碩士 / 國立成功大學 / 水利及海洋工程學系 / 86 / Equilibrium beaches are qualitatively decomposed into
storm beaches andnormal beaches. A storm beach has recession
near the shoreline and thedeposition of offshore bar built
from the eroded material. The geometry ofbottom profile of a
barred beach comprises a convex downward curve nearshoreand a
concave upward curve offshore. Therefore, the previous
proposed shapefunctions are monotonously decreasing which can
not sufficiently describe theconfiguration of the storm
beaches. In this paper beach profile data from bothlaboratory
and field survey were used to examine a reliable shape function
byregression analysis. The results showed that a fifth
polynomial is applicableto present the profile of a barred
beach. A general functional form relatedgeometric
characteristic of a storm profile to various forcing
parameters isderived on the basis of a wave dissipation model.
The predictive model hasbeen developed to describe the shape of
a barred beach and proven to favorablycompare with laboratory
data. Meanwhile, the momentum and energy equationswere used
to obtain wave deformation, set up and longshore current
induced byan obliquely regular or irregular wave. The good
agreement between the presentprediction and laboratory data
gives the verification of the accuracy of thispredictive model.
When the wave height, period and incidence angle and sandgrain
size are given, the present model can give the profile of a
barred beachand longshore current on the formed beach. The
results showed that the wavebreaks before it reaches the bar
crest and then wave height consequentlydecays during a
short distance, but the maximum value of longshore
currentoccurs at the bar crest.
| Identifer | oai:union.ndltd.org:TW/086NCKU1083002 |
| Date | January 1998 |
| Creators | Lin, Jeng-Yih, 林政毅 |
| Contributors | Tai-Wen, Hsu, 許泰文 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 51 |
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