Abstract:
Wave-wave interaction induced energy transferring among different wave frequencies, and nonlinear effect is more prominent in shallow water. During the process of wave evolution, there exists unsteady and steady wave transformation. To accurately simulate the whole process, the numerical model for water waves is required to have sufficiently high accuracy in both linear and nonlinear properties. Based on a two-layer Boussinesq-type model with high accuracy in dispersion and nonlinearity, a numerical model is established on non-staggered regular grids. A composite fourth-order Adams-Bashforth-Moulton scheme is used for time integration. To simulate the wave generated by the motion of the wave-making paddle, a two-point wave-making method suitable for the numerical model is used. The waves at the two points near incident boundary are multiplied by a sinusoidal function varying from 0 to 1 in one wave period. The numerical simulations are conducted on the nonlinear wave evolution process in the flume. Surface elevations and higher-order amplitudes at fixed points are compared with the results from physical experimental data, the good agreements are found. Finally, the numerical model is applied to simulate the wave evolutions with different wave amplitudes, and the variation of the recurrence length with respect to wave amplitude is analyzed. The results show that the computed recurrence length basically coincides well with the theoretical analysis for approximate linear waves, and it decreases nonlinearly with the enhancement of wave nonlinearity.