A BEM for the Hydrodynamic Analysis of Oscillating Water Column Systems in Variable Bathymetry

Abstract

<jats:p>In this work, a novel Boundary Element Method (BEM) is developed and applied to the investigation of the performance of Oscillating Water Column (OWC) systems, taking into account the interaction of the incident wave field with the bottom topography. The modelling includes the effect of additional upwave walls and barriers used to modify the resonance characteristics of the device and improve its performance as the U-OWC configuration. Numerical results illustrating the effects of depth variation in conjunction with other parameters—such as chamber dimensions as well as the parameters associated with the turbine and power take-off system—on the device performance are presented and discussed. Finally, a case study is presented regarding the potential installation of an OWC in a selected port site in the Black Sea, characterized by a good wave energy potential, on the coast of Romania.</jats:p>

The Influence of the Chamber Configuration on the Hydrodynamic Efficiency of Oscillating Water Column Devices

“…The variation of the radiation susceptance and radiation conductance coefficients versus Kh when h a /h = 0.125 and b/h = 1.0 for different values of w/b(= 2.0, 1.5, 1.0, 0.5, and 0.01) is shown in Figure 7a,b, respectively. In Figure 7a it is observed that the frequencies for which µ is zero are related to the peaks of maximum efficiency shown in Figure 6a, which is also evident from the maximum efficiency Equation (27). Figure 7a also shows that when the thickness ratio w/b increases, the range of the non-dimensional frequency Kh for which µ is negative also increases.…”

“…Figure 12 shows that the numerical solution and the experimental results of [21] are in good agreement for a linear turbine damping coefficient Λ = 5 × 10 −4 m 4 •s/kg. However, it is observed that by comparing the maximum theoretical efficiency obtained from Equation (27) and the experimental efficiency, the discrepancy is high. Therefore, special attention should be paid to turbine damping, as well as non-linear effects, in order to make an adequate estimation of the power absorption of an OWC device.…”

“…They concluded that the OWC structural design and bottom profile can significantly increase the hydrodynamic efficiency. A 2D BEM model for analyzing the OWC's response in general bathymetry regions was carried out by [27]. They showed that the effects of the bottom slope and curvature on the OWC performance could be important, especially when the wave climate leads the site-specific optimal design to low resonance frequencies.…”

Assessing Renewable Resources at the Saronikos Gulf for the Development of Multi-Generation Renewable Systems

“…The area has a low energy density resource potential, due to its sheltered characteristics and changes in bathymetry. However, even in such an area, the mean wave energy resource was 0.13-0.17 kW/m (130-170 W/m), which can be harnessed efficiently and contribute to local power production [34,35]. As waves propagate further into the Gulf, the islands of Aigina and Salamina are the main natural elements (obstacles) that reduce waves.…”

Special Issue “Advances and Challenges in Harvesting Ocean Energy”

“…The study lays a theoretical foundation for the design of further experiments and engineering prototypes to verify the validity of mathematical models by way of experimental analysis. In another work [12], a novel boundary element method is developed and applied to the investigation of the performance of oscillating water column (OWC) systems, taking into account the interaction of the incident wave field with the bottom topography. The modeling includes the effect of additional up wave walls and barriers used to modify the resonance characteristics of the device and improve its performance as the U-OWC configuration.…”