Hydroelastic Response of a Matlike Floating Circular Plate Advancing in Waves

The boundary value problem is formulated to predict the hydroelastic response of a matlike floating circular plate advancing slowly in waves. The plate is idealized as an elastic plate with zero draught, and the potential flow theory is employed with low forward-speed assumptions. These assumptions allow the steady disturbance potential due to forward speed to be neglected, simplifying the problem considerably. By applying the eigenfunction-expansion domain-matching method, analytical solutions are derived for the scattering and radiation potentials up to the leading-order terms of the speed-dependent parts. The far-field approach is adopted to obtain the expression for the wave drift force. Numerical results are also presented for the typical plate geometry, which demonstrates the significant effect of the forward speed on the hydroelastic response and wave drift force.

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Hydroelastic Response of a Mat-Like Floating Circular Plate Advancing in Waves: Analytical Solution

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 3 ◽

10.1115/omae2004-51152 ◽

2004 ◽

Author(s):

Tetsuya Matsui

Keyword(s):

Circular Plate ◽

Strain Response ◽

Forward Speed ◽

Leading Order ◽

Matching Method ◽

Bending Strain ◽

Speed Effect ◽

Hydroelastic Response ◽

Plate Geometry ◽

Scattering And Radiation

The boundary-value problem is formulated to predict the hydroelastic response of a mat-like floating circular plate advancing slowly in waves. The potential flow theory is employed with low forward-speed assumption. The plate is modeled as an elastic plate with zero draught. This assumption allows the steady disturbance potential due to forward speed be neglected, simplifying considerably the problem. By applying the eigenfunction-expansion domain-matching method analytical solutions are derived for the scattering and radiation potentials up to the leading-order terms of the speed-dependent parts. Numerical results are presented for the typical plate geometry. It is shown that the forward-speed effect on the hydroelastic response, especially on the bending strain response, of the plate is significant.

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Response of the Mega-Float Equipped With Novel Wave Energy Absorber

Volume 1: Offshore Technology; Ocean Space Utilization ◽

10.1115/omae2003-37170 ◽

2003 ◽

Cited By ~ 2

Author(s):

Sotaro Masanobu ◽

Shunji Kato ◽

Katsuya Maeda ◽

Yasuhiro Namba

Keyword(s):

Wave Energy ◽

Structural Design ◽

Estimation Method ◽

The Novel ◽

Additional Structure ◽

Energy Absorber ◽

General Wave ◽

Wave Drift ◽

Drift Force ◽

Hydroelastic Response

The hydroelastic response is significant from the viewpoint of the structural design of a Mega-Float. Equipping a Mega-Float with some additional structures, such as vertical plates, is one of the ways to reduce the hydroelastic response easily. However, in general, wave drift force acting on the Mega-Float may be increased, when the Mega-Float is equipped with the additional structures to reduce the response. In the present study, we developed a novel additional structure that was effective in the reduction of both hydroelastic response and wave drift force. Furthermore, we estimated the response of Mega-Float equipped with the additional structures, and compared the result with the value measured in at-sea experiments. As a result, we confirmed both the effectiveness of the novel additional structure and the validity of the estimation method.

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Non-Linear Wave Loads Acting on Obliquely Slowly Advancing Platform

Volume 4: Ocean Engineering; Ocean Renewable Energy; Ocean Space Utilization, Parts A and B ◽

10.1115/omae2009-79627 ◽

2009 ◽

Author(s):

Yasunori Nihei ◽

Sota Sugimoto ◽

Takashi Tsubogo ◽

Weiguang Bao ◽

Takeshi Kinoshita

Keyword(s):

Boundary Value Problems ◽

Potential Theory ◽

Boundary Value ◽

The Body ◽

Linear Wave ◽

Wave Loads ◽

Forward Speed ◽

Wave Drift ◽

Non Linear ◽

Drift Force

It is necessary to evaluate wave drift force for ships advancing obliquely. There are some approaches, for instance the strip method, solving the Navier-Stokes equation directly in the fluid domain (CFD), potential theory and so on. In the present study, the non-linear wave loads acting on the ship with constant oblique forward speed is considered based on the potential theory. Consistent perturbation expansion based on two parameters, i.e. the incident wave slope and the ratio of the forward speed compared to the phase velocity of the waves, is performed on a moving frame (body-fixed) coordinate system to simplify the problem. So obtained boundary value problems for each order of potentials is solved by means of the hybrid method. The fluid domain is divided into two regions by an artificial circular cylinder surrounding the body. The potential in the inner region is expressed by an integral over the boundary surface with a Rankin source as its Green function while it is expressed in the eigen function expansion for the outer region. Consequently, the boundary value problems can be solved efficiently. In the present paper, the authors will discuss the effects of the obliquely advancing on the wave drift force in a diffraction wave field up to the order proportional to the advancing speed. An ellipsoid model is used in the calculation and the wave drift force is evaluated for various Froude number.

