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Proceedings Papers

Paper presented at the The 29th International Ocean and Polar Engineering Conference, June 16–21, 2019

Paper Number: ISOPE-I-19-032

... ABSTRACT The

**Wigley****hull**is considered as the initial ship, which can be globally deformed by shifting method and locally deformed by RBF (Radial Basis Function) method to generate a bulbous bow. Two optimization cases are given. In case 1, only shifting method is used, while in case 2...
Abstract

ABSTRACT The Wigley hull is considered as the initial ship, which can be globally deformed by shifting method and locally deformed by RBF (Radial Basis Function) method to generate a bulbous bow. Two optimization cases are given. In case 1, only shifting method is used, while in case 2, shifting and RBF methods are both used. The genetic algorithm is taken to obtain two optimal ships with minimum wave drag. Further validation by CFD solver naoe-FOAM-SJTU turns out that for the hull without bulbous bow, through combination of the two methods, a hull that has a much fewer wave drag can be obtained. INTRODUCTION In the ship design process, hull form design is very important, which has attracted the attention of a large number of researchers and ship designers. In order to obtain a modified ship with better hydrodynamic performances, the initial hull should be optimized. In recent years, with the huge development of computer technology and calculation theories, the Simulation-Based-Design (SBD) approach is becoming possible rather than empirical or semi-empirical formulas. It is a new design way which integrates hull form modification method, numerical simulations and optimization technology. Scholars at home and abroad have done a series of researches on hull form optimization problems, and achieved good results. Peri, Rossetti, and Campana (2001) regarded the total resistance and the bow wave amplitude as the objective functions of the geometry of a tanker bulbous bow, and used three different optimization algorithms to do the optimizations, and the optimization results are finally verified by the model test. Campana, Peri, Tahara, and Stern (2006) used the Non-Uniform Rational B-Spline (NURBS) surface modeling method to modify a bulbous bow, and the modified hulls were evaluated by RANS-based solver, and the bulbous bow was optimized. Zhang, Ma, and Ji (2009) used Rankine source method to calculate the wave-making resistance and Non-Linear Programming (NLP) as the optimization algorithm to get the optimal hull form with minimum wave-making resistance. Yang and Huang (2016) used surrogate models to perform three optimization cases and are validated by cross validation, where each sample point is evaluated from the surrogate model constructed by the rest of the sample points. Wu, Liu, Zhao, and Wan (2017) used Free-Form Deformation (FFD) method to change the bulbous bow shape of DTMB-5415 in order to obtain optimal hulls with better resistance performances in different speeds. Tezdogan, Zhang, Yigit, Liu, Xu, Lai, Kurt, Djatmiko, and Incecik (2018) used a hybrid algorithm to optimize the total resistance in calm water of a fishing boat, where two optimal hulls were obtained by two schemes.

Proceedings Papers

Xinning Wang, Sotirios P. Chouliaras, Panagiotis D. Kaklis, Alexandros A. -I. Ginnis, Constantinos G. Politis, Konstantinos V. Kostas

Paper presented at the The 27th International Ocean and Polar Engineering Conference, June 25–30, 2017

Paper Number: ISOPE-I-17-415

... ABSTRACT This paper delivers a preliminary comparative study on the computation of wave resistance via a commercial CFD solver (STAR-CCM+®) versus an in-house developed IGA-BEM solver for a pair of hulls, namely the parabolic

**Wigley****hull**and the KRISO container ship (KCS). The CFD solver...
Abstract

ABSTRACT This paper delivers a preliminary comparative study on the computation of wave resistance via a commercial CFD solver (STAR-CCM+®) versus an in-house developed IGA-BEM solver for a pair of hulls, namely the parabolic Wigley hull and the KRISO container ship (KCS). The CFD solver combines a VOF (Volume Of Fluid) free-surface modelling technique with alternative turbulence models, while the IGA-BEM solver adopts an inviscid flow model that combines the Boundary Element approach (BEM) with Isogeometric Analysis (IGA) using T-splines or NURBS. IGA is a novel and expanding concept, introduced by Hughes and his collaborators (Hughes et al, 2005), aiming to intrinsically integrate CAD with Analysis by communicating the CAD model of the geometry (the wetted ship hull in our case) to the solver without any approximation. INTRODUCTION The prediction of wave resistance in naval architecture plays an important role in hull optimisation, especially for higher Froude numbers when wave-resistance's share in total resistance becomes higher. It is well known that the total resistance of a ship can be roughly decomposed into the sum of frictional, viscous-pressure and wave resistance. Model testing is commonly used to predict the resistance components for new ships (ITTC, 1987). With the recent improvements in CFD (Computational Fluid Dynamics) tools, CFD is likely to provide a decent alternative for saving time and money for the prediction of resistance for modern ship hulls. This is not, however, the case for ship-hull optimisation when the geometry is unknown, which increases drastically the overall computational cost and the significance of deviation between the accurate CAD model of a ship hull and its discrete approximation usually adopted by the CFD solvers. An alternative lower-cost path for the wave-resistance estimation can be employed by appealing to the Boundary Element Method (BEM) for solving the Boundary Integral Equation (BIE), which results from adopting the so-called Neumann-Kelvin model for the flow around an object moving on the otherwise undisturbed free-surface of an inviscid and irrotational liquid; see, e.g., (Brard, 1972) and (Baar and Price 1988). Our purpose is to initiate a systematic comparative study between a CFD solver (STAR-CCM+) and an in-house BEM solver enhanced with the IGA concept, which permits to tightly integrate the CAD model of a ship hull and its IGA-BEM solver; see, e.g. (Belibassakis et al 2013). Under the condition that this study will secure that the discrepancy between the results provided by the two solvers are acceptable within the operational range of Froude numbers, one can proceed to develop a hybrid mid-cost optimisation framework that combines appropriately the low-cost IGA- BEM solver (Kostas et al, 2015) with the high-cost CFD one. In the present paper our comparison will involve two hulls, namely the Wigley and the KCS hull, which have been extensively used in pertinent literature for experimental and computational purposes.

