共查询到20条相似文献，搜索用时 78 毫秒
1.
《Ocean Engineering》1999,26(4):363-380
A sea water intake well of size 20 m diameter and 15.5 m height in a water depth of 9.8 m is proposed north of the Visakhapatnam Port for a project to extract magnesia from sea water. A 1:25 scale model of the intake well was tested in the wave basin of the Ocean Engineering Centre, Indian Institute of Technology, Madras to measure the wave forces and moments on the intake well and the variation of water levels inside and outside the well. Accordingly, an intake well model of 0.8 m diameter and 0.62 m height was fabricated and fixed over a false bottom in a wave basin. The well model was subjected to the action of both regular waves for two test conditions, intake well inlet closed during installation and intake well inlet open. The experimental results on wave forces and moments were compared with the results of the Linear Diffraction Theory. The water level inside the well was measured to determine the submergence of suction pipes of pumps and location of the inlet opening of the intake well. The wave crest elevation in front of the well was also measured in order to fix the deck level of the well so as to avoid water overspill onto the deck. The salient results of the present study are presented and discussed in this paper. 相似文献
2.
A statistical model is developed to predict wave overtopping volume and rate of extreme waves on a fixed deck. The probability density function for the volume and rate of overtopping water are formulated based on the truncated Weibull distribution with the assumption of local sinusoidal profile for small amplitude waves. Sensitivity to the wave nonlinearity parameter and deck clearance is discussed. The statistical model is compared to laboratory data of the instantaneous free surface elevation measured in front of a fixed deck, and overtopping volume and overtopping rate measured at the leading edge of the deck. The statistical theory compared well with the measured exceedance probability seaward of the deck. The model prediction of the exceedance probability of deck overtopping gave qualitatively good agreement for large overtopping values. 相似文献
3.
Aymeric Jouon Jean Pierre Lefebvre Pascal Douillet Sylvain Ouillon Loys Schmied 《Coastal Engineering》2009,56(5-6):599-608
The south-west reef lagoon of New Caledonia is a semi-enclosed basin where, on first approximation, dominating sea state component corresponds to locally generated wind waves. This study aims to evaluate the ability of the wave model WAVEWATCH III to simulate wind wave distribution in this particular fetch-limited context, with a given parameterisation. In order to evaluate the consistency of the simulation results, wave parameters were measured in situ by a wave and tide recorder (WTR9 Aanderaa) and by an acoustic Doppler velocimeter (ADV Sontek). This study underlines specific constrains for the deployment of instruments to assess the characteristic parameters of low amplitude and high frequency wind-waves. Special care was taken in the comparison step as, on one hand the wave model did not simulate the propagation of low-frequency oceanic waves inside the lagoon, and on the other hand the measured spectra bear an intrinsic limitation for high frequencies. The approximation of a sea state dominated by wind waves is verified on the study site. The accuracy of the simulation results is discussed with regards to the wind forcing applied to the model. 相似文献
4.
A combined wind and wave energy converter concept, named STC concept was proposed. Model tests were performed in terms of operational and survival modes. Water entry and exit phenomena as well as green water on deck were observed during the survivability model tests. In this paper, a nonlinear numerical model based on a blended station-keeping potential-flow solver with a local impact solution for bottom slamming events and an approximated model for the water shipped on the deck is proposed to simulate these nonlinear phenomena. Physical investigation of the water entry and exit process was firstly carried out and uncertainty analysis of the model test results were performed. Numerical comparisons between the nonlinear solver and model test results are then performed in terms of mean, wave frequency and double wave frequency motion response components. The slamming and green water involved in the water entry process are specially investigated, in terms of the physical evolution and the effects on the dynamic motion responses. The validation work on the occurrence of slamming and water on deck as well as the slamming pressure are performed. 相似文献
5.
为向拟建、在建和已建冰区所有冷源取水工程海域的海冰环境监测和动态风险预警提供技术支撑,本文构建了海冰–海洋耦合条件下的拉格朗日粒子追踪预测模型,并以辽东湾某核电站取水口为例,模拟并探讨了寒潮天气下高风险冰块在24 h、48 h和72 h的运移轨迹及其进入取水口的概率。结果表明,由于取水口的走向与流向和风向几乎垂直,因此在口门外随机释放的1 200个高风险冰块粒子中只有不到6%的粒子进入到取水口内。通过分区域标识粒子颜色,发现这些粒子多来自于靠近取水口300 m范围内。敏感性分析的结果表明,当释放粒子数量增至5倍时,结论不变。该项研究为冷源取水安全预警提供了一种新方法。 相似文献
6.
