研究顯示：經由Fluent軟體模擬橋墩周圍流場，在水工試驗尚未進行前，可先經由數值模擬了解流場特性(如速度、壓力之分佈)；也可利用模擬所得床底剪應力帶入由相關公式推估橋墩周圍沖刷深度。以水工試驗後之試驗資料進行數值模擬比對合理後，則可對試驗無法量測處利用數值模擬結果進行探討；水工試驗多討論流場特性及沖刷深度，因此橋墩受力之資料上有所不足。本研究針對水工試驗不常探討橋墩受力狀況之情形，針對橋墩基底之受力進行分析，比較不同流量與不同床形下之受力狀況，希望未來能夠擴展到模擬洪水衝擊下之受力狀況。 This study is divided into two parts, the first part is validating numerical models using four kinds of turbulence models (standard k-ε, RNG k-ε, realizable k-εand RSM) to simulate the flow field around bridge piers and to compare the results of the four models with experimental data. The better model was chosen for the second part of the research. The second part is setting different boundary conditions to run numerical simulations. In this part, the characteristics of the flow field around bridge piers and the stress on the piers were studies and discussed. Before hydraulic tests, software "Fluent" can be used to simulate the flow field around bridge piers to obtain flow field characteristic data (e.g., velocity and pressure distribution), and simulated bed shear stress can be used to estimate the scour depth around piers. When the results of numerical simulation match the data from previous hydraulic tests, unmeasured locations can be investigated using numerical simulations. In hydraulic tests, the focuses are on the characteristic of flow field and scour depth, and usually not enough data regarding the forces on the piers. Therefore, in this study, different boundary conditions (e.g., flow depth, velocity and bed shape) were used in the numerical simulations and analysis of the forces on the piers. It is hoped that the results of this thesis can be extended in the future to simulate the loading condition of piers subjected to flood impact.
