共查询到20条相似文献，搜索用时 31 毫秒
1.
The responses of a monopile offshore wind turbine subjected to irregular wave loads are investigated numerically and experimentally, considering a range of sea states. An extensive experimental campaign was carried out on a fully flexible model, representative of a 5 MW offshore wind turbine, at 1:40 scale. An assessment of the experimental results for the response amplitude operator for regular waves and the 90th percentile seabed bending moment in long-crested irregular waves is carried out using two models (analytical and numerical) for uncertainty propagation, suggesting that bias errors in the model properties and in the wave elevation contribute the most to the total uncertainty. The experimental results are also compared to a numerical model using beam elements and Morison-type wave loads with second order wave kinematics. The numerical model does not capture all of the responses within the level of uncertainty of the experiments, and possible reasons for the discrepancies are discussed. 相似文献
2.
Tao Jianhua Tian Zhenfu
Professor Dept. of Mechanics Tianjin University Tianjin
Assistant Dept. of Mathematics Ningxia University Yinchuan Ningxia Hui Autonomous Region 《中国海洋工程》1991,(1)
Based on the singleline theory, a numerical simulation is presented to predict the shoreline evolution on sand beach. A parabolic equation of longshore sediment transport and boundary conditions are proposed. The combined effect of wave diffraction and refraction on the shoreline evolution on the downdrift side of the breakwater is taken into account and is calculated using the theory of regular waves and irregular waves. The present model is verified by the field observation data of erosion for half a year on the downdrift side of a harbor, and compared with some experimental results. The numerical results are in good agreement with the field measured and experimental data. 相似文献
3.
In 1995, Suh and Park developed a numerical model that computes the reflection of regular waves from a fully perforated-wall caisson breakwater. This paper describes how to apply this model to a partially perforated-wall caisson and irregular waves. To examine the performance of the model, existing experimental data are used for regular waves, while a laboratory experiment is conducted in this study for irregular waves. The numerical model based on a linear wave theory tends to over-predict the reflection coefficient of regular waves as the wave nonlinearity increases, but such an over-prediction is not observed in the case of irregular waves. For both regular and irregular waves, the numerical model slightly over- and under-predicts the reflection coefficients at larger and smaller values, respectively, because the model neglects the evanescent waves near the breakwater. 相似文献
4.
The reflection of regular and irregular waves from a partially perforated caisson breakwater with a rock-filled core is examined. The present mathematical model is developed by means of the matched eigenfunction method. Numerical results of the present model are compared with the experimental data of different researchers. Numerical examples are given to examine the effect of rock fill on the reflection coefficient. The differences between regular and irregular waves are also investigated by means of theoretical and experimental results. It is found that the minimum reflection coefficient of irregular waves is larger than that of corresponding regular waves, but the contrary is the case for the maximum reflection coefficient. 相似文献
5.
LIU Yong LI Yucheng TENG Bin MA Baolian 《海洋学报(英文版)》2007,26(3):129-141
The reflection of regular and irregular waves from a partially perforated caisson breakwater with a rock-filled core is examined. The present mathematical model is developed by means of the matched eigenfunction method. Numerical results of the present model are compared with the experimental data of different researchers. Numerical examples are given to examine the effect of rock fill on the reflection coefficient. The differences between regular and irregular waves are also investigated by means of theoretical and experimental results. It is found that the minimum reflection coefficient of irregular waves is larger than that of corresponding regular waves, but the contrary is the case for the maximum reflection coefficient. 相似文献
6.
