scholarly journals FLEXIBLE POROUS FLOATING BREAKWATERS

1968 ◽  
Vol 1 (11) ◽  
pp. 69 ◽  
Author(s):  
R.J. Kennedy ◽  
J. Marsalek
Keyword(s):  
Empirical Equation ◽  
Wave Theory ◽  
Ocean Waves ◽  
Systematic Investigation ◽  
Wave Action ◽  
Experimental Results ◽  
Model Scale ◽  
Floating Breakwaters

Observation of the effect of towed rafts of pulpwood on lake and ocean waves led to a systematic investigation at model scale. An empirical equation compatible with wave theory was devised and lines representing this equation together with points representing experimental results are shown for different conditions. An example of the application of the equation to prototype wave action is given. Four box booms with porous fronts, arranged m series, were substituted for the model pulpwood gam and proved to be effective m damping waves.

A Second Order Lagrangian Model for Irregular Ocean Waves

2005 ◽  
Vol 128 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Sébastien Fouques ◽  
Harald E. Krogstad ◽  
Dag Myrhaug
Keyword(s):  
Specular Reflection ◽  
Fluid Velocity ◽  
Equations Of Motion ◽  
Wave Theory ◽  
Ocean Waves ◽  
Second Order ◽  
Lagrangian Model ◽  
Lagrangian Description ◽  
Linear Wave ◽  
Irregular Solution

Synthetic aperture radar (SAR) imaging of ocean waves involves both the geometry and the kinematics of the sea surface. However, the traditional linear wave theory fails to describe steep waves, which are likely to bring about specular reflection of the radar beam, and it may overestimate the surface fluid velocity that causes the so-called velocity bunching effect. Recently, the interest for a Lagrangian description of ocean gravity waves has increased. Such an approach considers the motion of individual labeled fluid particles and the free surface elevation is derived from the surface particles positions. The first order regular solution to the Lagrangian equations of motion for an inviscid and incompressible fluid is the so-called Gerstner wave. It shows realistic features such as sharper crests and broader troughs as the wave steepness increases. This paper proposes a second order irregular solution to these equations. The general features of the first and second order waves are described, and some statistical properties of various surface parameters such as the orbital velocity, slope, and mean curvature are studied.

Wave Attenuation Performance of Floating Breakwater Needs to be Evaluated by Using Irregular Waves

2021 ◽  
Author(s):  
Chien Ming Wang ◽  
Huu Phu Nguyen ◽  
Jeong Cheol Park ◽  
Mengmeng Han ◽  
Nagi abdussamie ◽  
...  
Keyword(s):  
Transmission Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Irregular Waves ◽  
Regular Waves ◽  
Transmission Coefficients ◽  
Floating Breakwater ◽  
Floating Breakwaters

<p>Floating breakwaters have been used to protect shorelines, marinas, very large floating structures, dockyards, fish farms, harbours and ports from harsh wave environments. A floating breakwater outperforms its bottom-founded counterpart with respect to its environmental friendliness, cost-effectiveness in relatively deep waters or soft seabed conditions, flexibility for expansion and downsizing and its mobility to be towed away. The effectiveness of a floating breakwater design is assessed by its wave attenuation performance that is measured by the wave transmission coefficient (i.e., the ratio of the transmitted wave height to the incident wave height or the ratio of the transmitted wave energy to the incident wave energy). In some current design guidelines for floating breakwaters, the transmission coefficient is estimated based on the assumption that the realistic ocean waves may be represented by regular waves that are characterized by the significant wave period and wave height of the wave spectrum. There is no doubt that the use of regular waves is simple for practicing engineers designing floating breakwaters. However, the validity and accuracy of using regular waves in the evaluation of wave attenuation performance of floating breakwaters have not been thoroughly discussed in the open literature. This study examines the wave transmission coefficients of floating breakwaters by performing hydrodynamic analysis of some large floating breakwaters in ocean waves modelled as regular waves as well as irregular waves described by a wave spectrum such as the Bretschneider spectrum. The formulation of the governing fluid motion and boundary conditions are based on classical linear hydrodynamic theory. The floating breakwater is assumed to take the shape of a long rectangular box modelled by the Mindlin thick plate theory. The finite element – boundary element method was employed to solve the fluid-structure interaction problem. By considering heave-only floating box-type breakwaters of 200m and 500m in length, it is found that the transmission coefficients obtained by using the regular wave model may be smaller (or larger) than that obtained by using the irregular wave model by up to 55% (or 40%). These significant differences in the transmission coefficient estimated by using regular and irregular waves indicate that simplifying assumption of realistic ocean waves as regular waves leads to significant over/underprediction of wave attenuation performance of floating breakwaters. Thus, when designing floating breakwaters, the ocean waves have to be treated as irregular waves modelled by a wave spectrum that best describes the wave condition at the site. This conclusion is expected to motivate a revision of design guidelines for floating breakwaters for better prediction of wave attenuation performance. Also, it is expected to affect how one carries out experiments on floating breakwaters in a wave basin to measure the wave transmission coefficients.</p>

