scholarly journals THE EFFECT OF WAVE ENERGY SPECTRA ON WAVE RUN-UP

1968 ◽  
Vol 1 (11) ◽  
pp. 57 ◽  
Author(s):  
J.H. Van Oorschot ◽  
K. D'Angremond
Keyword(s):  
Energy Spectrum ◽  
Wave Energy ◽  
Irregular Waves ◽  
Energy Spectra ◽  
Wave Spectra ◽  
Hydraulic Actuators ◽  
Wave Generator ◽  
Run Up ◽  
Hydraulics Laboratory ◽  
Monochromatic Waves

Previous investigations carried out "by the Delft Hydraulics laboratory have shown the necessity of applying irregular waves m studies on wave run-up. The installation of a wave generator driven "by hydraulic actuators has created the possibility of producing irregular waves with arbitrary wave spectra. Investigations performed with this type of wave generator show the influence of the shape of the energy spectrum on the wave run-up on smooth straight slopes of 1:4 and 1:6. The results are compared with run-up figures derived from experiments with wind generated waves and with monochromatic waves.

scholarly journals EVALUATION OF INCIDENT WAVE ENERGY IN FLUME TEST

1986 ◽  
Vol 1 (20) ◽  
pp. 93
Author(s):  
Eliezer Kit ◽  
Oded Gottlieb ◽  
Dov S. Rosen
Keyword(s):  
Least Squares ◽  
Incident Wave ◽  
Wave Energy ◽  
Least Squares Method ◽  
Stationary Wave ◽  
Residual Energy ◽  
Irregular Waves ◽  
Wave Spectra ◽  
Reflected Wave ◽  
Incident Wave Energy

A two dimensional model study, carried out for a structure in a flume using irregular waves, presents the problem of determining the relationship between the total incident wave energy attacking the structure and its response to that attack (displacements, forces, etc.) in various sea states, The total incident wave energy can be evaluated indirectly only, because the wave energy measured in the flume contains an extent of residual wave energy in addition to that generated by the wave machine. This residual energy consists of the re-reflected wave energy from the paddle of the wave machine, assuming the existence of quasi-stationary wave conditions in the flume. A method originally presented by Gravesen et al. (1974), was applied in this study to evaluate the total incident wave energy. In view of the results obtained by this method, a physically more sound refinement is proposed for the evaluation of the total incident wave energy (and characteristic wave height). Results of model tests were analyzed by the CAMERI refinement and compared with the Gravesen method and with a cross-spectral least squares method, separating incident and reflected wave spectra from wave spectra measured in the flume, Good agreement was found between the results obtained employing the CAMERI refinement and the cross-spectral least squares method, Advantages and drawbacks of these methods are indicated,

Launching Dynamics Simulation of Ship-Board Rocket Gun

2012 ◽  
Vol 625 ◽  
pp. 140-145
Author(s):  
Wei Zeng ◽  
Yi Jiang
Keyword(s):  
Energy Spectrum ◽  
Dynamic Response ◽  
Spectral Density ◽  
Wave Energy ◽  
Dynamics Simulation ◽  
Irregular Waves ◽  
Dynamics Model ◽  
Energy Spectral Density ◽  
Ocean Wave Energy ◽  
Wave Energy Spectrum

As for the issue of ship-board rocket gun launch, the research on the influence of sea condition on initial disturbances of rockets was conducted. The launch system was simplified and the dynamics model was established. The energy spectral density of motion of ship in irregular waves was calculated based on ocean wave energy spectrum and the dynamic response of launch system was studied under three kinds of sea conditions. The result indicates that amplitudes of pitch and yaw increase, however, the rolling decreases when the sea condition level rises.

scholarly journals WAVE FORCES ON PILES IN RELATION TO WAVE ENERGY SPECTRA

1968 ◽  
Vol 1 (11) ◽  
pp. 61
Author(s):  
A. Paape
Keyword(s):  
Energy Density ◽  
Probability Distribution ◽  
Wave Energy ◽  
Wave Motion ◽  
Irregular Waves ◽  
Energy Spectra ◽  
Wave Forces ◽  
Density Spectrum ◽  
The Waves

The determination of wave forces on piles is for an important part based upon data obtained with regular laboratory waves. Nonlmearities m the mechanism that underlies these forces may lead to deviations when applying the data to predict forces exerted by irregular waves. Experiments have been performed with irregular waves to investigate wave forces, more particularly to study the influence of the energy density spectrum of the waves. Within the range of conditions m the experiments, the wave motion is sufficiently characterized by its energy and the frequency (or wave period) at which the energy density is maximum to determine the probability distribution of wave forces.

scholarly journals Coupling Methodology for Studying the Far Field Effects of Wave Energy Converter Arrays over a Varying Bathymetry

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2899 ◽  
Author(s):  
Gael Verao Fernandez ◽  
Philip Balitsky ◽  
Vasiliki Stratigaki ◽  
Peter Troch
Keyword(s):  
Numerical Simulations ◽  
Wave Energy ◽  
Near Field ◽  
Coupled Model ◽  
Propagation Model ◽  
Irregular Waves ◽  
Computational Time ◽  
Far Field ◽  
Field Effects ◽  
Numerical Tool

