SIMULATION OF OUTGOING WAVES AT THE BOUNDARIES OF A THREE DIMENSIONAL FULLY NONLINEAR NUMERICAL WAVE TANK

摘要

This paper presents an efficient boundary condition to simulate outgoing waves at the boundaries of the truncated domain in a three-dimensional numerical wave tank. The present study is based on coupling of two prescribed boundary conditions, namely, numerical beach and Orlanski boundary conditions. The use of a numerical beach is known to be efficient in the high frequency range, however, Orlanski boundary condition has been successfully applied in the low frequency range. The proposed study is based on coupling of these two prescribed boundary conditions to make use of their complementary bandwidths. The model has been calibrated to determine the optimal length and the most efficient damping factor within the numerical beach region. The semi-infinite tank has then been used to simulate nonlinear wave propagation in shallow water. The results of this simulation have been verified through a comparison with previous published experimental measurements. The model is then further applied to simulate the nonlinear wave diffraction by and the associated hydrodynamic forces on a bottom mounted surface piercing circular uniform cylinder. Further investigation of the efficiency of the coupled boundary condition when using a spatially-varying damping factor in the presence of scattered wave field is presented.