Tai-Wen Hsu Shih-Chun Hsiao Shan-Hwei Ou Swun-Kwang Wang Bin-Da Yang Shih-En Chou 《Ocean Engineering》2007,34(5-6):870-883
A numerical model based on the second-order fully nonlinear Boussinesq equations of Wei et al. [1995. Journal of Waterway, Port, Coastal and Ocean Engineering 121 (5), 251-263] is developed to simulate the Bragg reflection of both regular and irregular surface waves scattered by submerged bars. Particularly for incident regular waves, the computed results are observed to agree very well with the existing experimental data as presented by Davies and Heathershaw [1984. Journal of Fluid Mechanics 144, 419-446] and Kirby and Anton [1990. Proceedings of the 22nd International Conference on Coastal Engineering, ASCE, New York, pp. 757–768). In the case of incident irregular waves, the simulated results reveal that the distribution of Bragg reflection from irregular waves becomes more flat than that of regular waves. Due to lack of experimental data, the numerical results for incident irregular waves are compared with those of the evolution equation of the mild-slope equation [Hsu et al., 2002 Proceedings of the 24th Ocean Engineering Conference in Taiwan, pp. 70–77 (in Chinese)]. In addition, several parameters such as the number of bars, the relative height of bars and the spacing of bars affecting Bragg reflection are also discussed. 相似文献
7.
8.
Yao Guoquan Ma Zhixiong Ding Bingchan Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Assistant Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1991,(4)
The coefficient of deffraction of regular waves behind the double jetty has been computed in this paper at first by using the singularity distribution method. The model tests conducted for diffraction of irregular waves with a unidirectional frequency spectrum have confirmed good agreement between the data measured in experiments and the results computed by the singularity distribution method plus the linear superposition method for the energy of component waves in the directional frequency spectra. Therefore, this technique for component waves in the directional spectra has been further used to compute diffraction of irregular waves of multidirection, including the employment of a directional distribution function of the cos2 type, as well as the Bretschneider-Misuyann frequency spectrum. 相似文献
9.
Most of the large scaled casualties are caused by loss of structural strength and stability due to the progressive flooding and the effect of waves and wind. To prevent foundering and structural failure, it is necessary to predict the motion of the damaged ship in waves.This paper describes the motion of damaged ship in waves resulting from a theoretical and experimental study. A time domain theoretical model, which can be applied to any type of ship or arrangement, for the prediction of damaged ship motion and accidental flooding has been developed considering the effects of flooding of compartments. To evaluate the accuracy of the model, model tests are carried out in ship motion basin for three different damaged conditions: engine room bottom damage, side shell damage and bow visor damage of Ro–Ro ship in regular and irregular waves with different wave heights and directions. 相似文献
10.
《Coastal Engineering》2006,53(5-6):395-417
This paper is the second part of the work presented by Garcia et al. [Garcia, N., Lara, J.L., Losada, I.J., 2004. 2-D numerical analysis of near-field flow at low-crested breakwaters. Coastal Engineering 51 (10), 991–1020]. In the mentioned paper, flow conditions at low-crested rubble-mound breakwaters under regular wave attack were examined, using a combination of measured data of free surface, bottom pressure and fluid velocities from small-scale experiments and numerical results provided by a VOF-type model (COBRAS) based on the Reynolds-Averaged Navier–Stokes (RANS) equations. This paper demonstrates the capability of the COBRAS model to reproduce irregular wave interaction with submerged permeable breakwaters. Data provided by the numerical model are compared to experimental data of laboratory tests, and the main processes of wave–structure interaction are examined using both experimental and numerical results. The numerical model validation is carried out in two steps. First, the procedure of irregular wave generation is verified to work properly, comparing experimental and numerical data of different cases of irregular wave trains propagating over a flat bottom. Next, the validation of the numerical model for wave interaction with submerged rubble-mound breakwaters is performed through the simulation of small-scale laboratory tests on different incident wave spectra. Results show that the numerical model adequately reproduces the main aspects of the interaction of random waves with submerged porous breakwaters, especially the spectral energy decay at the structure and the spectrum broadening past the structure. The simulations give good results in terms of height envelopes, mean level, spectral shape, root-mean-square height for both free surface displacement and dynamic pressure inside the breakwater. Moreover, large-scale simulations have been conducted, on both regular and irregular incident wave conditions. The overall pattern of the wave interaction with a large-scale submerged breakwater is adequately reproduced by the numerical model. The processes of wave reflection, shoaling and breaking are correctly captured. The good results achieved at a near prototype scale are promising regarding the use of the numerical model for design purposes. 相似文献
11.