Proceedings Papers

Paper presented at the The 27th International Ocean and Polar Engineering Conference, June 25–30, 2017

Paper Number: ISOPE-I-17-260

... ABSTRACT This paper provides a time-domain simulation on green water of a

**Wigley****hull**sailing in regular head waves. To predict the strong nonlinear phenomenon of green water, a numerical model is established by utilizing FINE/Marine, a multiphase-flow software based on free-surface capturing...
Abstract

ABSTRACT This paper provides a time-domain simulation on green water of a Wigley hull sailing in regular head waves. To predict the strong nonlinear phenomenon of green water, a numerical model is established by utilizing FINE/Marine, a multiphase-flow software based on free-surface capturing method. The problem of green water impacting on deck is systematically investigated by varying the wavelengths and wave amplitudes. Based on viscous flow theory, a solid-liquid-gas three-phase flow coupling model is developed for more realistic simulation by adopting the BRICS compressible discrete scheme as the free-surface capturing scheme which reduces numerical diffusion near the free surface. This model can well process problems of breaking waves and evolution of complicated free surface. By using this numerical model, impact loads on deck and hull, ship-motion characteristics and hydrodynamic characteristics during the green water process are investigated. The snapshots of the fluid field and ship location are also illustrated and analyzed, which coincide with actual physical phenomenon satisfactorily. This study is helpful for the design of ship principal dimensions and structure strength. INTRODUCTION Extreme wave, a destructive large amplitude wave in sea, may cause serious structure damage and affect the stability and safety of ships and offshore platforms (Zhao and Hu, 2012). Under the large-amplitude waves, the response of vessel becomes strong non-linear, especially green water on deck. The problem of green water is one of the important factors influencing the ship on structure strength and navigation performance. Therefore, studies on green water are of farreaching significance to ship characteristics performance, design, manufacture and operation. Due to the strong non-linear motions and complicated phenomena, so far this subject is still challenging, especially for mathematical analysis and potential flow models. Most of the early researches are based on the experimental studies. Ochi (1964) analyzed the phenomenon of green water by combining the probabilistic process with the linear theory. The linear theory has difficulty to apply to large-amplitude motions. Besides, the probabilistic analysis is not able to calculate the wave impact loads on deck and superstructure (Lin et al, 2009). Later, numerical simulation of the green water based on potential flow theory is widely carried out. However, the potential flow theory assumes the fluid is incompressible and irrotational, and it does not take the fluid viscosity into account. It is difficult to address the non-linear influence, especially strong nonlinear phenomena of wave breaking, overturning and splashing. More detailed researches on green water problem can be found in Nielsen and Mayer (2004), and Zhu et al . (2006).

Proceedings Papers

Paper presented at the The 27th International Ocean and Polar Engineering Conference, June 25–30, 2017

Paper Number: ISOPE-I-17-303

... and hydrodynamic interactions are investigated. Numerical programs are developed and used to calculate hydrodynamic coefficients and forces of side by side arranged modified

**Wigley****hull**and a rectangular barge of zero speed. Present results agree well with model test data and resonance phenomenon are obtained...
Abstract

