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IDENTIFICATION OF ABKOWITZ MODEL FOR SHIP MANOEUVRING MOTION USING ε-SUPPORT VECTOR REGRESSION

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Journal of Hydrodynamics 2011年第3期23卷 353-360页

作者： ZHANG Xin-guang ZOU Zao-jian School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Naval Architecture Ocean and Civil Engineering and State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 China

By analyzing the data of longitudinal speed, transverse speed and rudder angle etc. in the simulated 10°/10°zigzag test, the hydrodynamic derivatives in the Abkowitz model for ship manoeuvring motion are identified by using e-Support Vector Regression （ε -SVR）. To damp the extent of parameter drift, a series of random numbers are added into the training samples to reconstruct the training samples. The identification results of the hydrodynamic derivatives are compared with the Planar Motion Mechanism （PMM） test results to verify the identification method. By using the identified Abkowitz model, 20°/20° zigzag test is numerically simulated. The simulated results are compared with those obtained by using the Abkowitz model where the hydrodynamic derivatives are obtained from PMM tests. The agreement is satisfactory, which shows that the regressive Abkowitz model has a good generalization performance.

关键词： ship manoeuvring Abkowitz model parameter identification e -Support Vector Regression ( ~ -SVR)

A LINEAR HYBRID MODEL OF MSE AND BEM FOR FLOATING STRUCTURES IN COASTAL ZONES

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Journal of Hydrodynamics 2006年第6期18卷 649-658页

作者： ZHANG Jun MIAO Guo-ping School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China The First Engineers Scientific Research Institute of the General Armaments Wuxi 214035 China

A linear hybrid model of Mild Slope Equation （MSE） and Boundary Element Method （BEM） is developed to study the wave propagation around floating structures in coastal zones. Both the wave refraction under the influence of topography and the wave diffraction by floating structures are considered. Hence, the model provides wave properties around the coastal floating structures of arbitrary shape but also the wave forces on and the hydrodynamic characteristics of the structures. Different approaches are compared to demonstrate the validity of the present hybrid model. Several numerical tests are carried out for the cases of pontoons under different circumstances. The results show that the influence of topography on the hydrodynamic characteristics of floating structures in coastal regions is important and must not be ignored in the most wave period range with practical interests.

关键词： hybrid model Mild Slope Equation (MSE),Boundary Element Method (BEM) marine floating structures,coastal regions wave propagation wave force

FLOW AROUND A CIRCULAR CYLINDER USING A FINITE-VOLUME TVD SCHEME BASED ON A VECTOR TRANSFORMATION APPROACH

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Journal of Hydrodynamics 2010年第2期22卷 221-228页

作者： WANG Jia-song School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240China

Flows around a circular cylinder displaying an unsteady vortex shedding process at the Reynolds numbers of 1000,3900 and 1×104 are studied using a finite-volume Total Variation Diminishing（TVD） scheme for solving the Unsteady Reynolds-Averaged Navier-Stokes（URANS） *** Elemental Velocity Vector Transformation（EVVT） approach is proposed for the local normal and tangential velocity transformation at the interfaces of main and satellite *** presented method is validated by comparing with the available experimental data and numerical *** is shown that the two-dimensional TVD finite volume method with the Renormalization Group（RNG） turbulence model can be used to determine hydrodynamic forces and captures vortex shedding characteristics very well.

关键词： Total Variation Diminishing(TVD) finite volume method Renormalization Group(RNG) turbulence model flow around circular cylinder Elemental Velocity Vector Transformation(EVVT)

NUMERICAL INVESTIGATION ON THE AEROELASTIC BEHAVIOR OF AN AIRSHIP WITH HULL-FIN CONFIGURATION

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Journal of Hydrodynamics 2010年第2期22卷 207-213页

作者： LIU Jian-min LU Chuan-jing - XUE Lei-ping Marine engineering Institute Jimei University Xiamen 361021 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240China State Key Laboratory of ocean engineering Shanghai Jiao Tong University Shanghai 200030 China

Numerical investigation was conducted on an airship of hull-fin configuration for aerodynamic and aeroelastic characteristics in three-dimensional viscous *** mathematical model was built and the corresponding numerical code was developed for the fluid-structure interaction *** governing equations of the viscous flow with LL-Low Reynolds modified model were solved by the standard SIMPLE algorithm based on the finite volume method.A fluid-structure coupled method was employed to solve the nonlinear aeroelasticity problem for the *** computational results of the viscous flow are in good agreement with the experimental *** simulation on the aeroelastic behavior of the airship in a trimmed flight reveals the effect of structure flexibility on the aerodynamic performance.

关键词： fluid-structure interaction airship aeroelasticity flexibility

Currents induced by vertical varied radiation stress in standing waves and evolution of the bed composed of fine sediments

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International Journal of Sediment Research 2009年第2期24卷 214-226页

作者： Jing-Xin ZHANG1 and Hua LIU21 Lecturer,Department of engineering Mechanics,School of Naval Architecture,ocean and civil engineering,Shanghai Jiao Tong University,800 Dongchuan Road,Shanghai 200240,China 2 Department of engineering Mechanics,School of Naval Architecture,ocean and civil engineering,Shanghai Jiao Tong University,800 Dongchuan Road,Shanghai 200240,China [a]Department of engineering Mechanics School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China [b]Department of Engineering Mechanics School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China

This paper extends the conventional concept of radiation stress(Longuet-Higgins and Stewart,1964) in progressive water waves to standing waves,so that its vertical profile could be defined and calculated in a new technical way. The hydrodynamic numerical model being coupled with the vertically varying radiation stress in standing waves is used to simulate the currents being induced by standing waves in the vertical section. Numerical modeling of suspended sediment transport is then carried out to simulate the evolution of the bed composed of fine sediments by the currents. The scour and deposition patterns simulated are in qualitative agreement with prior laboratory and field observations.

