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 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.

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.

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.

scholarly journals HYDRODYNAMIC PERFORMANCE OF A FREE SURFACE SEMICIRCULAR PERFORATED BREAKWATER

2011 ◽  
Vol 1 (32) ◽  
pp. 20 ◽  
Author(s):  
Hee Min Teh ◽  
Vengatesan Venugopal ◽  
Tom Bruce
Keyword(s):  
Free Surface ◽  
Wave Attenuation ◽  
Hydrodynamic Performance ◽  
Wave Transformation ◽  
Hydrodynamic Characteristics ◽  
Wave Forces ◽  
Irregular Wave ◽  
Energy Dissipater ◽  
Horizontal Wave ◽  
Perforated Breakwater

The increasing importance of the sustainability challenge in coastal engineering has led to the development of free surface breakwaters of various configurations. In this study, the hydrodynamic characteristics of a perforated semicircular free surface breakwater (SCB) are investigated for irregular wave conditions. The hydrodynamic performance of the breakwater is evaluated in the form of transmission, reflection and energy dissipation coefficients, which are then presented as a function of the relative submergence depth (D/d) and the relative breakwater width (B/Lp), where D = the depth of immersion, d = the water depth, B = the breakwater width and Lp = the wavelength corresponding to the peak wave period. It is found that the wave attenuation ability of the SCB model improves with the increase of D/d and B/Lp. The SCB performs better as an energy dissipater than as a wave reflector. Based on the analysis of measured data, some empirical equations are proposed to predict the performance of the breakwater under varying submergence depths. The behaviour of wave transformation around and within the breakwater’s chamber is discussed. Also, the measured horizontal wave forces acting on the SCB are reported.

scholarly journals Experimental Investigation of Horizontal Wave Pressure on the Caisson Protected by Armor Blocks on the Rubble-Mounted Core

2020 ◽  
Vol 8 (9) ◽  
pp. 691
Author(s):  
Sang-Ho Oh ◽  
Jae-Sung Lee
Keyword(s):  
Coverage Rate ◽  
Front Wall ◽  
Regular Waves ◽  
Wave Pressure ◽  
Physical Experiments ◽  
Adjustment Factors ◽  
Horizontal Wave ◽  
Exposed Part ◽  
Series Of Experiments ◽  
Model Setup

The horizontal wave pressure on the front wall of the caisson protected by armor blocks on the rubble-mounted core is investigated by carrying out physical experiments. There have been few previous studies regarding this type of structure, and the characteristics of horizontal wave pressure on the structure are still unclear. Considering this, a series of experiments were performed by changing the configuration of the coverage rate in front of the caisson and the shoulder width of the armor blocks. For each of the different configurations of the model setup, wave pressure on the caisson was measured under 20 regular waves of different wave periods and heights. By analyzing the obtained experimental data, it was possible to quantify the effects of the coverage rate and the shoulder width on the wave pressure. The wave pressure tended to increase up to maximally 1.5 to 2 times at the exposed part of the caisson if it was incompletely protected. In addition, the wave pressure at the top part of the caisson was substantially reduced with the increase of the shoulder width of the armor layer. Based on these results, adjustment factors for evaluating such effects have been suggested, which can be applicable for the practical design of the caisson covered with armor blocks on the rubble-mounted core.

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