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THE RADIATION AND DIFFRACTION OF WATER WAVES BY A BOTTOM-MOUNTED CIRCULAR CYLINDER IN A TWO-LAYER FLUID

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Journal of Hydrodynamics 2007年第1期19卷 1-8页

作者： YOU Yun-xiang SHI Qiang miao guo-ping School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China.

An analytical method was proposed to analyze the radiation and diffraction of water waves by a bottom-mounted circular cylinder in a two-layer fluid. Analytical expressions for added mass and damping coefficients, as well as the wave excitation forces of the circular cylinder were obtained by an eigenfunction expansion method. The hydrodynamic forces on the bottom-mounted circular cylinder in a two-layer fluid include not only the added mass and damping coefficients, but also the wave forces of the surface and internal-wave modes. This is different from the case of a homogenous fluid. Some examples were given, showing that density stratification can have a relative large effect on these hydrodynamic forces over a wide range of frequencies.

关键词： two-layer fluid bottom-mounted cylinder,surface-wave mode internal-wave mode hydrodynamic forces

SIMULATION OF TANK SLOSHING BASED ON OPENFOAM AND COUPLING WITH SHIP MOTIONS IN TIME DOMAIN

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Journal of Hydrodynamics 2012年第3期24卷 450-457页

作者： LI Yu-long ZHU Ren-chuan miao guo-ping FAN Ju State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University Shanghai 200240 China

Tank sloshing in ship cargo is excited by ship motions, which induces impact load on tank wall and then affects the ship motion. Wave forces acting on ship hull and the retardation function are solved by using three-dimensional frequency domain theory and an impulse response function method based on the potential flow theory, and global ship motion is examined coupling with nonlinear tank sloshing which is simulated by viscous flow theory. Based on the open source Computational Fluid Dynamics （CFD） development platform Open Field Operation and Manipulation （OpenFOAM）, numerical calculation of ship motion coupled with tank sloshing is achieved and the corresponding numerical simulation and validation are carried out. With this method, the interactions of wave, ship body and tank sloshing are completely taken into consideration. This method has quite high efficiency for it takes advantage of potential flow theory for outer flow field and viscous flow theory for inside tank sloshing respectively. The numerical and experimental results of the ship motion agree well with each other.

关键词： Open Field Operation and Manipulation (OpenFOAM) time domain simulation tank sloshing and coupling effect,Impulse-Response Function (IRF)

Numerical simulation of rolling for 3-D ship with forward speed and nonlinear damping analysis

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Journal of Hydrodynamics 2013年第1期25卷 148-155页

作者： YANG Chun-lei ZHU Ren-chuan miao guo-ping FAN Ju State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University

Strongly nonlinear characteristics of ship roll owing to viscous effect can be usually observed. To describe the nonlinear roll behavior, the CFD method has been frequently employed with obvious advantages compared with the traditional semi-empirical formula method in estimating the roll damping. Numerical simulations of free decay and forced rolling at various forward speeds and amplitudes for a 3-D ship hull are conducted in the present research to predict ship roll damping, in which a RANS solver is employed and a dynamic mesh technique is adopted and discussed in detail. Numerical results, including nonlinear flow characters around ships, rolling decay curves and damping coefficients, show that they are all in good agreement with available experimental data. The linear and nonlinear damping coefficients are estimated and analyzed by fitting with exponential functions for various rolling amplitudes, frequencies and speeds in the free decay simulations, and the damping coefficients are obtained by a polynomial fitting in the forced roll simulations. It is indicated that the damping coefficients increase with increasing rolling angle amplitude and velocity. It is also emphasized that the effect of forward speed is significant to roll damping and the nonlinear damping decreases with increasing velocity.

关键词： RANS method free decay forced roll nonlinear damping

ANALYTICAL RESEARCH ON THE WAVE DIFFRACTION OF ARC-SHAPED FLOATING BREAKWATERS

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Journal of Hydrodynamics 2006年第1期18卷 1-10页

作者： miao guo-ping CHENG Jian-sheng WANG Jing-quan YOU Yun-xiang School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China Engineering Institute of Engineering Corps PLA University of Science and Technology Nanjing 210007 China

An analytical method was developed to study the wave diffraction on are-shaped floating breakwaters. The floating breakwater was assumed to be rigid, thin, vertical, immovable and located in water of constant depth. The fluid domain was divided into two regions by imaginary interface, The velocity potential in each region is expanded by eigenfunctions. By satisfying continuity of pressure and normal velocity across the imaginary fluid interface, a set of linear algebraic equations could be obtained to determine the unknown coefficients for eigenfunctions. The accuracy of present model and the computer program were verified by a comparison with ex isting results for the case of arc-shaped bottom-mounted breakwaters. Numerical results, in the form of contour maps of the non-dimension wave amplitude around the breakwater, were presented for a range of wave and breakwater parame ters. Results show the wave diffraction on the arc-shaped floating breakwater is related to the incident wavelength and the draft of the breakwater.