ABSTRACT During offshore installation and underway replenishment, two vessels are side by side arranged in close proximity. A time domain high order Rankine panel method is developed and applied to analyze hydrodynamic interactions of side by side vessels in waves in the present paper. Radiation and diffraction problems are solved with linearity theorem. And for forward speed problem, both double body (DB) flow and uniform stream (US) linearized computations are carried out. Added mass, damping coefficients, hydrodynamic forces and motions responses of side by side vessels are computed and hydrodynamic interactions are investigated. Numerical programs are developed and used to calculate hydrodynamic coefficients and forces of side by side arranged modified Wigley hull and a rectangular barge of zero speed. Present results agree well with model test data and resonance phenomenon are obtained by computation. Further numerical investigation is carried out for a Supply ship and a Frigate advancing in waves parallel in close proximity. Ship motions of DB linearization computation are in generally better agreement with experiments than of US linearization method. Results of motions response of smaller Frigate in condition of two ships on parallel course are quite different with that of single ship condition due to the existence of bigger Supply ship. In addition, results show two ships with forward speed would undertake attracting lateral force. Detailed discussions on numerical results are carried out. INTRODUCTION Study on hydrodynamic interactions of side by side vessels in close proximity in waves is of great importance. The corresponding situations include offshore installation, LNG-FPSO system, and underway replenishment of ships advancing in waves. In these cases, hydrodynamic forces and vessels' motions response would be quite different in comparison to single body condition and should be carefully studied. Potential flow theory is favorable in ship hydrodynamic analysis due to its practicability. Original work was carried out by Korvin- Froukovsky(1955), Silverstein (1957), Hess and smith (1964) and other researches. After that, many have studied on ship seakeeping prediction. Among those, Tasai (1967), Ogilvie and Tuck (1969), Salvesen et al. (1970) came up with new strip theory, rational strip theory and STF method, respectively in early years. Strip theory is restricted by low speed and high frequency assumption and ship shall be slender, so it cannot be widely used in marine and ocean engineering. Three dimensional potential method that can be applied to ships and floating bodies with arbitrary form was then developed. The method is classified into free surface Green's function method and Rankine source method. The former adopts Green's function that satisfied linearized free surface and radiation condition, so source and diploe are only needed to be distributed on ship hull. Noblesse (1982), Newman (1984), Faltinsen and Michelsen (1974) used the method to solve wave body interactions in frequency domain. Clement (1998), Bingham (1994), Qiu (2013) studied on time domain simulation of ship seakeeping with transient Green's function. Rankine source method employs basic solution 1/r of Laplace equation as Green's function. Dawson (1977) first applied Rankine source method to compute steady ship wave. Nakos (1990) studied on steady and unsteady ship wave problems by quasi-linear formulation with frequency domain Rankine source method respectively. Kring et al. (1996) and Kim et al. (2013) developed a weak-scatterer time domain nonlinear method for forward speed problem.

Proceedings Papers

Paper presented at the The Twenty-fourth International Ocean and Polar Engineering Conference, June 15–20, 2014

Paper Number: ISOPE-I-14-312

... ship ship behavior resistance grid equation history wave profile experimental data computation free surface vertical wall case upstream oil & gas hydrodynamic force numerical simulation experimental result

**wigley****hull**ship motion water area fr 0 heave Numerical Simulations...
Abstract

Abstract Numerical simulations of ship navigation in confined water channel of varying channel width by using overset grid technique are presented. Three ship speed (Fr=0.267 and Fr=0.316 and Fr=0.40) and four canal width (B=1.0Lpp, B=1.5Lpp, B=2.0Lpp, B=3.0Lpp) were taken into account to analyze the channel bank effects and ship motions of heave and pitch. Finally a ship motion in a varying width channel is also carried out to validate the numerical results of ship heave, pitch and resistance in confined channel water by using the presented numerical method.

Proceedings Papers

Paper presented at the The Twenty-third International Offshore and Polar Engineering Conference, June 30–July 5, 2013

Paper Number: ISOPE-I-13-434

.... A dissipative 3D Green function is derived where the Laplace equation, free surface condition and the radiation condition are transformed using a Fourier transform to get the Havelock-Lunde formula of the double integral. Thin ship theory is adopted to determine the wave pattern behind a

**Wigley****hull**...
Abstract

ABSTRACT The wave resistance of a ship is determined using a dissipative potential flow model and a modified transverse cut techniques. The problem is modelled using Kelvin sources with a translating speed. Rayleigh damping is introduced in the model to represent a damping effect. A dissipative 3D Green function is derived where the Laplace equation, free surface condition and the radiation condition are transformed using a Fourier transform to get the Havelock-Lunde formula of the double integral. Thin ship theory is adopted to determine the wave pattern behind a Wigley hull. To evaluate the method and determine the wave resistance and a new and modified form of the Eggers transverse cut technique is used.

Proceedings Papers

Paper presented at the The Twenty-third International Offshore and Polar Engineering Conference, June 30–July 5, 2013

Paper Number: ISOPE-I-13-604

... influence the performance of ships in waves. turnock intensity offshore condition hull reference case ship boundary layer variation resistance propeller disc propeller turbulence intensity amplitude

**wigley****hull**bow shape propeller plane oscillation turbulence different bow section...
Abstract

ABSTRACT This paper addresses the prediction of ship performance in waves by means of RANS-based CFD. Lately, much attention has been given to modelling the complex geometry (moving hull and rotating propeller) which can sometimes distort or suppress the importance of the underlying physics. The approach here is to subject a fixed hull to waves and study how the flow around the hull is affected and what this means for the inflow to the propeller and the resulting propulsive performance of the ship. This study provides a straightforward approach for gaining insight into how hull design can influence the performance of ships in waves.