通过三维物理模型系列试验,对港珠澳大桥工程西人工岛、岛桥结合跨进行模拟。试验测量了不同波浪入射角度、波高、波周期以及梁底净高等影响因子下的岛桥结合跨箱梁所受的浮托力和水平力,分析了受力随波陡、相对梁底作用高度以及波浪入射角度的变化规律。研究表明,在一定条件下箱梁浮托力和水平力,随波陡的增大而减小,随梁底相对作用高度的增加而增大,波浪入射方向的影响主要表现为与箱梁沿波浪传播方向的有效长度相关。由于岛桥结合跨的特殊性,改进的Douglass公式并不适用于岛桥结合跨箱梁受力的计算。通过主要影响因子的量纲分析,建立针对岛桥结合跨箱梁浮托力和水平力的计算公式。研究成果可为今后同类工程以及数值模拟提供借鉴与参考。 相似文献
7.
Based on a parallel SPH-LES model, a three dimensional numerical wave basin is developed to study wave interaction with coastal structures. The OpenMP programming technology combined with an existing MPI program contained in the parallel version of SPHysics code has been implemented to enable the simulation of hundred millions of particles running on a computer cluster. As part of the numerical basin development work an active absorbing wave maker and a sponge layer are introduced. The dynamic boundary conditions are also corrected to reduce the spurious effects. Wave generation and propagation in the numerical wave basin is first tested and confirmed with analytical results. Then, the model is applied to simulate wave interactions with a vertical breakwater and a vertical cylinder in order to further assess the capability of the numerical wave basin. The predicted free surface elevation near the vertical breakwater is compared with the experimental data while the horizontal forces and overturning moments acting on the vertical cylinder are verified with the analytical results. In all these cases the model results show excellent agreement with the validation data. 相似文献
8.
建立三门湾附近海域的水动力和水质模型,研究核电站取排水工程对海湾水交换的影响。计算得到取排水工程建立后三门湾海域40 d的海水交换率由51.60%变为51.06%,降低了0.54%。将三门湾海域分区分析,结果发现靠近排水工程的汊道水交换率降低最多,降低了5.36%,其余区域水交换率也都有所降低,但是降低幅度不大。结果表明:取排水工程的建立使得湾内水流状况发生变化,不同区域的水交换率变化相差较大;排水工程切断了附近汊道水流与外海的交换,导致排水口附近海域水交换率降低最多。 相似文献
9.
Jesper Bartholdy 《Geo-Marine Letters》2006,26(3):133-140
A simple zero-dimensional model relating water-level measurements inside a tidal basin to current velocity in the inlet has been formulated and calibrated for the tidal inlet Grådyb in the Danish Wadden Sea. The model combines a dynamical and a continuity-based approach, and predicts velocity in the inlet with a high correlation between measured and calculated current velocities (R 2=0.94), when tested on the basis of an independent dataset. Once calibrated, the model requires only a minimum of input data (water level and water-level variation in time). It is therefore well suited to bridge the gap between discrete velocity observations (e.g. ADCP profiles used to evaluate the dynamics of an inlet prior to other observations of, amongst others, bedform behaviour) and longer time series of inlet dynamics, and this with a minimum of cpu-time. 相似文献
10.
The wave induced dynamic pressures around a circular cylinder of diameter 0.2 m due to regular waves were measured in a wave flume in a water depth of 1 m and in a wave basin in a water depth of 3 m. The experimental investigations were carried out with the cylinder inclined along and against the direction of wave propagation. The least-squares technique was employed to evaluate the coefficients of drag (CD) and inertia (CM) from the sectional force time histories obtained by integrating the measured circumferential pressure distribution. The variation of drag and inertia coefficients are presented as a function of Keulegan-Carpenter number (KC) for different inclinations of the cylinder. The comparison between the measured and the theoretical force derived from the evaluated hydrodynamic coefficients is found to be good. 相似文献
11.