Wen-Chuan Tiao 《Applied Ocean Research》2011,33(1):60-68
The present study focuses on building a systematic approach to identify, from experimental results, the nonlinearity in the dynamic system of a high-speed ship. The experimental program consists of tests in both regular and irregular head waves, and the measured quantities included wave elevation, vertical motions, and hull pressures. By contrasting these results to the quasi-linear behaviors of heave motion, the nonlinear behaviors of pressure are highlighted and presented. Three nonlinear assessments, the probability density function, and the variance spectra are provided. Based on these investigations, we conclude that the pressures, particularly, at the ship’s bow contain more nonlinearities than just the heave motion. They are identified mainly by the large amplitude of the higher harmonics and also by the large asymmetry in the measured signals. Furthermore, the coherence spectrum obtained from the third-order orthogonal frequency-domain Volterra model provides information regarding the magnitude of each order at the corresponding frequency, which serves as a strategy to simplify a complex problem or to achieve a balance between regular and irregular waves. The overall results show that the higher-order components are significant for the pressure system and the outcome of the proposed model can offer constructive feedback, which can lead to more practical applications. 相似文献
12.
The reflection of regular and irregular waves by a partially perforated caisson breakwater on a step bed 总被引：2，自引：0，他引：2
This study examines the reflection of regular and irregular waves from a partially perforated caisson breakwater located on a step bed. The step bed is treated as an idealized rubble mound foundation. Based on the linear potential theory, an analytical solution is developed to calculate the reflection coefficient of the structure subjected to regular waves. The matched eigenfunction expansion method is used for the solution. The regular wave method is also extended to irregular waves using a linear transfer function. The calculated results obtained for limiting cases are exactly the same as corresponding results given by the previous researchers. The present predictions also agree well with experimental data in the published literatures. Numerical experiments are conducted to examine the variations of the reflection coefficient versus its main effect factors, and some interesting results are presented. 相似文献
13.
This paper presents a 1D time-domain model for an oscillating water column (OWC) based on previous works on trapped air cavities for marine vehicles. The paper describes the coupling between the hydrodynamic and the thermodynamic forces for an OWC with an orifice. The model enables to obtain the water elevation and pressure variation inside the chamber in the time-domain for regular and irregular waves. The numerical predictions are compared with experimental data performed on a model scale OWC. 相似文献
14.
Hilbert Transform Applied to Separation of Waves 总被引：1，自引：0，他引：1
The analytical method (AM) for separation of composite waves is presented based on the Hilbert transform. It is ap-plicable to both regular and irregular trains of waves. The wave data series measured with two wave gauges in the experi-ments are separated into two series of incident and reflected waves. Then, the reflection coefficient can be easily ob-tained. The arrival of reflected waves can also be detected for improvement of the accuracy of the reflection coefficient.The reflection performance of the physical model can be estimated exactly without calculation of wave height and phasedifference. Numerical samples developed to test the method are proved to be accurate. Physical experiments are conduct-ed and compared with Goda‘s method and satisfactory results are obtained. 相似文献
15.
The analytical method (AM) for separation of composite waves is presented based on the Hilbert transform. It is ap-plicable to both regular and irregular trains of waves. The wave data series measured with two wave gauges in the experi-ments are separated into two series of incident and reflected waves. Then, the reflection coefficient can be easily ob-tained. The arrival of reflected waves can also be detected for improveraent of the accuracy of the reflection coefficient. The reflection performance of the physical model can be estimated exactly without calculation of wave height and phase difference. Numerical samples developed to test the method are proved to be accurate. Physical experiments are conduct-ed and compared with Goda s method and satisfactory results are obtained. 相似文献
16.
