scholarly journals Analisa Tegangan Mooring pada Floating breakwater Tipe Gergaji dengan Pemodelan Fisik

2022 ◽  
Vol 28 (3) ◽  
pp. 289-300
Author(s):  
Sujantoko Sujantoko ◽  
Eko Budi Djatmiko ◽  
Wisnu Wardhana ◽  
Aditya Hidayatullah
Keyword(s):  
Wave Flume ◽  
Floating Breakwater

Floating breakwater merupakan solusi alternatif dari penggunaan fixed breakwater karena dapat digunakan secara efektif di daerah pesisir dengan kondisi tertentu, desain yang fleksibel untuk dikembangkan, dan instalasinya lebih mudah. Salah satu aspek dasar dalam desain floating breakwater adalah sistem mooring, karena digunakan untuk menjaga struktur tersebut tetap pada posisinya dan selain itu juga akan mempengaruhi kinerjanya. Penelitian ini bertujuan untuk mengetahui besarnya tegangan mooring maksimum pada tali mooring melalui model fisik. Penelitian dilakukan pada floating breakwater tipe gergaji dan  pontoon sebagai pembanding. Model floating breakwater dibuat dari bahan Polylactid Acid dan model tali mooring digunakan jenis polyethylene. Pengujian fisik dilakukan di laboraturium wave flume dengan gelombang irregular dan variasi tinggi gelombang (Hs), periode gelombang (T), elevasi muka air (d), dan sudut mooring (q). Hasil penelitian ini diperoleh nilai tegangan mooring maksimum pada floating breakwater tipe gergaji dan tipe pontoon pada sudut mooring 30⁰ dan elevasi muka air 45 cm secara berturut turut yaitu 5,278 N dan 4,913 N, sedangkan tegangan terkecil terjadi pada sudut mooring 60⁰ dan elevasi muka air 41 cm secara berturut turut yaitu 1,030 N dan 1,273 N. Pada perbandingan nilai tegangan mooring antara floating breakwater tipe gergaji pada sudut mooring (30o, 45o, 60o) adalah lebih besar 10.82%-19.71%, 24.00-40.94%, dan 22.2%-39.42% terhadap tipe pontoon pada elevasi muka air 41cm, 43cm dan 45cm secara berturut-turut

Hydrodynamic Performance of a Novel Free Surface Pitching Breakwater

2014 ◽  
Author(s):  
Vengatesan Venugopal ◽  
Stefan Zlatev
Keyword(s):  
Body Shape ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
Scale Model ◽  
Reflected Waves ◽  
Irregular Wave ◽  
Wave Flume ◽  
Floating Breakwater ◽  
Wave Heights ◽  
Transmission Ct

A new concept floating breakwater was developed and tested to evaluate its hydrodynamic performance in this paper. This innovative floating breakwater has a rocking body shape which could also be used as a wave power device. A scale model was tested in a wave flume under regular and irregular wave conditions for various combinations of wave frequencies and wave heights. The breakwater has been tested for three immersion depths of 0.05 m, 0.09 m and 0.13 m from still water level. The measured transmitted and reflected waves were used to evaluate the coefficients of transmission (CT), reflection (CR) and dissipation (CL). The results illustrated that the breakwater model performed at its best when submerged at 0.13m, as this immersion depth produced lower coefficients of transmission (CT), lower reflection coefficients (CR) and higher energy dissipation (CL) coefficients. The comparison between regular and irregular waves produced similar ranges of transmission, reflection and energy coefficients.

Wave Response of a Novel Breakwater Concept With Oscillating Water Columns

2019 ◽  
Author(s):  
Mengmeng Han ◽  
Chien Ming Wang ◽  
Wenhui Duan
Keyword(s):  
Wave Height ◽  
Wave Force ◽  
Leeward Side ◽  
Wave Condition ◽  
Wave Flume ◽  
Numerical Studies ◽  
Floating Breakwater ◽  
Vertical Walls ◽  
Novel Concept ◽  
Oscillating Water Columns

Abstract A novel concept of a mega floating breakwater-windbreak is proposed for reducing both wave height and wind speed on its leeward side. L-shaped internal channels are installed inside the breakwater hull that surface from the floating breakwater as tubes that function like “trees” to break the wind. The channel openings are on the vertical walls at the upstream side of the breakwater, so that water is allowed to oscillate inside the channels and create extra viscous damping. Numerical studies using both linear boundary element method and CFD were carried out to determine the wave transmissibility and wave force on the breakwater with and without the internal channels. The wave condition in the Gold Coast, Australia was selected as an environmental input. Operating wave condition and extreme wave condition were separately investigated. Scaled dimensions were used to study the breakwater behavior in a wave flume. The results show that when water oscillates inside the channels, the transmitted wave height and lateral wave force acting on the breakwater will be reduced. In addition, since the viscous effect influences waves of all lengths, the internal channels improves the breakwater performance in blocking long waves.

