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Based on the potential flow theory and traditional boundary element method (BEM), Taylor expansion boundary element method (TEBEM) is introduced in this paper for the prediction of the flow field around ship, as a result, hull gesture and pressure distribution on hull surface are obtained. By this method, dipole strength of every field point is expanded in Taylor expansion, so that approximately continuous hull and free surface boundary condition could be achieved. To close the new equation system, the boundary condition of tangent velocity in every control point is introduced. With the simultaneous solving of hull boundary condition and free surface condition, the disturbance velocity potential could be obtained. The present method is used to predict the flow field and hull gesture of Wigley parabolic hull, Series 60 and KVLCC2 models. To validate the numerical model for full form ship, the wave profile, the computed hull gesture and hull surface pressure of KVLCC2 model are compared with experimental results.

One of the approaches for numerical prediction of the ship maneuvering in still water is based on the lifting theory. In this paper, a numerical method for the fast prediction of the maneuvering motion of the trimaran in still water is developed based on the Source and Quasi Continuous Vortex Lattice Method (SQCM). By the SQCM, the captive model test of the trimaran could be simulated, and the corresponding hydrodynamic coefficients could be obtained. Combined with the MMG maneuvering motion model, the rapid forecasting of the maneuvering motion characteristics of the trimaran is realized. The numerical method is validated by comparison with the tank test, and the turn and zigzag maneuvers of trimaran of different side-hull arrangements at various speeds are predicted. • The captive model test of the trimaran are simulated to obtain the force, moment, and hydrodynamic derivatives by the SQCM method. • The turn and zigzag maneuvers of the trimaran are predicted by the MMG model and the hydrodynamic derivatives. [ABSTRACT FROM AUTHOR]

Based on the open-source code OpenFOAM, a hybrid method based on the fully nonlinear potential flow method (FNPT) and the viscous flow method, combined with the propulsion model of the propeller and rudder, is used to simulate the turning and zigzag maneuvering motion of a single-screw ship in stern and beam waves. The wave is generated by FNPT, and the 6DOF maneuvering motion in waves and the ship-wave interaction are simulated by the viscous flow method in the internal field. The force and moment of the propeller and rudder are obtained by the propulsion model to improve the computational efficiency. The KVLCC2 model is used as the object for numerical simulation, and the numerical method is validated by the self-propulsion tank test. The maneuvering motion of the ship at the designed speed in stern and beam waves is simulated, and the turning and heading performance of the ship in the stern and beam waves is studied and analyzed by changing the wavelength. • The turn and zigzag maneuvers of a one-screw ship are simulated by a hybrid method, by which the 6DOF motion of the ship and the effect of the waves on the propulsion efficiency are considered. The numerical method is validated by comparison with the experimental data in two wave directions. • The turn and zigzag maneuvers of the ship in the initial stern and beam waves of different wavelengths are simulated. The effect of the wavelengths on the turning and course change of the ship in different initial wave headings is studied. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid method coupling potential flow method and viscous flow method is applied to simulate the autopilot trimaran in stern waves. The aim is to study the process of being captured by waves and the surf-riding characteristics of the trimaran. The FNPT-based QALE-FEM is used to simulate the wave tank of the external field, and the viscous flow method is used to simulate the autopilot of the trimaran in the wave tank. The sailing and 6DOF motion of the trimaran in waves of different parameters is simulated. The autopilot of a trimaran in stern waves of different lengths and steepness is simulated to study the characteristics of the trimaran's surf-riding in waves. When studying the effect of wave steepness, the wavelength is constant, and various forward speeds of trimaran could change the encounter frequency. However, the trimaran's wave steepness and forward speed are kept constant when the wavelength changes. By the computed results, it is found that the high speed and large wave steepness could significantly increase the vulnerability of trimaran's surf-riding in stern waves, and the wave passing the transom stern and side hulls could accelerate the trimaran to reach the wave celerity. • A hybrid method coupling the FNPT-based QALE-FEM and viscous flow theory is applied to simulate the navigation of trimaran in stern waves. An external domain by FNPT-based QALE-FEM is used to simulate a numerical wave tank. An internal domain by viscous flow method is used to simulate the trimaran's autopilot with the 6DOF motion taken into account. • By numerical simulation of the trimaran's autopilot in stern waves, the effect of the wave steepness, wavelength and initial speed of the trimaran on the surf-riding of trimaran was studied. • The process of the trimaran's motion in stern waves during the surf-riding was obtained, and the phenomenon before and after the surf-riding is analyzed by changing the wave celerity and trimaran's initial speed. [ABSTRACT FROM AUTHOR]

