Experimental validation of time domain simulations with HAMS-MREL and comparative analysis of linear and weakly nonlinear models for dense WEC arrays

Abstract

The accurate modelling of hydrodynamic interactions in dense arrays of Wave Energy Converters (WECs) is critical for optimizing design and predicting energy capture efficiency. This study presents the first time-domain experimental validation of the Boundary Element Method (BEM) multi body solver HAMS-MREL, for WEC arrays. The validation involves a comparative assessment of wave excitation forces from numerical predictions and physical measurements for an array of 5 floaters. Results exhibit good overall agreement, with Normalized Root Mean Square Error (NRMSE) values typically below 10 %, though with some exceptions. The results highlight solver limitations that vary with wave steepness and floater positioning within the array. Additionally, this study presents the first integration of HAMS-MREL with WEC-Sim for time-domain simulations, evaluating the linear HAMS-MREL and the weakly nonlinear WEC-Sim hydrodynamic models across various wave conditions. The comparative study conducted with the Ocean Grazer 4.0 case, a dense array of 18 floaters around a monopile, reveals the conditions under which linear modelling remains valid and when nonlinear approaches become necessary. Despite significant wave excitation force differences at wave steepness above 2 %, power output estimates remain within acceptable limits (∼10 %). These findings offer critical insights into appropriate model selection for different wave conditions.