Proceedings Papers

Paper presented at the The Twenty-third International Offshore and Polar Engineering Conference, June 30–July 5, 2013

Paper Number: ISOPE-I-13-486

... ABSTRACT A higher-order BEM (boundary element method) for seakeeping problems in the frame of linear potential theory is newly developed to predict radiation forces of a modified

**Wigley****hull**with forward speed. In this 3-D time domain approach, a rectangular computational domain moving...
Abstract

ABSTRACT A higher-order BEM (boundary element method) for seakeeping problems in the frame of linear potential theory is newly developed to predict radiation forces of a modified Wigley hull with forward speed. In this 3-D time domain approach, a rectangular computational domain moving with the same forward speed as a ship is introduced. For time-saving, only half computational domain is adopted due to the geometric symmetry of a ship. An artificial damping beach is installed at an outer portion of the free surface except the downstream side for satisfying the radiation condition. The velocity potential on the ship hull and the normal velocity on the free surface are obtained directly by solving the boundary integral equation, with the Rankine source used as the kernel function. The unsteady waves generated by a modified Wigley hull with forward speed are calculated. The forced oscillation tests in heave and pitch motions in a towing tank are also carried out. Then numerical results are compared with corresponding experimental data and other numerical solutions. Finally, the results are analyzed and discussed.

Proceedings Papers

Paper presented at the The Twenty-second International Offshore and Polar Engineering Conference, June 17–22, 2012

Paper Number: ISOPE-I-12-418

.... Thus the boundary integral equation is solved at each time stepping. After validat- ing the convergence with respect to time step and mesh size, the problem for computing the steady waves generated by the

**Wigley****hull**is consid- ered as an initial-value problem, increasing the ship s speed from a state...
Abstract

ABSTRACT: A 3-D time-domain numerical wave tank using a higher-order boundary element method is newly developed in the framework of linear potential theory, and ship waves generated by the standard Wigley model advancing at constant forward speed in otherwise calm water and the resultant steady wave resistance are computed as verification of the computer code developed. A rectangular computational domain moving with the same forward speed as the ship is introduced, in which an artificial damping beach is installed at an outer portion of the free surface except the downstream side for satisfying the radiation condition. The velocity potential on the ship hull and the normal velocity on the free surface are obtained directly by solving the boundary integral equation, with the Rankine source used as the kernel function. For numerical stability and accuracy, an iterative time-marching scheme is employed for updating both kinematic and dynamic free surface boundary conditions. Thus the boundary integral equation is solved at each time stepping. After validating the convergence with respect to time step and mesh size, the problem for computing the steady waves generated by the Wigley hull is considered as an initial-value problem, increasing the ship's speed from a state of rest up to a specified constant value. Computed results of the wave pattern and wave resistance are illustrated and compared with experimental measurements, showing satisfactory agreement. INTRODUCTION The prediction of the wave resistance and ship motions is one of the classic research topics in ship hydrodynamics. Nowadays, the work based on CFD techniques becomes popular benefiting from rapid evolution of the computer capability, such as, Zhang and Chwang (1999), Hu et al. (2005) and so forth. More invaluable references have been reported at proceedings of CFD workshop Tokyo, International conference on numerical ship hydrodynamics, ITTC and so forth.

Proceedings Papers

Paper presented at the The Eighteenth International Offshore and Polar Engineering Conference, July 6–11, 2008

Paper Number: ISOPE-I-08-205

...) and FNPT models (fully nonlinear potential model), may be used tosimulate the body-wave interaction problem procedure fnpt model mesh free surface simulation

**wigley****hull**upstream oil & gas single hull artificial intelligence incident angle tanizawa hull force difference node...
Abstract

ABSTRACT This paper presents some results about the responses of two moored 3D floating structures to steep waves obtained by using the QALE-FEM (quasi arbitrary Lagrangian-Eulerian finite element) method based on FNPT (fully nonlinear potential theory) models. In this method, the computational mesh is efficiently moved at every time step to conform to the variation of the fluid domain, eliminating the necessity of very costly procedure of regenerating mesh which is required by the conventional FEM method. By using this method, various cases with two moored 3D floating structures in steep waves are numerically simulated and the nonlinearity involved is investigated. INTRODUCTION The development of the oil/gas industry results in increasing uses of floating structures, such as LNG/LPG carriers. They are often moored near another one (for instance, a vessel is moored near a floating platform during offloading) and are often exposed to extremely steep waves. In such cases, the responses of the floating structures may be dramatically affected by each other. In addition, both structures undergo a motion with 6 degrees of freedom (DoFs) even when they are in head seas. Therefore, the nonlinear responses of two floating structures to steep waves needs to be carefully investigated for the purpose of optimizing the design/operation of the structures and avoiding the risk from the waves. Because of the strong nonlinear factors involved in this problem, the linear or higher order analytical solutions may be insufficient for the accuracy demands of offshore engineering and so a fully nonlinear model may be necessary (Beck & Read, 2000). Two types of fully nonlinear models, i.e. NS model (governed by the Navier-Stokes and the continuity equations together with proper boundary conditions) and FNPT models (fully nonlinear potential model), may be used tosimulate the body-wave interaction problem

