检索结果-南通市图书馆

Numerical investigation on local resonance within an array of C-shaped cylinders in water waves

Journal of Hydrodynamics 2024年第4期36卷 624-636页

作者： Jin Xu de-zhi ning Lifen Chen Huan-wen Liu State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian116024China Dalian Key Laboratory of Offshore Renewable Energy Dalian University of TechnologyDalian116024China College of Water Conservancy and Civil Engineering Ludong UniversityYantai264025China

In this work, computational fluid dynamics (CFD)—based simulations and linear diffraction analysis are carried out to investigate the interaction between water waves and metamaterials composed of an array of C-shaped cylinders. The flow visualization by CFD-based simulations reveals that local resonance is a result of constructive interference between the incident wave and the wave radiated from the cavity of the C-shaped cylinder. The wave-induced water motion inside the cavity acts as a source of generating this radiated wave, which has the same angular wave frequency and wavenumber but opposite propagation direction as the incident wave. In addition, it is found from the CFD-based simulations that the energy dissipation increases as the opening of the C-shaped cylinder becomes shorter and sharper, along with an increase in its outer radius, and the variation trend of energy dissipation is only affected by the outer radius. Meanwhile, except for very small opening lengths, variations in opening length, width, and outer radius do not significantly impact the wave attenuation effect of the C-shaped cylinder array. Moreover, the results obtained by CFD and the linear potential flow model are compared. The linear potential flow theory is proven to be a reliable approach for accurately predicting the local resonant frequency and transmission coefficients within the local resonant band across a range of geometric parameters. However, it is noted that this theory may have limitations when applied to cases with extremely small opening lengths, where it struggles to accurately predict the local resonant frequency and the intensity of local resonance.

关键词： Local resonance C-shaped cylinder array opening length wave attenuation computational fluid dynamics(CFD)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fully nonlinear modeling of radiated waves generated by floating flared structures

引用

Acta Mechanica Sinica 2014年第5期30卷 667-680页

作者： Bin-Zhen Zhou de-zhi ning Bin Teng Ming Zhao College of Ship Building Engineering Harbin Engineering University State Kay Laboratory of Coastal and Offshore Engineering Dalian University of Technology School of Computing Engineering and MathematicsUniversity of Western Sydney Penrith2751 NSW Australia

The nonlinear radiated waves generated by a structure in forced motion, are simulated numerically based on the potential theory. A fully nonlinear numerical model is developed by using a higher-order boundary element method （HOBEM）. In this model, the instantaneous body position and the transient free surface are updated at each time step. A Lagrangian technique is employed as the time marching scheme on the free surface. The mesh regridding and interpolation methods are adopted to deal with the possible numerical instability. Several auxiliary functions are proposed to calculate the wave loads indirectly, instead of directly predicting the temporal derivative of the velocity potential. Numerical experiments are carried out to simulate the heave motions of a submerged sphere in infinite water depth, the heave and pitch motions of a truncated flared cylinder in finite depth. The results are verified against the published numerical results to ensure the effectiveness of the proposed model. Moreover, a series of higher harmonic waves and force components are obtained by the Fourier transformation to investigate the nonlinear effect of oscillation frequency. The difference among fully nonlinear, body-nonlinear and linear results is analyzed. It is found that the nonlinearity due to free surface and body surface has significant influences on the numerical results of the radiated waves and forces.

关键词： Wave radiation Fully nonlinear Body- nonlinear HOBEM Flared structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Viscous numerical examination of hydrodynamic forces on a submerged horizontal circular cylinder undergoing forced oscillation

引用

Journal of Hydrodynamics 2019年第5期31卷 887-899页

作者： Bin Teng Hong-fei Mao de-zhi ning Chong-wei Zhang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

As a classical topic,the hydrodynamic forces on a submerged horizontal cylinder undergoing forced oscillation have been widely studied based on potential flow ***,the fluid viscosity and the flow rotation may play an important role when the oscillation amplitude of the circular cylinder is large,and large discrepancy will occur between the potential flow simulation and the experimental *** study focuses on the study of hydrodynamic forces on a submerged horizontal circular cylinder undergoing forced oscillation by means of a viscous fluid numerical wave tank(NWT)*** accuracy of the numerical model is validated against available experimental *** comparisons between the hydrodynamic forces on the circular cylinder predicted by the viscous fluid model and the potential flow model are conducted to show the viscous effects on the hydrodynamic *** the study on the flow fields,the mechanism of the viscous effects is explained by the vortex *** basic reason for the difference between the results based on the viscous fluid theory and the potential flow theory is revealed by analyzing the force components.