Based on the refraction-diffraction theory of irregular waves in the waters of slowly-varying cur-rents and depths,and the generation dissipation theory of wind wave,a model for nonlinear irregular wavesin coastal area is developed.In light of the specific conditions of coastal wave character and engineering ap-plication,a practical mathematical model for the nonlinear irregular waves is presented.with directional spec-trum in coastal area.Coast effect,refraction,whitecapping.bottom friction.current,wind and nonlinearaction are considered in this model.The numerical methods and schemes for wave refraction ray,energy con-servation of propagation,energy balance of the generation and dissipation of wind waves have been studied.Finally,the model is used for the directional wave spectrum computation in the Daya Bay.Compared withthe measured data with 956 wave bouys in the Daya Bay,the model results are in good agreement with themeasured results. 相似文献
17.
Dong Guohai Li Yucheng Wang Yongxue
Lecturer Doctor Dalian University of Technology Dalian
Professor Dalian University of Technology Dalian 《中国海洋工程》1995,(1)
- A large amount of experimental analysis and systematical theoretical calculation has been done by the authors to solve the problem of wave transformation and breaking, considering the effect of both current and topography, but only the wave energy loss due to spilling breaker in the surf zone has been discussed in this paper. Based on test result analysis and calculation with the Stream Function Wave Theory, the wave velocity field at breaking points has been obtained, and it is used to calculate the wave heights after breaking by the VOF (Volume of Fluid) method, in which the governing equations are continuity equation and Navier-Stokes Equation for imcompressible fluids. In the present paper, the improved VOF technique is used to calculate the wave heights of stable regular waves after breaking. Results fit the test data well, which shows that the VOF method is suitable to numerical simulation of regular waves after breaking. Besides, the breaker coefficient B of regular waves in the bore model is a 相似文献
18.
Yao Guoquan Ma Zhixiong Ding Bingcan Senior Engineer River Harbor Department Nanjing Hydraulic Research Institute Nanjing Assistant Engineer River Harbor Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1991,(3)
- This paper presents a calculation method for the diffraction of both regular waves and irregular waves of the single directional frequency spectrum behind a single jetty with a theoretical analysis, which has been confirmed through the model experiments, derives a method of computing the diffracted irregular waves behind the single jetty with the theoretical analysis on the basis of computation of the field data and gives the formulas and the figures of the computation of wave diffractions behind the vertical wall or mound single jetties. 相似文献
19.
Based on the time-dependent mild slope equation including the effect of wave energy dissipation, an expression for the energy dissipation factor is derived in conjunction with the wave energy balance equation. The wave height of regular and irregular waves is numerically simulated by use of the parabolic mild slope equation considering the energy dissipation due to wave breaking. Comparison of numerical results with experimental data shows that the expression for the energy dissipation factor is reasonable. The effects of the wave breaking coefficient on the breaking point and the distribution of wave height after breaking are discussed through the study of a specific experimental topography. 相似文献
20.
基于激波捕捉类Boussinesq模型对岛礁地形上波浪传播的数值模拟 总被引：2，自引：2，他引：0
为了探究激波捕捉类Boussinesq模型在模拟岛礁地形上规则波和不规则波传播的可行性,采用基于完全非线性Boussinesq方程并具有激波捕捉能力的数值模型Funwave-TVD对规则波和不规则波在岛礁地形上的传播进行了数值模拟,通过与试验数据对比,分析模型中空间步长的影响,验证模型在模拟波高、平均水位分布以及波谱空间演变的能力,结果表明:采用合适的空间步长,模型能较好地模拟规则波和不规则波在岛礁地形上的传播和演化过程。对于规则波,较小的空间步长可改善破碎点处波高峰值的预测,并能更好地预测波浪破碎后波高的空间分布,相比结合经验破碎的Boussinesq模型,Funwave-TVD能更好地模拟规则波在岛礁地形上的破碎,以及破碎以后行进涌波的再生成过程;对于不规则波,Funwave-TVD总体而言能较好地模拟涌浪有效波高、次重力波的生成及空间演化和平均水位,但会低估礁坪上次重力波波高,较粗的空间步长也会低估礁坪上涌浪有效波高。 相似文献