Proceedings Papers

Paper presented at the The Eighteenth International Offshore and Polar Engineering Conference, July 6–11, 2008

Paper Number: ISOPE-I-08-084

... transportation fr 0 ship length free surface froude number 0 wave elevation hydrofoil craft experimental measurement

**wigley****hull**real craft experiment gliding-hydrofoil craft experiment gliding-hydrofoil craft craft experiment high-speed craft Experiment and Numerical Study on Gliding-hydrofoil...
Abstract

ABSTRACT In this paper, a new type of high-speed craft with better performance Gliding-Hydrofoil Craft (GHC) has recently been developed in Jiangsu University of Science and Technology, China. Then a fiberglass gliding-hydrofoil craft is designed and built. Experiment method is chosen to study the rapidity of GHC. The experiment measurements show the rapidity of gliding-hydrofoil craft is improved. Meanwhile, one case of GHC is run with software FLUENT, the results show this software is fit for studying the hydrodynamics of surface ship. INTRODUCTION With the development of marine transport, greater number of high-speed craft are being designed and operated widely. There are many applications for high-speed craft, such as the increasing requirement for high-speed craft from the maritime transport and offshore industry, because of the high speed and low cost of these types of vessels. Particularly in deeper seas where large-scale helicopter operations become expensive, high speed craft are more advantageous. In addition, the military's requirement for high-speed craft is also increasing. In many cases, military crafts need to run at high speed to fulfill their mission even in bad sea conditions. Therefore, development of a highspeed craft for a seaway is a new challenge that is being demanded from the naval architects of today. This requires further research and investigation of various high-speed vessels. There are a wide variety of high-speed vessels in use, such as hydrofoil-supported vessels and submerged hull-supported vessels (e.g. planing craft, as shown in Fig.1.1.b). A planing hull craft is a high powered water-craft and is typically a submerged hull-supported vessel. Theoretical research on steady planing dates back to the early of 1930's. Compared with traditional displacement type vessels, planing crafts are more complicated. So, planing problems have been approximately solved by applying the basic assumption of zero-gravity, zero-viscosity and zero-compressibility.

Proceedings Papers

Paper presented at the The Eighteenth International Offshore and Polar Engineering Conference, July 6–11, 2008

Paper Number: ISOPE-I-08-343

... of hull form during optimization cycles. For purposes of illustration, the classical

**Wigley****hull**is taken as an initial hull and the hydrodynamic optimization tool is used to determine the optimal hull forms for three design speeds and for a given speed range with displacement constraint. INTRODUCTION...
Abstract

ABSTRACT This paper presents a practical hydrodynamic optimization tool for the design of a monohull ship. The main components of this tool consists of a practical design-oriented CFD tool, a NURBS representation for the hull surface, and a gradient-based optimization procedure. The CFD tool, which is used to evaluate the steady flow about a ship, is based on a new theory, called Neumann- Michell (NM) theory. The wave drag predicted by the NM theory is in fairly good agreement with experimental measurements. The hull surface is represented by NURBS, which allows for the large variation of hull form during optimization cycles. For purposes of illustration, the classical Wigley hull is taken as an initial hull and the hydrodynamic optimization tool is used to determine the optimal hull forms for three design speeds and for a given speed range with displacement constraint. INTRODUCTION Hydrodynamic optimization is an important aspect of ship design. For the development of new ships it has become increasingly important to both model hull forms accurately and evaluate hydrodynamic performance efficiently during the early stage of the design process. Today, computational methods in the fields of geometric modeling and fluid dynamics simulation are applied in determining a ship''s geometry and predicting its hydrodynamic performance. However, both Computer Aided Ship Hull Design (CASHD) and Computational Fluid Dynamics (CFD) are still mostly utilized consecutively, i.e., one after the other and without direct feedback. Usually, the hull''s geometry is modeled in a highly iterative process consuming a considerable amount of resources, i.e., time and labor, to meet all design criteria. Then, the geometry is passed on to the numerical flow field analysis using CFD tool. On the basis of the numerical results, the geometry is changed, often intuitively, by interactive modification. This approach does not generate an optimum hull form automatically.

Proceedings Papers

Paper presented at the The Seventeenth International Offshore and Polar Engineering Conference, July 1–6, 2007

Paper Number: ISOPE-I-07-290

...

