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1.
Numerical Investigation of Flow Motion and Performance of A Horizontal Axis Tidal Turbine Subjected to A Steady Current 总被引：2，自引：0，他引：2
Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-ε model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved. 相似文献
2.
曲折海湾中潮汐和环流的数值研究 总被引：1，自引：1，他引：0
YU Huaming WANG Zhaohu KUANG Liang WANG Lu BAO Xianwen WU He WANG Xin DENG Xiaodong 《海洋学报(英文版)》2015,34(1):119-128
The Shacheng Bay(SCB) is one of the most complex coastal bays in southeast China and due to the fact of complicated geometry and dynamic coastal processes, it is considered as a challenging area for the numerical simulation of its hydrodynamic characteristics. The most advanced finite volume ocean model, finite-volume coastal ocean model(FVCOM), has adopted to simulate this hydrodynamic system, where tidal currents, tidal residual current and dye diffusion processes were studied and analyzed quantitatively. The validation of this numerical model matches well with various observation data, including elevation and current data. The misfit of a tidal elevation has a relative standard error of 3.66% and 4.67% for M2 and S2 tide components. The current validation shows a good match with an average error of 10 cm/s and 8° in the speed major axis and its direction respectively between the simulation and the measurement. This proves the robustness and reliability of this model. It is also found that the cape effect is significant and important in this system. The dye diffusion simulations show a 53 d flushing period for the whole inner bay waterbody. The results are of its first kind for understanding the hydrodynamic system in the SCB and they can provide helpful and trustful scientific information for others. 相似文献
3.
To deal with the moving boundary hydrodynamic problems of the tidal flats in shallow water flow models, a new wetting and drying (WD) method is proposed. In the new method, a “predicted water depth” is evaluated explicitly based on the simplified shallow water equations and used to determine the status (wet or dry) together with the direction of flow. Compared with previous WD method, besides the water elevation, more factors, such as the flow velocity and the surface shear stress, are taken into account in the new method to determine the moving boundary. In addition, a formula is deduced to determine the threshold, as critical water depth, which needs to be preset before simulations. The new WD method is tested with five cases including three 1D ones and two 2D ones. The results show that the new WD method can simulate the wetting and drying process, in both typical and practical cases, with smooth manner and achieves effective estimation of the retention volume at shallow water body. 相似文献
4.
To deal with the moving boundary hydrodynamic problems of the tidal flats in shallow water flow models,a new wetting and drying (WD) method is proposed.In the new method,a "predicted water depth" is evaluated explicitly based on the simplified shallow water equations and used to determine the status (wet or dry) together with the direction of flow.Compared with previous WD method,besides the water elevation,more factors,such as the flow velocity and the surface shear stress,are taken into account in the new method to determine the moving boundary.In addition,a formula is deduced to determine the threshold,as critical water depth,which needs to be preset before simulations.The new WD method is tested with five cases including three 1D ones and two 2D ones.The results show that the new WD method can simulate the wetting and drying process,in both typical and practical cases,with smooth manner and achieves effective estimation of the retention volume at shallow water body. 相似文献
5.
A Vertical Two-Dimensional Model to Simulate Tidal Hydrodynamics in A Branched Estuary 总被引：1，自引：1，他引：1
A vertical (laterally averaged) two-dimensional hydrodynamic model is developed for tides, tidal current, and salinity in a branched estuarine system. The goveming equations are solved with the hydrostatic pressure distribution assumption and the Boussinesq approximation. An explicit scheme is employed to solve the continuity equations. The momentum and mass balance equations are solved implicitly in the Cartesian coordinate system. The tributaries are govemed by the same dynamic equations. A control volume at the junctions is designed to conserve mass and volume transport in the finite difference schemes, based on the physical principle of continuum medium of fluid. Predictions by the developed model are compared with the analytic solutions of steady wind-driven circulatory flow and tidal flow. The model results for the velocities and water surface elevations coincide with analytic results. The model is then applied to the Tanshui River estuarine system. Detailed model calibration and verification have been conducted with measured water surface elevations,tidal current, and salinity distributions. The overall performance of the model is in qualitative agreement with the available field data. The calibrated and verified numerical model has been used to quantify the tidal prism and flushing rate in the Tanshui River-Tahan Stream, Hsintien Stream, and Keelung River. 相似文献
6.
