Laboratory Observations of Waves in the Vicinity of WEC-Arrays

In order to better constrain models for simulating the environmental effects of large-scale arrays of Wave Energy Converters (WECs), we have performed laboratory experiments using five 1:33 scale, commercially-designed, point-absorber WECs. Multiple array configurations (1-device, 3-device, and 5device) were subjected to a wide range of wave conditions—both regular waves and fully-directional sea states. The experimental instrumentation was extensive and included: a large number of wave gages and current meters, a 3D WEC motion tracking system, and stereo video for 3D wave imaging in the near-field of the WEC-arrays. Initial results presented here quantify the degree of wave shadowing induced by the various incident wave conditions and demonstrate the dependence of shadowing on the chosen array configuration. Denser WEC-arrays lead to more shadowing, and frequency and directional spreading in the wave field smoothes the wave height variation and reduces the shadow in the lee of the arrays. The results also show a clear relationship between wave shadowing and device performance, which indicates that wave absorption, not scattering, is the dominant process producing the shadow. Keywords— wave energy, lab experiments, wave shadowing, environmental effects