Numerical investigation on a container ship navigating in irregular waves by a fully nonlinear time domain method

A three dimensional fully nonlinear time domain method is introduced to simulate ship advancing in regular and irregular waves with forward speed. The mixed Eulerian-Lagrangian (MEL) method and boundary element method are adopted to solve the boundary value problem. Spring analogy method is utilized to guarantee the optimization mesh of the transient free surface and wetted hull body. A local coordinate system is introduced, and the fully nonlinear disturbed wave is separated from the total wave. Auxiliary functions are deduced to decouple the strongly nonlinear hydrodynamic forces and ship motion. Then the motion and velocity potential can be updated with the fourth-order Runge Kutta method. A 13500 TEU container ship is chosen to verify the numerical codes, the numerical results in regular waves and irregular waves are both in good agreement with experimental data. The instantaneous pressure distribution around wetted body surface and wave elevation on the free surface of dangerous moments are presented and the strongly nonlinear states in the harsh irregular waves are analyzed.