Applying site specific resource assessment: Methodologies for replicating real seas in the FLOWAVE facility

Abstract

FloWave is the world’s first combined current and wave test basin with a circular design that provides the capability to generate waves from all directions. This makes possible the production of realistic site-specific sea states, with no intrinsic limitations on the creation of multidirectional wave fields. In order to do this effectively, real site data must be used and manipulated in order to preserve both the sites characteristics and the directional complexity. A variety of methods are trialled here for reducing a wave buoy dataset to a subset of representative sea states. Using a year of half-hourly sea states (17520 in total) provided by the European Marine Energy Centre (EMEC), Orkney, UK, six methods have been evaluated, with the aim of producing twenty representative directional spectra. After defining a group ‘compactness’ metric, it was found that clustering either directly on the wave frequency spectra or on the directional spectra yielded the most favourable results with respect to a range of key variables. These approaches enable the groupings to be based on complex spectral shapes, and thus have the capability to yield complex statistically representative directional spectra suitable for replication in the FloWave facility.