Desenvolvimento de Modelo de Manobra sob ação de ondas regulares pelo método das duas escalas

Abstract

The influence of regular waves on the maneuverability of ships was investigated. To achieve this goal, the two-timescale method was applied, which addresses the problem in higher-frequency and lower-frequency. For the wave-induced forces, only the mean second-order forces were provided to the maneuvering model, because they are in lower frequency. First, the maneuvering model in calm water was implemented based on MMG standard method using empirical data from the hydrodynamic derivatives of the hull and the rudder and propeller coefficients. Then, the seakeeping behavior was analyzed using the Strip Theory-based software PDStrip. After calculating the RAOs, the mean second-order wave forces were obtained. The mean second-order wave forces are treated as a quasi-static component of the maneuvering model, so they must be updated along with the variation of the ship’s velocity and heading. Therefore, a database of forces and moments as functions of the wave incidence angle and the absolute velocity of the ship was created. Various simulations with systematic variations of wavelength and amplitudes were performed to verify the impact of these parameters on the ship’s maneuvers in waves. The simulations for long waves have presented a good agreement with experimental data, but for short waves, the results were satisfactory only for lower wave amplitudes.