The Impact of Large Scale Wave Energy Converter Farms on the Regional Wave Climate
Over recent years the numerical simulation of Wave Energy Converters (WECs) has become a necessity. This enables the representation of many hydrodynamic interactions, allowing wave models to simulate processes from quantifying wave loading on a device to cumulative environmental impact of multiple arrays. This thesis explores highly flexible spatial models that allow actual device absorption characteristics to be incorporated, when the data becomes available. The simulation of DHI’s MIKE 21 Spectral Wave (SW) model for the Isle of Lewis was applied, where in situ wave measurement devices were used to generate boundary conditions and provide simulation calibration and validation. This quantifies one of the largest wave energy resources in Europe and acts as a base model for later device simulations. Multiple methods for simulating WECs within the SW model were tested, including the Reactive Polygon method. This flexible method for including device specific directional frequency based absorption and reflection was demonstrated by the simulation of a large array of Oyster devices in the nearshore region. Next, a method for including frequency-dependent power capture in a mid-range MIKE 21 Boussinesq Wave (BW) model was developed. Devices are represented as porosity layers, and frequency dependencies are achieved by propagating each component of the incident spectrum separately through the model, these are then recombining during a post-processing stage. A detailed comparison between the SW and BW results and governing equations motivated the development of a coupled simulation. An SW generated spectra interacts with devices in a BW simulation, the far-field device-disturbances of which are propagated in a second SW simulation. While the results of this demonstration model do not provide a totally accurate representation of spatial wave field, it remains the first of its type to be implemented. This thesis presents several new methods, which include important wave processes within computational simulations. These developments enable a much more accurate and efficient representation of the wave-device interactions for shallow water WECs.
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