Solution verification of WECs: comparison of methods to estimate numerical uncertainties in the OES wave energy modelling task

• High-fidelity models become more and more used in the wave energy sector. They offer a fully nonlinear simulation tool that in theory should encompass all linear and nonlinear forces acting on a wave energy converter (WEC). The focus on the studies using are usually dealing with validation. However, a validated model does not necessarily give reliable solutions. Solution verification is the methodology to estimate the numerical uncertainties related to a simulation. In this work we test four different approaches: the classical grid convergence index (GCI); a least-square version (LS-GCI), a simplified version of the least-square method (SLS-GCI) and the ITTC rec- ommended practice. The LS-GCI requires four or more solutions whereas the other three methods only need three solutions. We apply these methods to four different high- fidelity models for the case of a heaving sphere. We tested two parameters in the time-domain and two parameters in the frequency domain. It was found that the GCI and ITTC were hard to use on the frequency domain parameters as they require monotonic convergence which sometimes does not happen due to the differences in the solutions being very small. The SLS-GCI performed almost as well as the SL-GCI method and will be further investigated.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Marin teknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Marine Engineering (hsv//eng)

Nyckelord

CFD

numerical uncertainty

solution verification

wave energy converter

Publikations- och innehållstyp

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