**wigley****hull**theoretical prediction optimization calculation method slender-ship approximation experimental measurement series 60 simple free-surface green function exp expression yang practical method sinkage prediction A Practical Method for Predicting Sinkage and Trim Chi Yang 1...
Abstract

A practical method for computing the sinkage and trim experienced by a ship that advances at constant speed through calm water of large depth and lateral extent is considered. This method is based on a slender-ship approximation that defines the flow about a ship explicitly in terms of the ship speed and hull shape. Thus, the method is particularly simple, robust, and efficient. In spite of its simplicity, the method yields predictions of sinkage and trim in reasonable agreement with experimental measurements. INTRODUCTION The sinkage and trim experienced by a ship that advances at constant speed through calm water of large depth and lateral extent is considered. A large number of well-established alternative methods for computing steady free-surface flow about a ship have been developed. These methods include semi-analytical theories based on various approximations (thin-ship, slender-ship, 2D+t theories), potential-flow panel (boundary integral equation) methods that rely on the use of a Green function (elementary Rankine source, or Havelock source that satisfies the radiation condition and the Michell linearized free-surface boundary condition), and CFD methods that solve the Euler or RANS equations. These alternative calculation methods are reported in a huge body of literature, not reviewed here. Every one of these alternative calculation methods can be used to predict the sinkage and trim experienced by a ship; e.g. Subramani et al. (2000), Yang and Löhner (2002). Many practical applications require very quick assessment of numerous alternative designs, as is typically considered during preliminary and early design stages. For such practical applications, and for hydrodynamic hull-form optimization, a simple approximate calculation method that is easy and fast to implement, very robust, and highly efficient is useful, if not necessary. Such a method is presented in this study. The method is based on the slender-ship flow approximation and the simple free-surface Green function given in Noblesse (1983) and Yang et al. (2004).

Proceedings Papers

Paper presented at the The Fifteenth International Offshore and Polar Engineering Conference, June 19–24, 2005

Paper Number: ISOPE-I-05-454

... results obtained by a commercial software called WAMIT are used as the benchmarks. It is found that BEM can give the same result as analytical solution. Reasonable agreement is also found between our CIP results and analytical result. Numerical Wave Tank with a

**Wigley****hull**The second example...
Abstract

ABSTRACT A three-dimensional CIP (Constrained Interpolation Profile) method for highly nonlinear wave-body interaction problems is presented. In the current numerical model, the wave-body interaction problem is treated as a multiphase problem, which includes a liquid phase (water), a gas phase (air) and a solid phase (floating body). A CIP based finite difference calculations are carried out in a regular computation domain with a Cartesian grid system. The free surface is captured by CIP method with a sharpness enhancement technique. The solid body is represented by distribution of virtual particles on the surface. A couple of three-dimensional numerical simulations are carried out to validate the proposed 3-D numerical model. INTRODUCTION The goal of the current research is to develop a numerical simulation method for quantitatively prediction of local and global wave loads for highly nonlinear sea-keeping problems, such as slamming, water on deck, wave impact by green water, and capsizing. These problems are beyond the capability of traditional potential flow theory based BEM method. A CFD method that based on the solution of the full Navier- Stokes equation is necessary. A popular way for CFD simulation of a floating body in waves is to perform numerical solution inside the water domain and let the free surface and the body surface as domain boundaries that need to be determined. In the case a curvilinear grid or an unstructured grid that is adapted to these boundaries should be used. For a highly nonlinear problem that contains complicated deformation of free surface or violent motion of floating body, the difficulty of the grid generation may make numerical calculation too expensive or even impossible. Therefore in our numerical model we use a different approach to challenge such highly nonlinear problem.

Proceedings Papers

Paper presented at the The Fifteenth International Offshore and Polar Engineering Conference, June 19–24, 2005

Paper Number: ISOPE-I-05-253

...: ship bow wave, bow-wave height, bow-wave location, bow-wave steepness, wedge-like hulls,

**Wigley****hull**, series 60 hull INTRODUCTION The bow wave generated by a wedge-like hull advancing at constant speed U in calm water has been considered in Ogilvie (1972), Stand- ing (1974), Waniewski et al. (2002...
Abstract

ABSTRACT Elementary theoretical considerations (based on dimensional analysis, the shallow-draft and deep-draft limits, and thin-ship theory) and bowwave measurements for 6 wedge-like hull forms by Ogilvie (1972), Standing (1974), Waniewski et al. (2002) and Karion et al. (2003) show that the location Xb (distance from ship bow) and height Zb of the bow wave of a wedge-like hull advancing at speed U. Here, g is the acceleration of gravity, T is the ship draft, and αE is the half-angle of entrance at the waterline. These simple expressions also provide useful approximations of the bow-wave location Xb and height Zb for the Wigley model and the Series 60 model. INTRODUCTION The bow wave generated by a wedge-like hull advancing at constant speed U in calm water has been considered in Ogilvie (1972), Standing (1974), Waniewski et al. (2002) and Karion et al. (2003), where experimental measurements are reported for six wedge-like hulls. The measurements of bow-wave height and location reported in these four studies are analyzed here. OTHER HULL FORMS The wave-profile measurements reported in McCarthy (1985) for the parabolic Wigley hull and the Series 60 (Cb=0.6) model are now considered. These wave-profile measurements were performed within a Cooperative Experiment Program under the Resistance Committee of the International Towing Tank Conference. Only measurements for the Wigley and Series 60 models held in fixed position (no sinkage or trim permitted) are considered here. Two sets of measurements, reported by the Ship Research Institute and the University of Tokyo, are available for the Wigley hull. For the series 60 hull, measurements have been reported by Akishima Laboratories (Mitsui Zosen), the Hyundai Maritime Research Institute, the Korea Institute of Machinery and Metals, Seoul National University, and the University of Tokyo.

