Abstract
ABSTRACTWave propagation over a submerged bar is simulated using the open source CFD model REEF3D with various incident wave heights to study shoaling, wave breaking features and the process of wave decomposition into higher harmonics for relatively long waves of kd=0.52. The computed free surface elevations are compared with experimental data and good agreement is obtained for both non-breaking and spilling breaking waves for both the wave phase and free surface elevation, which has been difficult to obtain in current literature. The differences in the mode of wave shoaling over the weather side slope and the wave decomposition over the lee side slope of the submerged bar are discussed. The evolution of spilling breakers and plunging breakers over the bar crest is also studied. It is found that the free surface elevation continuously increases due to shoaling in the case of non-breaking waves, whereas breaking waves propagate with much lower free surface elevations after breaking over the bar crest. The power spectra of the free surface elevations at various locations indicate that the wave energy in the fundamental frequency is reduced by 76 for the non-breaking wave with kA=0.015 and by about 90 in other cases with higher incident wave heights with kA=0.023−0.034 due to energy dissipation and energy transfer to higher harmonic components as the wave propagates over the submerged bar.
Highlights
Wave propagation in shallow waters is influenced by sea bottom topography and wave transformation processes such as diffraction, shoaling and wave breaking
The power spectra of the free surface elevations at various locations indicate that the wave energy in the fundamental frequency is reduced by 76% for the non-breaking wave with kA = 0.015 and by about 90% in other cases with higher incident wave heights with kA = 0.023−0.034 due to energy dissipation and energy transfer to higher harmonic components as the wave propagates over the submerged bar
Wave propagation over a submerged bar is simulated for different incident wave heights and the numerical results are compared with experimental data
Summary
Wave propagation in shallow waters is influenced by sea bottom topography and wave transformation processes such as diffraction, shoaling and wave breaking. Numerical models accounting for both breaking and non-breaking waves over a submerged bar (Beji & Battjes, 1993) and having good agreement with experimental data for both the free surface elevation and the wave phase have not been presented in the current literature. This is especially true for longer waves with T = 2.5 s, where the wave decomposition process is seen to be much stronger in experiments compared with shorter waves with T = 1 s (Beji & Battjes, 1994). The addition of a submerged bar in front of a floating breakwater can be used to dissipate some wave energy and decompose the waves into shorter waves that can be effectively absorbed by the floating breakwater
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