An unsteady Cartesian grid based two-dimensional plus time method for simulating motion responses of high-speed vessels

Currently, the hydrodynamic simulation strategies for high-speed vessels exhibit a wide diversity. Direct three-dimensional (3D) Computational Fluid Dynamics simulation would be the most suitable choice if not for its time-consuming nature. To save computational resources and accelerate calculation speed, research works that utilize two-dimensional (2D) approaches to address three-dimensional problems have emerged over the past few decades, which represented by strip theory and two-dimensional plus time (2D+t) theory. Among them, Cartesian grid-based 2D+t method could be the most accurate one. However, this method, though often used to simulate ship-generated waves, is rarely applied to unsteady motion. A Cartesian grid-based unsteady 2D+t method is developed in this paper, which enables the simulation of the unsteady motions of high-speed vessels at semi-planning or near-planning states. A method for incorporating unsteady motion within the framework of 2D+t theory is proposed in the paper, along with the introduction of a novel central processing unit based multi-threaded task parallel method for multi-section parallel computation. With this method, a 3D unsteady motion problem of high-speed vessels is transformed into several 2D unsteady motion problems of deformable bodies. The proposed model is validated with selected cases, showing that the model is capable of simulating unsteady motion problems of high-speed vessels.