二維顯式有限解析法模式於交匯明渠流之研究

Abstract

本研究係延續二維顯式有限解析法(EFA)模式(許，2002)應用於主、支渠交匯流況之模擬。在模式驗證部分，首先針對不同交匯角、同渠寬比之主、支渠交匯實驗(Hanger,1989)驗證本模式對主渠上游水深之模擬能力。接著模擬同交匯角、不同渠寬比之主、支渠交匯實驗(謝,1998)，並比較主、支渠上游水深與迴流區分佈情形，以驗證本模式。另外模擬主、支渠交匯處局部流場之水深 (Gurram et al.,1997)，並與實驗值進行比較。最後則假設樹枝狀主、支渠交匯案例，進行模擬。 根據模擬結果顯示，在定量方面，本模式在進行不同交匯角度及不同渠寬比之主、支渠交匯流況時，不管是主、支渠上游或迴流區附近的水深模擬值，均與實驗值相近。在定性方面，迴流區之分佈範圍亦與實際物理現象符合。而在多條主、支渠交匯流況之模擬結果亦頗令人滿意。

This study is an extension of Hsu’s (2002) 2-D explicit finite analytic model, and an application for the simulation of open-channel junction flows. The model is first verified by using Hanger’s (1989) experimental data for junction flow with equal channel width but different junction angles. The computed water depths upstream of the junctions are compared with Hanger’s (1989) data. Hsieh’s (1998) experimental data for junction flows with different channel width but the same junction angle are then used. The upstream depths in the main channel and in the branch channel and the ranges of the circulation zones downstream of the junctions are compared. In addition, Gurram et al.’s (1997) experimental data for junction flow is adopted for the comparison of the simulated water surface profile along the right bank of the main channel in the junction reach. Finally, two assumed tree-type junction cases are simulated. According to the simulation results, the proposed model can accurately simulate the depths upstream the junctions and the water surface profile in the junction reach for abovementioned experimental data. Although the simulated widths of the circulation zones in Hsieh’s(1998) experiment are smaller than the measured, the results match the physical phenomenon qualitatively. For the case of assumed tree-type junction flows, the simulation results are satisfactory.