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 

scholarly journals Kinerja Model Fisik Konverter Energi Ombak Rangkaian Gear Searah pada Periode Ombak yang Bervariasi

2016 ◽  
Vol 22 (2) ◽  
pp. 71 ◽  
Author(s):  
Masjono Muchtar ◽  
Salama Manjang ◽  
Dadang A Suriamiharja ◽  
M Arsyad Thaha
Keyword(s):  
Physical Model ◽  
Wave Energy ◽  
Ocean Waves ◽  
Wave Energy Converter ◽  
Wave Period ◽  
Physical Model Test ◽  
Energy Converter ◽  
Wave Flume ◽  
Period Variations ◽  
Hydraulics Laboratory

To date there were few research on the effect of non-linearity properties of the ocean waves on the performance of wave energy converter (WEC), which uses a series of unidirectional gear. One such parameter is the variation of wave period. The influence of wave period variations on the performance of physical model of the wave energy converters have been investigated at the Hydraulics Laboratory, Department of Civil Engineering, Hasanuddin University Indonesia. This WEC physical model was fabricated and assembled at Politeknik ATI Makassar Indonesia. The investigation steps consists of physical model development, physical model investigation at wave flume prior to the wave period  variation, measuring input output parameters of the physical model under test and empirical model formulation based on observed data analysis. Physical model test carried out on the wave flume at the Hydraulics Laboratory of the Department of Civil Hasanuddin University, at a water depth of 25 cm, wave height between 5-9 cm and wave period between 1.2 - 2.2 seconds. Investigation result based on flywheel radial speed (RPM) and torque (Nm) indicated that calculated harvested power was inversely proportional with the wave period. The longer the period of the waves, the energy produced is getting smaller. The derived empirical formula was y = -85.598x + 208.53 and R² = 0.8881. Y is energy produced (Watt) and X is the wave period (Second). Formulations generated from this study could be used as a reference for future research in dealing with wave period variations on a design one way gear wave energy converter as a source of renewable energy.

Wave Transmission over the Low-Crested Sand Container Breakwaters

2015 ◽  
Vol 802 ◽  
pp. 57-62
Author(s):  
Hee Min Teh
Keyword(s):  
Shallow Water ◽  
Transmission Coefficient ◽  
Water Depth ◽  
Wave Transmission ◽  
Experimental Result ◽  
Regular Waves ◽  
Wave Flume ◽  
Test Models ◽  
Wave Transmission Coefficient ◽  
Transmission Ability

Breakwaters made of sand container is one of the most economical options for wave protection at coastal areas. These breakwaters have been adopted with mixed success at several locations in Malaysia. Nevertheless, the performance of these structure has not been properly studied and documented to date. This study is undertaken to study the wave transmission ability of the submerged sand container breakwater with respect to its width and height as well as the water depth. A number of experiments have been conducted in a wave flume to quantify the wave transmission coefficient of the test models of different layouts when exposed to regular waves. The experimental result has shown that the breakwater is effective in arresting the shorter period waves, particularly in shallow water. The height of the breakwater has to be increased in order to arrest the longer period waves.

scholarly journals Wave Energy Harnessing in Shallow Water through Oscillating Bodies

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2730 ◽  
Author(s):  
Marco Negri ◽  
Stefano Malavasi
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Wave Energy ◽  
Multibody System ◽  
Physical Models ◽  
Width Ratio ◽  
Wave Flume ◽  
Capture Width Ratio ◽  
Single Body ◽  
Two Systems

This paper deals with wave energy conversion in shallow water, analyzing the performance of two different oscillating-body systems. The first one is a heaving float, which is a system known in the literature. The second one is obtained by coupling the heaving float with a surging paddle. In order to check the different behaviors of the multibody system and the single-body heaving float, physical models of the two systems have been tested in a wave flume, by placing them at various water depths along a sloping bottom. The systems have been tested with monochromatic waves. For each water depth, several tests have been performed varying the geometrical and mechanical parameters of the two systems, in order to find their best configurations. It has been found that the multibody system is more energetic when the float and the paddle are close to each other. Capture width ratio has been found to significantly vary with water depth for both systems: in particular, capture width ratio of the heaving float (also within the multibody system) increases as water depth increases, while capture width ratio of the paddle (within the multibody system) increases as water depth decreases. At the end, the capture width ratio of the multibody system is almost always higher than that of the heaving float, and it increases as water depth increases on average; however, the multibody advantage over single body is significant for water depth less than the characteristic dimension of the system, and decreases as water depth increases.

