共查询到20条相似文献，搜索用时 109 毫秒
1.
2.
海岸波浪多次破碎波能耗散模型 总被引：1，自引：0，他引：1
在坡度很缓(接近或小于1∶100)的海岸，波浪在向海岸传播的过程中，可能经历多次破碎，而在两次波浪破碎之间将伴随着波浪恢复(波浪恢复到不破碎状态)。在现有海岸波高计算模型中，波浪破碎是通过波能耗散来模拟的，但所采用的波能耗散模型都不能自动考虑波浪出现多次破碎的过程，特别精确模拟这一过程中出现的波浪恢复。本文提出了解决这一问题的新的波能耗散模型，模型的建立是通过在Dally模型中重新建立稳定波能、饱和波高水深比和波能耗散系数，并引入了波浪恢复的判断条件实现的。该模型的波能耗散在波浪恢复区的值很小故能描述波浪恢复区的波浪运动。与实验结果的对比表明，新模型可以适合缓坡情况波浪多次破碎的波高模拟，而且对不同坡度的平坡和沙坝海岸(1∶100～1∶10)的破碎波模拟都可以给出与实验结果符合的结果，并且可以自动识别多次波浪破碎的存在和波浪恢复的发生。 相似文献
3.
本文在讨论破碎波判据研究的基础上(文献[1]),根据前人的破碎波研究结果,以及海浪的随机性,建立了一个包含摩擦风速和波浪要素的破碎波判据计算模式,报告了在海上和实验室进行验证的实测结果.其特点是利用良好的现场观测条件和先进的实验设备,对破碎波进行了测量,首次通过划分破碎波的状态,合理地给出了破碎波判据的实测结果,并比较分析了其他几种波浪破碎判据的实测结果及使用范围.本文的计算风浪破碎判据的模式与外海实测结果比较接近,但与实验室测量结果相差较大. 相似文献
4.
5.
6.
破碎波对近海海岸地形以及海岸建筑物影响强烈,通过物理模型实验对孤立波、规则波作用下破碎带的床面形态以及孔隙水压力进行分析。破碎波冲击海床,破碎处床面上形成沙坝和沙坑,与规则波相比,孤立波破碎时对床面的冲刷更加剧烈,床面形成的沙坝和沙坑尺度更大,且土体内孔隙水压力幅值也较大。同时研究了波面变化对孔隙水压力的影响,发现波面变化历时曲线与孔隙水压力历时曲线相似,与孔隙水压力梯度历时曲线更为相似,说明波面变化更能反映海床内部孔隙水压力梯度的变化。通过探讨波浪与海床之间相互耦合作用,发现破碎带地形变化使得波浪出现不同破碎类型,分析得出卷破波比崩破波作用下孔隙水压力幅值大。 相似文献
7.
8.
总结破碎波近年来的研究状况，从理论上对计算破碎波发生率进行分析。并利用先进的实验设备和良好的现场条件，从实验研究出发，在研究波浪破碎过程及其与环境参量的关系中，对破碎波发生率进行实际测量。利用不同的破碎波判据对破碎波发生率进行了计算、比较和分析，结果指出；利用不同的破碎波判据计算的破碎波发生率相差很大，甚至相差３～４倍。 相似文献
9.
10.
通过物理模型实验研究了海岸沙坝剖面和滩肩剖面的形成和演化过程,给出了稳定的沙坝剖面和滩肩剖面的几何特征。实验中考虑了两种初始坡度(1∶20和1∶10)和不同波高的规则波和不规则波,讨论了不同初始坡度海岸上破碎波空间分布特征。结果表明,沙坝产生后存在向岸和离岸两种运动形态,但最终将停留在稳定位置。稳定的沙坝剖面对应不同初始坡度和波浪存在不同的大沙坝和小沙坝分布。沙坝剖面由长时间小波高波浪序列作用后可转化为稳定滩肩剖面,该剖面不依赖于波浪和初始坡度。实验也给出了平衡剖面与理论曲线的对比以及剖面上泥沙粒径的分布。 相似文献
11.