The system with one floating rectangular body on the free surface and one submerged rectangular body has been applied to a wave energy conversion device in water of finite depth. The radiation problem by this device on a plane incident wave is solved by the use of an eigenfunction expansion method, and a new analytical expression for the radiation velocity potential is obtained. The wave excitation force is calculated via the known incident wave potential and the radiation potential with a theorem of Haskind employed. To verify the correctness of this method, an example is computed respectively through the bound element method and analytical method. Results show that two numerical methods. are in good agreement, which shows that the present method is applicable. In addition, the trends of hydrodynamic coefficients and wave force are analyzed under different conditions by use of the present analytical method. 相似文献
7.
This paper discusses mainly the formation mechanism and developmental conditions of tidal current ridges. The tidal current velocities of 1-3.5 knots and the supply of abundant loose sediments are the prerequisites for the formation of the tidal current ridges. The hydrodynamic mechanism is similar to that of straight rivers. In the trough between two ridges the tidal current moves forward in the form of two helical flows. The two flows converge and sink in the centre of the trough, and erode the trough deeply; they diverge and rise on the two sides of the trough, and accumulate the ridges. When the supply material and relief come to the dynamic equilibrium, the development of ridges keeps steady. 相似文献
8.
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. 相似文献
9.
《中国海洋工程》1987,(4)
- Based on the principle of conservation of wave action flux and the principle of linear superposition of stationary random process, the transformation of spectrum for wave surface elevation, horizontal velocity and acceleration in steady uniform current are discussed in this paper. A comparison between the calculation by spectrum analysis and by regular wave method is given also. It is shown that spectral method gives a more reasonable result, especially for the calculation of velocity and acceleration field. The theoretical results agree well with model test data. 相似文献
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11.
