Numerical Simulation of Nonlinear Wave Diffraction by a Vertical Cylinder

1992 ◽  
Vol 114 (1) ◽  
pp. 36-44 ◽  
Author(s):  
C. Yang ◽  
R. C. Ertekin
Keyword(s):  
Experimental Data ◽  
Circular Cylinder ◽  
Nonlinear Wave ◽  
Wave Diffraction ◽  
Three Dimensional ◽  
Vertical Cylinder ◽  
Radiation Condition ◽  
Wave Force ◽  
Second Order ◽  
Time Stepping

A three-dimensional time domain approach is used to study nonlinear wave diffraction by a fixed, vertical circular-cylinder that extends to the sea floor. In this approach, the development of the flow can be obtained by a time-stepping procedure, in which the velocity potential of the flow at any instant of time is obtained by the boundary-element method. In the numerical calculations, the exact body-boundary condition is satisfied on the instantaneous wetted surface of the cylinder, and an extended Sommerfeld condition is developed and used as the numerical radiation condition. The fourth-order Adams-Bashford method is employed in the time stepping scheme. Calculations are done to obtain the nonlinear diffraction of solitary waves and Stokes second-order waves by a vertical circular-cylinder. Numerical results are compared with the available linear and second-order wave-force predictions for some given wave height and wavelength conditions, and also with experimental data. Present horizontal force results agree better with the experimental data than the previous predictions.

Nonlinear wave forces on a circular cylinder

1989 ◽  
Vol 16 (2) ◽  
pp. 182-187 ◽  
Author(s):  
Michael Isaacson ◽  
Qi-Hua Zuo
Keyword(s):  
Circular Cylinder ◽  
Nonlinear Wave ◽  
Perturbation Methods ◽  
Wave Force ◽  
Offshore Structures ◽  
Wave Forces ◽  
Ocean Engineering ◽  
Time Stepping ◽  
Wave Effects ◽  
Accuracy And Stability

Nonlinear wave forces on a surface-piercing vertical circular cylinder are considered using a time-stepping method previously developed which is based on Green's theorem. Possible improvements in the efficiency, accuracy, and stability of the method are considered. Results based on this method are compared with those obtained previously using perturbation methods as well as with experimental results. It is found that the time-stepping method adopted here is quite reasonable. Wave force coefficients are given as functions of the governing parameters of the problem and the importance of nonlinear wave effects on the forces is assessed. Key words: hydrodynamics, ocean engineering, offshore structures, waves, wave forces.

scholarly journals Boussinesq Model and CFD Simulations of Non-Linear Wave Diffraction by a Floating Vertical Cylinder

2020 ◽  
Vol 8 (8) ◽  
pp. 575
Author(s):  
Sarat Chandra Mohapatra ◽  
Hafizul Islam ◽  
C. Guedes Soares
Keyword(s):  
Wave Diffraction ◽  
Perturbation Technique ◽  
Harmonic Wave ◽  
Vertical Cylinder ◽  
Numerical Data ◽  
Second Order ◽  
Wave Number ◽  
Linear Wave ◽  
Cfd Simulations ◽  
Boussinesq Model

A mathematical model for the problem of wave diffraction by a floating fixed truncated vertical cylinder is formulated based on Boussinesq equations (BEs). Using Bessel functions in the velocity potentials, the mathematical problem is solved for second-order wave amplitudes by applying a perturbation technique and matching conditions. On the other hand, computational fluid dynamics (CFD) simulation results of normalized free surface elevations and wave heights are compared against experimental fluid data (EFD) and numerical data available in the literature. In order to check the fidelity and accuracy of the Boussinesq model (BM), the results of the second-order super-harmonic wave amplitude around the vertical cylinder are compared with CFD results. The comparison shows a good level of agreement between Boussinesq, CFD, EFD, and numerical data. In addition, wave forces and moments acting on the cylinder and the pressure distribution around the vertical cylinder are analyzed from CFD simulations. Based on analytical solutions, the effects of radius, wave number, water depth, and depth parameters at specific elevations on the second-order sub-harmonic wave amplitudes are analyzed.

