A boundary element method for the hydrodynamic analysis of floating bodies in variable bathymetry regions

In this paper, two different 3D hydrofoils with profiles NACA0012 are simulated in the potential flow. Boundary element method (BEM) and nonuniform rational B-spline (NURBS) are coupled to reduce error and increase accuracy. The computer code is developed in different submergence depths (d), flow velocities (U), and various angles of attack (AoA), and the pressure is obtained by NURBS formulation. The pressure on a 3D hydrofoil with NACA412 profile iscompared with other existing methods. The validity of result is revealed. The accuracy of the results is acceptable. The competition of the two models’ results indicates that the increasing chord length leads to increase in C p min , and the decrease in depth and angle of attack leads to the growing value of C p min . Moreover, when the flow velocity is changed, the changes of potential and pressure coefficient distribution do not follow the specific trend. NURBS is a basic equation in different CAD packages because it is able to mesh surfaces. This study demonstrates that this algorithm does mesh surface of high quality, so it can be developed to generate mesh on the submerged three-dimensional bodies .

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Wave Drift Forces' Calculation on Two Floating Bodies Based on the Boundary Element Method—Attempt for Improvement of the Constant Panel Method

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4042180 ◽

2019 ◽

Vol 141 (4) ◽

Cited By ~ 1

Author(s):

Qiao Li ◽

Yasunori Nihei

Keyword(s):

Boundary Element Method ◽

Boundary Element ◽

Evaluation Method ◽

Panel Method ◽

Floating Bodies ◽

Wave Drift ◽

Wave Drift Forces ◽

Multiple Floating Bodies ◽

Drift Forces ◽

Element Method

An improved constant panel method for more accurate evaluation of wave drift forces and moment is proposed. The boundary element method (BEM) of solving boundary integral equations is used to calculate velocity potentials of floating bodies. The equations are discretized by either the higher-order boundary element method or the constant panel method. Though calculating the velocity potential via the constant panel method is simple, the results are unable to accurately evaluate wave drift forces and moment. An improved constant panel method is introduced to address these issues. The improved constant panel method can, without difficulty, employ the near-field method to evaluate wave drift forces and moment, especially for multiple floating bodies. Results of the new evaluation method will be compared with other evaluation method. Additionally, hydrodynamic interaction between multiple floating bodies will be assessed.

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

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

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 ◽

Direct Boundary Element Method ◽

Element Method

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.

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