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NUMERICAL STUDY OF MULTIDIRECTIONAL FOCUSING WAVE RUN-UP ON A VERTICAL SURFACE-PIERCING CYliNDER

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Journal of Hydrodynamics 2012年第1期24卷 86-96页

作者： SUN Zhong-bin liU Shu-xue li jin-xuan State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

In this article,a numerical model based on improved Boussinesq equations and the Finite Element Method（FEM）with unstructured triangular elements is proposed and verified by experimental results for the focusing wave group interaction with a vertical surface-piercing *** multidirectional focusing waves with different directional spreading parameters and their interaction with a vertical surface-piercing cylinder are numerically *** directional spreading parameter influences the wave form,that is,a wider directional spreading would induce a narrower wave form in *** wave run-up on the cylinder increases with the increase of the wave directional spreading parameter,but when the parameter is greater than 30-40,the wave run-up changes only slightly and the influence of the directional spreading can be neglected.A larger diameter cylinder may have a larger wave run-up at the front *** at the back side,it is other way round.

关键词： focusing waves Finite Element Method(FEM) improved Boussinesq equations run-up

Numerical Studies on the Generation and Propagation of Tsunami Waves Based on the High-Order Spectral Method

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China Ocean Engineering 2022年第2期36卷 268-278页

作者： HAO Jian li jin-xuan liU Shu-xue WANG Lei State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

An effective numerical model for wave propagation over three-dimensional(3D)bathymetry was developed based on the High-Order Spectral(HOS)method and combined with a moving bottom *** on this model,tsunami waves caused by various mechanisms were simulated and ***-dimensional bed upthrust and the effect of the uplift velocity of the bathymetry on the wave profiles of tsunami waves were ***,tsunami waves caused by 3D submarine slides were generated and the effects of the slide velocity,slide dimension and water depth on the tsunami waves were *** on wavelet analysis,the properties of the tsunami wave propagation were *** results show that the bottom movement can significantly affect the generation and propagation of tsunami waves and the studies could help understand the mechanisms of tsunamis caused by a moving bottom boundary.

关键词： tsunami waves High-Order Spectral(HOS)method moving bottom boundary wavelet analysis

Establishment of Numerical Wave Flume Based on the Second-Order Wave-Maker Theory

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China Ocean Engineering 2019年第2期33卷 160-171页

作者： ZHANG Hao-chen liU Shu-xue li jin-xuan WANG Lei State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

With growing computational power, the first-order wave-maker theory has become well established and is widely used for numerical wave flumes. However, existing numerical models based on the first-order wave-maker theory lose accuracy as nonlinear effects become prominent. Because spurious harmonic waves and primary waves have different propagation velocities, waves simulated by using the first-order wave-maker theory have an unstable wave profile. In this paper, a numerical wave flume with a piston-type wave-maker based on the second-order wave-maker theory has been established. Dynamic mesh technique was developed. The boundary treatment for irregular wave simulation was specially dealt with. Comparisons of the free-surface elevations using the first-order and second-order wave-maker theory prove that second-order wave-maker theory can generate stable wave profiles in both the spatial and time domains. Harmonic analysis and spectral analysis were used to prove the superiority of the second-order wave-maker theory from other two aspects. To simulate irregular waves, the numerical flume was improved to solve the problem of the water depth variation due to low-frequency motion of the wave board. In summary, the new numerical flume using the second-order wave-maker theory can guarantee the accuracy of waves by adding an extra motion of the wave board. The boundary treatment method can provide a reference for the improvement of nonlinear numerical flume.

关键词： second-order wave generation nonlinear wave spurious harmonic wave numerical flume

AN IMPROVED NUMERICAL METHOD FOR CALCULATIONS IN WAVE KINEMATICS

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Journal of Hydrodynamics 2009年第6期21卷 826-834页

作者： SUN Yi-yan liU Shu-xue li jin-xuan State Kay Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024

The prediction of wave kinematics is a necessary basis for ocean engineering design. In this article, an improved method to calculate the wave kinematics especially in the crest region is presented. This method is based on the local approximation method. According to one measured wave surface, the proposed solution focuses on a Fourier series expansion in a somewhat larger segment of the wave surface record. The horizontal and vertical kinematics under the wave crest can be directly predicted. Good agreement between the numerical results and the theoretical Stokes waves verifies the validity of the numerical model. The effectiveness of the numerical method is also proved by the calculation of the wave kinematics of the laboratory focused wave groups.