Choi Young-Kwang Seo Seung-Nam Choi Jin-Yong Shi Fengyan Park Kwang-Soon 《海洋学报(英文版)》2019,38(7):36-47
A wave forecasting system using FUNWAVE-TVD which is based on the fully nonlinear Boussinesq equations by Chen(2006) was developed to provide an accurate wave prediction in the Port of Busan, South Korea. This system is linked to the Korea Operational Oceanographic System(KOOS) developed by Park et al.(2015). The computational domain covers a region of 9.6 km×7.0 km with a grid size of 2 m in both directions, which is sufficient to resolve short waves and dominant sea states. The total number of grid points exceeds 16 millions,making the model computational expensive. To provide real-time forecasting, an interpolation method, which is based on pre-calculated results of FUNWAVE-TVD and SWAN forecasting results at the FUNWAVE-TVD offshore boundary, was used. A total of 45 cases were pre-calculated, which took 71 days on 924 computational cores of a Linux cluster system. Wind wave generation and propagation from the deep water were computed using the SWAN in KOOS. SWAN results provided a boundary condition for the FUNWAVE-TVD forecasting system. To verify the model, wave observations were conducted at three locations inside the port in a time period of more than 7 months. A model/model comparison between FUNWAVE-TVD and SWAN was also carried out. It is found that, FUNWAVE-TVD improves the forecasting results significantly compared to SWAN which underestimates wave heights in sheltered areas due to incorrect physical mechanism of wave diffraction, as well as large wave heights caused by wave reflections inside the port. 相似文献
12.
基于波浪作用下软质海崖的侵蚀机理,考虑波浪水动力和海崖土质条件,建立了一种波浪作用下软质海崖侵蚀量的计算模型,利用室内水槽试验进行验证和参数回归,并使用该模型计算了平潭岛东北部软质海崖的侵蚀状况,与实测数据进行对比分析。研究发现：（1）海崖最大侵蚀量基本发生在静水位线处,随波浪持续作用,最大侵蚀量位置有所上移,当波浪持续作用一定时间时侵蚀基本停止;（2）当波高超过某一临界值时,侵蚀才会发生,而波高非常大的波浪对侵蚀的贡献相对不是很大;（3）平潭岛东北部的两处海崖,每次强台风连续作用8h时的侵蚀距离计算值为0.31m和0.25m。 相似文献
13.
Green water overtopping analyzed with a SPH model 总被引：3，自引：0，他引：3
Wave overtopping on the decks of offshore platforms and ships can cause severe damage due to the high forces generated by the water. This phenomenon is analyzed within the framework of the Smoothed Particle Hydrodynamics (SPH) method. The presence of a fixed horizontal deck above the mean water level modifies strongly the wave kinematics. In particular, the flow in the wave crest is split into two, showing a different behavior above and below the deck. Numerical results generated by the SPH method are compared to laboratory experiments. The formation of a jet in the rear of the deck after overtopping is observed under extreme conditions. 相似文献
14.
针对目前小油田早期生产中存在的不足,提出一种适用于浅水海域的新型张力腿式储油处理平台,该平台主要由储油箱、浮箱、吸力桩、系泊链和甲板结构构成,具备原油处理和储存功能。应用非线性时域耦合分析法,研究了有义波高、平均波周期、水深对该平台的运动响应和系泊链张力的影响。计算结果表明,波高对平台动力响应有较大影响,有义波高每增加0.4 m,平台水平位移相应增加0.408 m,而系泊链力随有义波高的增加呈准线性增大;波周期对平台水平运动影响显著,平均波周期从6.5 s逐级变化至8.5 s时,最大水平位移自3.760 m渐增至5.467 m,而波周期对系泊链力影响较小,变化率一般小于10%;该新型平台对水深大于20 m的浅水海域有良好的动力特性,而对水深小于20 m的海域却表现异常。因此,该新型张力腿式平台能满足水深不小于20 m浅海区的油田早期生产需要。 相似文献
15.