关键词： Submerged horizontal circular cylinder forced oscillation hydrodynamic forces vortex effect

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The wave absorption efficiency of multi-layer vertical perforated thin plates

引用

Journal of Hydrodynamics 2018年第5期30卷 898-907页

作者： Bao-lei Geng Rong-quan Wang de-zhi ning National Engineering Laboratory for Port Hydraulic Construction Technology Tianjin Research Institute for Water Transportation EngineeringTianjin 300456China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

This paper analyzes the wave absorption efficiency of multi-layer perforated plates in an ideal fluid, based on the linear potential flow theory. The influence of the thickness, the porosity and the layout form of the plates on the wave absorptivity is studied on the assumption that all perforated plates are composed of the same materials and have the same thickness and porosity. The calculation results indicate that the larger the number of layers of the perforated plate set, the better the wave absorption efficiency, however, when the layer number exceeds a certain value, the efficiency of the plates is not significantly increased. For the case of porosity ？= 0.2, thickness b= 0.07 m and 4 layers of perforated plates with a distance l= 1.0 m between the layers, 90% of the energy of the wave within the incident wave period between 1.6 s and 4.4 s can be absorbed.

关键词： Wave absorptivity multi-layer vertical plate porous structure analytic method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A numerical piston-type wave-maker toolbox for the open-source library OpenFOAM

引用

Journal of Hydrodynamics 2019年第4期31卷 800-813页

作者： Dong-xu Wang Jia-wen Sun Jin-song Gui Zhe Ma de-zhi ning Ke-zhao Fang department of Ocean and Civil Engineering Dalian Ocean University Dalian 116023 China National Marine Environment Monitoring Center State Oceanic Administration Dalian 116023 China deepwater Engineering Research Center Dalian University of Technology Dalian 116024 China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

A novel numerical piston-type wave-maker toolbox for the OpenFOAM is developed and demonstrated in this paper. This toolbox is implemented in C++ for improving the solutions of nonlinear wave problems in the field of hydrodynamics. As a toolbox that generates waves using the piston-type method only, it contains several frequently used functions, including the generation and the absorption of waves of various forms, an active absorption system and the porous media flow. Furthermore, to illustrate the operability of the toolbox, some validations and applications are presented, including the regular waves, the irregular waves, and the solitary waves. In each case, a satisfactory agreement is obtained in comparison with the published experimental or theoretical results,so this toolbox may be applied with a considerable confidence.

关键词： Piston-type wave-maker OpenFOAM nonlinear wave hydrodynamics

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Using a Time-domain Higher-order Boundary Element Method to Simulate Wave and Current Diffraction from a 3-D Body

引用

Journal of Marine Science and Application 2010年第2期9卷 156-162页

作者：刘珍滕斌宁德志孙亮 State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University

To study wave-current actions on 3-D bodies a time-domain numerical model was established using a higher-order boundary element method(HOBEM).By assuming small flow velocities,the velocity potential could be expressed for linear and higher order components by perturbation expansion.A 4th-order Runge-Kutta method was applied for time *** artificial damping layer was adopted at the outer zone of the free surface mesh to dissipate scattering *** of the numerical method was carried out on run-up,wave exciting forces,and mean drift forces for wave-currents acting on a bottom-mounted vertical *** results were in close agreement with the results of a frequency-domain method and a published time-domain *** model was then applied to compute wave-current forces and run-up on a Seastar mini tension-leg platform.

关键词： wave-current diffraction time-domain simulation drift force higher-order boundary element method (HOBEM)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental Study on A Sloshing Mitigation Concept Using Floating Layers of Solid Foam Elements

引用

China Ocean Engineering 2019年第1期33卷 34-43页

作者： ning de-zhi SU Peng ZHANG Chong-wei State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University

A sloshing mitigation concept taking advantage of floating layers of solid foam elements is proposed in the present study. Physical experiments are carried out in a liquid tank to investigate the hydrodynamic mechanism of this concept. Effects of the foam-layer thickness, excitation amplitude, and excitation frequency on the sloshing properties are analyzed in detail. It is found that the floating layers of solid foam elements do not evidently affect the fundamental natural sloshing frequency of the liquid tank evidently among the considered cases. At the resonant condition, the maximum wave height and dynamic pressure are greatly reduced as the foam-layer thickness increases. Higher-order pressure components on the tank side gradually vanish with the increase of the foam-layer thickness. Cases with different excitation amplitudes are also analyzed. The phenomenon is observed when the wave breaking in the tank can be suppressed by solid foam elements.

