CFD Simulations of Self-Propulsion and Turning Circle Maneuver up to 90º of Ship in Waves

In the present work, a Reynolds-Averaged Navier-Stokes (RANS)-overset method is used to numerically investigate self-propulsion and turning circle maneuver in waves for a container ship. A computational fluid dynamics (CFD) solver naoe-FOAM-SJTU is used for the numerical computations of the fully appended Duisburg Test Case ship model. Overset grids are used to handle the motions of the ship hull appended with the propeller and the rudder. Open source toolbox waves2Foam is used to prevent wave reflection in the computational domain. The current numerical method is validated by comparing the ship speed in the self-propulsion case between CFD and Experimental Fluid Dynamics (EFD). Predicted ship 6-DOF motions, hydrodynamic forces, free surfaces, and inflow of the propeller are presented. The propulsion characteristic is mainly studied. Assuming the thrust identification method works even in unsteady conditions, the wake fraction and propulsion efficiency are discussed. The effect of orbital motion of water particle and ship motion on the propulsion performance are identified. In conclusion, the present RANS-overset method is a reliable approach to directly simulate self-propulsion and turning circle maneuver in waves.

An Investigation Into KCS Parametric Rolling Through Coupling Different DOFs

The research of parametric rolling has encountered many challenging problems due to its nonlinearity. In this paper, an in-house CFD code HUST-Ship based on fully structured overset grids is used for the investigation of KCS parametric rolling, which can overcome the shortcomings of potential flow method. Modeling errors and numerical errors are presented to improve the credibility of CFD simulation. The grid and time step are studied for the quantification of numerical errors. The phenomenon of parametric rolling is successfully captured in the paper and motion responses of KCS have a good agreement with experimental data. The characteristics of motions, forces and moments under parametric rolling are investigated by using fast Fourier transform. The relationship between wave characteristics and motion responses of ship is revealed in this paper. Following, a simulation model with three DOFs’ model (heave-roll-pitch model) is used to investigate the influence of surge motion on parametric rolling. Result shows that the excluding of surge motion has no qualitative influence on the prediction of parametric rolling. In general, the simulation limited to heave-roll-pitch coupling is adequate for its capture.