Hydrodynamic characteristics of an oscillating water column device
TL;DR: In this article, a wave energy device consisting of a thin vertical surface-piercing barrier next to a vertical wall in finite depth water is considered, and power is extracted due to a normally incident wave forcing the free surface of the fluid between the barrier and the wall to oscillate.
About: This article is published in Applied Ocean Research.The article was published on 1995-06-01. It has received 267 citations till now. The article focuses on the topics: Surface wave & Oscillating Water Column.
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TL;DR: A comprehensive review of wave energy converters and air turbines can be found in this paper, together with a survey of theoretical, numerical and experimental modelling techniques of OWC converters.
594 citations
TL;DR: In this article, a configuration of floating breakwater with asymmetric pneumatic chambers was proposed to increase the amplitude of the oscillating air-pressures inside both chambers over a wide range of wave frequency (thus to improve the performance in wave energy extraction).
197 citations
TL;DR: In this paper, an oscillating water column (OWC) is studied experimentally to examine energy efficiencies for power take-off in a wave environment with plane progressive waves of steepness ranging from kA = 0.01 to 0.22 and water depth ratios varying from kh=0.30 to 3.72.
Abstract: An oscillating water column device enables the conversion of wave energy into electrical energy via wave interaction with a semi-submerged chamber coupled with a turbine for power take off. This present work concentrates on the wave interaction with the semi-submerged chamber, whereby a shore based oscillating water column (OWC) is studied experimentally to examine energy efficiencies for power take-off. The wave environment considered comprises plane progressive waves of steepnesses ranging from kA=0.01 to 0.22 and water depth ratios varying from kh=0.30 to 3.72, where k, A, and h denote the wave number, wave amplitude, and water depth, respectively. The key feature of this experimental campaign is a focus on the influence of front wall geometry on the OWC’s performance. More specifically, this focus includes: front wall draught, thickness, and aperture shape of the submerged front wall. We make use of a two-dimensional inviscid theory for an OWC for comparative purposes and to explain trends noted in the experimental measurements. The work undertaken here has revealed a broad banded efficiency centered about the natural frequency of the OWC. The magnitude and shape of the efficiency curves are influenced by the geometry of the front wall. Typical peak magnitude resonant efficiencies are in the order of 70%.
176 citations
TL;DR: In this paper, a numerical method based on a two-phase level set with the global mass correction and immersed boundary method is developed to simulate wave interaction with a semi-submerged chamber.
158 citations
TL;DR: In this paper, a stochastic method has been developed to evaluate the average performance of an oscillating water column wave energy device equipped with an assumedly linear Wells turbine, represented by a set of sea states, characterized by their power spectra, the free-surface elevation being a Gaussian random variable in each sea state.
155 citations
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TL;DR: In this paper, a theory for predicting the absorption of the power in an incident sinusoidal wave train by means of a damped, oscillating, partly or completely submerged body is given.
Abstract: A theory is given for predicting the absorption of the power in an incident sinusoidal wave train by means of a damped, oscillating, partly or completely submerged body. General expressions for the efficiency of wave absorption when the body oscillates in one or, in some cases, two modes are given. It is shown that 100% efficiency is possible in some cases. Curves describing the variation of efficiency and amplitude of the body with wavenumber for various bodies are presented.
470 citations
TL;DR: In this article, the efficiency of energy absorption of a system of uniform oscillatory surface pressure distributions was derived based on linear water-wave theory and the results showed the close analogies which exist with theories for absorbing oscillatory rigid bodies and a number of new reciprocal relations for pressure distributions.
Abstract: Some general results are derived for the efficiency of energy absorption of a system of uniform oscillatory surface pressure distributions. The results, which are based on classical linear water-wave theory, show the close analogies which exist with theories for systems of absorbing oscillatory rigid bodies and a number of new reciprocal relations for pressure distributions are suggested and proved. Some simple examples illustrating the general results are given and compared with the corresponding results for rigid bodies.
356 citations
225 citations
TL;DR: In this paper, a Galerkin approximation method was proposed to solve the wave scattering problem in finite-depth water with respect to vertical barriers in a rectangular tank and a vertical barrier in a vertical pool.
Abstract: Scattering of waves by vertical barriers in infinite-depth water has received much attention due to the ability to solve many of these problems exactly. However, the same problems in finite depth require the use of approximation methods. In this paper we present an accurate method of solving these problems based on a Galerkin approximation. We will show how highly accurate complementary bounds can be computed with relative ease for many scattering problems involving vertical barriers in finite depth and also for a sloshing problem involving a vertical barrier in a rectangular tank.
195 citations
TL;DR: In this paper, Salter has demonstrated experimentally that a horizontal cylinder in the free surface of water can be a device to extract energy from the incident waves and proposed a design which is based on the idea of a tethered-float breakwater, and gives the theoretical design criteria for maximum power extraction from a general floating cylinder with one or two degrees of freedom.
Abstract: Salter has demonstrated experimentally that a horizontal cylinder in the free surface of water can be a device to extract energy from the incident waves This paper proposes a design which is based on the idea of a tethered-float breakwater, and gives the theoretical design criteria for maximum power extraction from a general floating cylinder with one or two degrees of freedom It is shown that the rate of energy extraction must be equal to the rate of radiation damping and that the floating body must be made to resonate Then for a body with one degree of freedom, the maximum efficiency at a given frequency can be at least one half if the body is symmetrical about a vertical axis, and greater for an asymmetrical body For a body with two degrees of freedom, all the wave power can be extracted Hydrodynamical aspects of the controlled motion are examined Viscous effects are ignored
172 citations