Fully Nonlinear Waves and Their Kinematics: NWT Simulation Vs. Experiment

A 2D fully nonlinear NWT is developed based on the potential theory, mixed Eulerian-Lagrangian (MEL) time marching scheme, and boundary element method (BEM) . Wave profiles and wave kinematics of highly nonlinear waves are calculated using the NWT and the results are compared with linear, Stokes second-order theory and experimental values. It is confirmed that the spatial variation of intermediate-depth waves along the direction of wave propagation is caused by the unintended generation of second-order free waves, which was originally investigated both experimentally and theoretically (3` d order pe turbation theory) by Goda. The various phenomena observed by Goda are clearly reproduced by the present fully nonlinear NWT . It is shown that the wave kinematics above mean water level can be significantly different from the perturbation-based prediction. It is also found that small mean positive or negative flows can be generated below mean water level depending on the water depth and wave condition .