For renewable wave energy to operate at grid scale, large arrays of Wave Energy Converters (WECs) need to be deployed in the ocean. Due to the hydrodynamic interactions between the individual WECs of an array, the overall power absorption and surrounding wave field will be affected, both close to the WECs (near field effects) and at large distances from their location (far field effects). Therefore, it is essential to model both the near field and far field effects of WEC arrays. It is difficult, however, to model both effects using a single numerical model that offers the desired accuracy at a reasonable computational time. The objective of this paper is to present a generic coupling methodology that will allow to model both effects accurately. The presented coupling methodology is exemplified using the mild slope wave propagation model MILDwave and the Boundary Elements Methods (BEM) solver NEMOH. NEMOH is used to model the near field effects while MILDwave is used to model the WEC array far field effects. The information between the two models is transferred using a one-way coupling. The results of the NEMOH-MILDwave coupled model are compared to the results from using only NEMOH for various test cases in uniform water depth. Additionally, the NEMOH-MILDwave coupled model is validated against available experimental wave data for a 9-WEC array. The coupling methodology proves to be a reliable numerical tool as the results demonstrate a difference between the numerical simulations results smaller than 5% and between the numerical simulations results and the experimental data ranging from 3% to 11%. The simulations are subsequently extended for a varying bathymetry, which will affect the far field effects. As a result, our coupled model proves to be a suitable numerical tool for simulating far field effects of WEC arrays for regular and irregular waves over a varying bathymetry.

scholarly journals BREAKWATER ARMOR DISPLACEMENT THRESHOLDS: A POSSIBLE CORRELATION WITH CUMULATIVE WAVE ENERGY

1984 ◽  
Vol 1 (19) ◽  
pp. 186
Author(s):  
Daniel L. Behnke ◽  
Frederic Raichlen
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Wave Length ◽  
Simple Wave ◽  
Wave Theory ◽  
Irregular Waves ◽  
Reconstruction Technique ◽  
Regular Wave ◽  
Regular Waves ◽  
Three Dimensional Model

An extensive program of stability experiments in a highly detailed three-dimensional model has recently been completed to define a reconstruction technique for a damaged breakwater (Lillevang, Raichlen, Cox, and Behnke, 1984). Tests were conducted with both regular waves and irregular waves from various directions incident upon the breakwater. In comparison of the results of the regular wave tests to those of the irregular wave tests, a relation appeared to exist between breakwater damage and the accumulated energy to which the structure had been exposed. The energy delivered per wave is defined, as an approximation, as relating to the product of H2 and L, where H is the significant height of a train of irregular waves and L is the wave length at a selected depth, calculated according to small amplitude wave theory using a wave period corresponding to the peak energy of the spectrum. As applied in regular wave testing, H is the uniform wave height and L is that associated with the period of the simple wave train. The damage in the model due to regular waves and that caused by irregular waves has been related through the use of the cumulative wave energy contained in those waves which have an energy greater than a threshold value for the breakwater.

scholarly journals OPTIMIZATION OF THE WAVECAT WAVE ENERGY CONVERTER

2012 ◽  
Vol 1 (33) ◽  
pp. 5 ◽  
Author(s):  
Hernan Fernandez ◽  
Gregorio Iglesias ◽  
Rodrigo Carballo ◽  
Alberte Castro ◽  
Marcos Sánchez ◽  
...  
Keyword(s):  
Physical Model ◽  
Wave Energy ◽  
Model Tests ◽  
Irregular Waves ◽  
Intermediate Water ◽  
Plan View ◽  
Santiago De Compostela ◽  
Wave Energy Converters ◽  
Physical Model Tests ◽  
The Difference

The development of efficient, reliable Wave Energy Converters (WECs) is a prerequisite for wave energy to become a commercially viable energy source. Intensive research is currently under way on a number of WECs, among which WaveCat©—a new WEC recently patented by the University of Santiago de Compostela. In this sense, this paper describes the WaveCat concept and its ongoing development and optimization. WaveCat is a floating WEC intended for operation in intermediate water depths (50–100 m). Like a catamaran, it consists of two hulls—from which it derives its name. The difference with a conventional catamaran is that the hulls are not parallel but convergent; they are joined at the stern, forming a wedge in plan view. Physical model tests of a 1:30 model were conducted in a wave tank using both regular and irregular waves. In addition to the waves and overtopping rates, the model displacements were monitored using a non-intrusive system. The results of the physical model tests will be used to validate the 3D numerical model, which in turn will be used to optimize the design of WaveCat for best performance under a given set of wave conditions.

Experimental Assessment of the Performance of CECO Wave Energy Converter in Irregular Waves

2018 ◽  
Author(s):  
Claudio A. Rodríguez ◽  
F. Taveira-Pinto ◽  
P. Rosa-Santos
Keyword(s):  
Wave Energy ◽  
Transfer Functions ◽  
Nonlinear Effects ◽  
Model Tests ◽  
Experimental Results ◽  
Irregular Waves ◽  
Scale Model ◽  
Experimental Assessment ◽  
Simplified Approach ◽  
Wave Basin

A new concept of wave energy device (CECO) has been proposed and developed at the Hydraulics, Water Resources and Environment Division of the Faculty of Engineering of the University of Porto (FEUP). In a first stage, the proof of concept was performed through physical model tests at the wave basin (Rosa-Santos et al., 2015). These experimental results demonstrated the feasibility of the concept to harness wave energy and provided a preliminary assessment of its performance. Later, an extensive experimental campaign was conducted with an enhanced 1:20 scale model of CECO under regular and irregular long and short-crested waves (Marinheiro et al., 2015). An electric PTO system with adjustable damping levels was also installed on CECO as a mechanism of quantification of the WEC power. The results of regular waves tests have been used to validate a numerical model to gain insight into different potential configurations of CECO and its performance (López et al., 2017a,b). This paper presents the results and analyses of the model tests in irregular waves. A simplified approach based on spectral analyses of the WEC motions is presented as a means of experimental assessment of the damping level of the PTO mechanism and its effect on the WEC power absorption. Transfer functions are also computed to identify nonlinear effects associated to higher waves and to characterize the range of periods where wave absorption is maximized. Furthermore, based on the comparison of the present experimental results with those corresponding to a linear numerical potential model, some discussions are addressed regarding viscous and other nonlinear effects on CECO performance.

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