scholarly journals FLOATING BREAKWATERS AS PUBLIC PLATFORMS – IMPACT ON POSTURAL STABILITY

2018 ◽  
pp. 63
Author(s):  
Elizabeth Freeman ◽  
Kristen Splinter ◽  
Ron Cox
Keyword(s):  
Energy Dissipation ◽  
Degrees Of Freedom ◽  
Wave Attenuation ◽  
Cost Effective ◽  
Irregular Waves ◽  
Main Function ◽  
Wave Flume ◽  
Floating Breakwater ◽  
Safety Considerations ◽  
Floating Breakwaters

Floating Breakwaters are used extensively to provide cost effective protection from wind and vessel waves. Floating breakwaters are commonly multitasked, being used as a point of mooring for vessels or simply an access way to other pontoons in a small boat harbour, as well as their main function as wave dissipators. A floating breakwater does not completely stop the incident wave; rather it partially transmits, partially reflects and partially dissipates the wave energy. Cox et al (2007) completed wave flume testing of a number of floating breakwaters and reported on performance in irregular waves with particular emphasis on wave transmission and reflection, energy dissipation and restraining forces. Motion measurements were limited by the instrumentation. This paper discusses the results from a further series of laboratory experiments on the dynamic motions of an active floating breakwater system. The performance is related to wave attenuation, wave reflection and energy dissipation as well as safety considerations for standing persons based on high resolution measurements of accelerations in all six degrees of freedom.

scholarly journals STUDI KARAKTERISKTIK GELOMBANG PADA FLOATING BREAKWATER TIPE TERPANCANG DAN TAMBAT

2021 ◽  
Vol 12 (1) ◽  
pp. 39-52
Author(s):  
Sujantoko Sujantoko ◽  
Wisnu Wardhana ◽  
Eko Budi Djatmiko ◽  
Haryo Dwito Armono ◽  
Wahyu Suryo Putro ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Physical Model ◽  
Transmission Coefficient ◽  
Water Depth ◽  
Wave Energy ◽  
Ocean Engineering ◽  
Wave Flume ◽  
Floating Breakwater ◽  
Type 3 ◽  
Transmission And Reflection

Floating breakwater (PGT) is designed to be applied as a wave barrier to reduce beach abrasion and wave energy so that waves coming to the beach have their energy reduced. Compared to conventional breakwater structures, PGT structures are more advantageous if the area to be protected from impact waves has a large enough depth. This structure is more flexible because the elevation follows the tides, so this structure can be used as a wharf at the same time. It is also free from the scouring and sedimentation that often occurs on the feet of conventional breakwater structures. This study aims to attenuate and reflect waves from various PGT configurations of piling and mooring types, by testing the physical model of PGT in the wave flume laboratory of the Department of Ocean Engineering ITS, at a water depth of 80 cm, a wave height of 3.5-5.5 cm, a wave period of 0.5-2 seconds, and the angle of the mooring rope (45o, 60o, 90o). PGT is arranged in a variety of longitudinal and transverse directions to the coast. Based on the experiment, it is known that the effect of configuration and width on the PGT structure on wave transmission and reflection is influenced by the mooring angle. Configuration 3 with the largest width can give the best transmission coefficient Kt = 0.797 at 45o mooring angle and reflection coefficient Kr = 0.572 at 90o mooring angle. In type 3 fixed-configuration gives the greatest value Kt = 0.431-0.623 and Kr = 0.053-0.997 compared to other configurations. Because in configurations 1 and 2 the back of the structure is not supported by piles, so a swing occurs which generates waves. While the effect of the slope of the wave, Kt will increase as the number of waves slopes decreases, conversely the value of Kt decreases with the increase in the slope of the wave.Keywords: Floating breakwater, piling, tethered,  mooring 

An Experimental Study of Effects of Water Depth on Wave Scattering and Motion Responses of a Moored Floating Breakwater in Regular Waves

2011 ◽  
Author(s):  
Zhenhua Huang ◽  
Wenbin Zhang
Keyword(s):  
Water Depth ◽  
Measurement Unit ◽  
Regular Waves ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Wave Flume ◽  
Motion Responses ◽  
Floating Breakwater ◽  
Series Of Experiments ◽  
Floating Breakwaters