Proceedings Papers

Paper presented at the The Fourteenth International Offshore and Polar Engineering Conference, May 23–28, 2004

Paper Number: ISOPE-I-04-300

... flow around a circular cylinder submerged in an infinite fluid and the three-dimensional steady flow around a

**Wigley****hull**travelling in an initially undisturbed free surface. INTRODUCTION The physical processes that describe the behaviour of a ship in a seaway are extremely complex yet have...
Abstract

ABSTRACT A general time-domain method is introduced that is capable of solving both steady and unsteady fluid flow around realistic hull forms. An indirect boundary-integral method is formulated by distributing Rankine point sources outside the fluid domain. The resulting initialboundary value problem is solved by employing the Euler-Lagrange approach to evaluate the unknown velocity field at a series of time steps. Individual nodes on the free surface are tracked by time-stepping the free surface boundary conditions. By way of example, the present method is applied to solve the two-dimensional flow around a circular cylinder submerged in an infinite fluid and the three-dimensional steady flow around a Wigley hull travelling in an initially undisturbed free surface. INTRODUCTION The physical processes that describe the behaviour of a ship in a seaway are extremely complex yet have to be predicted as accurately as possible to meet specific design criteria. In practice, the performance of a ship is investigated separately in still water and in waves. The former addresses the power requirement of a ship in calm water, which provides a lower limit to the total required power in an irregular seaway. Traditionally, hydrodynamic analyses of ships are carried out in towing tanks on scaled models, which is an expensive and time consuming procedure. Advances in computing technology in recent years indicate that a numerical towing tank simulation on a standalone workstation might be possible in the near future. Several commercial codes are currently available (Huang and Sclavounos 1998; Raven, 1996) that are capable of solving the three-dimensional nonlinear wave resistance and/or seakeeping problem. However, due to the complexity of the physical problem, these are either as expensive as traditional model tests (with regard to high computational time) or limited to simulation of a certain type of vessel often at a particular speed range.

Proceedings Papers

Paper presented at the The Fourteenth International Offshore and Polar Engineering Conference, May 23–28, 2004

Paper Number: ISOPE-I-04-407

... remains in estimating the overall motion of the ship in waves. equation journee calculation artificial intelligence newman singularity kd 0

**wigley****hull**wave contour forward speed reservoir characterization velocity potential ship free surface elevation boundary condition upstream...
Abstract

ABSTRACT This paper deals with the numerical calculations of free surface flow around a ship moving in calm water as well as in waves. The hydrodynamic problem of a surface ship advancing in waves at constant forward speed is analyzed using 3-D sink-source method. The body boundary condition is linearised about the undisturbed position of the body and the free surface condition is linearised about the mean water surface. The potential is represented by a distribution of sources over the surface of the ship and its waterline. The problem is solved by the method of singularities distributed over the hull surface. Hess & Smith (1964) method is used to obtain the density of these singularities. The hull is represented by plane polygonal elements. Numerical solution of the surface ship case is approximately obtained by considering each of these elements as a constant singularity. Potential of any particular point in the free surface around the moving hull is determined by using the 3-D Green function with forward speed which satisfies the boundary conditions for a pulsating source in the fluid. Typical contours of wave patterns around moving surface ships are calculated from the velocity potential. Finally added mass and damping coefficients for heave and pitch with forward speed at =0.2 n F are calculated and compared with the published experimental and numerical results. These will be helpful for the accurate estimation method of relative wave height of a sea going ship and wave breaking load on the deck. INTRODUCTION The wave-induced motions of a ship have several implications for ship performance, increased resistance, deck wetness, slamming, vertical acceleration and propeller emergence, etc. while all of these aspects are important subjects in ship hydrodynamics, the fundamental problem remains in estimating the overall motion of the ship in waves.

Proceedings Papers

Paper presented at the The Twelfth International Offshore and Polar Engineering Conference, May 26–31, 2002

Paper Number: ISOPE-I-02-303

... on a level set method, one of the interface capturing methods. grid viscous flow computation diffraction mode reservoir simulation flux incident wave resistance equation time history ship motion free surface

