本文運用有限體積法二維變量流演算模式模擬洪水波在傾斜平面及複式渠道之傳 遞情形。此演算模式在估算元素邊界之質量通量與動量通量時，將元素與元素交界面上之通 量變化視為一維黎曼問題（ Riemann problem ）來處理，並以 Osher 方法計算通過該元素 所有邊界面之總淨通量，首先模擬洪水波流經傾斜平面以檢測此模式處理乾濕交界邊界之能 力，結果顯示此模式能有效的處理乾濕交界邊界，然後運用此模式模擬洪水波在實驗室複式 渠道之傳遞情形，模擬結果與實驗結果比較顯示，漲水期間計算水深與實驗量測水深大致相 符，但退水期間計算水深略大於實驗量測水深。 Flood waves in an inclined plane and in a .composite channel were numerically simulated via a twodimensional unsteady-flow model based on the finitevolume method. With the finite-volume method, it is necessary to estimate the mass and momentum flux through each side of an element. The flux was treated as a local one-dimensional Riemann problem and solved with the Osher scheme in the unsteady-flow model. First we simulated a flood wave propagating through an inclined plane to examine the ability of the model in dealing with the interface between dry and wet elements. The simulated results show that the proposed unsteadyflow model can handle such an interface quite well. The model was then applied for simulation of a flood wave in a laboratory composite channel. The computer-simulated water-depth hydrographs were compared with the experimental data. The comparison shows that the simulated water depths in the rising limb of the hydrographs are quite close to the measured water depths, while that in the falling limb are slightly larger than the measured ones.
