scholarly journals WAVE FORCES INDUCED BY IRREGULAR WAVES ON A VERTICAL CIRCULAR CYLINDER

1978 ◽  
Vol 1 (16) ◽  
pp. 144 ◽  
Author(s):  
Hajime Ishida ◽  
Yuichi Iwagaki
Keyword(s):  
Circular Cylinder ◽  
Laboratory Experiments ◽  
Large Diameter ◽  
Small Diameter ◽  
Diffraction Theory ◽  
Irregular Waves ◽  
Wave Forces ◽  
Irregular Wave ◽  
Water Level Variations ◽  
Particle Velocities

In order to examine the irregular wave forces on a small diameter cylinder, laboratory experiments have been conducted on water particle velocities and wave forces with various kinds of irregular waves. As the results, it is indicated that the time variation and the spectral distribution of wave forces can be calculated adequately from the water level variations by using the methods proposed by Reid1' and Borgman2' respectively. Moreover, with respect to the irregular wave forces on a large diameter cylinder, a new calculation method was shown by means of applying Reid's linear filters1' to MacCamy and Fuchs's diffraction theory.

Numerical Simulation of Irregular Wave Forces on a Horizontal Cylinder

2016 ◽  
Author(s):  
Ankit Aggarwal ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Hans Bihs ◽  
Øivind Asgeir Arnsten
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Numerical Model ◽  
Circular Cylinder ◽  
Wave Generation ◽  
Numerical Results ◽  
Irregular Waves ◽  
Wave Forces ◽  
Ghost Cell ◽  
Irregular Wave

In the present study, the irregular wave forces on a fully submerged circular cylinder are investigated using the open-source computational fluid dynamics (CFD) model REEF3D. A complete three dimensional representation of the ocean waves requires the consideration of the sea surface as an irregular wave train with the random characteristics. The numerical model uses the incompressible Reynolds-averaged Navier-Stokes (RANS) equations together with the continuity equation to solve the fluid flow problem. Turbulence modeling is carried out using the two equation k-ω model. Spatial discretization is done using an uniform Cartesian grid. The level set method is used for computing the free surface. For time discretization, third-order total variation diminishing (TVD) Runge Kutta scheme is used. Ghost cell boundary method is used for implementing the complex geometries in the numerical model. MPI is used for the exchange of the value of a ghost cell. Relaxation method is used for the wave generation. The numerical model is validated for the irregular waves for a wave tank without any structure. Further, the numerical model is validated by comparing the numerical results with the experimental data for a fully submerged circular cylinder under regular waves and irregular waves. The numerical results are in a good agreement with the experimental data for the regular and irregular wave forces. The JONSWAP spectrum is used for the wave generation. The free surface features and kinematics around the cylinder is also presented and discussed.

Irregular Wave and Current Loads on a Fish Farm System

2018 ◽  
Author(s):  
Arnt G. Fredriksen ◽  
Basile Bonnemaire ◽  
Øyvind Nilsen ◽  
Leiv Aspelund ◽  
Andreas Ommundsen
Keyword(s):  
Particle Velocity ◽  
Fish Farm ◽  
Fluid Particle ◽  
Irregular Waves ◽  
Engineering Practice ◽  
Irregular Wave ◽  
Environmental Force ◽  
The Mean ◽  
Particle Velocities ◽  
Farm System

Accurate calculation of the design mooring loads on an aquaculture fish farm mooring system is often a difficult task. The fish farm system has a large horizontal extension with variable environmental conditions across the entire structure. In addition, the drag loads on the fish nets are thought to be the governing environmental force. This means that the mean position of the fish farm is a function of the mean of the fluid particle velocity squared, where the fluid particle velocity must be taken as the sum of current and wave induced fluid particle velocities. Additional offsets will be slowly varying, where the response time will depend on the total mooring stiffness. The magnitudes depend on the height and length on wave groups in the irregular sea state. The paper presents simulations of the response of such a system to a set of combined irregular waves and current conditions. The response evolution in time is discussed as well as parameters affecting the maximum responses in the systems (displacements and loads). Finally, the resulting loads on the fish farm in irregular waves are compared to loads obtained in equivalent regular waves, as this is an often used engineering practice when analyzing the response and mooring loads of a fish farm.

scholarly journals Irregular Wave Forces on a Large Vertical Circular Cylinder

2016 ◽  
Vol 94 ◽  
pp. 504-516 ◽  
Author(s):  
Ankit Aggarwal ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Hans Bihs ◽  
Øivind Asgeir Arntsen
Keyword(s):  
Circular Cylinder ◽  
Wave Forces ◽  
Irregular Wave

scholarly journals WAVE FORCES ON A ROW OF CYLINDRICAL PILES OF LARGE DIAMETER

1978 ◽  
Vol 1 (16) ◽  
pp. 146
Author(s):  
J.C.W. Berkhoff ◽  
J. V.d. Weide
Keyword(s):  
Wave Field ◽  
Numerical Computation ◽  
Large Diameter ◽  
Scattered Wave ◽  
Mutual Interference ◽  
Irregular Waves ◽  
Wave Forces ◽  
Helmholz Equation ◽  
Cylindrical Piles ◽  
Single Piles