关键词： anti-sloshing sloshing floating foam potential flow liquid tank

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimization of Baffled Rectangular and Prismatic Storage Tank Against the Sloshing Phenomenon

引用

China Ocean Engineering 2020年第5期34卷 664-676页

作者： Hassan SAGHI ning de-zhi CONG Pei-wen ZHAO Ming department of Civil Engineering Hakim Sabzevari UniversitySabzevar ***Iran State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China School of Computing Engineering and MathematicsUniversity of Western SydneyPenrithNSW 2751Australia

The fluid motion in partially filled tanks with internal baffles has wide engineering applications. The installation of baffles is expected to reduce the effect of sloshing as well as the consequent environmental damages. In the present study, a series of experimental tests are performed to investigate the sloshing phenomenon in a baffled rectangular storage tank. In addition, the sloshing phenomenon is also modeled by using Open Foam. Based on the experimental and numerical studies, optimization of the geometric parameters of the tank is performed based on some criteria such as tank area, entropy generation, and the horizontal force exerted on the tank area due to the sloshing *** optimization is also carried out based on the entropy generation minimization analysis. It is noted that the optimum baffle height is in the range of h_b/h_w=0.5-0.75 in the present study(where h_b and h_w are the baffle height and water depth, respectively). Based on the results, the optimal design of the tank is achieved with R_A= 0.9-1.0(where R_A=L/W, L and W are the length and width of the tank, respectively). The results also show that the increase of h_b can lead to a decrease of the maximum pressure and horizontal force exerted on the tank. It is also noted that the horizontal force exerted on the tank firstly continues to increase as the sway motion amplitude ***, as the normalized motion amplitude parameter, a/L(The parameter a is the motion amplitude), exceeds0.067, the effect of motion amplitude on the force is not obvious. The same optimization is also performed in the multiple-variable-baffled tank and prismatic storage tank.

关键词： baffled rectangular storage tank experimental tests sloshing phenomenon optimization entropy generation Open Foam

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Hydrodynamic Performance of A Porous-Type Land-Fixed Oscillating Water Column Wave Energy Converter

引用

China Ocean Engineering 2022年第1期36卷 1-14页

作者： Robert MAYON ning de-zhi ZHANG Chong-wei Lars JOHANning State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China College of Engineering Mathematics and Physical SciencesUniversity of ExeterPenryn CampusPenrynCornwallTR109FEUK

A hybrid, porous breakwater-Oscillating Water Column(OWC) Wave Energy Converter(WEC) system is put forward and its hydrodynamic performance is investigated using the fully nonlinear, open-source computational fluid dynamics(CFD) model, OpenFOAM. The permeable structure is positioned at the weather side of the OWC device and adjoined to its front wall. A numerical modelling approach is employed in which the interstices within the porous structure are explicitly defined. This permits the flow field development within the porous structure and at the OWC front wall to be observed. The WEC device is defined as a land-fixed, semi-submerged OWC chamber. A range of regular incident waves are generated at the inlet within the numerical tank. The OWC efficiency and the forces on the structure are examined. Results are compared for the simulation cases in which the porous component is present or absent in front of the OWC chamber. It is found that the incorporation of the porous component has minimal effect on the hydrodynamic efficiency of the OWC, reducing the efficiency by less than 5%. Nevertheless,the forces on the front wall of the OWC can be reduced by up to 20% at the higher wave steepness investigated,through inclusion of the porous structure at the OWC front wall. These findings have considerable implications for the design of hybrid OWC-breakwater systems, most importantly in terms of enhancing the durability and survivability of OWC WECs without significant loss of operational efficiency.

关键词： OWC porous breakwater hydrodynamic performance wave loads CFD

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Hydrodynamic Performance of An Integrated System of Breakwater and A Multi-Chamber OWC Wave Energy Converter

引用

China Ocean Engineering 2024年第4期38卷 543-556页

作者： ning de-zhi ZHANG Xiang-yu WANG Rong-quan ZHAO Ming State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China Dalian Key Laboratory of Offshore Renewable Energy Dalian University of TechnologyDalian 116024China School of Computing Engineering and MathematicsUniversity of Western SydneyPenrith NSW 2751Australia

A multi-chamber oscillating water column wave energy converter(OWC-WEC)integrated to a breakwater is *** hydrodynamic characteristics of the device are analyzed using an analytical model based on the linear potential flow theory.A pneumatic model is employed to investigate the relationship between the air mass flux in the chamber and the turbine *** effects of chamber width,wall draft and wall thickness on the hydrodynamic performance of a dual-chamber OWC-WEC are *** results demonstrate that the device,with a smaller front wall draft and a wider rear chamber exhibits a broader effective frequency *** device with a chamber-width-ratio of 1:3 performs better in terms of power ***,results from the analysis of a triplechamber OWC-WEC demonstrate that reducing the front chamber width and increasing the rearward chamber width can improve the total performance of the *** the number of chambers from 1 to 2 or 3 can widen the effective frequency bandwidth.

关键词： oscillating water column power extraction efficiency potential flow theory wave energy converter multi-chamber

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：