| Summary: | 碩士 === 國立交通大學 === 土木工程系所 === 95 === Flows through vegetations have extremely complicated variation and are affected by the diameter, height, and spacing of the vegetated stems. Hence, this study tries to understand the phenomenon of varied flow velocities passing the submerged vegetations, using the non-intrusive color particle image velocimetry method (CPIV) to measure the vertical 2-D flow field. The CCD takes the instantaneous images of vegetated channel flow field and makes analysis of the images to obtain the distribution of velocity vectors and the related physical properties in the flow field.
The experiment in this study is constructed under two types of bed materials: one is a smooth flat panel and the other is a vegetated one with a height of 1.5 cm. These two types of bed materials are compared with twelve sets of experimental cases. The flow discharges in the experiment are controlled with levels of 60, 80, and 100 (l/min) with flow depths of 5 and 6 cm in the upstream boundary conditions. From the results, the average energy loss is 11.81% in the case of vegetated bed and 9.81% in the bed with smooth flat panel. Energy loss is accelerated with increasing discharge or decreasing depth. The surface of the vegetation could change the flow field and dissipate energy.
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