本研究以流場模擬軟體OpenFOAM 進行三種船艏構型的阻力試驗及2DOF運動模擬，假設為不可壓縮流、求解RANS 配合SST k-ω 模型，目的為降低船模於靜水狀態(Calm water condition)之阻力值並了解船艏形狀對艏部造波及運動的交互影響。研究針對(1)傳統型(2)斧形艏(3)穿浪逆船艏，分別以靜態網格及動態網格進行阻力試驗模擬。靜態網格分為巡航船速及設計船速進行，結果與成功大學拖航水槽之實驗數據比較，評估船體於龍骨水平狀態(Even-keel condition)下於兩種船速之阻力表現及流場變化；動態網格為接續靜態網格的結果，對三種船型進行質量及重心位置的校正，校正船體因網格生成過程中所產生的幾何誤差，再預估巡航船速下阻力值及運動量，比較不同船型在加入姿態變化後的表現。在過程中，兩種模擬亦分別進行驗證與確認(Verification and Validation, V&V)分析，並通過驗證數值收斂性及確認數值的不確定性，確立可信度。
靜態網格模擬中，在巡航船速下能使傳統型艏阻力誤差在中網格時約1%。
相較於傳統型艏，發現壓力阻力將隨著後傾角增加而減少且能夠達到總阻力降低的目的，斧型艏約能達到0.63%減阻效果、最佳之穿浪逆船艏為後傾角50 度艏，減阻幅度達8%。但在設計船速時造浪的波高變大許多，可能發生上浪現象導致阻力上升的情形發生，且減阻的表現因船艏外型緣故使壓力阻力不減反增而呈跳動變化，斧形艏減阻效果約0.5%，穿浪逆船艏的部分原最佳之後傾角50 度艏發生上浪現象，在與巡航船速表現綜合評估後建議選擇後傾角30 度。
動態網格模擬中，姿態變化造成的差異能夠直接反映在阻力表現上，傳統型艏之中網格阻力誤差變為2.7%，而減阻效果中斧型艏能有0.14%減阻效果同時微幅的降低運動量，而後傾角30 度之穿浪逆船艏能夠達到約3.5%減阻效果，但發生縱搖量大幅增加約25%的狀況，這樣的結果可以提供用來做適航性的評估。
關鍵字：OpenFOAM、阻力模擬、船體造波、船艏傾角、動態網格

The research uses OpenFoam software to conduct calm water resistance test simulation for three bow types: (1) Flared bow, (2) Axe bow, (3) Inverted bow. The simulation predicts ship hull resistance by static mesh, and the resistance, pitch and heave by dynamic mesh. The resistance value for each bow type satisfies the requirement of verification and validation analysis, and their uncertainty values are obtained.
Using static mesh, we conduct two different ship speeds: (1) cruising speed, (2) design speed. At cruising speed, the resistance error of flared bow for medium grid is 1%.
Against the value of the flared bow, the total resistance reduction of the axe bow is 0.63%.
The inverted bow with 50 degrees continuous rake angles can almost reach 8%. The resistance reduction is caused by the pressure resistance which decreases when the bow rake angle increases. At design speed, the high speed causes the large wave height. The resistance reduction becomes worse for each bow type, even green water on deck occurs.
Using dynamic mesh, we choose axe bow and the inverted bow with 30 degrees continuous rake angle based on the result in the static mesh study. First, a correction procedure to correct ship mass and longitudinal location of center of gravity is conducted.
It has been proved that the prediction of ship vertical motions can be improved. The resistance error of the flared bow slightly increases to 2.7%. The total resistance reduction has a good improvement for both axe bow and the inverted bow. The pitch value of the inverted bow increases about 25% against the flared bow’s value.
Key words: OpenFOAM, resistance simulation, bow rake angle, dynamic mesh

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