Second-Order Radiation Condition of Scattering Wave and Its Application

1990 ◽  
Vol 112 (3) ◽  
pp. 177-180
Author(s):  
J. Li ◽  
H. Huang
Keyword(s):  
Differential Operators ◽  
Three Dimensional ◽  
Radiation Condition ◽  
Second Order ◽  
Wave Forces ◽  
Interior Region ◽  
Linear Differential Operators ◽  
Scattering Wave ◽  
Linear Differential ◽  
Radiation Conditions

The first and second-order radiation conditions for scattering waves in two and three-dimensional problems have been derived by virtue of a sequence of linear differential operators. The wave forces on a large circular cylinder are computed by using finite element methods with first and second-order radiation conditions and the Sommerfeld condition, respectively. The results show that an improvement in accuracy is achieved by employing the second-order radiation condition. The interior region in which finite elements are employed can be restricted to a much smaller one, compared with that using the Sommerfeld condition and the computing efforts and required storage in the computer are reduced.

Second-Order Diffraction Loads on Plural Vertical Cylinder With Arbitrary Cross Sections

1987 ◽  
Vol 109 (4) ◽  
pp. 314-319
Author(s):  
K. Masuda ◽  
W. Kato ◽  
H. Ishizuka
Keyword(s):  
Boundary Value Problem ◽  
Cross Sections ◽  
Present Method ◽  
Boundary Value ◽  
Vertical Cylinder ◽  
Wave Force ◽  
Second Order ◽  
Wave Forces ◽  
Order Diffraction ◽  
Rectangular Cylinders

The purpose of the present study is development of a powerful numerical method for calculating second-order diffraction loads on plural vertical cylinder with arbitrary cross sections. According to the present method, second-order wave force can be obtained from a linear radiation potential without solving second-order boundary value problem. The boundary value problem for the radiation potential is solved with the hybrid boundary element method. The computations for circular and rectangular cylinders were carried out and compared with the experiments. In addition, second-order wave forces on twin circular cylinder are calculated with the present method.

On the Second-Order Wave Radiation of an Oscillating Vertical Circular Cylinder in Finite-Depth Water

1996 ◽  
Vol 40 (03) ◽  
pp. 224-234
Author(s):  
Ömer Gören
Keyword(s):  
Circular Cylinder ◽  
Surface Condition ◽  
Vertical Cylinder ◽  
Finite Depth ◽  
Second Order ◽  
Field Analysis ◽  
Wave Number ◽  
Wave Radiation ◽  
Integral Theorem ◽  
Nonhomogeneous Boundary Condition

A vertical circular cylinder which is in periodic oscillatory motion with small amplitudes in finite depth is considered. The usual assumptions necessary for the potential flow stand valid in the present study. A classical perturbation procedure is employed to solve the nonlinear problem through the second-order. According to the solution method presented, the fluid domain is separated into interior and exterior regions in which boundary-value problems (BVP) are decomposed into two BVPs each having one nonhomogeneous boundary condition. A nonhomogeneous second-order free-surface condition is treated by means of a modified form of Weber's integral theorem. Eigenfunction expansions are used for homogeneous solutions. Thus, to conclude the solution, the exterior and interior solutions are then matched on the common boundary. Numerical results are given for a heaving vertical circular cylinder. Wave field analysis around a vertical cylinder shows that the second-order wave pattern is typically dominated by the second-order wave number related to the second-order dispersion relation. The procedure also satisfies the conditions at infinity through the second-order.

Nonlinear Wave Forces on a Pair of Vertical Cylinders

1991 ◽  
Vol 113 (1) ◽  
pp. 1-8
Author(s):  
K. Masuda ◽  
T. Nagai
Keyword(s):  
Numerical Calculation ◽  
Circular Cylinder ◽  
Nonlinear Wave ◽  
Cross Sections ◽  
Present Method ◽  
Integration Method ◽  
Vertical Cylinder ◽  
Experimental Results ◽  
Wave Forces ◽  
Vertical Cylinders

The present paper is concerned with development of a powerful scheme for calculating nonlinear wave forces on a pair of vertical cylinders with arbitrary cross sections. The Laguerre integration method is applied and its convergence is confirmed in the cases of a single vertical cylinder and a twin circular cylinder. Further, the present method is compared with the method given by Eatock-Taylor and Hung [9], and then the computational times and those properties for a numerical calculation are investigated. The numerical results for maximum wave forces on the vertical cylinders obtained by the present method are compared with the experimental results, so that the usefulness is clarified.

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