為了模擬與控制載具的運動，需要求解其六自由度運動方程式，其中所涵蓋的流體動力係數最為重要，每艘不同外形的載具在運動時所承受的流體動力不同，會反映在其流體動力係數上，故流體動力係數會直接影響載具運動模擬的準確度，本文利用計算流體動力學去建立一套求解載具各項流體動力係數的方法，並使用ANSYS公司的套裝軟體FLUENT作為求解器。
本文先是探討了計算流體動力學的基礎理論並介紹計算的過程，再來說明流體動力係數的理論與求解方法，而在實際地進行載具的流體動力係數求解前，先引用前人研究的文獻來進行驗證比較，以此來證明本文使用之計算方法的可靠性；計算前亦進行網格獨立性的分析，以確定所使用的網格數量為適當，最後即進行求解本文研究之載具的各項流體動力係數，包含有三個平移運動(縱移、橫移與起伏)和三個旋轉運動(橫搖、縱搖與平擺)，各個自由度的運動也涵蓋其耦合項的影響，即每個自由度運動下可分別得到三個方向的受力和三個方向的受力矩，並找出其中對載具運動具有影響力的流體動力係數，以供求解運動方程式的使用。

In order to simulate the motion of underwater vehicle, we have to solve the six DOFs equations of motions. Determining the hydrodynamic coefficients in the equations is the most important job before we can solve the equations. However, the hydrodynamic forces vary with vehicle’s outline shape and it will reflect on the hydrodynamic coefficients. In the present study, we establish the method to solve the hydrodynamic coefficients of the underwater vehicle by CFD analysis based on the existing software, i.e. the FLUENT solver.
At first, we will simply describe the related basic hydrodynamic theory and the procedure for the calculation in the present study. Then we illustrate the method to solve all related hydrodynamic coefficients. The previous researched papers by other authors are also quoted here. Adopting the existing body geometry used by other author as the calculation model, we calculate the hydrodynamic coefficients and compare the existing results to verify the validity of the present method used in this paper. In order to ascertain the appropriate number of grid generation, we also make the analysis of grid independence. Finally, the hydrodynamic coefficients of the underwater vehicle including three translational modes and three rotational modes are obtained through the calculations of the forces with respect to each mode. Through the comparisons with the existing experimental data, we found that the results obtained by the present CFD analysis technique are generally acceptable although some improvements are still needed be done in the future.

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