| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 91 === The one part of this paper is to develop the numerical model based on the 2nd — order fully nonlinear Boussinesq equations of Wei et al. (1995), and the Boussinesq model has been applied to compute wave fields for several cases of wave propagation for the rationality of the model. The another part of this paper is to apply the Boussinesq model to the simulation of the Bragg reflection of monochromatic and random waves due to artificial sand bars, for which experimental data have been presented by Davies and Heathershaw (1984) and Kirby and Anton (1990). The numerical results are compared with the theoretical solutions of Miles (1981) and the corresponding results using the evolution equation for mild slope equation of Hsu et al. (2003). For the monochromatic wave, the Boussinesq model can predict the reflection coefficients of the primary and second-harmonic resonance well. For the random waves, the reflection coefficients of the primary resonance are smaller and the reflection bandwidth is wider than the monochromatic wave, so the Bragg reflection of random waves is different from that of the monochromatic wave.
In addition, the Boussinesq model is applied to study the affecting factors of the Bragg reflection, including the number, the height and the spacing of artificial sand bars. The results are that increasing the number and the height of the sand bars, the reflection coefficients of the primary and second-harmonic resonance raise and increasing the spacing of sand bars, the reflection coefficients of the second-harmonic resonance increase, but that of the primary resonance decrease.
|
|---|
