmission coefficient,t K occurs around B /L 0.41 ~ 0.43,and the twin plate breakwater is more effective in different water depths.The maximum of pressure ratio decreases from 1.8 to 1.1 when the relative submergence depth of top plate is increased from 0.8to +0.8. 相似文献
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A numerical wave tank is used to investigate the onset and strength of unforced wave breaking, and the waves have three types of initial spectra： constant amplitude spectrum, constant steepness spectrum and Pierson-Moscowitz spectrum. Numerical tests are performed to validate the model results. Then, the onset of wave breaking is discussed with geometric, kinematic, and dynamic breaking criteria. The strength of wave breaking, which is always characterized by the fractional energy loss and breaking strength coefficient, is studied for different spectra. The results show how the energy growth rate is better than the initial wave steepness on estimating the fractional energy losses as well as breaking strength coefficient. 相似文献
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A numerical wave tank is used to investigate the onset and strength of unforced wave breaking, and the waves have three types of initial spectra: constant amplitude spectrum, constant steepness spectrum and Pierson-Moscowitz spectrum. Numerical tests are performed to validate the model results. Then, the onset of wave breaking is discussed with geometric, kinematic, and dynamic breaking criteria. The strength of wave breaking, which is always characterized by the fractional energy loss and breaking strength coefficient, is studied for different spectra. The results show how the energy growth rate is better than the initial wave steepness on estimating the fractional energy losses as well as breaking strength coefficient. 相似文献
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为了研究真实海洋表面马蹄波的波形特征,通过物理模型试验研究了马蹄波的波形特征参数。研究中通过引入满足共振条件的扰动波成功在试验室内产生了马蹄波,测量和分析了马蹄波的波面升高和水平弧形波峰的几何特征,定义了新的垂向几何参数和水平几何特征参数,给出了不同水深情况下的这些参数的结果,得出了水深对马蹄波几何形态的影响。理论分析了马蹄波的横向结果,并与试验测量结果和弧形处理结果进行了对比。结果表明,马蹄波波形受水深影响较大;水深越浅,马蹄波的波面形状越接近椭圆余弦波,横向波长也越大。 相似文献
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海草所形成的植物消波体系能有效防止岸线的侵蚀。利用Sánchez-González等的实验数据分析了波浪非线性对海草消波特性的影响。研究结果表明,相对水深和波陡对海草床的波能衰减系数影响依赖于海草淹没度。相对波高一定时,拖曳力系数随相对水深的增大而增大。对给定的相对水深,拖曳力系数随波陡的增大而减小。波浪非线性对于规则波和非规则波海草消波特性的影响并不一致。用无量纲参数（邱卡数、雷诺数、厄塞尔数）表达拖曳力系数的效果取决于拖曳力系数与无量纲参数的关系中是否充分考虑波浪非线性对拖曳力系数的影响。 相似文献
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声波在松散沉积物上的反射 总被引：3，自引：0，他引：3
将海底沉积物的为一种松散的湿颗粒介质，并假设海水与沉积物的界面是平的，由位移，动量密度及压强在界面处在连续性，导出平面声波在其上的反射系数，建立反射系数与沉积物的具体参数的联系。所得结果可化为前人用唯象理论所获得的形式。将理论与实验比较的结果表明，两者的一致性是好的。 相似文献
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分析了平面渡与桩列透空堤的相互作用.根据对矩形桩列上力平衡原理和非线性流阻等水动力学特征分析,导出一组计算反射、传递系数和波浪荷载的理论公式.计算公式内所有参数均是已知的,用它们预测的结果与现有的试验数据很好吻合. 相似文献
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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. 相似文献
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Yang Zhengji Zuo Qihua
Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1991,(2)
The wave forces on 1, 2 and 4 vertical circular piles under the action of several wave trains of the same wave parameters, such as Hs,Tp and Mo, but different wave group factor GF are measured in the laboratory. After comparing these forces, it may be concluded that the mean and significant wave forces are almost of no difference for the wave trains with different GF. When GF is larger, the one-tenth of the wave froce extreme is slightly increased and the maximum wave force is much larger than the ones with smaller GF, to which attention must be paid in engineering practice. 相似文献
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刚性植物分布方式对海啸波消减影响实验研究 总被引：1，自引：0，他引：1
在理论分析的基础上通过物理模型实验探究了刚性植物分布方式对海啸波消减的影响。实验中借助孤立波模拟海啸波,分析了矩形、交错、组合三类分布方式下孤立波沿程波高、透射系数以及拖曳力系数的变化情况。结果表明,植物分布密度相等时,孤立波在矩形和组合分布植物模型前的壅高均大于交错分布植物模型。同时,植物分布密度一定时,分布方式将对植物消波产生影响,且植物间横向间距L2比纵向间距L1的影响更大。在雷诺数2000≤Rep≤4000且体积分数小于或等于0.331的条件下,各植物模型的拖曳力系数随植物分布密度的增大而增大。 相似文献