臺灣博碩士論文加值系統

本研究針對海上風機規劃設計時所需要的海洋中結構物所受外力計算，針對其樁基礎在海中受到的外力以OpenFOAM (Open Source Field Operation and Manipulation)計算流體力學(Computational Fluid Dynamics)數值模式，計算其所受整體外力。
本研究採用RANS k-ε model，模擬當外海波浪經過樁式結構物時，波浪與結構物之間的交互作用，流體的各項物理特徵，以及計算出其受力大小。
研究針對三種不同型式的離岸基樁擺設進行模擬，在波浪條件下分別討論波浪與支撐樁基礎交互作用、波浪通過樁基礎情形及受力大小分部等。在文中分為物理現象探討及受力情形探討，其中物理現象探討當波浪通過時在結構物附近處之壓力、渦度、速度及加速度分佈情形；受力情形探討則描述整體結構物(基樁)受到波浪作用的力量大小，亦討論六腳樁型式的擺放方式，其底部斜桿的各別受力大小。
最後針對模式計算出的受力大小，與經驗公式Morison equation計算做比較，比較結果差異最大在15.9%之內，工程上使用會再以安全係數做修正，確保在工程上有更進一步的安全性。

This study is aim to evaluate the environmental forces on offshore structures during planning and design stages. A public domain software OpenFOAM (Open Source Field Operation and Manipulation), RANS k-ε model, was adopted to calculate the forces on the offshore wind turbine foundation pile. This model has simulated the phenomena of interaction between waves and structures and the physical characteristics of the fluid when the ocean waves passing through the pile structures. As for the total horizontal forces on the pile and bending moments at the sea bed were calculated with a self-developed Matlab programing.
In this paper, three different kinds of pile foundations were simulated, one is monopile and two six-piled foundations which basically has the same shape but facing the incoming waves with different angle. The CFD outputs of physical characteristics of the fluid mainly include water surface variation, pressure field, velocity and acceleration flow patterns when waves passing around the pile structures. The forces on each element of six-piled foundation were also discussed in this paper.
Finally, the comparison between the results from CFD simulations and the results from empirical Morison equation has shown that the maximum difference is 15.9% which are good enough for the purpose of engineering planning and design, simply because some kind of safety factor would be used in detail engineering design.

摘要 iii
Abstract iv
目錄 v
圖次 viii
表次 xi
第一章 緒論 1
1.1前言 1
1.2文獻回顧 2
1.2.1 前人實驗及研究 2
1.2.2 OpenFOAM 4
1.3研究動機 5
1.4 研究目的 5
1.5 研究方法與研究流程 5
第二章 數值模式理論 7
2.1 OpenFOAM軟體介紹 7
2.2 控制方程式 7
2.3數值模式 8
2.4 數值技巧 9
2.5邊界條件 14
2.5.1 造波邊界Stoke I 14
2.5.2 造波邊界Stoke V 15
2.5.3 消波邊界 16
2.5.4 空氣與水交界面 16
2.5.5 結構物邊界 Wall Function 17
2.6 網格設置 21
2.7 電腦輔助設計 21
第三章 數值模式建置 23
3.1數值模擬建模流程 23
3.2 數值模式與水工驗證 24
3.2.1 stoke I 波浪理論公式 28
3.2.2 Morison公式計算外力 28
3.2.3 數值模式與理論公式結果比較 29
3.2.4 數值模式與水工實驗比較 31
3.3 實際案例數值模擬 35
3.3.1 單樁型式基樁模擬 36
3.3.2 六腳樁型式基樁模擬 40
第四章 結果與討論 45
4.1單樁型式基礎 45
4.1.1 壓力場 45
4.1.2 速度場 48
4.1.3 加速度場 53
4.1.4 圓柱受力探討 57
4.2 六腳樁型式基礎 60
4.2.1 壓力場 60
4.2.2 速度場 65
4.2.3 加速度場 76
4.2.4六腳樁受力探討 87
4.2.4.1 六腳樁型式A 87
4.2.4.2 六腳樁型式B 90
4.3各種樁基礎型式受力整理 93
第五章 結論與建議 94
5.1 結論 94
5.2 建議 95
參考文獻 96
附件A 五階波浪力Morison計算程式 99
附件B RANS控制方程式說明 126