关键词： Standing wave Vertical variation in radiation stress Scour pattern Suspended sediment

A THREE-DIMENSIONAL DESINGULARIZED HIGH ORDER PANEL METHOD BASED ON NURBS

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Journal of Hydrodynamics 2008年第2期20卷 137-146页

作者： GAO Zhi-liang ZOU Zao-jian State Key Laboratory of ocean engineering Shanghai Jiaotong University Shanghai 200030 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China

A desingularized high order panel method based on Non-Uniform Rational B-Spline （NURBS） was developed to deal with three-dimensional potential flow problems. A NURBS surface was used to precisely represent the body geometry. Velocity potential on the body surface was described by the B-spline after the source density distribution on the body surface had been solved. The collocation approach was employed to satisfy the Neurnann boundary condition and Gaussian quadrature points were chosen as both the collocation points and the source points. The singularity was removed by a combined method, so the process of the numerical computation was non-singular. In order to verify the method proposed, the unbounded flow problems of sphere and ellipsoid, the wave-making problem of a submerged ellipsoid were chosen as computational examples. It is shown that the numerical results are in good agreement with analytical solutions and other numerical results in all cases, and sufficient accuracy of numerical solution can be reached with a small number of panels.

关键词： potential flow high order panel method Non-Uniform Rational B-Spline (NURBS) desingularization

The sloshing of stratified liquid in a two-dimensional rectangular tank

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Science China(Physics,Mechanics & Astronomy) 2011年第1期54卷 2-9页

作者： WU GuoXiong1,2 1 State Key Laboratory of ocean engineering,College of Naval Architecture,ocean and civil engineering,Shanghai Jiao Tong University,Shanghai 200240,China 2 Department of Mechanical engineering,University College London,Torrington Place,London WC1E 7JE,UK 1. State Key Laboratory of ocean engineering College of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 20024 China2. Department of Mechanical Engineering University College Londo Torrington Place London WC1E 7JE UK

The sloshing of inviscid liquid of stratified density in a rectangular tank is *** the flow is no longer irrotional,the governing equation is found to be quite different from the Laplace equation used for the liquid of constant *** particular it contains terms of mixed temporal and spatial *** problem is solved based on the variable separation method and Laplace transform for the constant Vaisala-Brunt *** is found that the stratification of density may have small effects on those natural frequencies associated with the constant density,but many new natural frequencies have appeared as a result of its effect.

关键词： sloshing density stratification resonance rectangular tank

SEEPAGE ANALYSIS OF LANDFILL FOUNDATIONS IN SHANGHAI LAOGANG LANDFILL PHASE IV

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Journal of Hydrodynamics 2006年第5期18卷 613-619页

作者： ZHANG Qian-fei WANG Yan-ming XU Yong-fu School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China Shanghai Municipal engineering Design Institute Shanghai 200092 China

A complex seepage flow field with unknown free surface was formed in the Shanghai Laogang Municipal Solid Waste （MSW） Landfill by the perimeter cut-off wall around the landfill site and the Prefabricated Vertical Drains （PVD） in the foundation of landfill. First, the equivalent vertical permeability was presented based on the drainage mechanism of PVD and the related calculation method was studied to macroscopically reflect the impact of PVD on the seepage flow status of the landfill foundation. With the influence of the cut-off wall and the PVD on the infiltration of groundwater, the total inflow was classified into two parts： the lateral inflow through the cut-off wall outside the landfill, and the upward infiltration through the PVD from the foundation of the landfill. Seepage analysis was conducted using the finite element method according to the actual scenario of Laogang Landfill, and the lateral infiltration and the upward infiltration were calculated, respectively. The results show that the total inflow into the landfill area was mostly supplied by the upward infiltration through the PVD and the perimeter cut-off wall was significantly effective to depressurize the seepage pressure and to reduce the flow rate.

关键词： Municipal Solid Waste (MSW) landfill foundations of landfill cut-off wall Prefabricated Vertical Drain (PVD) lateral infiltration upward infiltration finite element analysis

FLOW NOISE MEASUREMENT OF SURFACE SHIP WITH TOWED MODEL

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Journal of Hydrodynamics 2008年第6期20卷 784-789页

作者： GAO Xiao-peng BI Yi MIAO Guo-ping School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200030 China College of Naval Architecture and Power Naval University of Engineering Wuhan 430033 China

In this article, a new acoustic test technique using towed model was introduced to study flow noise caused by a surface ship. The project of model test was be properly designed for acoustic signal collecting and with the help of appropriate data processing method different kinds of acoustic sources could be successfully identified. A lot of work about fuid noise could be carried on with the towed model, and the noise corresponding to low frequency which is especially interested for its long distance radiating with small attenuation could also be studied in this way.

关键词： acoustic test surface ship towed model flow noise short-time Fourier transform