LiST: A Linear Seakeeping Time-domain potential flow model using multi-resolution meshes

Abstract

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• A time-domain Rankine panel method for seakeeping with forward speed is presented. • The code allows the use of multi-resolution meshes to improve efficiency. • An incident impulse wave is used to calculate RAOs. • Results are analyzed in calm water, head waves and following waves. A time-domain potential-flow solver is developed to study the linearized ship-wave interaction problem with forward speed. A Rankine panel method is implemented to model both a hull advancing in calm water and in waves. The former case is important in evaluating the wave-making resistance of hulls while the latter gives the hydrodynamic loads and motion responses for ships interacting with ocean waves. A constant panel method with an indirect approach is adopted to obtain a robust and efficient simulation tool. The problem is formulated such that no connectivity information on the mesh is necessary, allowing the use of multi-resolution meshes that reduce the computational costs in a simple and efficient way. The calm water problem is validated on a Wigley hull. A convergence analysis is conducted, investigating both the wave resistance and the wave profile. For the unsteady seakeeping problem, tests with an impulse wave are implemented to reduce simulation times. The radiation and diffraction loads, and the motion responses for the RIOS bulk carrier in head waves are presented. In addition, the S175 containership is studied in head and in following seas, showing the method is capable of predicting the hull response in both sea conditions with forward speed. A final test in irregular waves demonstrates the ability of the solver in simulating realistic sea conditions.