Experimental validation of Orcaflex-based numerical models for the PEWEC device

Abstract

To design a Wave Energy Converter mooring system that ensures maintainability, resistance, and low costs, without affecting productivity, it is necessary to foster reliable numerical models. In the present paper, the validation of Orcaflex© simulations against the experiment results of the Pendulum Wave Energy Converter (PEWEC) 1:25 scale model, conducted at the University of Naples Federico II, is presented. The experiments consist of free-decay and static pull-out tests to assess the inertial properties of the model and mooring system; tests in operative and extreme regular and irregular waves to fully characterize the mooring system and the device dynamics. The same wave records measured in the towing tank have been used in numerical simulations. PEWEC motion results from numerical simulations and experiments are given in terms of Response Amplitude Operators (RAOs) for regular waves, as statistical values in tabular form, and in Taylor's diagrams for irregular waves. The most probable fairleads tensions for the load dimensioning have been obtained from the Generalized Extreme Value (GEV) distribution of experimental and numerical data. The obtained differences show that the numerical model accurately predicts the experimental data and correctly estimates the dimensioning load of the mooring lines.