Due to the mobility and low costs, floating breakwaters have been frequently considered as alternatives for protecting marinas and harbors from wave attacks. Main advantages of using floating breakwaters include (i) the exchange of water between a harbor and ocean, and (ii) an adjustable elevation varying with tidal levels. When floating breakwaters are used in shallow water environments (during low tides), the presence of seabed may affect the dynamics of the floating breakwaters. In the present study, a series of experiments were carried out in a wave flume of 1.5m wide and 45m long to study the effects of water depth on the performance of a moored floating breakwater. An inertial measurement unit mounted on the breakwater measures the motion responses. The wave reflection and transmission coefficients and the responses of the breakwater to regular waves are presented for four difference water depths.

scholarly journals PENGARUH KEDALAMAN PEMECAH GELOMBANG TERAPUNG PIPA ANYAMAN ECENG GONDOK TERHADAP TINGGI GELOMBANG REFLEKSI DAN TRANSMISI

TEKNIK HIDRO ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 63-71
Author(s):  
Nenny T Karim ◽  
Andi Makbul Syamsuri
Keyword(s):  
Wave Flume ◽  
Floating Breakwater

Penelitian kali ini bertujuan untuk mengetahui pengaruh kedalaman dan pengaruh periode pada floating breakwater dengan melakukan permodelan dalam skala laboratorium dengan menggunakan bahan eceng gondok kering yang dirakit. Dalam penelitian ini yang dihitung adalah kedalaman refleksi dan kedalaman transmisi gelombang dari model fisik floating breakwater berbahan dasar eceng gondok, yang merupakan perbandingan antara tinggi gelombang datang (Hi) dengan tinggi gelombang yang direfleksikan (Hr) dan tinggi gelombang datang (Hi) dengan tinggi gelombang yang ditransmisikan (Ht), sehingga akan diketahui efektifitas dari floating breakwater dalam meredam gelombang. Model floating breakwater berbahan dasar eceng gondok di uji di wave flume menggunakan gelombang irreguler dengan tinggi gelombang 1 sampai 3 cm dan periode 1,7 detik, 1,9 detik, 2,1 detik dan dengan 3 variasi kedalaman tenggelam model yakni 15 cm, 18 cm dan 21 cm. Hasil penelitian menunjukkan padakedalaman mtenggelam model 15 cm Hr berkisar 0,1 – 0,5 CM dan Ht berkisar 2 – 2,8 cm. Pada kedalaman 18 cm Hr berkisar 0,2 – 0,45 cm dan Ht berkisar 1,8 – 2,2 cm. Pada kadalaman 21 cm Hr berkisar 0,15 – 0,45 cm dan Ht berkisar 1,6 – 2,15 cm. Dari hasil pengujian menunjukkan kedalaman tenggelam model 21 cm lebih efektip mengurangi tinggi gelombang Refleksi dan tinggi gelombang Transmisi. Kata kunci : Floating Breakwater, Gelombang Refleksi, Gelombang Transmisi.

Performance of an F-type floating breakwater: A numerical and experimental study

2016 ◽  
Vol 231 (2) ◽  
pp. 583-599
Author(s):  
Wenyang Duan ◽  
Shupeng Xu ◽  
Qianlong Xu ◽  
R Cengiz Ertekin ◽  
Shan Ma
Keyword(s):  
Floating Body ◽  
Linear Potential ◽  
Two Dimensional ◽  
Transmission Coefficients ◽  
Wave Flume ◽  
Transmission And Reflection Coefficients ◽  
Numerical Predictions ◽  
Floating Breakwater ◽  
Experimental Findings ◽  
The Cost

Floating breakwaters are structures with large ratio of length to breadth. The profile of an floating breakwater is the key to the hydrodynamic properties of it. In this work, a new kind of an F-type floating breakwater is presented. Its profile is asymmetric and looks like the English letter “F.” We present both numerical and experimental findings on this F-type floating breakwater. Based on linear potential-flow theory, first, the boundary-element method is presented to study the interaction problem of a two-dimensional floating body with waves. Following that, the two-dimensional experiments are conducted in a wave flume to measure the diffracted and radiated waves, the resulting transmission and reflection coefficients, and the motion responses of the F-type floating breakwater. It is shown that the experimental data are, in general, in good agreement with the numerical predictions. The transmission coefficients that are measured and calculated are under 0.5 when the ratio of B/λ (the ratio of model breadth to wavelength), when the F-type floating breakwater is fixed, is larger than 0.18. The ratio of B/λ, when the F-type floating breakwater is allowed to slide vertically only, is larger than 0.2 and the ratio of B/λ, when the F-type floating breakwater is allowed to rotate and slide, is larger than 0.22. To understand how the profile geometry can affect the performance of the F-type floating breakwater, a parametric study of the F-type floating breakwater’s main dimensions, including its profile breadth, draft, and angle, is conducted on the wave transmission coefficient. It is found that the transmission coefficients are particularly sensitive to the change in draft for certain sea conditions. These results are important since seeking the optimal principal dimensions can ensure minimum volume of displacement, thereby using less material and reducing the cost of construction sharply.

