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系統識別號 U0026-1108201700344300
論文名稱(中文) 波流與波狀底床交互作用之數值模擬研究
論文名稱(英文) Numerical Simulation of Wave-Current Interaction with Sinusoidal Bottom
校院名稱 成功大學
系所名稱(中) 水利及海洋工程學系
系所名稱(英) Department of Hydraulics & Ocean Engineering
學年度 105
學期 2
出版年 106
研究生(中文) 蔡宗良
研究生(英文) Chung-Liang Tsai
學號 N86041191
學位類別 碩士
語文別 中文
論文頁數 77頁
口試委員 口試委員-蔡清標
口試委員-劉景毅
口試委員-吳南靖
指導教授-蕭士俊
中文關鍵字 波流交互作用  布拉格共振  均勻流  順向流  逆向流  波狀底床  三點法 
英文關鍵字 Bragg resonance  following current  opposing current  three-point method  OpenFOAM. 
學科別分類
中文摘要 當波浪通過波狀底床時,特定頻率之波浪會與底床有顯著的交互作用現象, 進而產生強反射,此現象稱作布拉格共振(Bragg resonance),而前人研究中提 出受到均勻順向流作用下,共振發生頻率會改變,本文以開源計算流體力學軟 體OpenFOAM進行模擬,希望能以數值分析的方式,模擬受順向、逆向均勻 流作用下之布拉格共振現象,並瞭解局佈流場之特性。
本模式求解雷諾平均N-S方程式,以有限體積法進行偏微分方程式之離散, 並以流體體積法(VOF)追蹤自由液面變化,為合理模擬入、反射波受流作用為 相反,模式選擇造波方法為內質源造波法(Internal mass source wavemaker),配 合數值海綿層消波(Numerical sponge layer),造流方法則以鬆弛法(Relaxation method)概念造流,這些數值方法不僅成功模擬波浪與順、逆向均勻流交互作 用,且無須為了避免反射問題將水槽拉長,進行長時間模擬,另外為了分析有 流作用下之反射率,本研究重新推導計算反射率法-三點法並考慮流的影響。
純波、純流、波流交互作用之數值結果與Tsao(1959)之解析解比較,波高 的模擬於波流交互作用時略有不符,故以調整已知波高來造出預期之波浪,而 波長的模擬則與理論預測相當符合。
本研究應用使用之水槽設計參考Magne等人(2005)之實驗水槽設計,於波 狀底床前後考慮存在緩衝斜坡段,數值計算結果趨勢與實驗資料相符合,且能 夠以理論共振發生條件預測主要、次要共振發生之條件,並進一步分析波狀底 床附近之速度場、渦度場。
英文摘要 Present study aims to simulate Bragg resonance phenomenon in the presence of uniform
currents with OpenFOAM CFD tools. Water waves interact with both following and
opposing currents passing through sinusoidal bottom with ramps.
Incident waves are generated by internal mass source method, and sponge layers located at
two sides of flume, which are used for dissipating the outgoing waves and maintaining a
uniform current simultaneously. Theoretically, wave number will change due to the
existence of current. In order to estimate reflectivity, present study modifies the three-point
method considering different wave number between incident and reflected wave.
Numerical model in the study solves the Reynolds Averaged Navier-Stokes (RANS)
equations with k-eplison turbulence closure scheme, and free surface deformation is tracked
by volume of fluid method (VOF).
The numerical model simulation capability in wave-current interaction is validated by
theoretical solution and results are in good agreements. After that, wave, current and
sinusoidal bottom interaction are simulated with different current strength and direction.
Results of the case with no current are compared with experiment data and find resonance
occurring conditions of main and secondary resonance. The conditions successfully predict
resonance occurrence both in following and opposing current conditions. Besides, when
current passes through sinusoidal bottom, there is obvious vortex occurring because of
separation phenomenon.
Present study realizes wave and current interaction in OpenFOAM, especially opposing
current condition, and applies to Bragg resonance simulation. Numerical results extend the
theory resonance condition deriving from potential flow model, which find secondary
resonance condition and successfully predict resonance occurrence under uniform current
even if obvious vortex occurs near the bottom.
論文目次 摘要 I
目錄 IX
表目錄 XI
圖目錄 XII
符號表 XVIII
第一章 緒論 1
1-1 研究動機 1
1-2 文獻回顧 2
1-3 本文架構 5
第二章 數值模式及方法 6
2-1 模式介紹 6
2-1-1 OpenFOAM 7
2-1-2 OlaFOAM 7
2-2 數值模式 8
2-2-1 控制方程式-RANS 8
2-2-2 紊流閉合模式 11
2-2-3 流體體積法 12
2-2-4 數值造波、流及吸波方法 15
2-2-5 有限體積法 19
2-2-6 邊界條件及起始條件 20
2-2-7 模式計算流程概述 23
2-3 反射率計算-三點法(Three points method) 24
第三章 模式及方法驗證 28
3-1反射率計算方法驗證 28
3-1-1 入、反射波組合驗證 28
3-1-2 波高計間距測試 31
3-2 波流交互作用驗證 32
3-2-1 純流、純波驗證 35
3-2-2 均勻流場下波流交互作用 42
第四章 布拉格共振 45
4-1 問題描述 45
4-2 數值水槽配置 46
4-3 計算結果與討論 48
4-3-1 純波、純流與底床交互作用 48
4-3-2 均勻順向流條件作用 56
4-3-3 均勻逆向流條件作用 61
第五章 結論與建議 69
5-1 結論 69
5-2 建議 70
參考文獻 71
附錄A 最小平方法求反射率之推導 74

參考文獻 1. Caubilla, P. H., (2015). Computational fluid dynamics to wave action on structures, Doctoral thesis.
