Wave diffraction by floating bodies in water of finite depth using an exact DtN boundary condition

2021 ◽  
Vol 239 ◽  
pp. 109711
Author(s):  
Un-Ryong Rim
Keyword(s):  
Boundary Condition ◽  
Wave Diffraction ◽  
Finite Depth ◽  
Floating Bodies

Numerical Simulation of Nonlinear Wave Diffraction by a Vertical Cylinder in a Narrow Flume, Wide Tank, and Infinitely Wide Tank

2003 ◽  
Author(s):  
Alaa M. Mansour ◽  
A. Neil Williams
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Nonlinear Wave ◽  
Wave Diffraction ◽  
Open Boundary ◽  
Computational Domain ◽  
Open Boundary Condition ◽  
Lateral Direction ◽  
Cylinder Diameter ◽  
Side Walls

In this paper, a three dimensional numerical wave tank model has been used to simulate fully nonlinear wave diffraction by a uniform vertical circular cylinder. The cylinder has been placed in a narrow flume of a width equal to four times the cylinder diameter. The runup and the hydrodynamic forces on the cylinder has been compared to the results when a similar cylinder is placed in a similar tank but with a width equal to sixteen times the cylinder diameter. The model has been further extended by applying an open boundary condition to the side-walls to simulate an infinitely wide tank and hence more realistically simulate open sea condition. The proposed open boundary condition in the lateral direction is based on coupling of two prescribed boundary conditions, namely, numerical beach and Orlanski boundary conditions. The use of this coupled boundary condition has been found to be very efficient in eliminating any significant wave reflection from the side-walls back into the computational domain.

scholarly journals Computation of the Diffraction Transfer Matrix and the Radiation Characteristics in the Open-Source BEM Code NEMOH

2016 ◽  
Author(s):  
Francesc Fàbregas Flavià ◽  
Cameron McNatt ◽  
François Rongère ◽  
Aurélien Babarit ◽  
Alain H. Clément
Keyword(s):  
Open Source ◽  
Transfer Matrix ◽  
Body Wave ◽  
Finite Depth ◽  
Interaction Theory ◽  
Floating Bodies ◽  
Radiation Characteristics ◽  
Speed Up ◽  
Multi Body ◽  
Good Agreement

Until now, widely available boundary element method (BEM) codes did not allow the calculation of two non-conventional hydrodynamic operators, which characterize the way a body diffracts and radiates waves, known as Diffraction Transfer Matrix and Radiation Characteristics respectively. When embedded into the finite-depth interaction theory developed by [1], they drastically speed up the computation of the added mass, damping and excitation force coefficients of a group (“farm”) of floating bodies. This paper presents the implementation of their computation in the open source BEM solver NEMOH using the methodology proposed by [2]. Results for two different geometries, a cylinder and a square box, are presented and compared to an alternative computational approach developed by [3]. A very good agreement between them is found. In addition, the hydrodynamic operators of the cylinder are compared to a semi-analytical solution available in the literature showing a good match. Results obtained using the finite-depth interaction theory are shown for a generic multi-body wave energy converter (WEC) demonstrating how the capabilities added to the BEM software NEMOH can facilitate the numerical modeling of the hydrodynamic interactions in large arrays of bodies.

scholarly journals On wave diffraction of two-dimensional moonpools in a two-layer fluid with finite depth

2019 ◽  
Vol 173 ◽  
pp. 571-586 ◽  
Author(s):  
Xin Xu ◽  
Xingyu Song ◽  
Xinshu Zhang ◽  
Zhiming Yuan
Keyword(s):  
Wave Diffraction ◽  
Finite Depth ◽  
Two Dimensional

scholarly journals Application of Adomian Decomposition Method to Bounded and Unbounded Stokes’ Problems

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Chi-Min Liu ◽  
Ray-Yeng Yang
Keyword(s):  
Boundary Condition ◽  
Exact Solution ◽  
Unknown Function ◽  
Decomposition Method ◽  
Adomian Decomposition Method ◽  
Finite Depth ◽  
Adomian Decomposition ◽  
Stokes Problems ◽  
Mathematical Techniques ◽  
Expansion Point

The well-known Stokes’ problems are reexamined by applying the Adomian decomposition method (ADM) associated with other mathematical techniques in this paper. Both the finite-depth (bounded) and infinite-depth (unbounded) cases are analyzed. The present paper raises and deals with two major concerns. The first one is that, for Stokes’ problems, it lacks one boundary condition at the expansion point to fully determine all coefficients of the ADM solution in which an unknown function appears. This unknown function which is dependent on the transformed variable will be determined by the boundary condition at the far end. The second concern is that the derived solution begins to deviate from the exact solution as the spatial variable grows for the unbounded problems. This can be greatly improved by introducing the Padé approximant to satisfy the boundary condition at the far end. For the second problems, the derived ADM solution can be easily separated into the steady-state and the transient parts for a deeper comprehension of the flow. The present result shows an excellent agreement with the exact solution. The ADM is therefore verified to be a reliable mathematical method to analyze Stokes’ problems of finite and infinite depths.

Computation of Wave-Body Interactions Using the Panel-Free Method and Exact Geometry

2006 ◽  
Vol 128 (1) ◽  
pp. 31-38 ◽  
Author(s):  
W. Qiu ◽  
H. Peng ◽  
J. M. Chuang
Keyword(s):  
Integral Equation ◽  
Boundary Integral Equation ◽  
Body Surface ◽  
Analytical Description ◽  
Finite Depth ◽  
Boundary Integral ◽  
The Body ◽  
Floating Bodies ◽  
Wigley Hull ◽  
The Time Domain

A panel-free method was developed earlier to solve the radiation and the diffraction problems of floating bodies in waves in the time domain. This method has been extended to compute wave interactions with bodies in water of infinite depth and finite depth in the frequency domain. After removing the singularities in the boundary integral equation and representing the body surface exactly by either analytical description or NURBS surfaces, the boundary integral equation can be discretized over the exact body surface by Gaussian quadratures. Accuracy of the method is demonstrated by its application to the radiation and the diffraction problems of a floating hemisphere, a vertically floating axisymmetric cylinder, and a Wigley hull. Computed added-mass, damping coefficients, and wave exciting forces agree well with published results.

scholarly journals SHORELINE CHANGE AT OARAI BEACH: PAST, PRESENT AND FUTURE

1984 ◽  
Vol 1 (19) ◽  
pp. 141 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Hans Hanson ◽  
Soichi Harikai
Keyword(s):  
Boundary Condition ◽  
Numerical Simulations ◽  
Wave Diffraction ◽  
Shoreline Change ◽  
Breaking Waves ◽  
Longshore Current ◽  
Current Pattern ◽  
Shoreline Position ◽  
Time Periods ◽  
Intuitive Method

Large breakwaters and groins are being constructed at Oarai Harbor, Japan. As a result the beach is significantly deforming. The first part of this paper documents past and recent shoreline change at Oarai. The general characteristics of the offshore waves, breaking waves, and longshore current pattern are described and used to explain qualitative features of the observed shoreline change. The second part presents results of numerical simulations of shoreline change at the site which occurred over different time periods. The model includes three sources of wave diffraction, a rigorous formulation of the seawall boundary condition, and sand bypassing at groins. The modeling of historical shoreline change was reasonably successful. As an exercise in investigating problems associated with prediction, the model was used to forecast the shoreline position at the site five years from now. The prediction of the wave history was the main problem encountered. A simple intuitive method was devised to estimate the probable range in variation of the wave history, and the results are discussed in connection with the shoreline forecast.

Sign in / Sign up

Export Citation Format

Share Document