Numerical modelling of the HAB Energy Buoy: Stage 1

This report presents the results of the first stage of the project "Numerical modelling of the HAB Energy Buoy". The objectives of this stage are to develop a numerical model of the HAB Energy Buoy, a self-reacting wave energy device consisting of two heaving bodies, and to investigate a number of variations of the device geometry in order to arrive at a design optimized for the target deployment site. The findings will be used as a basis to inform planned small-scale wave tank tests. A review of literature on self-reacting wave energy devices consisting of two heaving bodies has been conducted and a summary of the main findings is presented. A numerical model of the HAB Energy Buoy has been developed in the frequency domain using two alternative formulations of the equations of motion. The model is capable of predicting the power capture, motion response, and power take-off loads of the device. The model is further able to give an estimate of the power production of the device in a given wave climate as well as other statistical estimates of the device motions and loads. The performance of different device shapes and dimensions has been evaluated, where displacement limits appropriate for each configuration are imposed to give a more realistic prediction of the power capture and help ensure a fair comparison. Recommendations with regard to the HAB design are finally suggested.