1.許泰文. 2003. 近岸水動力學. 科技圖書股份有限公司
2.李明峯. 2013. 單錨浮式發電載具之動力研究. 國立中山大學海洋環境工程學系碩士班碩士論文
3.Morison, J. R., Johnson, J. W., & Schaaf, S. A. (1950). The force exerted by surface waves on piles. Journal of Petroleum Technology, 2(05), 149-154.
4.Skjelbreia, L., & Hendrickson, J. (1960). Fifth order gravity wave theory. Coastal Engineering Proceedings, 1(7), 10.
5.Dixon, A.G., Greated, C.A., Salter, S.H., (1979). Wave-Forces on Partially Submerged Cylinders. Journal of the Waterway Port Coastal and Ocean Division-Asce 105 (4), 421-438.
6.Dean, R. G., & Dalrymple, R. A. (1991). Water wave mechanics for engineers and scientists.
7.Jasak, H. (1996). Error Analysis and Estimation for the Finite Volume Method with Applications to Fluid Flows, 1996 (Doctoral dissertation, Ph. D. Thesis, University of London Imperial College).
8.Chaplin, J.R., Rainey, R.C.T., Yemm, R.W., (1997). Ringing of a vertical cylinder in waves. Journal of Fluid Mechanics 350, 119-147.
9.Kriebel, D.L., (1998). Nonlinear wave interaction with a vertical circular cylinder: Wave forces. Ocean Engineering 25 (7), 597-605.
10.Bai, W., Taylor, R.E., (2007). Numerical simulation of fully nonlinear regular and focused wave diffraction around a vertical cylinder using domain decomposition. Applied Ocean Research 29 (1-2), 55-71.
11.Flocard, F., Finnigan, T., (2010). Laboratory experiments on the power capture of pitching vertical cylinders in waves. Ocean Engineering 37 (11), 989-997.
12.Eric Furbo , (2010). Evaluation of RANS turbulence models for flow problem with significant impact of boundary layers
13.Westphalen, J., Greaves, D.M., Williams, C.J.K., Hunt-Raby, A.C., Zang, J., (2012). Focused waves and wave-structure interaction in a numerical wave tank. Ocean Engineering 45, 9-21.
14.Higuera, P., Lara, J. L., & Losada, I. J. (2013). Simulating coastal engineering processes with OpenFOAM®. Coastal Engineering, 71, 119-134.
15.Mo, W.H., Jensen, A., Liu, P.L.F., (2013). Plunging solitary wave and its interaction with a slender cylinder on a sloping beach. Ocean Engineering 74, 48-60.
16.Pourtaghi, A., Lotfollahi-Yaghin, M., (2013). Hydrodynamic inline force prediction on vertical cylinders: a comparative study of neural network and its adaptive wavelets (wavenets). Journal of marine science and technology 18 (3), 418-434.
17.Bai, W., Hannan, M.A., Ang, K.K., (2014). Numerical simulation of fully nonlinear wave interaction with submerged structures: Fixed or subjected to constrained motion. Journal of Fluids and Structures 49, 534-553.
18.IHFOAM Manual. (2014).
19.Li, J., Wang, Z., Liu, S., (2014). Experimental study of interactions between multi-directional focused wave and vertical circular cylinder, part II: Wave force. Coastal Engineering 83, 233-242.
20.OpenFOAM User-Manual. (2015).
21.Higuera, P., Losada, I. J., & Lara, J. L. (2015). Three-dimensional numerical wave generation with moving boundaries. Coastal Engineering, 101, 35-47.
22.Cao, H.J., Wan, D.C., (2015). RANS-VOF solver for solitary wave run-up on a circular cylinder. China Ocean Engineering 29 (2), 183-196.
23.Hsieh, C. M., Cheng, M. H., Hwang, R. R., & Hsu, J. R. C. (2016). Numerical study on evolution of an internal solitary wave across an idealized shelf with different front slopes. Applied Ocean Research, 59, 236-253.
24.Hsieh, C. M., Cheng, M. H., Hwang, R. R., Yang, W. C., & Lin, T. C. (2016). Numerical Study on the 3D Interaction between an Internal Solitary Wave and Vertical Cylinder. In The Twelfth ISOPE Pacific/Asia Offshore Mechanics Symposium. International Society of Offshore and Polar Engineers.
25.Jeong, Y. J., Park, M. S., & You, Y. J. (2017). Experimental Study on Shape Dependent Wave Force of Offshore Support Structures. International Journal of Engineering and Technology, 9(2).