數值與實驗探討明渠流於下游河段段面變化對自由液面影響

A study on the free surface profiles in an open channel with cross-sectional variation by numerical and experimental methods

陳瑩(Ying Chen)

指導教授 ： 鄧志浩

中原大學/工學院/生物環境工程研究所/碩士(2013年)

https://doi.org/10.6840/cycu201301032

摘要

本研究主要是利用最小平方有限元素法(LSFEM)求解三維二相流不可壓縮流體的動量與質量守恆方程式，模擬自由液面之流場，並配合水工實驗之實際觀測結果，與模擬結果相互比對，探討在渠道下游段面變化之問題。
　　經由多次不同流量對下游段面變化之主題做出模擬分析與水工試驗之數據，歸納出其結果。渠道段面突然的縮減，會使水體產生劇烈的變化，尤其是上游的水位湧高現象與角落處的爬升現象，隨著流速越大，其現象會越明顯。
　　渠道下游段面之改變，對兩端邊壁自由液面之影響會較渠道中央自由液面影響來的大，而不論渠道段面漸漸擴大或縮減，流速對渠道中央自由液面之影響為流速大時，其水位下降幅度較大。

關鍵字

最小平方有限元素法 ； 自由液面 ； 段面變化

並列摘要

In this study, we examined the 3D free surface profiles with downstream cross section expanded or reduced the least-squares finite element method (LSFEM) has been used to solve the momentum and mass conservation equations. The experimental results were compared with the simulation results and shown in good agreement with each other. The flow phenomena in the open channel with downstream cross-section variation were discussed in detail.
　　By changing the inflow condition, the analysis between the simulation and experimental results stated that channel cross-sectional reduced will produce dramatically changes in water level, especially the water level in the upstream section where water accumulates in the corner. With the larger inlet velocity, the water level increasing phenomenon will be more obvious.
　　The level of free surface at the side walls is larger than at the central of channel when the cross-section is changed. Regardless of the cross-section is gradually expanded or shrunk, with the larger inlet velocity, the lower free surface level.

並列關鍵字

cross-sectional variation ； two-phase ； least-squares finite element method

參考文獻

鄭雅允(2003) "二相流模式探討明渠流在不規則底床運行之現象",私立中原大學土木工學系碩士學位論文

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丁琦瑋(2012) "數值與實驗探討明渠流在多階跌水底床運行之現象",私立中原大學土木工學系碩士學位論文

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