In this paper, based on the open-source code OpenFOAM, a hybrid method coupling the FNPT-based QALE-FEM and the viscous flow method is used to simulate the turn and zigzag maneuvers of the single-screw ship in waves. The external domain adopts the fully nonlinear potential flow theory to simulate the wave tank. The internal domain simulates the interaction between waves and ships by the viscous flow method. The 6DOF motion equations are combined with the propulsive factors in waves to simulate the ship maneuvering during the simulation. The KVLCC2 model is used for numerical simulation. The numerical method is validated by the comparison with the self-propelled maneuvering test. Then, the turning and zigzag maneuvers of the ship in different initial wave headings and wave parameters are simulated, and the influences of wave heading and wave parameters on ship maneuvering are discussed. • The turn and zigzag maneuvers of a one-screw ship is simulated by a hybrid method. During the simulation, the 6DOF motion of the ship are taken into account, and the propulsive factors in waves are used, which could significantly improve the efficiency. The computed results of the trajectory and motion are compared with the experimental results for validation. • By the simulation of turn and zigzag maneuvers in waves, the effect of the initial wave heading, initial speed, and the wavelength on the turn and zigzag maneuvers of ship is studied. [ABSTRACT FROM AUTHOR]

As one of the widely used high-performance ships, the hydrodynamic characteristics of the trimaran ships have been widely investigated in recent years. But, the study on the maneuverability and the skill of the maneuvering simulation are still limited. In this paper, a hybrid method coupling the FNPT-based (fully nonlinear potential flow theory) QALE-FEM (quasi arbitrary Lagrangian-Eulerian finite element method) with the viscous flow method is applied to simulate the turn and zigzag maneuvers of the trimaran in both calm water and waves. The environment of calm water and incident waves is simulated by the numerical tank of QALE-FEM. The maneuvering of the trimaran is carried out in the scope of the numerical tank by the viscous flow method. The grid convergence test is carried out first, and the computed results are compared with the experimental results. Then, the turn and zigzag maneuvers of a trimaran model in both calm water and waves are simulated to study the trimaran's maneuvering characteristics. 1) A hybrid method coupling the FNPT-based QALE-FEM and viscous flow theory is applied to simulate turn and zigzag maneuvers of a trimaran in both calm water and head waves. An external domain by FNPT-based QALE-FEM is used to simulate a numerical tank. An internal domain by viscous flow method is used to simulate the maneuvering of the trimaran, which could take the nonlinear effect into accounts, such as green water and side-hull intermittent emergence. 2) The turn and zigzag maneuvers in calm water and waves are simulated, and the effect of the speed on the turn and zigzag maneuvers are analyzed. 3) By numerical simulation of trimaran's maneuver in waves, the effect of wavelength and wave steepness on the maneuverability of the trimaran was studied. [ABSTRACT FROM AUTHOR]

As a kind of high-performance ship, compared with traditional mono-hull, the side-hull position of a trimaran plays an essential role in the hydrodynamics and motion characteristics, which is more significant for the seakeeping performance of a trimaran in waves of different headings. In this paper, the moving forward of trimaran in waves of various headings was simulated by a hybrid numerical method, which combines the fully nonlinear potential flow theory and viscous flow theory. The numerical method was validated firstly. Then, the trimaran model with two different layouts was obtained by increasing the hull separation and moving the side hulls forward. Finally, the motion of the trimaran with different layouts in waves of various headings was simulated, and the effect of layout on the motion response and added resistance were investigated. • A hybrid method coupling the FNPT-based QALE-FEM and viscous flow theory is applied to study the influence of side hull position on the seakeeping performance of the trimaran in waves, and the wave heading ranges from head wave to stern wave. • To move the side hull forward could reduce the roll motion of trimaran in most working conditions, which is not as predicable as the effect of hull separation on the roll motion. • The hull separation has little effect on the added resistance and motion of trimaran in waves. The main advantage of larger hull separation is to reduce the roll motion of trimaran. • The effect of the side hull position will get less noticeable when the wave steepness or wave length getting larger. [ABSTRACT FROM AUTHOR]