关键词： Fourier series expansion wave kinematics focused wave

Hydroelastic Investigation on A Pile Breakwater Integrated with A Flexible Tail for Long-Wave Attenuation

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China Ocean Engineering 2022年第5期36卷 667-681页

作者： ZHANG Chong-wei ZHUANG Qian-ze li jin-xuan HUANG Luo-feng NING De-zhi State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China School of Water Energy and EnvironmentCranfield UniversityCranfield MK430ALUnited Kingdom

A novel concept of wave attenuator is proposed for the defense of long waves,through integrating a flexible tail to the lee-side surface of a pile *** flexible tail works as a floating blanket made up of hinged blocks,whose scale and stiffness can be easily adjusted.A two-phase-flow numerical model is established based on the open-source computational fluid dynamics(CFD)code OpenFOAM to investigate its wave attenuation *** Navier−Stokes equations are solved in the fluid domain,where an additional computational solid mechanics(CSM)solver is embedded to describe the elastic deformation of the floating *** coupling of fluid dynamics and structural mechanics is solved in a full manner to allow assess of wave variation along the deforming *** accuracy of the numerical model is validated through comparison with experimental *** of the flexible tail on performance of the pile breakwater are investigated *** behaviours of the tail are examined,and characteristics of its natural frequency are *** safety reasons,the wave loads impacting on the main body of the pile breakwater and the stress distribution over the tail are specially *** is found that both the length and stiffness of the tail can affect the wave-attenuation performance of the breakwater.A proper choice of the length and stiffness of the tail can greatly improve the long-wave defending capability of the pile *** maximum stress over the flexible tail can be restrained through optimising the deformation and stiffness of the tail.

关键词： wave attenuator pile breakwater OpenFOAM fluid-structure interaction wave transmission coastal protection

Focused Wave Properties Based on A High Order Spectral Method with A Non-Periodic Boundary

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China Ocean Engineering 2015年第1期29卷 1-16页

作者：李金宣柳淑学 State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

In this paper, a numerical model is developed based on the High Order Spectral （HOS） method with a non-periodic boundary. A wave maker boundary condition is introduced to simulate wave generation at the incident boundary in the HOS method. Based on the numerical model, the effects of wave parameters, such as the assumed focused amplitude, the central frequency, the frequency bandwidth, the wave amplitude distribution and the directional spreading on the surface elevation of the focused wave, the maximum generated wave crest, and the shifting of the focusing point, are numerically investigated. Especially, the effects of the wave directionality on the focused wave properties are emphasized. The numerical results show that the shifting of the focusing point and the maximum crest of the wave group are dependent on the amplitude of the focused wave, the central frequency, and the wave amplitude distribution type. The wave directionality has a definite effect on multidirectional focused waves. Generally, it can even out the difference between the simulated wave amplitude and the amplitude expected from theory and reduce the shifting of the focusing points, implying that the higher order interaction has an influence on wave focusing, especially for 2D wave. In 3D wave groups, a broader directional spreading weakens the higher nonlinear interactions.

关键词： focused wave high order spectral method numerical model

Observations of Freak Waves in Random Wave Field in 2D Experimental Wave Flume

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China Ocean Engineering 2013年第5期27卷 659-670页

作者：李金宣李鹏飞柳淑学 State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

Long time series of wave field are experimentally simulated by JONSWAP spectra with random phases in a 2D wave flume. Statistic properties of wave surface, such as significant wave height, skewness and kurtosis, are analyzed, and the freak wave occurrence probability and its relations with Benjamin-Feir index （BFI） are also investigated. The results show that the skewness and the kurtosis are significantly dependent on the wave steepness, and the kurtosis increases along the flume when BFI is large. The freak waves are observed in random wave groups. They occur more frequently than expected, especially for the wave groups with large BFI.

关键词： freak waves Benjamin-Feir instability random wave groups

An Improved Coupling of Numerical and Physical Models for Simulating Wave Propagation

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China Ocean Engineering 2014年第1期28卷 1-16页

作者：阳志文柳淑学李金宣 State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Department of Mechanical Engineering Technical University of Denmark

An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model （FEM） based Boussinesq equations is applied for the numerical wave simulation, and a 2D piston-type wavemaker is used for the physical wave generation. An innovative scheme combining fourth-order Lagrange interpolation and Runge-Kutta scheme is described for solving the coupling equation. A Transfer function modulation method is presented to minimize the errors induced from the hydrodynamic invalidity of the coupling model and/or the mechanical capability of the wavemaker in area where nonlinearities or dispersion predominate. The overall performance and applicability of the coupling model has been experimentally validated by accounting for both regular and irregular waves and varying bathymetry. Experimental results show that the proposed numerical scheme and transfer function modulation method are efficient for the data transfer from the numerical model to the physical model up to a deterministic level.

关键词： coupling numerical model physical model wave propagation transfer function modulation

Physical Simulation of Multidirectional Irregular Wave Groups

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China Ocean Engineering 2012年第3期26卷 443-456页

作者：刘思柳淑学李金宣孙忠滨 State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology

Real waves are multidirectional waves. In the present study, the calculation method for the wave maker driving signals for generating multidirectional wave groups in physical wave basin is proposed. Its validity is first confirmed by a numerical model for which the incident boundary condition is determined by use of the proposed method. Then, the physical simulation of multidirectional wave groups is performed in laboratory wave basin. The experimental results show that multidirectional waves with expected wave groupiness, which includes not only its group height but also its group length, can be satisfactorily zenerated at the soecified oosition in the tphvsical wave basin.

关键词： multidirectional wave wave groups wave maker signals physical simulation