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 PHYSICAL AND NUMERICAL MODELING OF THE WAVECAT© WAVE ENERGY CONVERTER

2011 ◽  
Vol 1 (32) ◽  
pp. 64 ◽  
Author(s):  
Hernan Fernandez ◽  
Gregorio Iglesias ◽  
Rodrigo Carballo ◽  
Alberte Castro ◽  
Pedro Bartolomé
Keyword(s):  
Physical Model ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Intermediate Water ◽  
Energy Converter ◽  
Santiago De Compostela ◽  
Design Elements ◽  
Wave Flume ◽  
Fixed Model ◽  
The University

Wave energy presents a great potential in many coastal regions. This paper deals with WaveCat©, a new Wave Energy Converter (WEC) recently patented by the University of Santiago de Compostela. First, the WaveCat© concept and its main design elements. It is a floating WEC intended for intermediate water depths (50–75 m), whose principle of energy capture is wave overtopping. WaveCat© consists of two hulls, like a catamaran (hence its name); however, unlike a catamaran, the hulls are convergent so as to leave a wedge between them. Waves propagate into this wedge and, eventually, overtop the inner hull sides. Overtopping water is collected in onboard tanks and, subsequently, drained back to sea, propelling ultra-low head turbines in the process. The wave flume tests carried out on a 3D, fixed model at a 1:67 scale are presented. Development work is ongoing, including a numerical model—which is currently being validated based on the results from the physical model—and a 3D, floating physical model at a larger scale (1:30).

Experimental Study on the Dynamic Response of a Moored Floating Wave Energy Device

2003 ◽  
Author(s):  
E. Vijayakrishna Rapaka ◽  
R. Natarajan ◽  
S. Neelamani
Keyword(s):  
Wave Energy ◽  
Damping Ratio ◽  
Wave Length ◽  
Scale Model ◽  
Mooring Line ◽  
Ocean Engineering ◽  
Energy Device ◽  
Mooring Lines ◽  
Wave Flume ◽  
Engineering Department

A detailed experimental investigation conducted on a moored Oscillating Water Column (OWC) wave energy device has been reported in this paper. The experiments were conducted on 1:20 scale model of the wave energy device, which was moored to the bed using 6 mooring lines in a 2m wide (deep and shallow water) wave flume at Ocean Engineering Department, IITM, Chennai. A range of hydrodynamic parameters with different damping ratio of the OWC chamber at scope 4 (length of the mooring line/depth of water) for a constant water depth was used. The effect of non-dimensionalized parameters like non-dimensionlized wave frequency parameter (ω2B/2g) and device breadth to wave length ratio (B/L) on the mooring force and on the efficiency of the wave energy device has been studied. The motion responses and mooring forces were measured and the test results are analysed and presented with discussions in this paper.

Guided wave‐based cable damage detection using wave energy transmission and reflection

2021 ◽  
Author(s):  
Zhi‐Feng Tang ◽  
Xiao‐Dong Sui ◽  
Yuan‐Feng Duan ◽  
Peng‐fei Zhang ◽  
Chung Bang Yun
Keyword(s):  
Damage Detection ◽  
Wave Energy ◽  
Guided Wave ◽  
Energy Transmission ◽  
Cable Damage ◽  
Transmission And Reflection

scholarly journals Representative Transmission Coefficient for Evaluating the Wave Attenuation Performance of 3D Floating Breakwaters in Regular and Irregular Waves

