碩士 / 國立中興大學 / 土木工程學系所 / 98 / rise in water level, the decks of bridges crossing the river gets inundated. Hence, the present study emphasizes on the investigation of the characteristic of velocity field under a partially inundated bridge deck. The Froude number of the approaching flow ranges from 0.13 to 0.55. Both the flow visualization and particle image velocimetry (PIV) measurement techniques were used in this study.
Based on the data obtained by PIV and flow visualization techniques, the flow structure under a partially inundated bridge deck is classified into four flow field categories as Type I to Type IV. These four fields can be classified using Froude numbers.
Further, for Type I and Type II categories, the characteristics of streamwise mean velocity profiles in the shear layer under bridge deck can be described by the center point of shear layer ysc, the specific width bs, and velocities of the upper and lower boundary of the specific width usu and usd. The similarity of the shear layer velocity profiles under bridge deck can be established by using dimensionless shear layer thickness (y - ysc)/bs and dimensionless mean velocity deficit (u - usu)/(usd – usu). The similarity curve equation can be expressed as:
(u-usu)/(usd-usu)=-0.859×tanh[1.341〔(y-ysc)/bs〕-0.012]+0.494
In addition, the present study also demonstrates the turbulence characteristics, bottom boundary velocity field, and bed shear layer distribution.
| Identifer | oai:union.ndltd.org:TW/098NCHU5015102 |
| Date | January 2010 |
| Creators | Li-Fang Lo, 羅立芳 |
| Contributors | 林呈 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 100 |
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