Based on the Reynolds-Averaged Navier-Stokes (RANS) equations and the Volume of Fluid (VOF) method, a numerical wave tank, including wave generation, propagation and damping zones, is set up. Nonlinear regular waves of large amplitude are simulated in a vertical two-dimensional (2D) wave flume. The wave generation with the relaxation zone, which damps the reflected waves from structures in the numerical wave flume, is implemented using the momentum source method. The computed wave profiles agree well with the target wave profiles. Interactions between wave and floating semi-submersible box-type breakwater are studied. The relationships between the ratio of breakwater length to wavelength and transmission coefficients are predicted and compared with the analytical solution of linear waves and the experimental data. Results demonstrate that the transmission coefficient is markedly affected by both ratio of breakwater length to wavelength and the water draught. But wave amplitude does not distinctly affect the transmission coefficient for regular waves. For the cases of interaction of a floating breakwater and large amplitude wave, the effects of wave breaking, run-up and overtopping are discussed.
floating breakwater, momentum source term, numerical wave tank, transmission coefficient
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