Numerical reproduction of fully nonlinear multi-directional waves by a viscous 3D numerical wave tank

摘要

Fully nonlinear multi-directional waves are reproduced by use of a viscous 3D numerical wave tank (NWT) simulation technique. The governing equations, Navier-Stokes and continuity equations, are discretized by a finite-difference/volume method in the framework of a rectangular/body-fitted coordinate system, and the boundary values are updated at each time step in a time-marching procedure. The fully nonlinear kinematic free-surface condition is satisfied by the marker-density function technique. The directed incident waves are generated by multi-segmented wavemaker on the basis of the so-called "snake-principle", and the outgoing waves are numerically dissipated inside an artificial damping zone located at the opposite side of the wavemaker. In this study, the results for the generation of regular waves, including numerical convergence tests, irregular waves, and multi-directional random waves are presented. Furthermore, the generation of following waves, which are one kind of directional waves, is examined using a fluid acceleration wavemaker, and the hydrodynamic forces acting on an advancing ship in such a wave condition are discussed.