scholarly journals Development of a Boundary Element Method-based numerical wave tank technique for the prediction of nonlinear wave kinematics and dynamics around offshore structures

2009 ◽  
Author(s):  
H. G. Sung
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Nonlinear Wave ◽  
Offshore Structures ◽  
Kinematics And Dynamics ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Wave Kinematics ◽  
Numerical Wave ◽  
Element Method

scholarly journals 2-D Numerical Wave Tank by Boundary Element Method Using Different Numerical Techniques

2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Farid Habashi Aliabadi ◽  
Parviz Ghadimi ◽  
Seyed Reza Djeddi ◽  
Abbas Dashtimanesh
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Numerical Wave Tank ◽  
Numerical Techniques ◽  
Wave Tank ◽  
Numerical Wave ◽  
Element Method

Development of 3-D Numerical Wave Tank and Applications on Comb-Type Breakwater

2010 ◽  
Author(s):  
Zhuo Fang ◽  
Liang Cheng ◽  
Ningchuan Zhang
Keyword(s):  
Offshore Structures ◽  
Wave Generation ◽  
Irregular Waves ◽  
Secondary Wave ◽  
Wave Forces ◽  
Numerical Wave Tank ◽  
Wave Reflections ◽  
Wave Tank ◽  
Numerical Wave ◽  
Source Wave

In this study, a 3-D numerical wave tank is developed, based on a commercial computational fluid dynamics (CFD) package (FLUENT) to predict wave forces on coastal and offshore structures. A source wave-generation method is introduced to FLUENT through user-defined functions to generate incident waves. Spongy layers are used on both upstream and downstream sides of the wave tank to reduce the effects of wave reflections and secondary wave reflections. Various wave trains, such as linear monochromatic waves, second order Stokes waves and irregular waves were generated by using different source functions. It is demonstrated through numerical examples that the source wave-generation method can accurately generate not only small amplitude waves but also nonlinear waves. The present numerical wave tank is validated against standing waves in front of a vertical breakwater. Interactions between waves and a comb-type breakwater are simulated using the present model. The numerical results are compared with physical experimental results. It is found that the present numerical wave tank simulated the wave and breakwater interactions well.

scholarly journals Generation of Offshore Environments in the Numerical Wave Tank to Model Metocean Conditions Interaction with Offshore Structure Near the Free Surface

2021 ◽  
Vol 945 (1) ◽  
pp. 012018
Author(s):  
Mushtaq Ahmed ◽  
Zafarullah Nizamani ◽  
Akihiko Nakayama ◽  
Montasir Osman
Keyword(s):  
Free Surface ◽  
Offshore Structures ◽  
Operating Conditions ◽  
Wave Crest ◽  
Extreme Conditions ◽  
Numerical Wave Tank ◽  
Offshore Structure ◽  
Wave Tank ◽  
Numerical Wave ◽  
Operating Wave

Abstract Offshore structures play a vital role in the economy of offshore oil-producing countries, where mostly fixed jacket type structures are used to produce oil and gas installed in shallow water. In an offshore environment where structures are installed, there exist met ocean forces such as wind, waves, and currents. These met ocean conditions when interacting with offshore structures near the free surface, generate loads. The estimation of such loads is very much important for the proper design of these structures. The primary aim of this study is to investigate the interaction of waves with a jacket platform by generating offshore environments in the numerical wave tank (NWT). To achieve this goal, ANSYS Fluent is used for the flow analysis by using continuity and Navier Stokes equation. Results are verified and validated with the analytical work. Wave crests under operating condition generate a force of 1.3 MN which is the lowest in magnitude as compared to wave crest which produces 4.5 MN force under extreme conditions. Unlike operating wave crest, the operating wave trough generates a higher force of 1 MN than extreme conditions which account for 1.5 MN forces. Forces produced by the extreme offshore environment are 30% higher than those generated under operating conditions. It is concluded from the results that a positive force is exerted onto the structure during the water entry phase while a negative force is observed when the water leaves the structure.

scholarly journals A Semi-Infinite Numerical Wave Tank Using Discrete Particle Simulations

2020 ◽  
Vol 8 (3) ◽  
pp. 159 ◽  
Author(s):  
Sangmin Lee ◽  
Jung-Wuk Hong
Keyword(s):  
Wave Height ◽  
Numerical Technique ◽  
Analytical Formula ◽  
Offshore Structures ◽  
Wave Steepness ◽  
Numerical Wave Tank ◽  
Time Step ◽  
Wave Tank ◽  
Wide Range ◽  
Numerical Wave

With an increasing number of offshore structures for marine renewable energy, various experimental and numerical approaches have been performed to investigate the interaction of waves and structures to ensure the safety of the offshore structures. However, it has been very expensive to carry out real-scale large experiments and simulations. In this study, numerical waves with various relative depths and a wide range of wave steepness are precisely simulated by minimizing the wave reflection with a mass-weighted damping zone located at the end of a numerical wave tank (NWT). To achieve computational efficiency, optimal variables including initial spacing of smoothed particles, calculation time step, and damping coefficients are studied, and the numerical results are verified by comparison with both experimental data and analytical formula, in terms of wave height, particle velocities, and wave height-to-stroke ratio. Those results show good agreement for all wave steepness smaller than 0.067. By applying the proposed methodology, it is allowed to use a numerical wave tank of which the length is smaller than that of the wave tank used for experiments. The developed numerical technique can be used for the safety analysis of offshore structures through the simulation of fluid-structure interaction.

Numerical Prediction of Air Gap Response of Floating Offshore Structures Using Direct Boundary Element Method

2005 ◽  
Author(s):  
Saeid Kazemi ◽  
Atilla Incecik
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Offshore Structures ◽  
Air Gap ◽  
Analytical Prediction ◽  
Sea Waves ◽  
Floating Structure ◽  
The Caspian Sea ◽  
Direct Boundary Element Method ◽  
Element Method

The air gap response and potential deck impact of ocean structures under waves is the main topic of this research. In this paper, an analytical prediction of the air gap for floating offshore structures using direct Boundary Element Method (BEM) is presented. The main advantage of direct boundary element method is the fact that one can determine the total velocity potential directly. Direct BEM is more versatile and computationally more efficient than indirect BEM. Besides, the direct BEM can easily be coupled with other numerical methods, e.g. finite element method (FEM) in order to carry out structural analysis of the platform’s deck due to possible impact. Firstly, the direct boundary element method will be reviewed. Secondly, the boundary value problem of interaction between regular sea waves and a semi-submersible and air gap responses due to the motion of the platform and the local wave elevations (including both radiation and diffraction waves) will be described. Then, the direct boundary element method will be applied to predict of the air gap at different field points of ALBORZ semi-submersible drilling unit, which is the largest semi-submersible drilling platform under construction for a location in the Caspian Sea, North of Iran. In addition, the results obtained from the direct BEM will be compared with those obtained by the designers of the ALBORZ semi-submersible. To determine the influence of the structure’s motions on the air gap, the results for both fixed and free-floating structure cases will be compared. Physical simulations using model will be carried out in the future in order to compare the results of the experiments with predictions.

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