博士 / 國立臺灣海洋大學 / 河海工程學系 / 96 / The purpose of this study is to investigate the influence of partially reflecting boundaries on waves in a harbor. Particular attention is paid to the reflection characteristics of the harbor wall. For this, a series of laboratory experiments using porous quay-wall, porous floating dock, and composite quay-wall with various porosities and wall width are carried out. Introduce these results into a DRBEM model of harbor tranquility to discuss the influence of real wave absorption characteristics of boundaries on the harbor tranquility simulation results; and further, the reflection coefficients of the harbor rear-wall are treated as constant and variable respectively. Results of simulation show that as the constant reflection coefficient of quay-wall deposed, the first mode of response curve decrease obviously as it compared with the variable coefficient. In other words, using constant reflection coefficient will overestimate the energy dissipation efficiency of the quay-wall.
In this study, the DRBEM numerical scheme is performed to investigate the resonant problem in a harbor with uneven seabed can simplify the complicated domain integral for solving inhomogeneous Helmholtz equation by applying a conventional BEM, which also can improve numerical efficiency. To verify the validity of the present model, the numerical results are compared with the experimental and theoretical results obtained by Ippen and Goda (1963), Lee (1972) and Tsay et al. (1986). The trend of response curve obtained by present model is in agreement with the experimental and theoretical results.
The laboratory tests are designed to examine the reflection characteristics of porous quay-wall, porous floating dock and composite quay-wall. To summarizes the experimental results of wave reflecting characteristics, as for porous quay-wall, with the same porosity value (sn) the reflection coefficient decreases as the quay-wall width (bp/h) increases and the frequency for minimal reflection coefficient decreases also; and with the same porosity value and quay-wall width, the frequency of minimal reflection coefficient decreases as the relatively effective depth (he/h) decreases. As for porous floating dock, relative higher Hd/h have minimal reflection coefficient for longer period waves ( ), while the short period ( ) waves are unobvious as changing the height of porous floating dock. As for composite quay-wall, the frequency of minimal reflection decreases as the quay-wall width (bp/h) increases.
In this study, a series of reflection coefficient curves were fitted from experimental results which can be applied for the reference of practical quay-wall design. Furthermore, by using these fitted reflection coefficient curves on the DRBEM schemed numerical wave model can be a more rational approach for studying harbor resonance.
| Identifer | oai:union.ndltd.org:TW/096NTOU5192035 |
| Date | January 2008 |
| Creators | Hui-Ming Fang, 方惠民 |
| Contributors | Sung-Shan Hsiao, 蕭松山 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 163 |
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