Wave Modelling for Potential Wave Energy Sites Around the Outer Hebrides

This paper presents the results of a numerical wave modelling study carried out to assess the near shore wave energy resource around potential wave energy sites at the Outer Hebrides in the United Kingdom. This study uses Danish Hydraulic Institute’s MIKE 21 Spectral Wave model suite. Input boundary conditions are obtained from a Datawell directional wave buoy located approximately 16 km off the coast of Lewis in 60 metre depth. Additional data collected from a submerged Acoustic Wave and Current profiler (AWAC) located at 13 metre depth offshore at one of the wave energy development sites was used to calibrate and validate the wave model for separate time periods. The calibration process allows the manipulation of white capping, bottom friction and wave breaking parameters to alter the energy dissipation across the model domain. The altered parameters gave a significantly better agreement between modelled and measured results than the model defaults. While the average wave conditions provided a relatively straightforward calibration process the more extreme storm events significantly under predicted the wave height. After several trials in altering model coefficients a good agreement was reached between the model results and the AWAC data. These new sets of calibration parameters enable the simulation of wave heights within 13% for the AWAC data and marginally more for wave periods for the first 6 months of 2012.