||The Performance Assessment of Wave and Tidal Array Systems (PerAWaT) project, launched in October 2009 with £8m of ETI investment. The project delivered validated, commercial software tools capable of significantly reducing the levels of uncertainty associated with predicting the energy yield of major wave and tidal stream energy arrays. It also produced information that will help reduce commercial risk of future large scale wave and tidal array developments.
This report concerns the fully nonlinear simulations of the behaviour and performance of a single axisymmetric device and small arrays of axisymmetric devices, respectively, in irregular waves subject to linear and nonlinear power take-off (PTO) forces with different control strategies. The key objectives of the work were to simulate irregular waves effectively, to model the operation of axisymmetric devices subject to both linear and nonlinear PTO forces and to investigate the effect of device and array control strategies. The report outlines how these objectives have been met and any issues arising from their completion. An investigation into the importance of nonlinear contributions to free-surface elevation and also to the device response and power take-off by simulating a particular sea state with increasing significant wave height values is also reported. The different responses of the devices in irregular waves subject to linear and nonlinear PTO forces are also analysed and reported here