Practical approach to investigate the statistics of nonlinear pressure on a high-speed ship by using the Volterra model

Abstract

The present method takes the results of the verified theory for regular waves and bridges a high-order numerical model to construct the time histories of ship responses in irregular waves. The theory is based on the strip method, with the nonlinearities of the force components calculated over the hull's instantaneous wetted surface, and the numerical model adopts the nonlinear third-order Volterra model. The advantage of this method is systematically leading the contributions of the high-order harmonics excited in regular waves into the response predictions for irregular waves. This study focuses on the nonlinear behavior of the pressure on the hull surface of a high-speed vessel in irregular waves of sea state five. A series of experiments was carried out involving both regular and irregular head waves. The ISSC 1979 wave spectrum was followed, with a significant wave height ( H 1/3) of 3.2 m and an average zero up-crossing period ( T H 1 / 3 ) of 8.0 s. It was confirmed that even for the strong nonlinearities, such as the pressure responses near the waterline or near the keel on the bow zone, the present method is more realistic than that of the usual linear practice.