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

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 1, Parts A and B ◽

Application of Direct Boundary Element Method to Three Dimensional Hydrodynamic Analysis of Interaction Between Waves and Floating Offshore Structures

10.1115/omae2004-51429 ◽

2004 ◽

Author(s):

Saeid Kazemi ◽

Atilla Incecik

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Three Dimensional ◽

Offshore Structures ◽

Sea Waves ◽

Offshore Structure ◽

Hydrodynamic Analysis ◽

Hydrodynamic Behaviour ◽

A three-dimensional hydrodynamic analysis of interaction between a floating offshore structure and sea waves has been carried out using a novel approach which is based on the weighted residual technique and the direct boundary element method. The main advantage of the 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 BEM can easily be coupled with other numerical methods, e.g. finite element method (FEM) in order to carry out structural analysis of deck of the platform due to impact. Firstly, the boundary value problem of three-dimensional interaction between regular sea waves and a semi-submersible will be described. Secondly, the direct boundary element method has been applied to predict hydrodynamic behaviour of Khazar Semi-Submersible Drilling Unit (KSSDU), which is the largest semi-submersible drilling platform under construction for a location in the Caspian Sea, North of Iran. The rigid body motion responses in six degrees of freedom of KHAZAR semi-submersible in response to encountering waves have been calculated by using the direct boundary element method. The results obtained from the direct BEM will be compared with those obtained by the results based on the conventional boundary element method (indirect BEM) which were obtained by the designers of KHAZAR semi-submersible.

Some improvements of accuracy and efficiency in three dimensional direct boundary element method

International Journal for Numerical Methods in Engineering ◽

10.1002/nme.1620330706 ◽

1992 ◽

Vol 33 (7) ◽

pp. 1451-1464 ◽

Cited By ~ 12

Author(s):

Yin-Sheng Li ◽

Tatsuo Obata ◽

Hideo Koguchi ◽

Toshio Yada

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Three Dimensional ◽

An improved direct boundary element method for substrate coupling resistance extraction

Proceedings of the 15th ACM Great Lakes symposium on VLSI - GLSVSLI '05 ◽

10.1145/1057661.1057683 ◽

2005 ◽

Cited By ~ 1

Author(s):

Xiren Wang ◽

Wenjian Yu ◽

Zeyi Wang ◽

Xianlong Hong

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Substrate Coupling ◽

Coupling Resistance ◽

Volume 2: Prof. Carl Martin Larsen and Dr. Owen Oakley Honoring Symposia on CFD and VIV ◽

Validation Study of Smoothed Particle Hydrodynamics in Fluid and Structure Interaction and the Comparison to Boundary Element Method

10.1115/omae2017-62285 ◽

2017 ◽

Author(s):

Nhu Nguyen ◽

Krish P. Thiagarajan ◽

Matthew Cameron

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Smoothed Particle Hydrodynamics ◽

Computational Time ◽

Floating Structure ◽

Structure Interaction ◽

Advantages And Disadvantages ◽

Particle Hydrodynamics ◽

Smoothed Particle ◽

The purpose of this research is to validate the usage of Smoothed Particle Hydrodynamics (SPH) method in solving fluid-structure interaction problems as well as study its advantages and disadvantages compared to another well-known technique Boundary Element Method (BEM). The goal is achieved by 1) evaluating the Response Amplitude Operator (RAO) and 2) analyzing the drifting motion of a 1:10 scaled 3m-discus oceanographic buoy developed by the National Oceanographic and Atmospheric Administration (NOAA), using both experimental and numerical approaches. For the experimental study, the testing was carried out in an 8-m long wave tank and the buoy motions were measured using non-intrusive techniques. For numerical analysis, the project used DualSPHysics — open source code — and ANSYS AQWA — one of the leading software widely used in the marine applications — to simulate all the experimental scenarios via SPH and BEM techniques respectively. It is observed that while BEM has clear advantages in computational time and the ability to study applicable range of frequencies, SPH, in addition to its capability to simulate drifting motion of the floating structure, has shown to outperform the RAO predictions from BEM (especially in low frequency region). In higher frequency regions, the lack of experimental data hinders the conclusion on which method might be more suitable, as both have their own limitations.

Analysis of Scattered Waves on Ground with Irregular Topography Using the Direct Boundary Element Method and Neumann Series Expansion

Bulletin of the Seismological Society of America ◽

10.1785/0120060178 ◽

2007 ◽

Vol 97 (4) ◽

pp. 1144-1157 ◽

Cited By ~ 11

Author(s):

H. Mogi ◽

H. Kawakami

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Series Expansion ◽

Neumann Series ◽

Neumann Series Expansion ◽

Irregular Topography ◽

Study on Numerical Methods for Acoustic Radiation of Open Structure

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.439-440.692 ◽

2010 ◽

Vol 439-440 ◽

pp. 692-697

Author(s):

Li Jun Li ◽

Xian Yue Gang ◽

Hong Yan Li ◽

Shan Chai ◽

Ying Zi Xu

Keyword(s):

Boundary Element Method ◽

Numerical Methods ◽

Boundary Element ◽

Acoustic Radiation ◽

Coupling Method ◽

Open Structure ◽

Acoustic Coupling ◽

Infinite Element Method ◽

For acoustic radiation of open thin-walled structure, it was difficult to analyze directly by analytical method. The problem could be solved by several numerical methods. This paper had studied the basic theory of the numerical methods as FEM (Finite Element Method), BEM (Boundary Element Method) and IFEM (Infinite Element Method), and the numerical methods to solve open structure radiation problem. Under the premise of structure-acoustic coupling, this paper analyzed the theory and flow of the methods on acoustic radiation of open structure, including IBEM (Indirect Boundary Element Method), DBEM (Direct Boundary Element Method) coupling method of interior field and exterior field, FEM and BEM coupling method, FEM and IFEM coupling method. This paper took the open structure as practical example, and applied the several methods to analyze it, and analyzed and compared the several results to get relevant conclusions.