APPLICATION OF ACOUSTIC METHODS IN RESEARCHES OF THE BOTTOM SEDIMENT DYNAMICS

2018 ◽  
Author(s):  
Б. Дивинский ◽  
B. Divinskiy ◽  
И. Грюне ◽  
I. Gryune ◽  
Р. Косьян ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Sediment Concentration ◽  
Irregular Waves ◽  
Single Frequency ◽  
Contactless Measurement ◽  
Measurement Means ◽  
Uniform Field ◽  
Wave Flume ◽  
Acoustic Methods ◽  
Back Scattering

Acoustic methods belong to contactless measurement means, possess high spatial and time resolution. Thus, the use of multifrequency allows directly profile both concentration and granulometric structure of the suspended substances. In 2008 in the Big Wave Flume (Hanover, Germany) by efforts of the Russian and German scientists there have been carried out the experiment on studying the bottom material suspension laws under the influence of irregular waves. The Aquascat 1000 acoustic back scattering sensor (ABS) manufactured by British company Aquatec (www.aquatecsubsea.com), equipped by a three-frequency transmitter with frequencies 1,0, 2,0 and 3,84 MHz, has been set on distance of 0,75 m from the bottom and 111 m from wave generator at the total depth of 3,2 m. Several dozen series of measurements at various parameters of surface waves have been carried out. The general picture of suspension is so that the external dynamic influence (currents, wave movements, turbulence, gravitation forces) creates a non-uniform field (gradient) of the suspended particles and in most cases due to this the average size of particles undergoes to the spatial-time variations. For this reason while defining the mass concentration of suspended sediment, using the single frequency transmitter there is necessity for numerous definition of the suspension granulometric structure what by isn’t always possible. If two and more frequencies are used the observed results comparison can give the information on average diameters of particles and on that basis the calculation of suspended sediment concentration is possibleLet's emphasize the basic advantages of back scattering acoustic gauges usage: – Obtaining the particles sizes and concentration distribution profiles is possible; – The initial granulometric structure of bottom sediments can be unknown (at use of several frequencies). The following can be referred to some lacks of the device: – The system should be calibrated in laboratory conditions; – In a positive feedback conditions the iterative computing process can converge to zero or to infinity. In this case experiments with a variation of carrier frequencies chosen for the analysis allow partially solve the problem (say experiments with different frequencies pairs, as 2/1 of MHz or 4/2 MHz).

Kajian Model Fisik Pengaruh Freeboard dan Susunan Buis Beton Sebagai Pemecah Gelombang Tenggelam Ambang Rendah (Pegar) Dalam Mereduksi Gelombang

2017 ◽  
Vol 1 (2) ◽  
pp. 34
Author(s):  
Zulkarnain Zulkarnain ◽  
Nadjadji Anwar
Keyword(s):  
Low Cost ◽  
Relative Depth ◽  
Submerged Breakwater ◽  
Wave Flume ◽  
Concrete Cylinder ◽  
Engineering Department ◽  
Sea Area ◽  
The Waves ◽  
Transmission Test ◽  
Better Than

The Research Center and Development of Water (Puslitbang) is currently developing the Submerged Breakwater in shallow sea area (PEGAR). The author is interested to examine the material that easily obtained in the field of RCP concrete cylinder. The observation is how it to be ability in function as submerged breakwater an go green and low cost. The physical model of wave transmission test is how the response to the structure in ability to damping of wave as the breakwater function. In this research breakwater used is submerged breakwater type by using concrete cylinder (buis beton). The purpose from this research is to know how the response of breakwater structure to the waves through it, with some variation of the structure by creating a structure with three variations of the arrangement and freeboard that is the relative depth with the crest width is constant. The wave generated test in this study is using regular waves in wave flume at FTSP Civil Engineering Department of Institute Technology Ten November. From the analysis of the effect of the installation of submerged breakwater by using concrete cylinder to the wave damping value, it can be concluded that the factors that are very influential is the freeboard and the composition of concrete cylinder. Scenario A (rigid vertical massive) is capable of producing the smallest value of kt is 0.33. As for scenario B (rigid horyzontal massive) with a damping value of 0.5, while the scenario C (rigid permeable) is only able to produce kt value of 0.71. Scenario A is better than scenario B and C Because the position of arrangement of A is very good used to damp wave in small or big freeboard conditions.

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