Low-frequency waves in the surf and swash zones on various beach slopes are discussed using numerical simulations. Simulated surface elevations of both primary waves and low-frequency waves across the surf zone were first compared with experimental data and good agreement found. Low-frequency wave characteristics are then discussed in terms of their physical nature and their relationship to the primary wave field on a series of sea bottom slopes. Unlike primary waves, low-frequency wave energy increases towards the shoreline. Low-frequency waves in the surf and swash are a function of incident waves and the sea bottom slope and hence the saturation level of the surf zone. Wave energy on a gently sloping beach is dominated by low-frequency waves while primary waves play a significant role on a steep beach. Low-frequency wave radiation from the surf zone on a given beach depends on primary wave frequency and beach slope. However, a very poor correlation was found between surf similarity parameter and low-frequency wave radiation. 相似文献
12.
A.R. Packwood 《Coastal Engineering》1983,7(1):29-40
Packwood, A.R., 1983. The influence of beach porosity on wave uprush and backwash. Coastal Eng., 7: 29–40.A numerical model is described to calculate the influence of a porous bed on the run-up of a bore on a gently sloping sandy beach. It is shown that fine-medium grade sands have very little effect in the run-up phase. Significant differences between impermeable and porous bed solutions are found in the backwash which might explain certain sand erosion and deposition phenomena. 相似文献
13.
M.J.F. Stive 《Coastal Engineering》1985,9(2):151-158
A measurement programme, conducted in a small-scale wave flume, which comprised the breaking of periodic and random waves on a gently sloping beach, was partly repeated in a large-scale wave flume. The results are used here to make a scale comparison. The quantities considered in the comparison are wave heights, set-up and vertical profiles of maximum seaward, maximum shoreward and time-mean horizontal velocities. It appears that, both qualitatively and quantitatively, scale effects in these quantities are virtually absent in the wave height range of 0.1 m to 1.5 m. 相似文献
14.
In this paper the variations of radiation stress and mean water level are studied for the two-dimensional shoaling and breaking of progressive, periodic waves on a plane, gently sloping laboratory beach. Observations of radiation stress and mean water level were made for two initial conditions. The observed variations are compared to the variations as calculated by a linear theory, James' nonlinear theory, and a new nonlinear theory based on Cokelet's work. It is shown that the nonlinear theories are qualitatively and quantitatively superior to the linear theory, thus indicating that the effects of finite amplitude are important for the present case. 相似文献
15.
Energy dissipation in waves breaking on gentle slopes 总被引：1，自引：0，他引：1
M.J.F. Stive 《Coastal Engineering》1984,8(2):99-127
The flow field of waves breaking on a gently sloping beach is shown to closely resemble that of hydraulic jumps. This supports the use of the hydraulic jump formulation for the breaking wave energy dissipation. A correction to this formulation, which takes into account the effects of turbulent flow, is found to explain the observed discrepancies between the classical theoretical result and the experiments satisfactorily. These findings are used to propose a simple, semi-empirical model for the wave height decay which includes the set-up. The model is generalized to a wider range of wave conditions by analyzing published data. 相似文献
16.
This study presents sand activation depth (SAD) measurements recently obtained on two contrasting beaches located along the Atlantic coast of France: the gently sloping, high-energy St Trojan beach where wave incidence is usually weak, and the steep, low-energy Arçay Sandspit beach where waves break at highly oblique angles. Comparisons between field measurements and predictions from existing formulae show good agreement for St Trojan beach but underestimate the SAD on the Arçay Sandspit beach by 40–60%. Such differences suggest a strong influence of wave obliquity on SAD. To verify this hypothesis, the relative influence of wave parameters was investigated by means of numerical modelling. A quasi-linear increase of SAD with wave height was confirmed for shore-normal and slightly oblique wave conditions, and a quasi-linear increase in SAD with wave obliquity was also revealed. Combining the numerical results with previously published relations, both a new semi-empirical and an empirical formula for the prediction of SAD were developed which showed good SAD predictions under conditions of oblique wave breaking. The new empirical formula for the prediction of SAD (Z 0) takes into account the significant wave height (H s), the beach face slope (β) and the wave angle at breaking (α), and is of the form $ Z_{0} = 1.6\tan {\left( \beta \right)}H^{{0.5}}_{{\text{s}}} {\sqrt {1 + \sin {\left( {2\alpha } \right)}} } This study presents sand activation depth (SAD) measurements recently obtained on two contrasting beaches located along the
Atlantic coast of France: the gently sloping, high-energy St Trojan beach where wave incidence is usually weak, and the steep,
low-energy Ar?ay Sandspit beach where waves break at highly oblique angles. Comparisons between field measurements and predictions
from existing formulae show good agreement for St Trojan beach but underestimate the SAD on the Ar?ay Sandspit beach by 40–60%.