关键词： arc-shaped floating breakwater wave diffraction velocity potential eigenfunctions

WAVE DIFFRACTION ON ARC-SHAPED BOTTOM-MOUNTED BREAKWATERS

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Journal of Hydrodynamics 2005年第4期17卷 391-397页

An analytical method was developed to study the wave diffraction effects on arc-shaped bottom-mounted breakwaters. The breakwater was assumed to be rigid, thin, impermeable and vertically located in water of constant depth. The fluid domain was divided into two regions by imaginary cylindrical interface. The velocity potential in each region was expanded with cigcnfunctions. By satisfying continuity of pressure and normal velocity across the imaginary fluid interface, a set of linear algebraic equations could be obtained to determine the unknown coefficients for eigenfunction expansions. The accuracy of the present model was verified by a comparison with existing results for the case of an isolated straight-line breakwater. Numerical results, in the form of contour maps of the non-dimensional wave amplitude around the breakwater and diffracted wave amplitude at three typical sections, were presented for a range of wave parameters. Results show the arc-shaped bottom-mounted breakwater is generally effective in defending against waves. The wave amplitudes at most sheltered areas are commonly 10%-50% of incident wave amplitudes under most wave conditions.

关键词： arc-shaped breakwater wave diffraction velocity potential eigenfunction

THE SIMULATION AND ANALYSIS OF TANK SLOSHING WITH POROSITY GIRDER BY MULTI-DOMAIN BOUNDARY ELEMENT METHOD

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Journal of Hydrodynamics 2010年第4期22卷 546-553页

作者： HE Zhao ZHU Ren-chuan miao guo-ping School of Naval Architecture Ocean and Civil Engineering State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 China

The simulations of nonlinear sloshing in both two-dimensional and three-dimensional liquid tanks with porosity girder are carried out in time domain by using the Multi-domain Boundary Element Method（MBEM）.The comparison of the present results and the references is conducted and shows they agree well with each *** three-dimensional effect and the influence of the width of liquid tank and the height and porosity of the girder on the natural period of the model are also discussed.

关键词： Multi-domain Boundary Element Method (MBEM) sloshing girder with porosity time domain nonlinearity natural period three-dimensional effect

EFFECT OF ESCAPE DEVICE FOR SUBMERGED FLOATING TUNNEL (SFT) ON HYDRODYNAMIC LOADS APPLIED TO SFT

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Journal of Hydrodynamics 2012年第4期24卷 609-616页

作者： DONG Man-sheng miao guo-ping YONG Long-chang NIU Zhong-rong PANG Huan-ping HOU Chao-qun School of Civil Engineering Hefei University of Technology Hefei 230009 China State Key Laboratory of Ocean Engineering -Shanghai JiaoTong Universityl Shanghai 200030 China School of Transportation Engineering Hefei University of Technology'Hefei 230009 China

This paper presents a potential approach to settle the problem of surviving major safety accidents in Submerged Floating Tunnel （SFT） that detachable emergency escape devices are set up outside SFT. The Computational Fluid Dynamics （CFD） technology is used to investigate the effect of emergency escape devices on the hydrodynamic load acting on SFT in uniform and oscillatory flows and water waves by numerical test. The governing equations, i.e., the Reynolds-Averaged Navier-Stokes （RANS） equations and k - ε standard turbulence equations, are solved by the Finite Volume Method （FVM）. Analytic solutions for the Airy wave are applied to set boundary conditions to generate water wave. The VOF method is used to trace the free surface. In uniform flow, hydrodynamic loads, applied to SFT with emergency escape device, reduce obviously. But, in oscillatory flow, it has little influence on hydrodynamic loads acting on SFT. Horizontal and vertical wave loads of SFT magnify to some extend due to emergency escape devices so that the influence of emergency escape devices on hydrodynamic loads of SFT should be taken into consideration when designed.

关键词： Submerged Floating Tunnel (SFT) conceptual design flow Airy wave escape device hydrodynamic load

A TIME DOMAIN INVESTIGATION ON THE HYDRODYNAMIC RESONANCE PHENOMENA OF 3-D MULTIPLE FLOATING STRUCTURES

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Journal of Hydrodynamics 2008年第5期20卷 611-616页

作者： ZHU Hai-rong ZHU Ren-chuan miao guo-ping The State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200030 China

A 3-D time domain method is developed to investigate the gap influence on the wave threes for 3-D multiple floating structures. Special hydrodynamic resonance due to small gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. By comparison with the results from the frequency domain technique, the results obtained from the time domain method reveal the similar resonant phenomena and hydrodynamic interaction. The resonant wave numbers are also proved around kL-nπ （n = 1,2 ……∞） with a corresponding frequency shift. The strong hydrodynamic interaction feature is practically significant for the design of module structures and the links （connection） in whole the floating body system.

关键词： time domain resonance hydrodynamic interaction multiple floating bodies gap influence

THE RADIATION PROBLEM OF MULTIPLE STRUCTURES WITH SMALL GAPS IN BETWEEN

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Journal of Hydrodynamics 2006年第5期18卷 520-526页

作者： ZHU Ren-chuan miao guo-ping ZHU Hai-rong The State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China

Influence of gaps on hydrodynamic interactions of multiple floating structures is considered in the present investigation. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have showed the existence of the sharp peak force response on each floating body at some special resonant wave numbers, which are also proved to be around kL =nπ （n= 1, 2, ...,∞） with a corresponding frequency shift. Width and depth of a gap also give influences on the resonant frequency and resonant amplitude of added mass and damping forces due to the radiation motions of the multiple bodies. The strong hydrodynamic interaction feature may have a big influence on the integrated loads of multiple floating structures system.

关键词： resonance hydrodynamic interaction multiple floating bodies gap influence