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Mean Wave Drift Force on a Barge-Type Floating Wind Turbine With Moonpools

10.1115/omae2021-62241 ◽

2021 ◽

Author(s):

Lei Tan ◽

Tomoki Ikoma ◽

Yasuhiro Aida ◽

Koichi Masuda

Keyword(s):

Wind Turbine ◽

Vertical Axis ◽

Offshore Wind ◽

Hydrodynamic Performance ◽

Vertical Axis Wind Turbine ◽

Rotating Speed ◽

Wave Drift ◽

Floating Offshore Wind Turbines ◽

Drift Force ◽

Gyroscopic Effects

Abstract The barge-type foundation with moonpool(s) is a promising type of platform for floating offshore wind turbines, since the moonpool(s) could improve the hydrodynamic performance at particular frequencies and reduce the costs of construction. In this paper, the horizontal mean drift force and yaw drift moment of a barge-type platform with four moonpools are numerically and experimentally investigated. Physical model tests are carried out in a wave tank, where a 2MW vertical-axis wind turbine is modelled in the 1:100 scale. By varying the rotating speed of the turbine and the mass of the blades, the gyroscopic effects due to turbine rotations on the mean drift forces are experimentally examined. The wave diffraction and radiation code WAMIT is used to carry out numerical analysis of wave drift force and moment. The experimental results indicate that the influence of the rotations of a vertical-axis wind turbine on the sway drift force is generally not very significant. The predictions by WAMIT are in reasonable agreement with the measured data. Numerical results demonstrate that the horizontal mean drift force and yaw drift moment at certain frequencies could be reduced by moonpool(s).

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Identification of wave drift force QTFs for the INO WINDMOOR floating wind turbine based on model test data and comparison with potential flow predictions

Journal of Physics Conference Series ◽

10.1088/1742-6596/2018/1/012017 ◽

2021 ◽

Vol 2018 (1) ◽

pp. 012017

Author(s):

Nuno Fonseca ◽

Maxime Thys ◽

Petter Andreas Berthelsen

Keyword(s):

Wind Turbine ◽

Test Data ◽

Model Test ◽

Potential Flow ◽

Wave Drift ◽

Floating Wind Turbine ◽

Drift Force

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Viscous-flow-based investigation of Cloaking phenomenon among multi-floating bodies and experimental verification

MATEC Web of Conferences ◽

10.1051/matecconf/201927201016 ◽

2019 ◽

Vol 272 ◽

pp. 01016

Author(s):

Z K Wang ◽

G H He ◽

Z G Zhang ◽

Y H Meng

Keyword(s):

Experimental Research ◽

Scattered Wave ◽

Floating Body ◽

Offshore Platforms ◽

Floating Bodies ◽

Cfd Simulations ◽

Wave Drift ◽

Real Coded Genetic Algorithm ◽

Drift Force ◽

Interaction Problem

The safety of mooring systems on offshore platforms seems more and more significant with the utilization of offshore space and resources, so the reduction of wave drift force is the key issue in this wave-body interaction problem. The wave drift force acting on the inner floating body surrounded by multiple small floating bodies can be reduced obviously with the occurrence of a phenomenon, which is called the Cloaking phenomenon. The Cloaking phenomenon refers to the reduction or complete elimination in amplitude of the scattered waves. In this paper, a real-coded genetic algorithm was used to optimize the parameters of outer floating bodies to minimize the scattered wave energy, and then the wave drift force acting on the inner body can be reduced. Furthermore, associated CFD simulations and experimental research were conducted with the above optimized parameters to investigate and verify the Cloaking phenomenon more systemically. It is shown that the wave drift force acting on the inner floating body in the Cloaking configuration can be reduced obviously both in numerical and experimental research, and the reduction of the wave drift force is closely related to the change of wave field around the structure.

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On Approximations of the Wave Drift Forces Acting on Semi-Submersible Platforms With Heave Plates

Volume 1: Offshore Technology; Offshore Geotechnics ◽

10.1115/omae2016-54166 ◽

2016 ◽

Author(s):

Bernard Molin ◽

Jean-Baptiste Lacaze

Keyword(s):

Wave Field ◽

Scattered Wave ◽

Diffraction Radiation ◽

Morison Equation ◽

Wave Drift ◽

Horizontal Wave ◽

Heave Plate ◽

Drift Force ◽

Wave Drift Forces ◽

Drift Forces

The horizontal wave drift force acting on a vertical floating column, without then with a heave plate, is considered. Computations are performed with a diffraction-radiation code and through the Morison and Rainey equations. Focus is on wave frequencies around the heave resonance where the drift force may be significant, even though the scattered wave-field being weak. It is found that the Morison equation overpredicts the drift force while Rainey equations perform rather well.

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