Development and Application of Two-Dimensional Numerical Tank using Desingularized Indirect Boundary Integral Equation Method

Oh, Seunghoon; Cho, Seok Kyu; Jung, Dong-Ho; Sung, Hong Gun

doi:10.26748/ksoe.2018.32.6.447

Cited by 5 publications

(3 citation statements)

References 12 publications

(4 reference statements)

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“…Zhou et al [15] compared their results of various motion modes with those reported by Bai and Eatock Taylor [14]. Recently, Oh et al [16] solved the radiation problem for a wave maker by applying the desingularized indirect PNWT. Feng et al [17] solved the linear diffraction and radiation problems for a hemispheric buoy by calculating the integral of the Rankine source on the free surface panel.…”

Section: Introductionmentioning

confidence: 99%

Development of a Three‐Dimensional Fully Nonlinear Potential Numerical Wave Tank for a Heaving Buoy Wave Energy Converter

Kim

Koo

2019

Mathematical Problems in Engineering

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The hydrodynamic performance of a vertical cylindrical heaving buoy-type floating wave energy converter under large-amplitude wave conditions was calculated. For this study, a three-dimensional fully nonlinear potential-flow numerical wave tank (3D-FN-PNWT) was developed. The 3D-FN-PNWT was based on the boundary element method with Rankine panels. Using the mixed Eulerian–Lagrangian (MEL) method for water particle movement, nonlinear waves were produced in the PNWT. The PNWT can calculate the wave forces acting on the buoy accurately using an acceleration potential approach. The constant panels and least-square gradient reconstruction method were applied to regridding of computational boundaries. An artificial damping zone was employed to satisfy the open-sea conditions at the end free surface boundaries. The diffraction and radiation problems were solved, and their solutions were confirmed by a comparison with previous studies. The interaction of the incident wave, floating body, and power take-off (PTO) behavior was examined in the time domain using the developed 3D-FN-PNWT. From comparison, the difference between the conventional linear analysis and the nonlinear analysis in large-amplitude waves was examined.

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Section: Introductionmentioning

confidence: 99%

Development of a Three‐Dimensional Fully Nonlinear Potential Numerical Wave Tank for a Heaving Buoy Wave Energy Converter

Kim

Koo

2019

Mathematical Problems in Engineering

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“…In the three-dimensional NWT, the physical wave tank experiments are numerically simulated through techniques such as the boundary element or finite element methods, which is an analysis technique for nonlinear wave analysis and nonlinear motion analysis. Koo and Kim (2004), Oh et al (2018), and Wu and Eatock Taylor (1995) have conducted analyses using a two-dimensional nonlinear NWT. In particular, Wu and Eatock Taylor (1995) analyzed the radiation problem with a circular cylinder using the boundary element method and finite element method for a two-dimensional nonlinear NWT.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Wave Run-up of a Circular Cylinder with Various Diffraction Parameters and Body Drafts

Jeong

Koo

Kim

2020

J. Ocean Eng. Technol.

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Wave run-up is an important phenomenon that should be considered in ocean structure design. In this study, the wave run-up of a surface-piercing circular cylinder was calculated in the time domain using the three-dimensional linear and fully nonlinear numerical wave tank (NWT) techniques. The NWT was based on the boundary element method and the mixed Eulerian and Lagrangian method. Stokes second-order waves were applied to evaluate the effect of the nonlinear waves on wave run-up, and an artificial damping zone was adopted to reduce the amount of reflected and re-reflected waves from the sidewall of the NWT. Parametric studies were conducted to determine the effect of wavelength, wave steepness, and the draft of the cylinder on the wave run-up of the cylinder. The maximum wave run-up value occurred at 0°, which was in front of the cylinder, and the minimum value occurred near the circumferential angle of 135°. As the diffraction parameter increased, the wave run-up increased up to 1.7 times the wave height. Furthermore, the wave run-up was 4% higher than the linear wave when the wave steepness was 1/35. In particular, the crest height of the wave run-up increased by 8%.

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“…In particular, the MEL method, which is flexible for the analysis of the strong nonlinearity of free surface and wave-body interactions, was applied using various solution methods of the Laplace equation such as boundary element method (BEM), finite element method (FEM), and harmonic polynomial cell (HPC) (Longuet-Higgins and Cokelet, 1976;Wu et al, 1998;Shao and Faltinsen, 2014). Because the mentioned solution method of the Laplace equation inevitably requires matrix operation, the MEL method, which reconstructs the free surface grid every time step to reflect the completely nonlinear free surface, requires high computational costs for calculations of a solution of boundary value problem (Oh et al, 2018). In contrast, the higher-order spectral (HOS) method of Dommermuth and Yue (1987), based on a higher-order analysis method, can determine the solution of the boundary value problem using the fast Fourier transform (FFT) without a matrix operation.…”

Section: Introductionmentioning

confidence: 99%

Higher-order Spectral Method for Regular and Irregular Wave Simulations

Oh¹,

Jung²,

Cho³

2020

J. Ocean Eng. Technol.

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In this study, a nonlinear wave simulation code is developed using a higher-order spectral (HOS) method. The HOS method is very efficient because it can determine the solution of the boundary value problem using fast Fourier transform (FFT) without matrix operation. Based on the HOS order, the vertical velocity of the free surface boundary was estimated and applied to the nonlinear free surface boundary condition. Time integration was carried out using the fourth order Runge-Kutta method, which is known to be stable for nonlinear free-surface problems. Numerical stability against the aliasing effect was guaranteed by using the zero-padding method. In addition to simulating the initial wave field distribution, a nonlinear adjusted region for wave generation and a damping region for wave absorption were introduced for wave generation simulation. To validate the developed simulation code, the adjusted simulation was carried out and its results were compared to the eighth order Stokes theory. Long-time simulations were carried out on the irregular wave field distribution, and nonlinear wave propagation characteristics were observed from the results of the simulations. Nonlinear adjusted and damping regions were introduced to implement a numerical wave tank that successfully generated nonlinear regular waves. According to the variation in the mean wave steepness, irregular wave simulations were carried out in the numerical wave tank. The simulation results indicated an increase in the nonlinear interaction between the wave components, which was numerically verified as the mean wave steepness. The results of this study demonstrate that the HOS method is an accurate and efficient method for predicting the nonlinear interaction between waves, which increases with wave steepness.

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Development and Application of Two-Dimensional Numerical Tank using Desingularized Indirect Boundary Integral Equation Method

Cited by 5 publications

References 12 publications

Development of a Three‐Dimensional Fully Nonlinear Potential Numerical Wave Tank for a Heaving Buoy Wave Energy Converter

Development of a Three‐Dimensional Fully Nonlinear Potential Numerical Wave Tank for a Heaving Buoy Wave Energy Converter

Numerical Study on Wave Run-up of a Circular Cylinder with Various Diffraction Parameters and Body Drafts

Higher-order Spectral Method for Regular and Irregular Wave Simulations

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