scholarly journals Horizontal Forces Due to Waves Acting on Large Vertical Cylinders in Deep Water

1972 ◽  
Vol 94 (4) ◽  
pp. 862-866
Author(s):  
E. R. Johnson
Keyword(s):  
Deep Water ◽  
Large Diameter ◽  
Wave Force ◽  
Circular Cylinders ◽  
Wave Forces ◽  
Typical Application ◽  
Model Studies ◽  
Horizontal Wave ◽  
Horizontal Wave Force ◽  
Vertical Cylinders

The special case of horizontal wave forces on large vertical cylinders in deep water is considered. The typical application for such a case is the calculation of horizontal forces on column stabilized floating ocean platforms. Existing literature discussing horizontal wave forces on cylinders does not generally agree on how to predict these forces. Since for large diameter cylinders in deep water the maximum force is completely inertial, the problem of deriving a solution is considerably simplified. In this study, an expression for the maximum horizontal wave force on large diameter circular cylinders mounted vertically in deep water has been analytically derived. Experimental model studies were also conducted and the resulting measured forces were within 20 percent of predicted forces. An example of how to predict horizontal wave forces using the methods of this report is given.

scholarly journals Influence of the Perforated Rate on the Wave Attenuation Performance of Perforated Caisson Set on a Rubble Bed

2021 ◽  
Author(s):  
Peihong Zhao ◽  
Dapeng Sun ◽  
Hao Wu
Keyword(s):  
Reflection Coefficient ◽  
Wave Attenuation ◽  
Wave Force ◽  
Wave Forces ◽  
Front Wall ◽  
Minimum Value ◽  
Physical Experiments ◽  
Horizontal Wave ◽  
Horizontal Wave Force ◽  
Perforated Caisson

A Jarlan-type perforated caisson (JTPC) was an important form of structure in offshore and coastal engineering and its wave attenuation performance was greatly affected by μ (the perforated rate). In the present research, a numerical model based on VARANS equations was tested by comparing the simulation results with physical experiments and then adopted to study the effect of a larger range of μ on wave attenuation performance which included both the horizontal wave forces and the reflection coefficients. Conclusions were drawn that the total horizontal wave force and the reflection coefficient both tended to decrease and then increase with increasing μ; when the reflection coefficient reached its minimum value as about μ=0.2, the wave force at the seaward side of the perforated front wall tended to be equal to that at the solid rear wall; the total horizontal wave force reached its minimum value as about μ=0.3.

scholarly journals Influence of Wave-Absorbing Chamber Width on the Wave Attenuation Performance of Perforated Caisson Sitting on Rubble-Mound Foundation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Peihong Zhao ◽  
Dapeng Sun ◽  
Hao Wu
Keyword(s):  
Numerical Model ◽  
Wave Attenuation ◽  
Wave Force ◽  
Reflection Coefficients ◽  
Wave Forces ◽  
Front Wall ◽  
Horizontal Wave ◽  
Rubble Mound ◽  
Horizontal Wave Force ◽  
Perforated Caisson

A Jarlan-type perforated caisson consisted of a perforated front wall, a solid rear wall, and a wave-absorbing chamber between them. The wave-absorbing chamber was the main feature of the perforated caisson, and its width had a great effect on wave attenuation performance. In this study, a larger range of the wave-absorbing chamber width was observed in model experiments to investigate the effect on wave attenuation performance including the reflection coefficients and the horizontal wave forces of a perforated caisson sitting on a rubble-mound foundation. A resistance-type porosity numerical model based on the volume-averaged Reynolds-averaged Navier–Stokes (VARANS) equations was validated by comparing the present results with those of previously reported and present experiments. The validated numerical model was then used for extended research. It was found that the reflection coefficients, the total horizontal wave force, and its components all tended to oscillate in a decrease ⟶ increase ⟶ decrease manner with increasing the wave-absorbing chamber width. The reflection coefficients and wave forces acting on both sides of the perforated front wall were found to be synchronized regardless of perforation ratio or the rubble-mound foundation height.

scholarly journals A Field Experiment on Wave Forces on an Energy-Absorbing Breakwater