In order to determine wave forces on a row of three cylindrical piles (Figure 2), a numerical computation procedure was applied using a solution of the Helmholz equation, in which the scattered wave field is described as the result of a series of singular sources located along the circumference of the pile [^Berkhoff, 1976, reference lj . Results of the computations were verified by means of model experiments, using both regular and irregular waves. It is shown that for the two pile geometries, included in the study, strong mutual interference will occur, resulting in transverse forces which are much higher than those found for single piles.

scholarly journals STUDY OF STATISTICAL CHARACTERISTICS OF IRREGULAR WAVE PRESSURE ON A COMPOSITE BREAKWATER

1986 ◽  
Vol 1 (20) ◽  
pp. 131
Author(s):  
Chien-Kee Chang ◽  
Ching-Her Hwang
Keyword(s):  
Pressure Distribution ◽  
Wave Height ◽  
Wave Force ◽  
Shock Pressure ◽  
Irregular Waves ◽  
Statistical Characteristics ◽  
Wave Forces ◽  
Incoming Wave ◽  
Wave Pressure ◽  
Irregular Wave

Wave pressure is the most important external force for the design of breakwater. During recent years, there has been considerable development in the technology of vertical face breakwater; however, there is no reliable method to compute wave forces induced by irregular waves. The purpose of this study is to obtain statistical characteristics of irregular wave pressure distribution from the data of model tests. The results of this study shown that vertical face breakwater under the action of irregular waves, some waves are reflected, so that the next wave breaks a critical distance resulting in a rapidly rising shock pressure on the breakwater. On the average, the wave pressure increase with incoming wave height, but the maximum wave force does not necessarily occur for the largest wave height. It can be occurred for serval larger wave group in an appropiate phase composition. The irregular wave pressure distribution on the breakwater is quite uniform; the ratio of tested and calculated wave pressures decreases with the reduction of relative crest height of breakwater. Coda formula can predict the total horizontal force of the upper part of breakwater quite well except exetreme shock pressure occurred by non-breaking waves. Wave forces calculated by Miche-Rundgren and Nagai wave force formula are about 10% cummulated exceeding percentage of wave force obtained from model test.

scholarly journals Wave forces on fixed vertical axisymmetric bodies

1994 ◽  
Vol 16 (1) ◽  
pp. 20-28
Author(s):  
Nguyen Tien Dat
Keyword(s):  
Boundary Element Method ◽  
Circular Cylinder ◽  
Boundary Element ◽  
Small Diameter ◽  
Program Package ◽  
Wave Forces ◽  
The One ◽  
Axisymmetric Bodies ◽  
Good Agreement ◽  
Element Method

In this paper, wave forces on fixed vertical axisymmetric bodies are considered by the hybrid boundary element method. A program package on Fortran IV on PC has been developed and applied for the cases of a vertical circular (large and small diameter), step circular cylinder, circular dock, ... The results have been given good agreement with the one obtained by others.

Nonlinear Wave Interaction with Vertical Cylinder of Large Diameter

1977 ◽  
Vol 21 (02) ◽  
pp. 120-124
Author(s):  
H. Raman ◽  
N. Jothi Shankar ◽  
P. Venkatanarasaiah
Keyword(s):  
Nonlinear Wave ◽  
Large Diameter ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Diffraction Theory ◽  
Second Order ◽  
Wave Forces ◽  
Height Distribution ◽  
Linear Solution ◽  
Nonlinear Diffraction

A nonlinear diffraction theory for interaction of waves with a vertical cylinder of large diameter is presented. The nonlinear second-order solution is examined in comparison with a linear solution and other existing second-order solutions. The computed nonlinear wave forces are found to compare very well with the experimental results. The effect of nonlinearity on the crest height distribution around the cylinder is also studied. It is found that as the ratio of wave height to water depth decreases the nonlinear solution approaches the linear solution.

scholarly journals CORRELATION OF WATER LEVEL VARIATIONS WITH WAVE FORCES ON A VERTICAL PILE FOR NONPERIODIC WAVES

2011 ◽  
Vol 1 (6) ◽  
pp. 46
Author(s):  
Robert O. Reid
Keyword(s):  
Fixed Point ◽  
Velocity Field ◽  
Circular Cylinder ◽  
Water Level ◽  
Linear Combination ◽  
The Other ◽  
Wave Forces ◽  
Independent Functions ◽  
Serial Sequences ◽  
Water Level Variations

This paper describes the design and application of numerical transforms for the estimation of the field of motion associated with irregular, nonperiodic surface waves from measured serial sequences of water level at a fixed point. The design of these transforms is based upon the linear theory for long-crested waves. The method is applied in the analysis of wave forces exerted upon a vertical circular cylinder, where the measured reaction is considered to be expressible as a linear combination of two independent functions of time. One of these functions depends (nonlinearly) upon the velocity field, the other depends (linearly) upon the acceleration field. The covariance of these functions with the measured reaction allows a direct means of evaluation of the drag and inertial coefficients for the cylinder.

Sign in / Sign up

Export Citation Format

Share Document