Fully nonlinear multidirectional waves by a 3-D viscous numerical wave tank

A finite-difference scheme and a modified marker-and-cell (MAC) method are used for numerical wave tank (NWT) simulations to investigate the character istics of nonlinear multidirectional waves. The Navier-Stokes (NS) equation s are solved for two fluid layers and the boundary values updated at each t ime step by a finite-difference time-marching scheme in the frame of rectan gular coordinate system. The fully nonlinear kinematic free-surface conditi on is satisfied by the density-function technique developed for two fluid l ayers. The directional incident waves are generated from the inflow boundar y by prescribing a snakelike motion along the wavemaker direction. The outg oing waves are numerically dissipated inside an artificial damping zone loc ated at the end of the tank. Using the NS-MAC NWT with both solid and trans parent side-wall conditions, the effects of side-wall reflections are studi ed Bull's-eye waves are also numerically generated by the phase control of neighboring wavemaker segments or the reverse process of cylindrical wavema kers. The simulation results are compared with the computations by an indep endently developed potential-based NWT and the experiments conducted in the Offshore Technology Research Center's 3-D wave basin.