• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.29 no.1
• /
• pp.47-53
• /
• 2005

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using NURBS(Non-Uniform Rational B-Spline) surface patches. To verity the validity of the developed program the numerical calculations for Wigley hull and Series 60(C${_B}$=0.6) hull had been performed and the results obtained after the numerical calculations had been compared with the original hulls.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2010.10a
• /
• pp.44-45
• /
• 2010

파랑 중에서 선체의 운동은 선체의 형상과 선속변화에 따라 다양하게 나타나며, 관련연구는 실험적 방법과 수치 해석을 함께 병행하여 지속적으로 진행되고 있다. 파랑조건에 적합한 최적 선형 확보는 선체의 운동응답 결과로 고찰할 수 있다. 파랑 중 선체의 운동응답을 알아보기 위해 초기 선형인 Wigley 선형에 적용하였으며, 수치해의 정도를 선행연구결과와 비교분석하였다. 그리고 서로 다른 모델에 대하여 나타나는 운동응답을 상호 비교하였다. 형상에 따른 Wigley 선형의 선체 운동응답에 대하여 일반화된 선형형상에서 나타날 수 있는 파랑 중 운동응답을 얻을 수 있었다.

• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.2
• /
• pp.39-47
• /
• 1997

In the present paper, viscous flow fields around a wigley hull with appendages are analysed to study interactions between the hull and appendages. Navier-Stokes and continuity equations are solved by a finite volume method in a body-fitted coordinate system which conforms three dimensional ship geometries with appendages. A Sub-Grid Scale(SGS) turbulent model is used for a calculation of high Reynolds number flow. Numerical computations has been done for a Wigley hull form at $Rn=1.0{\times}10^6$. The results show that the present approach can predict, at least in qualitative sense, the influence of the appendages upon the flow field around a ship.

• Journal of Navigation and Port Research
• /
• v.30 no.10 s.116
• /
• pp.869-875
• /
• 2006

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using NURBS(Non-Uniform Rational B-Spline) surface patches. To verity the validity of the developed program the numerical calculations for Wigley hull and Series 60( $C_B=0.6$) hull have been performed and the results obtained by the numerical calculations have been compared with the original hulls.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.3
• /
• pp.87-99
• /
• 1994

Reynolds Averaged Navier-Stokes equations are solved numerically for the computation of turbulent flow around a Wigley double model. A second order finite difference method is applied for the spatial discretization on the nonstaggered grid system and 4-stage Runge-Kutta scheme for the numerical integration in time. In order to increase the time step, residual averaging scheme of Jameson is adopted. Pressure field is obtained by solving the pressure-Poisson equation with the appropriate Neumann boundary condition. For the turbulence closure, 0-equation turbulence model of Baldwin-Lomax is used. Numerical computation is carried out for the Reynolds number of 4.5 million. Comparisons of the computed results with the available experimental data show good agreements for the velocity and pressure distributions.

• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.2
• /
• pp.27-38
• /
• 1997

This paper is concerned with the calculation of the wave resistance for SWATH ships based on a low order Rankine source panel method. Two types of free surface boundary conditions, Dawson type (double model approximation) and Kelvin type (free stream approximation) are used. For the free surface boundary calculation, an analytic differentiation is employed instead of implementing a finite difference scheme. Then, the radiation condition is satisfied by, so called, the panel shift method. The numerical results using the above two methods are compared with those using the thin ship/modified slender body approximation and also with the experimental results. The SWATH models considered are a single strut SWATH and a twin strut SWATH together with the variations of two demihull separation distance. In order to prove the validity of the program developed, the numerical calculations for a Wigley mono hull and Wigley twin hulls are compared with the available experimental results.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.05a
• /
• pp.37-42
• /
• 2003

Fundamental Study for optimizing ship hull form using SQP(sequential quadratic programming) method in a resistance point of view is presented. The Wigley hull is used as an initial hull and numerical calculations are carried out according to various froude numbers. To obtain the ship resistance the wave resistance is evaluated by a Rankine source panel method with nonlinear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of a hull surface is represented and modified by B-spline surface patch. The displacement and the waterplane transverse 2nd moment of inertia of the hull is fixed during the optimization process. And the shp design program called EzHULL is used to draw the lines of the optimized hull form to perform the model test.

• Journal of the Society of Naval Architects of Korea
• /
• v.29 no.3
• /
• pp.71-79
• /
• 1992

In order to obtain the wave-making resistance of a ship, so-called the Neumann-Kelvin problem is solved numerically. For computing the Havelock source, which is the Green's function of the problem, we adopted the methods given by Newman(1987) for the term representing the local disturbance, and Baar and Price(1988) for the wave disturbance, respectively. In the numerical code we developed, the source strength is assumed as bilinear on each panel and continuous throughout the hull surface. The wave-making resistance is calculated using the algorithm of de Sendagorta and erases(1988), which makes use of the wave amplitude far downstream. The Wigley hull was chosen for the sample calculation, and our results showed a good agreement with other existing experimental and numerical results.

• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.4
• /
• pp.61-71
• /
• 1997

Numerical and experimental studies are carried out to analyse the resistance characteristics of a hydrofoil catamaran which is advancing on calm water with uniform speed. For the hydrofoil catamaran with modified Wigley hull which has asymmetric transverse section and transom stem, the studies are carried out for the range of Froude number 0.2 to 1.0 and the angle of attack of the hydrofoil $0.0^{\circ}$ to $3.0^{\circ}$. The model tests are carried out in the ship model basin of Inha University. Also the numerical computations using a finite difference method are performed for the simulations of fluid flow around the hull form and the results are compared with the results of the model tests. The present computation results show well quantitative agreement with the experimental results. The experimental results show that the shape and angle of attack of the foils exerts a considerable influence on the running posture and resistance performance of ship.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.4
• /
• pp.58-65
• /
• 1994

It is very important to understand characteristics of solution due to the variation of computational grid sizes, especially when turbulence model not incorporating wall-function is used. The present paper performs numerical investigation on the grid dependency of numerical solution for three dimensional turbulent flow field around a ship. In the present study a finite volume method with a modified sub-grid scale turbulence model and a numerically constructed non-orthogonal curvilinear coordinate system capable of conforming complex ship geometries are used. Numerical studies are then performed for a mathematical Wigley hull and the Series 60, $C_B=0.8$ hull forms. The results for various grid sizes are compared with each other and with measured data to show grid dependencies of numerical solutions.