|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 introduces the methodology to be used for assessing the fully nonlinear hydrodynamic response of wave energy converters (single devices and arrays of point absorbers). It describes the key steps for implementing the boundary element potential flow model OXPOT, addressing issues such as the formulation of higher order elements and discontinuous elements, mesh generation and regridding, use of an artificial damping layer, time stepping, and the use of domain decomposition to improve computational efficiency. Examples of implementation of the model are given, including comparison of results with experimental data.
Additionally, by way of introduction, the report briefly raises some technical issues which might be addressed in the development of a design methodology for wave energy converters. Several of these were investigated in the course of obtaining results reported in subsequent deliverables.
Furthermore, the report also outlines the intended stages of applying the nonlinear methodology, including the evaluation of a range of cases of increasing realism and complexity. Consideration is also given to modelling the behaviour of wave energy converters in both regular and irregular seas.
Issues of validation are to be addressed through comparison withexperimental results from WG2 WP1 and WG2 WP2. The results for the nonlinear model will then be used in an assessment of the accuracy of linear models applied to various scenarios.