Decomposition and prediction of initial uniform bi-directional water waves using an array of wave-rider buoys

Prediction of incident waves to Wave Energy Converters (WEC) is essential to maximize the energy absorption by controlling the WEC. Nevertheless, little work has been done on the deterministic prediction of bi-directional waves whose wave directions of components are 180∘ opposite. To decompose and predict such bi-directional waves, an array of three wave-rider buoys are considered. Buoys on both sides are used for decomposing bi-directional waves into progressive and regressive wave components, and the surface elevation of the middle buoy is predicted by these decomposed waves. The deterministic wave prediction is based on the impulse response function, and a cosine-filtered impulse response function is proposed to reduce an error due to the truncation of the infinite length of the function. Predictions of initial uniform bi-directional waves are shown to demonstrate the performance of the impulse response function method to time-series prediction. Both numerical and experimental comparisons are carried out to validate the proposed methods. The experimental validation revealed that the proposed bi-directional prediction method can predict such waves with at most 5% Mean Absolute Error within this experiment.