In recent years floating breakwaters are considered for creating calm basin under open sea conditions for short period of time. In this paper, experimental studies on the performance characteristics of a horizontal floating plate breakwater are presented. The results of this two-dimensional model study are for regular waves of shallow and intermediate water depths. Analysis of the results shows that the transmission coefficient is strongly influenced by wave steepness and relative length of breakwater. It is also found to be dependent, to a lesser extent, on the relative depth of draft. Mooring forces are found to increase with increasing wave steepness and relative depth of draft. The performance of this breakwater is compared with other types of breakwater reported by earlier workers. 相似文献
16.
Green water loads on moored or sailing ships occur when an incoming wave significantly exceeds the freeboard and water runs onto the deck. In this paper, a Navier–Stokes solver with a free surface capturing scheme (i.e. the VOF model; [Hirt and Nichols, 1981]) is used to numerically model green water loads on a moored FPSO exposed to head sea waves. Two cases are investigated: first, green water on a fixed vessel has been analysed, where resulting waterheight on deck, and impact pressure on a deck mounted structure have been computed. These results have been compared to experimental data obtained by [Greco, 2001] and show very favourable agreement. Second, a full green water incident, including vessel motions has been modelled. In these computations, the vertical motion has been modelled by the use of transfer functions for heave and pitch, but the rotational contribution from the pitch motion has been neglected. The computed water height on deck has been compared to the experimental data obtained by [Buchner, 1995a] and it also shows very good agreement. The modelling in the second case was performed in both 2-D and 3-D with very similar results, which indicates that 3-D effects are not dominant. 相似文献
17.
液化天然气(LNG)接收站取水流道内水流形态十分复杂,泥沙淤积问题往往难以避免,特别是在含沙量较高水域,流道内回淤泥沙可能威胁接收站的正常运营。结合现场实测资料,建立取水泵站流道内泥沙物理模型试验,模拟了位于含沙量较高海域的舟山LNG取水流道内泥沙淤积强度及其分布特征。研究结果表明,取水泵站内主要淤积部位发生在前池、过滤池末端、吸水间进口和中部以及应急消防泵附近。在LNG运营和停机期间,消防泵和位于吸水间的海水泵均有埋淤风险。结合试验结果和周边已运营LNG取水泵站泥沙淤积及清淤情况,建议在关注区设立射流冲刷装置,可减少人工清淤频次,提高取水安全保证率,从而增加运营效益。 相似文献
18.
An experimental study has been carried out on the forces from plunging breaking regular and irregular waves on a vertical cylinder on a shoal. Total as well as local wave forces have been measured. Engineering formulae for the calculation of the horizontal forces and overturning moments have been derived. The duration of the impact forces have been measured and compares fairly well with theoretical values. 相似文献
19.
In this paper, we present a spectral analysis based on wave loads to select suitable side-hull arrangements for a trimaran ship traveling in waves. Neglecting the steady flow effect, the three-dimensional source-distribution method, using a pulsating source potential incorporating the panel method, is adopted to solve the corresponding hydrodynamic coefficients. The significant values for wave loads, including shear forces, bending moments, and torsion moments at different locations on the main hull and connected deck with respect to different staggers and clearances, are derived by the spectral analysis. Several ship speeds and wave headings are also considered for comparison. This study offers more information for selecting the side-hull arrangement from the viewpoint of wave loads on trimaran ships, which may be regarded as helpful references for seakeeping design of these types of ships. 相似文献
20.
Articulated towers are a compliant type of platform particularly suited for deep water applications. In the design of articulated towers, it is very important that the motion characteristics include sufficient stability, less acceleration in the deck and the smallest possible loading on the articulated joint. The mass distribution along the tower also plays an important role in the motion characteristics of the tower. Multi-leg articulated towers with three or more towers (legs or shafts), which have been developed from the conventional single tower have reduced horizontal movements and have more deck area compared to the single-leg articulated towers. The experimental and analytical investigations on such towers are not available in the published literature. In this paper, both analytical treatment and an experimental program for a three-leg articulated tower model have been reported. The effect of mass distributions on the variations of the bending moment and the deck accelerations are also presented. The model has been tested in a 2 m wave flume for various wave frequencies and wave heights of regular waves. The model is also analysed using a computer program developed, and the comparison of theoretical results with the experimental results is presented. 相似文献