| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 94 === This study experimentally investigates the velocity distribution of fully developed turbulent flow over and within a porous bed. The porous bed is simulated by two glass beads, having porosity equal to 34.9% and 43.3%. The characteristics of turbulent flow in an open channel with a porous bed are measured by an Acoustic Doppler Velocimeter(ADV) and Electromagnetic flowmeter. Effects of several parameters on the velocity distribution, such as, relative porous depth, Reynolds number, channel slope and permeability (K) are investigated and discussed. The Reynolds numbers, based on the mean velocity of clear fluid region and the clear fluid depth, vary from about 9094.31 to 43537.67. The measured velocity distributions show a significant decrease of velocity over a porous bed with increasing permeability due to the penetration of turbulence into the porous medium and momentum transfer near the interface. The thickness of turbulence penetration is only dependent on the permeability of a porous bed rather than the flow conditions over a porous bed.
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