**wigley****hull**ship run unstructured grid method discrepancy Proceedings...
Abstract

ABSTRACT This paper presents viscous flow simulation around a Wigley ship running in incident waves. One of the authors has been developing a CFD code SURF, which solves the Navier-Stokes equations in unstructured grid system with pseudocompressibility assumption. In the present work, we modify the code to compute the flows around ship running in the incident waves. Also in order to treat ship motions, we introduce moving grid system into SURF. One of advantages to solve viscous flows of incident wave problem is to evaluate viscous flow field around propeller. Then numerical results and discussions are done. INTRODUCTION In order to evaluate propulsive performance of ships in actual seas, an estimation of flows around a ship running in incident waves is required. Although many works related to the problems have been carried out, they are mostly based on a potential flow theory, for instance see [1],[2], therefore one cannot estimate viscous flow field, which is essential for the prediction of the propulsive performance. So far, the researches on the propulsive performance have been carried out mainly through the experiment [3],[4], they show that when the ship is running in waves, the mean velocity coming into the propeller plane increases comparing with that the ship runs in still water. This fact is very interesting to consider the propulsive performance in waves and in this sense, we can recognize that the evaluation of the viscous flows around ship in waves is important. One of the authors has been developing a CFD code SURF [5], [6], which solves the Navier-Stokes equations in unstructured grid system with pseudo-compressibility assumption, because an unstructured grid method has great advantage to solve flows around a complex form. In SURF, expression of the free surface is based on a level set method, one of the interface capturing methods.

Proceedings Papers

Paper presented at the The Ninth International Offshore and Polar Engineering Conference, May 30–June 4, 1999

Paper Number: ISOPE-I-99-316

... of the forward speed into the three-dimensional technique by using the simplified linearized tree surface condition(Salvesen, et. al., 1970). calculation steady flow effect fn 0 long wave surge motion green function pitch motion unsteady flow three-dimensional technique formula 2

**wigley****hull**...
Abstract

ABSTRACT: A three-dimensional method for predicting the motions of a ship running in waves is presented. Basically the method developed here is based on the source distribution technique and the general formulations include the effect of steady flow and unsteady flow. Three algorithms are used for treating the corresponding Green functions and derivatives, i.e. The Hess & Smith algorithm for the part of simple source l/r. The complex plane contour integral of Shen & Farell algorithm for the Double integral of steady flow. The series expansions of Telste & Noblesse algorithm for the Cauchy principal value integral of unsteady flow. The steady flow potential is especially considered in the calculations of diffraction and radiation problems, and the effects on ship motions are discussed. INTRODUCTION In the past years, the methods of solving the seakeeping problems for a ship advancing in waves have been well developed, either by two-dimensional technique or three-dimensional technique. The strip theory., has been recognized as the most practical tool for predicting ship motions and early used by Korvin-Kroukovsky(1955) to investigate the heaving and pitching motions of a ship in head seas. A number of approaches for the strip theory were also made by many authors, e.g. Ogilvie and Tuck(1969), Salvesen et. al.(1970) and Kim et al.(1980). Although the stripwise computation technique can offer significant valuable contributions to ship motion analysis, there are still some problems cannot be treated well by the strip theory. Therefore sometimes the three-dimensional theory must be used. Chang(1977) firstly published a three-dimensional method to calculate the ship motion with speed effect in frequency domain. Inglis and Price(1981 a, 1981 b) also considered the effect of the forward speed into the three-dimensional technique by using the simplified linearized tree surface condition(Salvesen, et. al., 1970).

Proceedings Papers

Paper presented at the The Eighth International Offshore and Polar Engineering Conference, May 24–29, 1998

Paper Number: ISOPE-I-98-274

... using entirely different methods: Rankine singularity method and Kelvin-Havelock singularity method. ship frequency series 60

**wigley****hull**steady flow effect unsteady flow panel distribution inglis ship research steady term boundary condition fn 0 exciting force steady flow...
Abstract

ABSTRACT The paper presents a three-dimensional solution for the exciting forces and moments on a ship in waves. Basically the general formulations are based on the source distribution technique, by which the ship hull surface is regarded as the assembly of many panels. With the simplified free surface condition, the influence of ship speed on the hydrodynamic forces is then considered through its modifications of the pressure calculation, body boundary condition and additional contour integral along the interaction of hull surface and the free surface. Three algorithms for treating the corresponding Green functions are used, i.e. (1) The Hess & Smith algorithm for the part of simple source l/r. (2) The complex plane contour integral of Shen & Farell's algorithm for the Double integral of steady flow. (3) The series expansions of Telste & Noblesse's algorithm for the part of Cauchy principal value integral of unsteady flow. The present study reveals that the effect of steady flow is generally small, but it still cannot be neglected in some cases especially for the ship in oblique waves. It is also found that the suitable selection for the body mesh distribution is important by using the present technique. INTRODUCTION The two-dimensional theoretical methods, either the ordinary strip theory or the modified strip theory, have been applied to predict the ship motion in waves for many years. Some authors have offered remarkable contributions in the corresponding respects, e.g. KorvinKroukovsky(1955), Salvesen et. al.(1970) and Kim et al.(1980). Recently, because of the amazing development of the high efficient computer, the three-dimensional theory can then be applied to analyze the corresponding hydrodynamic problems. Two classes of linearized theories conventionally have been solved using entirely different methods: Rankine singularity method and Kelvin-Havelock singularity method.