Coupling methodology for modelling the near field and far field effects of an array of wave energy converters (original) (raw)
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In this study, a series of modules is integrated into a wave-to-wire (W2W) model that links a Boundary Element Method (BEM) solver to a Wave Energy Converter (WEC) motion solver which are in turn coupled to a wave propagation model. The hydrodynamics of the WECs are resolved in the wave structure interaction solver NEMOH, the Power Take-off (PTO) is simulated in the WEC simulation tool WEC-Sim, and the resulting perturbed wave field is coupled to the mild-slope propagation model MILDwave. The W2W model is run for verified for a realistic wave energy project consisting of a WEC farm composed of 10 5-WEC arrays of Oscillating Surging Wave Energy Converters (OSWECs). The investigated WEC farm is modelled for a real wave climate and a sloping bathymetry based on a proposed OSWEC array project off the coast of Bretagne, France. Each WEC array is arranged in a power-maximizing 2-row configuration that also minimizes the inter-array separation distance d x and d y and the arrays are locate...
Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays
2013
This project will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. We will develop a predictive understanding of the effects of an array of wave energy converters on the wave conditions and the potential for any wave field modifications to change nearshore current and sediment transport patterns 2. Project Scope This project addresses Topic Area 2: "Marine and Hydrokinetic Site-specific Environmental Studies/Information" under FOA Number DE-FOA-0000069 and is an industry-led partnership that will perform environmental testing studies regarding the installation of arrays of wave energy conversion devices. The study will perform benchmark laboratory experiments using an array of 1:33 scale wave energy conversion devices. The experiments will quantify the wave scattering effects of these arrays and be used to develop and test numerical models for wavestructure interaction and far-field hydrodynamic effects. 3. Accomplishments (Task Deliverables) 3.1.
A Review of Numerical Modelling of Wave Energy Converter Arrays
Volume 7: Ocean Space Utilization; Ocean Renewable Energy, 2012
Large-scale commercial exploitation of wave energy is certain to require the deployment of wave energy converters (WECs) in arrays, creating ‘WEC farms’. An understanding of the hydrodynamic interactions in such arrays is essential for determining optimum layouts of WECs, as well as calculating the area of ocean that the farms will require. It is equally important to consider the potential impact of wave farms on the local and distal wave climates and coastal processes; a poor understanding of the resulting environmental impact may hamper progress, as it would make planning consents more difficult to obtain. It is therefore clear that an understanding the interactions between WECs within a farm is vital for the continued development of the wave energy industry. To support WEC farm design, a range of different numerical models have been developed, with both wave phase-resolving and wave phase-averaging models now available. Phase-resolving methods are primarily based on potential flo...
Laboratory Observations and Numerical Modeling of the Effects of an Array of Wave Energy Converters
Coastal Engineering Proceedings, 2012
This paper investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, in collaboration with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. Using measured power absorption characteristics as a WEC parameterization for SWAN was developed. This parameterization was verified by comparison to the observational data set. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field.
Physical modelling of wave energy converter arrays in a large-scale wave basin: the WECwakes project
Tests have been performed in the Shallow Water Wave Basin of DHI (Hørsholm, Denmark), on large arrays of up to 25 heaving point absorber type Wave Energy Converters (WECs), for a range of geometric layout configurations and wave conditions. WEC response and modification of the wave field have been measured to provide data for the understanding of WEC array interactions and for the evaluation of array interaction numerical models. Each WEC consists of a buoy with a diameter of 31.5 cm and power take-off is modelled by realizing friction based energy dissipation through damping of the WEC's motion. Wave gauges were located within and around the WEC array. Wave conditions studied include regular, polychromatic, long-and short-crested irregular waves. A rectilinear arrangement of WEC support structures has been employed such that several array configurations could be studied. The experimental arrangement and the obtained database are presented. Results have been obtained for power a...
Energies
Wave Energy Converters (WECs) need to be deployed in large numbers in an array layout in order to have a significant power production. Each WEC has an impact on the incoming wave field, by diffracting, reflecting and radiating waves. Simulating the wave transformations within and around a WEC array is complex; it is difficult, or in some cases impossible, to simulate both these near-field and far-field wake effects using a single numerical model, in a time-and cost-efficient way in terms of computational time and effort. Within this research, a generic coupling methodology is developed to model both near-field and far-field wake effects caused by floating (e.g., WECs, platforms) or fixed offshore structures. The methodology is based on the coupling of a wave-structure interaction solver (Nemoh) and a wave propagation model. In this paper, this methodology is applied to two wave propagation models (OceanWave3D and MILDwave), which are compared to each other in a wide spectrum of tests. Additionally, the Nemoh-OceanWave3D model is validated by comparing it to experimental wave basin data. The methodology proves to be a reliable instrument to model wake effects of WEC arrays; results demonstrate a high degree of agreement between the numerical simulations with relative errors lower than 5% and to a lesser extent for the experimental data, where errors range from 4% to 17%.
