Effects of Loading Conditions on Hydrodynamics of a Hard-Chine Planing Vessel Using CFD and a Dynamic Model

Planing vessels usually have low ratios of resistance to weight, so they can move fast on sea surface than the displacement or semi-displacement ships. Access to higher speeds is one of the attractions for designers and users. To achieve higher speeds, reducing the hydrodynamic resistance is a necessity for this class of vessels. In this study, a 3D finite volume approach is used to analyze the hydrodynamics of the Cougar high-speed vessel, a hard chine planing hull. In addition to use of the URANS equations for momentum, SIMPLE algorithm for coupling of the pressure and velocity field and the k-e for turbulence modeling, the fluid phases of air/water and the free surface are modeled using the volume of fraction (VOF) scheme. Moreover, in the simulations, instead fixing the freedom of the model regards to the computational domain, the vessel motions are also considered to have two degrees of freedom, 2-DOF, using the newly developed moving mesh technique of Overset. The grid independency study shows a good consistency between the numerical results and experiments for the vessel resistance, trim angles and the heave. Main emphasis of this paper is on study of the effects of different loading conditions, the vessel weight and the longitudinal center of gravity, on the hydrodynamic characteristics such as resistance, trim angle and the vessel sinkage. All of the numerical simulations are done using the commercial software of Star CCM+