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1563
Author(s):  
Pasquale G. F. Filianoti ◽  
Luana Gurnari
Keyword(s):  
Water Discharge ◽  
Wave Force ◽  
Eastern Coast ◽  
Small Scale ◽  
Wave Forces ◽  
Wave Pressure ◽  
Horizontal Wave ◽  
Caisson Breakwater ◽  
Horizontal Wave Force ◽  
Energy Absorbing

The U-OWC is a caisson breakwater embodying a device for wave energy absorption. Under the wave action, the pressure acting on the upper opening of the vertical duct fluctuates, producing a water discharge alternatively entering/exiting the plant through the U-duct, formed by the duct and the chamber. The interaction between incoming waves and the water discharge alters the wave pressure distribution along the wave-beaten wall of this breakwater compared with the pressure distributions on a vertical pure reflecting wall. As a consequence, the horizontal wave forces produced on the breakwater are also different. A small scale U-OWC breakwater was put off the eastern coast of the Strait of Messina (Southern Italy) to measure the horizontal wave force. Experimental results were compared with Boccotti’s and Goda’s wave pressure formulas, carried out for conventional upright breakwaters, to check their applicability on the U-OWC breakwaters. Both models are suitable for design of U-OWC breakwaters even if they tend to overestimate by up to 25% the actual horizontal loads on the breakwater. Indeed, the greater the absorption of the energy is, the lower the wave pressure on the breakwater wall is.

scholarly journals Experimental Investigation on Hydrodynamic Coefficients of a Column-Stabilized Fish Cage in Waves

2019 ◽  
Vol 7 (11) ◽  
pp. 418
Author(s):  
Zhao ◽  
Chen ◽  
Bi ◽  
Cui
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Drag Force ◽  
Inertial Force ◽  
Element Model ◽  
Wave Force ◽  
Hydrodynamic Coefficients ◽  
Horizontal Wave ◽  
Horizontal Wave Force ◽  
The Finite Element Model

This study on hydrodynamic coefficients of a column-stabilized fish cage under wave action plays an important role in the anti-wave design of cages. The regular wave test was used to study the horizontal wave force of the jacket and column-stabilized fish cage under different wave heights, periods, and incident angles; the finite element model of the jacket and the column-stabilized fish cage was established according to the test model. On the basis of the calculation of the finite element model, combined with the wave force obtained from the experiment, the hydrodynamic coefficients of the structure was fitted by the least squares method, and then the drag force, inertial force, and total force of the structure under different conditions were calculated. The results show that the hydrodynamic coefficients of the jacket and netting under the wave condition were more obvious with the change of the KC number and wave incident angles. And as the wave height increased, the drag force, the inertial force, and the proportion of the drag force to the horizontal wave force both increased. When the wavelength was large, the same trend occured as the wave period increased. When the wave incident angles were different, the forces of the jacket and the column-stabilized fish cage were always small in lateral low-frequency waves, which is consistent with the change law of hydrodynamic coefficients of the jacket and netting.

Approximation of Surge and Pitch Loads on Truncated Vertical Cylinders

2003 ◽  
Author(s):  
Keyvan Sadeghi ◽  
Atilla Incecik ◽  
Martin Downie ◽  
Hoi-Sang Chan
Keyword(s):  
Computer Program ◽  
Deep Water ◽  
Parametric Study ◽  
Unit Length ◽  
Diffraction Theory ◽  
Circular Cylinders ◽  
Offshore Platforms ◽  
Vertical Cylinders

Truncated vertical circular cylinders are used to make deep water floating offshore platforms like Truss Spars. When the draft of the cylindrical hull is not deep enough, prediction of the surge and pitch diffraction loads by integration of McCamy and Fuchs expression of the force per unit length over the cylinder draft causes an error which is not negligible. Using hydrodynamic arguments the approximated surge and pitch loads by McCamy and Fuchs diffraction theory are modified. The modified results are compared with the results of a parametric study using the computer program WaMIT 4.01 based on the linear diffraction theory, reported by Weggel [1].

scholarly journals Numerical Simulation of Breaking Wave Loading on Standing Circular Cylinders with Different Transverse Inclined Angles

