ABSTRACT

Panel methods based on potential flow theory have been widely employed for wave-structure interactions, since these methods could provide fast, reliable and accurate predictions for the forces acting on and the motions of the marine structures if the strong nonlinear forces are not included in the analyses. In reality, some panel methods can be regarded as the industry standards, and also some open sources are available.

The comparisons in this research work include: 1) the comparison between WAMIT and HAMS; 2) the comparisons to see the improvement using the options of irregular frequency removal (IRR); 3) the comparisons on the original TALOS and the circular TALOS; 4) the comparison for the incomplete panels on the circular TALOS; 5) the comparison for the overlapped panels on the circular TALOS.

INTRODUCTION

Panel methods based on potential flow theory are matured techniques, widely applied in studying the wave-structure interactions, since these methods could provide fast, reliable and accurate predictions for the forces acting on and the motions of the marine structures if the strong nonlinear forces are not present in the analyses. This is true for many applications, especially for the conventional ocean platforms for which the platforms have been designed to have small motions (or linear motions) in waves (Unneland 2007; Perez and Fossen 2008b; Perez and Fossen 2008a), and now it is also widely used for wave energy converters, for which the structural motions may be designed to be large so to extract more energy from waves. However, in reality, for real wave energy converters (WECs), the applications of PTO could make the structural motions smaller, thus the panel methods based on the potential flow theory is still applicable for wave-structure interactions for wave energy converters (Duclos, Babarit, and Clement 2006; Falcao 2008; Cordonnier et al. 2015; WEC-SIM 2015; Bailey, Robertson, and Buckham 2016; Sheng and Lewis 2016; Penalba, Kelly, and Ringwood 2017; Wendt et al. 2017; Sheng 2019a; Falcao 2010; Sheng 2019b), though the limited CFD applications in wave energy converters can be also found (Devolder et al. 2018; Wendt 2019; Ransley et al. 2017). Due to the nature of time dependence in wave-structure interactions, CFD applications would meet the challenges of significant computational burden, due to vast computations. For instance, for an irregular waves of an average period 8s, to reach a meaningful statistics, the computation must cover more than 100 wave cycles, that is, a modelling for more than 800s. We can imagine how much computational resources would be required. This is why the panel methods are so widely employed.

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