| Summary: | 碩士 === 國立嘉義大學 === 土木與水資源工程學系研究所 === 94 === In natural rivers, the flow courses are almost meandering and their cross sections are compound type. Due to the interaction between the main channel and the flood plain, the flow structure and the hydraulic characteristics of meandering compound channel flow are extremely complicated. Flume tests were used to investigate the hydraulic characteristics of meandering compound channel with overbank flow. Three dimensional electromagnetic current and wave gauge were used to measure velocity and stage respectively. In addition, the visualization technique was used to capture and interpret the surface flow behavior. The difference in direction of rotation of the flow before and after inundation at a bend section was clearly observed by velocity measurement. At the middle section of the crossing reach, there was a secondary cell in the main channel due to the flow form flood plain plunging into the main channel. The core flow in the upper layer of the main channel occurred near convex side at a bend and at middle in crossing reach. According to the visualization technique results, the flow which from flood plain plunged into the main channel will flow in the core flow region in the main channel while the water depth was not deep. As the water depth increased, the flow both in the main channel and in the flood plain will flow parallel to the boundary of the flood plain. For experimental results of velocity profile in the main channel, the power law used for simulating primary velocity profile in the main channel is found to be quite inadequate.
|
|---|
