Wave-energy distribution and hurricane effects on Margarita Reef, southwestern Puerto Rico

Coral Reefs ◽  
1994 ◽  
Vol 13 (1) ◽  
pp. 21-32 ◽  
Author(s):  
A. Lugo-Fern�ndez ◽  
M. L. Hern�ndez-�vila ◽  
H. H. Roberts
Author(s):  
D. Clabby ◽  
A. Henry ◽  
M. Folley ◽  
T. Whittaker

The power output from a wave energy converter is typically predicted using experimental and/or numerical modelling techniques. In order to yield meaningful results the relevant characteristics of the device, together with those of the wave climate must be modelled with sufficient accuracy. The wave climate is commonly described using a scatter table of sea states defined according to parameters related to wave height and period. These sea states are traditionally modelled with the spectral distribution of energy defined according to some empirical formulation. Since the response of most wave energy converters vary at different frequencies of excitation, their performance in a particular sea state may be expected to depend on the choice of spectral shape employed rather than simply the spectral parameters. Estimates of energy production may therefore be affected if the spectral distribution of wave energy at the deployment site is not well modelled. Furthermore, validation of the model may be affected by differences between the observed full scale spectral energy distribution and the spectrum used to model it. This paper investigates the sensitivity of the performance of a bottom hinged flap type wave energy converter to the spectral energy distribution of the incident waves. This is investigated experimentally using a 1:20 scale model of Aquamarine Power’s Oyster wave energy converter, a bottom hinged flap type device situated at the European Marine Energy Centre (EMEC) in approximately 13m water depth. The performance of the model is tested in sea states defined according to the same wave height and period parameters but adhering to different spectral energy distributions. The results of these tests show that power capture is reduced with increasing spectral bandwidth. This result is explored with consideration of the spectral response of the device in irregular wave conditions. The implications of this result are discussed in the context of validation of the model against particular prototype data sets and estimation of annual energy production.


Author(s):  
Marie-Aure´lie Kerbiriou ◽  
Marc Prevosto ◽  
Christophe Maisondieu ◽  
Aure´lien Babarit ◽  
Alain Cle´ment

Sea-states are usually described by a single set of 5 parameters, no matter the actual number of wave systems they contain. We present an original numerical method to extract from directional spectra the significant systems constituting of a complex sea-state. An accurate description of the energy distribution is then given by multiple sets of parameters. We use these results to assess the wave climatology in the Bay of Biscay and to estimate the power harnessable in this area by a particular Wave Energy Converter, the SEAREV. Results show that the fine description of sea-states yields a better assessment of the instantaneous device response. The discrepancy between the classical and multi-sets descriptions show that the new one is preferable for the assessment of harnessable power and for device design.


1980 ◽  
Vol 1 (17) ◽  
pp. 139
Author(s):  
Volker Barthel

A field investigation program on waves in the Weser Estuary, German Bight of the North Sea, was started to learn about the complex wave climate in this region. The comparison of results in the various locations shows that most of the' wave energy is transferred from deep water across the reef region to the wadden area. The comparison of spectra in the different sites and the parametrization of these multipeak- spectra gives another feasibility to describe estuarine waves.


Geophysics ◽  
2021 ◽  
Vol 86 (6) ◽  
pp. T509-T521
Author(s):  
Owen Huff ◽  
Bin Luo ◽  
Ariel Lellouch ◽  
Ge Jin

Guided waves that propagate in deep low-velocity zones can be described using the displacement-stress eigenfunction theory. For a layered subsurface, these eigenfunctions provide a framework to calculate guided-wave properties at a fraction of the time required for fully numerical approaches for wave-equation modeling, such as the finite-difference approach. Using a 1D velocity model representing the low-velocity Eagle Ford Shale, an unconventional hydrocarbon reservoir, we verify the accuracy of the displacement eigenfunctions by comparing with finite-difference modeling. We use the amplitude portion of the Green’s function for source-receiver eigenfunction pairs as a proxy for expected guided-wave amplitude. These response functions are used to investigate the impact of the velocity contrast, reservoir thickness, and receiver depth on guided-wave amplitudes for discrete frequencies. We find that receivers located within the low-velocity zone record larger guided-wave amplitudes. This property may be used to infer the location of the recording array in relation to the low-velocity reservoir. We also study guided-wave energy distribution between the different layers of the Eagle Ford model and find that most of the high-frequency energy is confined to the low-velocity reservoir. We corroborate this measurement with field microseismic data recorded by distributed acoustic sensing fiber installed outside of the Eagle Ford. The data contain high-frequency body-wave energy, but the guided waves are confined to low frequencies because the recording array is outside the waveguide. We also study the energy distribution between the fundamental and first guided-wave modes as a function of the frequency and source depth and find a nodal point in the first mode for source depths originating in the middle of the low-velocity zone, which we validate with the same field data. The varying modal energy distribution can provide useful constraints for microseismic event depth estimation.


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