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行政院國家科學委員會專題研究計畫成果報告:亂流突暴現象對非均勻砂礫啟動機率之影響
Date Issued
2005
2005-10-31
Date
2005
2005-10-31
Author(s)
DOI
932211E002022
Abstract
The effects of near-bed coherent flow
structures on the entrainment probabilities of
mixed-size sediment are investigated in this
study. The 4th-order Gram-Charlier
probability density function (GC pdf) of
near-bed streamwise velocity is employed to
account for the higher-order correlations
associated with turbulent bursting. As
compared to the previous models using
normal and lognormal pdfs, the present
results demonstrate significantly improved
agreement with the observed data for the
unisize and mixed-size sediments under
partial- and full-transport conditions. The
results also reveal that for fully rough beds
the 3rd-order GC pdf approximates the
4th-order one, however, for smooth beds the
4th-order GC pdf must be used to capture the
effects of higher-order correlations.
structures on the entrainment probabilities of
mixed-size sediment are investigated in this
study. The 4th-order Gram-Charlier
probability density function (GC pdf) of
near-bed streamwise velocity is employed to
account for the higher-order correlations
associated with turbulent bursting. As
compared to the previous models using
normal and lognormal pdfs, the present
results demonstrate significantly improved
agreement with the observed data for the
unisize and mixed-size sediments under
partial- and full-transport conditions. The
results also reveal that for fully rough beds
the 3rd-order GC pdf approximates the
4th-order one, however, for smooth beds the
4th-order GC pdf must be used to capture the
effects of higher-order correlations.
Subjects
Entrainment probability
turbulent bursting
near-bed coherent flow structures
mixed-size sediment
Publisher
臺北市:國立臺灣大學生物環境系統工程學系暨研究所
Coverage
計畫年度:93;起迄日期:2004-08-01/2005-10-31
Type
report
File(s)
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Name
932211E002022.pdf
Size
913.74 KB
Format
Adobe PDF
Checksum
(MD5):7989dd8407ed083c462594d760b63cb4