Photodeflection signal formation in photothermal measurements: comparison of the complex ray theory, the ray theory, the wave theory, and experimental results

2007 ◽  
Vol 46 (22) ◽  
pp. 5216 ◽  
Author(s):  
Dorota Korte Kobylińska ◽  
Roman J. Bukowski ◽  
Boguslaw Burak ◽  
Jerzy Bodzenta ◽  
Stanislaw Kochowski
Keyword(s):  
Wave Theory ◽  
Experimental Results ◽  
Ray Theory ◽  
Complex Ray

Strength Analysis of Oil Tanker Under Numerical Wave

2018 ◽  
Author(s):  
Cheng Shu ◽  
Li Hong ◽  
Zhang Dongxu
Keyword(s):  
Structural Strength ◽  
Fluid Structure Interaction ◽  
Ocean Waves ◽  
Wave Action ◽  
Stokes Wave ◽  
Strength Analysis ◽  
Two Phase ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Equivalent Load

The strength of an oil carrier is generally checked using static load or equivalent load of wave action in accordance with relevant specifications. In order to accurately calculate the stress and the deformation of an oil carrier under wave action, the fluid-structure interaction system in the platform Workbench is used in this work. And, the pressure-based solver, the two-phase flow model and UDF (User Defined Function) in the software FLUENT are used to compile the three-order Stokes Wave so as to simulate ocean waves. Forces acting on the surface of the oil carrier are obtained by calculating the flow field, and the structural strength of the carrier is then investigated under sagging and hogging conditions. The results show that: the three-order Stokes Wave matches well with the theoretical result, and it is feasible to research the strength of the oil carrier by generating waves using this numerical method. In addition, the method of fluid-structure interaction is applied to investigate the structural strength of the fully-loaded carrier under sagging and hogging conditions.

To Simulate the Stability of Undersea Pipeline Under Typhoon Wave Action by Numerical Analysis

2010 ◽  
Author(s):  
Lien-Kwei Chien ◽  
Wen-Chien Tseng ◽  
Sheng-Tse Chuang
Keyword(s):  
Lateral Displacement ◽  
Meteorological Data ◽  
Wave Theory ◽  
Relative Displacement ◽  
Periodic Wave ◽  
Wave Action ◽  
Western Coast ◽  
Wave Loading ◽  
Structure Damage ◽  
Typhoon Wave

When the typhoon comes, the undersea pipelines usually are caused the destory, lateral displacement and floating easily by wave loading. Therefore, the main reason of the unstable seabed may be the typhoon wave loading. This study from the ocean geotechnical viewpoint, the study area of undersea gas pipeline route from Taoyuan to Taichung in western coast of Taiwan was selected. In this study, further by using the GeoStudio QUAKE/W software program to simulate the wave laoding. The marine meteorological data including strength parameters was collected and also jointed with wave theory. At the same time, under the wave action condition, pipeline weight and embedded depth are also discussed. This study assesses the influences of the undersea pipeline stability, and the purpose is to decrease structure damage. Based on the results of theoretical calculation and numerical simulation, it can be found the undersea pipeline induced by periodic wave loading occur the relative displacement maximum up to reach about 0.93.

Director's Report

1900 ◽  
Vol 6 (1) ◽  
pp. 147-150
Author(s):  
E. J. Allen
Keyword(s):  
Systematic Investigation ◽  
Wave Action ◽  
Detailed Account ◽  
Bottom Fauna ◽  
General Area ◽  
The South ◽  
Bottom Deposits ◽  
Considerable Portion ◽  
The Town

After the completion of the investigation of the fauna and bottom-deposits of the outlying grounds extending from the neighbourhood of the Eddystone to Start Point, a detailed account of which was given in the last number of the Journal of the Association, a systematic investigation upon a similar plan was undertaken of the inshore grounds. The general area originally contemplated for detailed charting may be roughly described as lying between the 30-fathom line and the shore, and extending from the neighbourhood of Bolt Tail to Looe. In such an area the conditions are necessarily much more complicated than those which were met with on the Eddystone to Start grounds, where the depths varied but little from 30 fathoms, and where any effect upon the bottom fauna due to wave action was very slight. A further unfortunate complication has been introduced by the fact that immense quantities of refuse have been deposited all over the grounds immediately to the south and west of Plymouth Sound, by barges working in connection with the harbour improvement schemes in the Hamoaze and at Keyham, as well as by the barges belonging to the Plymouth Corporation, which discharge the refuse from the town. To such an extent has this deposit taken place that many of the most fruitful dredging and trawling grounds in the immediate neighbourhood have been rendered practically unworkable, and we have been compelled to abandon any serious systematic investigation of a considerable portion of the area originally contemplated.

