ABSTRACT
This research demonstrates the use of the Moving Frame Method (MFM) to extract the equations of motion of a multi-body wave energy converter, M4, subject to hydrodynamic forcing. The MFM adopts notation from the Special Euclidean group, along with the mathematical views of Cartan. This notation is consistent, from 2D to 3D single bodies to multi-bodies. This work introduces hydrodynamic forces into the MFM, using linearization by Cummins’ equation in order to model the M4 in the time-domain, subject to irregular JONSWAP wave spectra. The impulse response function is pre-computed, and hydrodynamic coefficients are taken from a WAMIT diffraction model. The differential equations are advanced in time using a Runge-Kutta method. Results are compared to the earlier experimental work and show excellent agreement across the full range of peak periods investigated, opening the door for analysis of more complex marine and wave energy devices in all six degrees of freedom.