2. Chawla, A., Kirby, J. T., (1998). Experimental study of wave breaking and blocking on opposing currents, 26th International Conference on Coastal Engineering.
3. Chawla, A., Kirby, J. T., (2002). Monochromatic and random wave breaking at blocking points, Journal of geophysical research, 107 (C7), 4-1-19.
4. Chen, Y.-L., Hsiao, S.-C., (2015). Interaction of waver waves and a slender pile in the presence of a uniform current Navier-Stokes model, Proceedings of the 37th Ocean Engineering Confrence in Taiwan.
5. Chen, Y.-L., Hsiao, S.-C., (2016). Generation of 3D waver waves using mass source wavemaker applied to Navier-Stokes model”, Costal Engineering, 109, 76-95.
6. Davies, A. G. and Heathershaw, A. D., (1984). Surface-wave propagation over sinusoidally varying topography, J. Fluid Mech., 144, 419-443.
7. Hsu, T.-W., Hsiao, S.-C., Ou, S.-H., Wang, S.-K., Yang, B.-D., Chou, S.-E., (2007). An application of Boussinesq equations to Bragg reflection of irregular waves, Ocean Engineering, 34, 870-883.
8. Hsu, T.-W., Hsieh, C.-M, Hwang, R. R., (2004). Using RANS to simulate vortex generation and dissipation around impermeable submerged double breakwaters, Costal Engineering, 51, 557-579.
9. Hsu, T.-W., Lin, J.-F., Hsiao, S.-C., Ou, S.-H., Babanin, A. V., Wu, Y.-T., (2014). Wave reflection and vortex evolution in Bragg scattering in real fluids, Ocean Engineering, 88, 508-519.
10. Huang, C.-J., Dong, C.-M., (2002). Propagation of water waves over rigid rippled beds, Journal of waterway, port, coastal and ocean engineering, 128(5), 190-201.
11. Jasak, H., (1996). Error Analysis and Estimation for the finite volume method with applications to fluid flows, Doctoral thesis.
12. Kirby, J. T., Dalrymple, R. A., (1983). A parabolic equation for the combinend refraction-diffraction of Sokes wave by mildly varying topography, J. Fluid Mech., Vol. 139, 453-466.
13. Kirby, J. T., (1998). Current effects on resonant reflection of surface water waves by sand bars, J. Fluid Mech., Vol. 186, 501-520.
14. Lin, P., Liu, P. L.-F., (1998). A numerical study of breaking waves in the surf zone, J. Fluid Mech., Vol. 359, 239-264.
15. Lin, P., Liu, P. L.-F., (1999). Internal wave-maker for Navier-Stokes equations models, J. Waterway, Port, Coastal, Ocean Eng., 124(4), 207-215.
16. Lin, C.-Y., Huang, C.-J., (2004). Decomposition of incident and reflected higher harmonic waves using four wave gauges, Coastal Engineering, 51, 395-406.
17. Lopes, P. M. B., (2013). Free-surface flow interface and air-entrainment modelling using OpenFOAM, Doctoral thesis.
18. Magne, R., Rey, V., Ardhuin, F., (2005). Measurement of wave scattering by topography in the presence of currents”, Physics of Fluid, 17, 126601.
19. Rusche, H., (2002). Computational fluid dynamics of dispersed two-phase flows at high phase fractions, Doctoral thesis.
20. Tsao, S., (1959). Behaviour of surface waves on a linearly varying flow. Tr. Mosk. Fiz.-Tekh. Inst. Issled Mekh. Prikl. Mat., 3, 66-84.
21. Thomas, G. P., (1997). Wave-current interactions in the near-shore region. In: Hunt JN, editor. Gavity waves in water of finite depth, advances in fluid mechanics. Computational Mechanics Publications, 66-84.
22. Wang, B.-L., Liu, H., (2005). Higher order boussinesq-type equations for water waves on uneven bottom, Applied Mathematics and Mechanics, Vol. 26, 6.
23. Xiao, H., Huang, W., Tao, J., Liu, C., (2013). Numerical modeling of wave-current forces acting on horizontal cylinder of marine structure by VOF method, Ocean Engineering, 67, 58-67.
24. Zhang, J.-S., Zhang, Y., Jeng, D.-S., Liu, P.L.-F., Zhang, C., (2014). Numerical simulation of wave-cuttent interaction using a RANS solver, Coastal Engineering, 75, 157-164.
25. 洪靖博(2011),「Numerical study of linear waves propagating over a submerged parabolic obstacle in the presence of a steay uniform current」,國立成功大學水利及海洋工程研究所碩士論文。
26. 許時倫(2012),「剪力流中規則波通過底床拋物線型結構物之數值研究」,國立成功大學水利及海洋工程學系碩士論文。
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