The Inertial Effect in Rotational Fluorescence Depolarization

1992 ◽  
Vol 47 (9) ◽  
pp. 971-973 ◽  
Author(s):  
A. Kawski ◽  
P. Bojarski ◽  
A. Kubicki
Keyword(s):  
Empirical Equation ◽  
Molecular Geometry ◽  
Moment Of Inertia ◽  
Experimental Results ◽  
Inertial Effect ◽  
Fluorescence Depolarization ◽  
Moments Of Inertia ◽  
Low Viscosity ◽  
The Moment ◽  
Semi Empirical

Abstract The influence of the moment of inertia on the rotational fluorescence depolarization is discussed. Based on experimental results obtained for five luminescent compounds: 2,5-diphenyloxazole (PPO), 2,2'-p-phenylene-bis(5-phenyloxazole) (POPOP), p-bis[2-(5-α-naphthyloxazolyl)]-benzene (α-NOPON), 4-dimethylamino-ω-methylsulphonyl-trans-styrene (3a) in n-parafines at low viscosity (from 0.22 x 10-3 Pa • s to 0.993 x 10-3 Pa • s) and diphenylenestilbene (DPS) in different solvents, a semi-empirical equation is proposed, yielding moments of inertia that are only two to five times higher than those estimated from the molecular geometry

scholarly journals ANALYSIS OF PERMEABLE BREAKWATERS

1986 ◽  
Vol 1 (20) ◽  
pp. 155
Author(s):  
Hitoshi Murakami ◽  
Yoshihiko Hosoi ◽  
Yoshitaka Goda
Keyword(s):  
Cross Section ◽  
Water Exchange ◽  
Water Concentration ◽  
Wave Action ◽  
Theoretical Solution ◽  
Experimental Results ◽  
Concentration Change ◽  
Vertical Slit ◽  
Transmission Coefficients ◽  
The Cross

This paper discusses the characteristics of hydraulic and water exchange due to the wave action against vertical slit-type breakwaters. The theoretical solution of the reflection and the transmission coefficients for the breakwater models is compared with the experimental results. Furthermore, the water exchange discharge and the water concentration change through the gap of the permeable breakwater are examined experimentally. Finally the most effective geometry of the cross section is suggested for the breakwaters used here.

scholarly journals Rolling Spherical Triboelectric Nanogenerators (RS-TENG) under Low-Frequency Ocean Wave Action

2021 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Yuzhou Wang ◽  
Ali Matin Nazar ◽  
Jiajun Wang ◽  
Kequan Xia ◽  
Delin Wang ◽  
...  
Keyword(s):  
Mechanical Energy ◽  
Low Frequency ◽  
Electrical Energy ◽  
Ocean Waves ◽  
Open Circuit ◽  
Green Energy ◽  
Wave Action ◽  
Ocean Wave ◽  
Maximum Output ◽  
Triboelectric Nanogenerators

Triboelectric nanogenerators (TENG), which convert mechanical energy (such as ocean waves) from the surrounding environment into electrical energy, have been identified as a green energy alternative for addressing the environmental issues resulting from the use of traditional energy resources. In this experimental design, we propose rolling spherical triboelectric nanogenerators (RS-TENG) for collecting energy from low-frequency ocean wave action. Copper and aluminum were used to create a spherical frame which functions as the electrode. In addition, different sizes of spherical dielectric (SD1, SD2, SD3, and SD4) were developed in order to compare the dielectric effect on output performance. This design places several electrodes on each side of the spherical structure such that the dielectric layers are able to move with the slightest oscillation and generate electrical energy. The performance of the RS-TENG was experimentally investigated, with the results indicating that the spherical dielectrics significantly impact energy harvesting performance. On the other hand, the triboelectric materials (i.e., copper and aluminum) play a less important role. The copper RS-TENG with the largest spherical dielectrics is the most efficient structure, with a maximum output of 12.75 V in open-circuit and a peak power of approximately 455 nW.

A Second Order Lagrangian Model for Irregular Ocean Waves

2004 ◽  
Author(s):  
Se´bastien Fouques ◽  
Harald E. Krogstad ◽  
Dag Myrhaug
Keyword(s):  
Specular Reflection ◽  
Fluid Velocity ◽  
Equations Of Motion ◽  
Wave Theory ◽  
Ocean Waves ◽  
Second Order ◽  
Lagrangian Model ◽  
Lagrangian Description ◽  
Linear Wave ◽  
Irregular Solution

Synthetic Aperture Radar (SAR) imaging of ocean waves involves both the geometry and the kinematics of the sea surface. However, the traditional linear wave theory fails to describe steep waves, which are likely to bring about specular reflection of the radar beam, and it may overestimate the surface fluid velocity that causes the so-called velocity bunching effect. Recently, the interest for a Lagrangian description of ocean gravity waves has increased. Such an approach considers the motion of individual labeled fluid particles and the free surface elevation is derived from the surface particles positions. The first order regular solution to the Lagrangian equations of motion for an inviscid and incompressible fluid is the so-called Gerstner wave. It shows realistic features such as sharper crests and broader troughs as the wave steepness increases. This paper proposes a second order irregular solution to these equations. The general features of the first and second order waves are described, and some statistical properties of various surface parameters such as the orbital velocity, the slope and the mean curvature are studied.

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