Experimental Study into the Diffracted Wave Field Downstream of an Array of Wave Energy Converters in Irregular Waves

For wave energy to be a viable renewable energy source, conversion devices will eventually be deployed in large arrays. Presently, knowledge of device interactions within arrays is limited to numerical studies; however, for development in array design and deployment to progress, verification through experimentation is needed. Experiments were conducted with arrays of submerged spheres representing generic wave energy converters subject to a realistic irregular wave series. Using nonintrusive stereo-videogrammetry, the domain within and downstream of the devices was measured at high resolution, and hence the wave field characteristics by wave diffraction were mapped through processing of the time record. It is shown that the experimental diffracted wave field matches the existing numerical models within the region measured, showing shadows of attenuation and amplification of the wave energy flux spreading from the array. These lead to possibilities for optimisation of arrays making use of constructive interference present. Ultimately, these results offer a contribution to the acknowledged need for experimental validation of existing models, while presenting videogrammetry as a viable alternative to traditional wave measurement technologies.