SMAC方法應用於下射式閘門流

下射式閘門流是屬於水工結構物的一種。一般應用在渠道上游以控制其流量。本文利用連續方程式以及雷諾運動方程式，以SMAC方法模擬一個二維、不可壓縮黏性流體流經一下射式閘門的流動。模擬的流況為：閘門上游有一水深y_0，流速為U_L的水流由閘門上游遠處流經下射式閘門，閘門的開口高度為a。模擬的流況有二：分別爲閘門開口高度a與上游均匀流水深y_0比為0.3及0.4；上游福祿數範圍爲0.2～0.25；摩擦係數f值的範圍爲0.01～0.025。模擬的重點包括渦度黏滯係數、閘門上、下游之自由面、閘門板上之壓力等。討論的重點包括質點分佈圖、流線圖、閘門上游及下游水面線、閘門板上的壓力分佈等等。上游水面線與標準階梯法所求得的水面線相當接近；而閘門板上壓力分佈與前人研究所得結果及理論一致。

關鍵字

下射式閘門流；渦度黏滯係數； SMAC方法

並列摘要

Underflow gate is one of the hydraulic structures, which is usually used as a control on open channel flows. Based upon the Reynolds equations of motions and the continuity equation, the method of SMAC (Simplified MAC) was utilized to simulate a two dimensional, imcompressible viscous flow passing through the underflow gate. There is a uniform flow with a depth y_0 and a velocity U_L upstream of the underflow gate. Values of the ratios of gate opening a and the inflow depth y_0, 0.3 and 0.4, are investigated in this study. The range of the upstream Froude number is from 0.2 to 0.25; while that of the friction coefficient is between 0.01 and 0.025. The main awareness of this simulation are the eddy viscousities, water surface profiles and pressure distributions on the gate. The upstream water surface profile is in good agreement with those computed by the standard step method. Besides, the pressure distribution on the gate is also in good consistency with previously studies.

並列關鍵字

Undergate flows ； Eddy viscosity ； SMAC method

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