2021 ◽  
Vol 9 (4) ◽  
pp. 388
Author(s):  
Huu Phu Nguyen ◽  
Jeong Cheol Park ◽  
Mengmeng Han ◽  
Chien Ming Wang ◽  
Nagi Abdussamie ◽  
...  
Keyword(s):  
Transmission Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Transmitted Wave ◽  
Irregular Waves ◽  
Hydrodynamic Analysis ◽  
Evaluation Approach ◽  
Floating Breakwater ◽  
Floating Breakwaters ◽  
Evaluation Approaches

Wave attenuation performance is the prime consideration when designing any floating breakwater. For a 2D hydrodynamic analysis of a floating breakwater, the wave attenuation performance is evaluated by the transmission coefficient, which is defined as the ratio between the transmitted wave height and the incident wave height. For a 3D breakwater, some researchers still adopted this evaluation approach with the transmitted wave height taken at a surface point, while others used the mean transmission coefficient within a surface area. This paper aims to first examine the rationality of these two evaluation approaches via verified numerical simulations of 3D heave-only floating breakwaters in regular and irregular waves. A new index—a representative transmission coefficient—is then presented for one to easily compare the wave attenuation performances of different 3D floating breakwater designs.

scholarly journals A STUDY OF DISORDERED SYSTEMS WITH GAIN: STOCHASTIC AMPLIFICATION

2000 ◽  
Vol 14 (16) ◽  
pp. 1669-1681 ◽  
Author(s):  
SANDEEP K. JOSHI ◽  
A. M. JAYANNAVAR
Keyword(s):  
Reflection Coefficient ◽  
Disordered Systems ◽  
Random Phase Approximation ◽  
Random Medium ◽  
Random Phase ◽  
Localization Length ◽  
Critical Length ◽  
Sample Length ◽  
Coherent Amplification ◽  
Transmission And Reflection

A study of statistics of transmission and reflection from a random medium with stochastic amplification as opposed to coherent amplification is presented. It is found that the transmission coefficient t, for sample length L less than the critical length L c grows exponentially with L. In the limit L→∞ transmission decays exponentially as < ln t>=-L/ξ where ξ is the localization length. In this limit reflection coefficient r saturates to a fixed value which shows a monotonic increase as a function of strength of amplification α. The stationary distribution of super-reflection coefficient agrees well with the analytical results obtained within the random phase approximation (RPA). Our model also exhibits the well known duality between absorption and amplification. We emphasize the major differences between coherent amplification and stochastic amplification where-ever appropriate.

scholarly journals Wave power extraction from a bottom-mounted oscillating water column converter with a V-shaped channel

2014 ◽  
Vol 470 (2167) ◽  
pp. 20140074 ◽  
Author(s):  
Zhengzhi Deng ◽  
Zhenhua Huang ◽  
Adrian W. K. Law
Keyword(s):  
Water Column ◽  
Water Depth ◽  
Wave Energy ◽  
High Efficiency ◽  
Expansion Method ◽  
Opening Angle ◽  
Energy Extraction ◽  
Oscillating Water Column ◽  
Wave Direction ◽  
Power Extraction

An analytical theory is developed for an oscillating water column (OWC) with a V-shaped channel to improve the pneumatic efficiency of wave energy extraction. An eigenfunction expansion method is used in a cylindrical coordinate system to investigate wave interaction with the OWC converter system. Auxiliary functions are introduced to capture the singular behaviours in the velocity field near the salient corners and cusped edges. Effects of the OWC dimensions, the opening angle and length of the V-shaped channel, as well as the incident wave direction, on the pneumatic efficiency of wave energy extraction are examined. Compared with a system without the V-shaped channel, our results show that the V-shaped channel can significantly increase the conversion efficiency and widen the range of wave frequency over which the OWC system can operate at a high efficiency. For typical coastal water depths, the OWC converter system can perform efficiently when the diameter of the OWC chamber is in the range of 1 5 – 1 2 times the water depth, the opening angle of the V-shaped channel is in the range of [ π /2, 3 π /4] and the length of the V-shaped channel is in the range of 1–1.5 times the water depth.

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