2020 ◽  
Vol 10 (4) ◽  
pp. 1347
Author(s):  
Sen Qu ◽  
Shengnan Liu ◽  
Muk Chen Ong ◽  
Shuzheng Sun ◽  
Huilong Ren
Keyword(s):  
Experimental Data ◽  
Vertical Cylinder ◽  
Wave Force ◽  
High Order ◽  
Numerical Results ◽  
Circular Cylinders ◽  
Wave Forces ◽  
Breaking Wave ◽  
Time Step ◽  
Inclined Angle

The purpose of this paper is to numerically simulate the breaking wave past a standing cylinder with different transverse inclined angles. The numerical simulations are carried out by solving the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations with the k − ω S S T turbulence model. The air–water interface is captured using the Volume of Fluid (VOF) method. The convergence studies on the grid and time-step are performed by examining the total horizontal breaking wave forces on the vertical cylinder. The present numerical results have been validated with the published experimental data. A good agreement is obtained between the present numerical results and the experimental data in terms of the surface elevation and the horizontal breaking wave force. Moreover, the total horizontal breaking wave force is decomposed into low-order and high-order wave forces through Fast Fourier Transform (FFT). It is observed that the free surface elevations in front of the cylinder and the normalized high-order wave force have a minimum value when the transverse inclined angle of the cylinder is 45°. The secondary load causing the higher-harmonic ringing motion of structures is not observed when the cylinder is placed with the transverse inclined angles of 30° and 45°.

Numerical calculation of total horizontal wave force on a perforated caisson with a top cover based on smoothed particle hydrodynamics method

2016 ◽  
Vol 231 (1) ◽  
pp. 31-45 ◽  
Author(s):  
Xiaocheng Tang ◽  
Feng Jiang ◽  
Hongzhou Chen ◽  
Zhao Jin ◽  
Li Zhang ◽  
...  
Keyword(s):  
Test Data ◽  
Smoothed Particle Hydrodynamics ◽  
Wave Force ◽  
Horizontal Force ◽  
Particle Hydrodynamics ◽  
Horizontal Wave ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Horizontal Wave Force ◽  
Perforated Caisson

The revised smoothed particle hydrodynamics method based on Riemann solution has been used to calculate the total horizontal wave force acting on a perforated caisson with a top cover. The interaction process between the wave and perforated caisson is simulated in a two-dimensional numerical wave flume which is verified by linear regular wave theory, water particles flowing in or out of the dissipation chamber are also described in this article, including the distribution of velocity vector. The effect of main non-linear influence factor on total horizontal force is examined here; wave pressure distribution along the height of the perforated caisson in front, inner side or the rear wall of the dissipation chamber is also presented in order to exhibit the more practical performance of perforated caisson with a top cover. The relationship between the total horizontal force and top cover height is anglicized, and the influence of top cover height on components of the total horizontal force is discussed here. A comparison between the numerical total horizontal force results and values tested from the test data is finished; it can be seen that the numerical results agree well with the test data. It is concluded that the smoothed particle hydrodynamics method described in this article can be utilized to calculate the total horizontal force on a perforated caisson with a top cover.

Combined Wave and Current Forces on Large-Diameter Submarine Pipelines

1989 ◽  
Vol 26 (01) ◽  
pp. 23-33
Author(s):  
José M. Andrés
Keyword(s):  
Large Diameter ◽  
Reynolds Numbers ◽  
Wave Force ◽  
Frequency Domain Method ◽  
Wave Forces ◽  
Transfer Coefficients ◽  
Mean Values ◽  
Force Coefficients ◽  
Force Transfer ◽  
Inertia Coefficient

This paper deals with the analysis of combined wave and current forces acting on an 8.3-ft-diameter, 70-ft-long submarine pipeline mounted on a steep slope at Keahole Point on the island of Hawaii, Hawaii. Force transfer coefficients have been obtained for a large number of wave and current conditions. In the absence of strong currents, mean values of wave force coefficients calculated by a frequency-domain method have proven to predict extremely well the distribution of peak wave forces. In cases where current effects are relevant, a wave-by-wave analysis of the loads indicates that, for the range of Reynolds numbers and Keulegan Carpenter parameter covered in this study, the inertia coefficient decreases as the value of the ratio of current to maximum wave velocity increases. The same result is also found by a mean-square method in which overall force coefficients are computed for the whole record length.

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