Such differences suggest a strong influence of wave obliquity on SAD. To verify this hypothesis, the relative influence of
wave parameters was investigated by means of numerical modelling. A quasi-linear increase of SAD with wave height was confirmed
for shore-normal and slightly oblique wave conditions, and a quasi-linear increase in SAD with wave obliquity was also revealed.
Combining the numerical results with previously published relations, both a new semi-empirical and an empirical formula for
the prediction of SAD were developed which showed good SAD predictions under conditions of oblique wave breaking. The new
empirical formula for the prediction of SAD (Z
0) takes into account the significant wave height (H
s), the beach face slope (β) and the wave angle at breaking (α), and is of the form . The use of a dataset from the literature demonstrates the predictive skill of these new formulae for a wide range of wave
heights, wave incidence and beach gradients. 相似文献
17.
Gu Jialong Shen Xianrong
Professor Hohai University Nanjing
Engineer The Investigation Design Institute Bureau of Communications of Zhejiang Province Hangzhou 《中国海洋工程》1991,(2)
In accordance with the similarity between breaking waves and hydraulic jumps, the expressions for estimating wave decay and wave energy dissipation in the surf zone are derived based on the fundamental equations of fluid mechanics. Using the numerical solution of cnoidal wave theory, the various kinematic properties of waves in the surf zone, including the relative wave crest height, wave energy, and radiation stress are discussed. The values calculated with the method proposed in this paper are in good agreement with the experimental data gained by other researchers. The present expressions can be used in the studies of sediment transport on gently sloping beaches, especially on muddy beaches. 相似文献
18.
This paper is focussed on the derivation of a set of general scaling laws valid for both beach and dune erosion volumes based on scaling law analysis, existing and new experimental results. This latter experiments concern beach profile changes in three different laboratory flumes using identical wave conditions based on Froude scaling. The experiments with planar sloping beaches have been done at three scales: large-scale Hannover wave flume experiment (beach slope of 1 to 15), medium scale Barcelona wave flume experiment (beach slope of 1 to 15) and small-scale Delft wave flume experiments (beach slopes of 1 to 10, 15 and 20) using an identical wave train of irregular waves (single topped spectrum). 相似文献
19.
植被斜坡岸滩海啸波消减数值模拟研究 总被引：1，自引：0，他引：1
An explicit one-dimensional model based on the shallow water equations(SWEs) was established in this work to simulate tsunami wave propagation on a vegetated beach. This model adopted the finite-volume method(FVM)for maintaining the mass balance of these equations. The resistance force caused by vegetation was taken into account as a source term in the momentum equation. The Harten–Lax–van Leer(HLL) approximate Riemann solver was applied to evaluate the interface fluxes for tracing the wet/dry transition boundary. This proposed model was used to simulate solitary wave run-up and long-periodic wave propagation on a sloping beach. The calibration process suitably compared the calculated results with the measured data. The tsunami waves were also simulated to discuss the water depth, tsunami force, as well as the current speed in absence of and in presence of forest domain. The results indicated that forest growth at the beach reduced wave energy loss caused by tsunamis. A series of sensitivity analyses were conducted with respect to variable parameters(such as vegetation densities, wave heights, wave periods, bed resistance, and beach slopes) to identify important influences on mitigating tsunami damage on coastal forest beach. 相似文献
20.
建立了求解一维全非线性Green-Naghdi水波方程的中心有限体积/有限差分混合数值格式。采用结构化网格对守恒形式的控制方程进行离散和积分,界面数值通量采用有限体积法计算,剩余项则采用中心有限差分格式求解。其中,采用中心迎风有限体积格式计算控制体界面数值通量,并结合界面变量的线性重构方法,使其在空间上具有四阶精度,通过引入静压重构技术和波浪破碎指标使模型具备处理海岸水-陆动边界及波浪破碎的能力。时间积分则采用具有总时间变差减小(Total Variation Diminishing,TVD)性质的三阶龙格-库塔法进行。应用该模型对孤立波在常水深和斜坡海岸上的传播过程及规则波跨越潜堤传播的实验进行了数值模型研究,数值计算同解析解及实验数据吻合良好。 相似文献