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研究生:林禹安
研究生(外文):Yu-An Lin
論文名稱:水面下圓柱體尾流之大渦流模擬
論文名稱(外文):Large Eddy Simulation of Circular Cylinder beneath the Water Surface
指導教授:朱佳仁朱佳仁引用關係
指導教授(外文):Chia-Ren Chu
學位類別:碩士
校院名稱:國立中央大學
系所名稱:土木工程學系
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:2017
畢業學年度:105
語文別:英文
論文頁數:109
中文關鍵詞:大渦模擬阻力係數升力係數沉沒比阻滯比福祿數
外文關鍵詞:Large Eddy SimulationDrag coefficientLift coefficientSubmergence ratioBlockage ratioFroude number
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設計水面之下的跨河管線以及海底纜線時,必須考量水流之衝擊力,以避免管 線之損壞。本研究整合大渦流模式與 VOF 法探討水面下的圓柱體之尾流及圓柱體 受水流之衝擊力。模擬結果先與水槽實驗量測得之自由水面比較、驗證,以增加數 值模式的可信度。再利用數值模式針對圓形斷面之柱體進行一系列的模擬,檢視福 祿數、沉沒比、阻滯比等參數對圓柱體的阻力與升力之影響。數值模擬結果顯示: 因為水深限縮流場的關係,造成水流加速通過圓柱,使得水流施予圓柱的阻力係數 隨著阻滯比變大而增大。當福祿數 FrD = 0.45 時,水面沒有明顯地起伏地流過圓柱 上方;但當福祿數 FrD - 0.68 和沉沒比 h* = 0.75 時,圓柱上方的水面壅高,並在圓 柱後方發生水躍現象。研究結果亦發現:當沉沒比下降(圓柱接近水面)時,因為圓 柱上方受自由水面之影響,發生圓柱上下表面的動壓力不對稱的現象,導致圓柱受 到向上的升力。當圓柱沉沒比 h* > 2.0 時,圓柱表面的動壓分佈就不再受水面影響, 圓柱表面上下壓力對稱,升力係數趨於零。本研究之成果可應用在淹沒於水中管線 的結構設計。
The hydrodynamic loadings on the pipelines are essential parameters for pipeline design, especially when the pipelines are submerged in the river flow during flood events. This study focuses on the interaction between the free surface flow and a submerged cylinder with circular cross-section. This study integrates a Large Eddy Simulation (LES) model and the Volume of Fluid (VOF) method to examine the effect of free surface on the hydrodynamic loading of a submerged circular pipeline. The simulation results are verified by the results of flume experiments. Then the numerical model is utilized to investigate the influences of the Froude number, submergence ratio and blockage ratio on the flow field and the force coefficients of the circular cylinder. The simulation results reveal that the drag coefficient of the cylinder increases as the blockage ratio increases. When the Froude number FrD < 0.45, the water surface is smooth and undisturbed; when FrD > 0.68 and submergence ratio h* = 0.75, the water surface is elevated by the submerged cylinder and dropped behind the cylinder to create a forced jump. The simulation results indicate that the dynamic pressure on the upper side of the cylinder is affected by the water surface and the pressure distribution became asymmetric when the cylinder is very close to the water surface. This leads to the lift coefficient deviated from zero when the submergence ratio h*  2.0. The results of this study can be used for the structure design of submerged pipelines.
Abstract III
Content IV
Table Captions V
Figure Captions VI
1. Introduction 1
2. Numerical Model 3
3. Model Validation 6
3.1 Un-confined case 6
3.2 Confined case 8
4. Results and Discussion 11
4.1 Effect of water depth h1 = h2 11
4.1.1 Water depth effect (Case A) 12
4.1.2 Submergence effect (Case S) 14
4.1.3 Blockage effect (Case B) 15
4.2 Effect of water depth h1 > h2 17
4.2.1 upstream Froude number (Case C) 17
4.2.2 downstream Froude number (Case D)17
5. Conclusions 18
References 20
[1] Achenbach E. Distribution of local pressure and skin friction around a circular cylinder in cross-flow up to Re = 5 x 106. J. Fluid Mech. 1968; 34: 625–639.
