Experiments on the evolution of two-dimensional submerged berm under constant water depth
| Autor: | Zhi-Cheng Huang, 黃志誠 |
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| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The objectives of this study are to investigate the effects of the berm geometries and wave conditions on the accumulative transport rate and the evolution process of submerged berms. The experiments were conducted in a wave flume under a constant water depth condition. The bathymetry was obtained by the image processing method which includes the image formation, image analysis and image interpretation. The results were discussed in two main categories which were the analysis of the sediment transport and the wave transformation. It was demonstrated that the berm evolution process accompanied with the formations of sand ripples and the sediment would be convected away the original placed while it diffused.Under the same wave condition and berm width, the berm height was an important element of the wave reflection. However, the reflection coefficient declined as the berm bottom-width is one half to the incoming wave length.Under the same wave condition, both the extensions of the berm height and the berm width reduced the wave transmission. For berm application, an average dimensionless transport rate was formulated in terms of the Shields parameter. The critical Shield parameter,was employed to distinguish whether the berm was stable or movable. Results also showed that the disappearing rate decreased while the berm was broader and more sand would be transported away as the berm height is extended. Finally, a formula was suggested to predict the disappearing rate of the berm at the quasi-equilibrium state. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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