长江口水下三角洲地形地貌对于长江口航道安全、生态环境、海岸带工程等均具有重要意义,本次研究拟采用世界上第一颗静止水色卫星GOCI(Geostationary Ocean Color Imager)开展长江口Kd(490)的季节和潮汐变化规律研究,以期为采用机载激光测深提供预评估信息。研究得到结论如下:长江口及邻近海域水体为典型的二类水体,悬浮泥沙含量最高可由杭州湾内几千mg/L迅速降低至10 mg/L以下,因此,分段式的漫衰减系数反演算法适用于研究区域;Kd(490)反演结果表明长江口及邻近海域的Kd(490)值的季节变化特征表现为冬高夏低,春秋居中,长江冲淡水流量和季风是影响其季节变化的主要因素,而在一个潮周期内,Kd(490)值总体表现为低潮期低于高潮期,悬浮泥沙浓度和潮水的潮位是长江口及邻近海域的Kd(490)值的重要影响因素;研究指出,长江口及杭州湾内激光可探测深度约在5~22 m范围内,夏季退潮低潮位最适合激光雷达观测。由此可见,GOCI 8景/d,1景/h的分辨率可以实现Kd(490)的动态变化监控,而且可以实现在相同潮位下更为合理地描述Kd(490)值的季节变化,为机载激光雷达探测的进一步开展提供了技术支持。 相似文献
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近年来,应用数值模型模拟台风引起的风暴潮运动越来越普遍,模型中对于风拖曳力系数的确定,一般都从相对风速出发,可引用的公式也较多,但这些公式很少考虑潮位变化对此系数的影响.在强潮河口、海岸海域,潮位变幅大,最高潮位甚至可达风速参考高度(10m)的近一半,如长江口和杭州湾.在数值模拟中不考虑风暴潮和天文潮共同引起的潮位变化,会造成风应力高潮时被低估、低潮时被高估的现象,从而影响风暴潮模拟的精度.为此本文对现有的风拖曳力系数加以改进,提出了考虑潮位影响的风拖曳力系数表达式,并应用于长江口、杭州湾9711号台风风暴潮的模拟中,增水模拟结果得到了明显改善,可进一步推广应用于强潮河口、海岸的风暴潮增水模拟中. 相似文献
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利用Delft3D数学模型对长江口水动力条件、上海市现有及拟建排放口污水排放的稀释扩散场进行了模拟。模型利用潮汐数据和排放口附近的现场实测数据进行了率定和验证，分别对丰水期、枯水期的大、小潮情况下的流速场、潮位场及污水扩散场进行了研究。结果表明：长江口的水动力条件有利于污水的稀释扩散；现状排放量对长江口水环境影响不大；但如果污水在排放前不进行一定的处理，规划排放量排人长江口将会严重恶化其水质，特别是枯水期小潮时最为严重。建议根据长江口和杭州湾的环境容量，结合排放口的稀释扩散能力，合理确定污水排放方案。 相似文献
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Zhu Shouxian Shi Fengyan Zhu Jianrong Ding Pingxing .StateKeyLaboratoryofEstuarineandCoastalResearch EastChinaNormalUniversity Shanghai China .MeteorologyInstituteofthePLAScienceandEngineeringUniversity Nanjing 《海洋学报(英文版)》2001,(1)
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在湛江附近海域建立了三维动边界水动力模型，通过验证，结果与观测数据符合良好，并在此模型基础上分别模拟计算了湛江东海岛填海大堤现状以及1958年大堤修建之前湛江海域的水动力场，通过两种情况下的流场、潮位、纳潮量以及水交换率的比较，分析了东海岛大堤的存在对湛江湾水动力环境的影响。 相似文献
17.
A 3-D numerical model is set up in a large domain covering the Hang zhou Bay and the Changjiang Estuary based on the ECOM model in orthogonal curvilinear coordinates.The numerical schemes for baroclinic pressure gradient (BPG) terms and convective terms are improved in the paper according to the characteristics of velocity field and mass transport in the area.The model is validated by the simulations of residual current and salinity transport in the Hangzhou Bay and the Changjiang Estuary. 相似文献
18.
长江口整治工程对盐水入侵影响研究 总被引：5，自引：1，他引：5
根据实测资料分析了长江口的盐水入侵问题。采用调和常数得到外海控制潮位，用流量控制上游边界，建立了长江口、杭州湾及邻近海域正交曲线坐标系下的二维潮流和盐度数学模型。模型验证了长江口洪、枯季时大、中、小潮的潮位、流速、流向和盐度，较好地模拟了口外顺时针旋转流和口内往复流的特征，反映了外海盐水入侵和北支盐水倒灌的运移特性。在此基础上对长江口综合整治规划方案进行了研究，讨论了整治工程对减轻长江口盐水入侵的作用。 相似文献
19.
杭州湾潮汐特征时空变化及原因分析 总被引：2，自引：2，他引：0
杭州湾是世界著名的强潮河口湾,一直是研究的热点。基于杭州湾口内外实测潮汐资料,对杭州湾潮汐特征及时空变化进行了系统分析,包括高潮位、低潮位、平均潮位、潮差、涨潮历时以及天文潮变化,同时分析了20世纪80年代以来潮汐特征变化的原因。结果表明:最近50年来,杭州湾年平均高潮位和海平面抬高,潮差增大;澉浦年平均低潮位抬高,涨潮历时缩短,浅海分潮增大;钱塘江河口治江缩窄是造成杭州湾潮汐变化的主要因素;浙江和邻近海域的涉海工程可能是造成浙江沿海海平面上升的主要原因之一。 相似文献