Renewable Energy, 2019
This research focuses on the numerical modeling of wave fields around (oscillating) structures such as wave energy converters (WECs), to study both near and far field WEC effects. As a result of the interaction between oscillating WECs and the incident wave field, additional wave fields are generated: the radiated and the diffracted wave field around each WEC. These additional wave fields, together with the incident wave field, make up the perturbed wave field. Several numerical methods are employed to analyse these wave fields around WECs. For example, for investigating wave-structure (wave-WEC) interactions, wave energy absorption and near field effects, the commonly used and most suitable models are based on Boundary Element Methods for solving the potential flow formulation, or models based on the Navier-Stokes equations. These models are here referred to as 'wave-structure interaction solvers'. On the other hand, for investigating far field effects of WEC farms in large areas, wave propagation models are most suitable and commonly employed. However, all these models suffer from a common problem; they cannot be used to model simultaneously both near and far field effects due to limitations. In this paper, a generic coupling methodology is presented, developed to combine the advantages of the above two approaches; (a) the approach of wave-structure interaction solvers, which are used to investigate near field effects because they can more correctly model wave energy absorption and the resulting wave fields induced by oscillating WECs or WEC farms. These solvers suffer from high computational cost and thus are mainly used for limited: (i) areas around WECs; (ii) number of WECs, and (b) the approach of wave propagation models, which are used for predicting far field effects and which can model the effect of WEC farms on the wave field and the shoreline in a costeffective manner, but usually cannot deliver high-fidelity results on wave energy absorption by the WECs.
Impact of wave interactions effects on energy absorption in large arrays of wave energy converters
Ocean Engineering, 2012
This paper presents a parametric study on arrays of wave energy converters (WECs). Its goal is to assess the influence of interactions between bodies on the overall yearly energy production of the array. Generic WECs (heaving cylinder and surging barge) are considered. Nine to twenty-five WECs are installed along regular square and triangular grids; the influence of the separating distance between the WECs is investigated. Results show that constructive and destructive interactions compensate each other over the considered range of wave periods. The influence of the separating distance can be limited, especially if the damping of the power takeoff is tuned properly, and if the WECs have a large bandwidth. It is found that grouping the devices into arrays have generally a constructive effect. Diffracted and radiated waves in the array lead to a sufficient increase in the energy absorption which overcomes the reduction due to masking effects.
An overview of the WECwakes project: physical modeling of an array of 25 wave energy converters
Experiments have been performed in the DHI Shallow Water Wave Basin (Denmark), on large arrays of up to 25 heaving point absorber Wave Energy Converters (WECs), for a range of geometric layout configurations and wave conditions. WEC response, surge forces on the WECs and modification of the wave field are measured to provide data for the understanding of WEC array interactions/effects. Wave conditions studied, include regular, polychromatic, long- and short-crested irregular waves. The experimental arrangement and the obtained database are presented. For irregular long-crested waves, up to 18.1% attenuation of significant wave height is observed downwave a rectilinear array of 25 heaving WECs.
Volume 8A: Ocean Engineering, 2014
Knowledge of the wave perturbation caused by an array of Wave Energy Converters (WEC) is of great concern, in particular for estimating the interaction effects between the various WECs and determining the modification of the wave field at the scale of the array, as well as possible influence on the hydrodynamic conditions in the surroundings. A better knowledge of these interactions will also allow a more efficient layout for future WEC farms. The present work focuses on the interactions of waves with several WECs in an array. Within linear wave theory and in frequency domain, we propose a methodology based on the use of a BEM (Boundary Element Method) model (namely Aquaplus) to solve the radiation-diffraction problem locally around each WEC, and to combine it with a model based on the mild slope equation at the scale of the array. The latter model (ARTEMIS software) solves the Berkhoff’s equation in 2DH domains (2 dimensional code with a z-dependence), considering irregular bathyme...