[2] Achenbach E, Heinecke E. On vortex shedding from smooth and rough cylinders in the range of Reynolds numbers 6× 103 to 5× 106. J. Fluid Mech. 1981; 109:239–251.
[3] Bimbato, AM, Pereira LAA, Hirata MH. Study of the vortex shedding flow around
a body near a moving ground. J. Wind Eng. Ind. Aerodyn. 2011; 99(1): 7-17.
[4] Blevins RD. Applied Fluid Dynamics Handbook. Van Nostrand Reinhold Co., New
York, 1984, 568 p.
[5] Bouscasse B, Golagrossi A, Marronea S, Souto-Iglesias A. SPH modeling of
viscous flow past a circular cylinder interacting with a free surface. Computers &
Fluids 2017; 146: 190-212.
[6] Cabot W, Moin P. Approximate wall boundary conditions in the large eddy
simulation of high Reynolds number flow. Flow Turbulence and Combustion 2000; 63: 269-291.
[7] Catalano P, Wang M, Iaccarino G, Moin P. Numerical simulation of the flow around a circular cylinder at high Reynolds numbers. International Journal of Heat and Fluid Flow 2003; 24 (4): 463-469.
[8] Chu C-R, Chung C-H, Wu T-R, Wang C-Y. Numerical analysis of free surface flow over a submerged rectangular bridge deck. Journal of Hydraulic Engineering 2016; 142 (12): 10.1061/(ASCE)HY.1943-7900.0001177.
[9] Deardorff JW. A numerical study of three dimensional turbulent channel flow at large Reynolds numbers. J. Fluid Mech. 1970; 41: 453-480.
[10] DeLong M. Two examples of the impact of partitioning with Chaco and Metis on the convergence of additive-Schwarz preconditioned FGMRES. Technical Report LA-UR-97-4181, Los Alamos National Laboratory, New Mexico, U.S.A. 1997.
[11] Hirt CW, Nichols BD. Volume of fluid (VOF) method for the dynamics of free boundaries. J Comput Phys 1981; 39(1): 201-225.
[12]Hoerner SF. Fluid Dynamic Drag: Theoretical, Experimental and Statistical Information. Hoerner Fluid Dynamics, New Jersey. 1965.
[13] Liang H, Zong Z, Zou L, Zhou L, Sun L. Vortex shedding from a two-dimensional cylinder beneath a rigid wall and a free surface according to the discrete vortex method. European Journal of Mechanics-B/Fluids 2014; 43: 110-119.
20
[14] Lin M-Y. and Huang L-H. Free-surface flow past a submerged cylinder. J. of Hydrodynamic 2010; 22 (5): 209-214.
[15] Lloyd TP, and M. James. Large eddy simulations of a circular cylinder at Reynolds numbers surrounding the drag crisis. Applied Ocean Research 59 (2016): 676-686.
[16] O’Neil J. and Meneveau C. Subgrid-scale stresses and their modelling in a turbulent plane wake. J. Fluid Mech., 1997; 349: 253-293.
[17] Reichl P, Hourigan K, Thompson MC. Flow pass a cylinder close to a free surface. J. Fluid Mech 2005; 533: 269-296.
[18] Roshko A. Perspectives on bluff body aerodynamics. J. Wind Eng. Ind. Aerodyn. 1993; 49: 79-100.
[19] Schlichting H. Boundary Layer Theory, McGraw-Hill Inc., New York, 1979, p.817.
[20] Smagorinsky J. General circulation experiments with the primitive equations: I. The
basic experiment. Mon Weather Review 1963; 91: 99-164.
[21] Warschauer KA, Leene JA. Experiments on mean and fluctuating pressures of
circular cylinders at cross flow at very high Reynolds numbers. In: Proc. Int. Conf. on Wind Effects on Buildings and Structures, Tokyo, Japan (see also Zdravkovich 1997), 1971; 305–315.
[22] Williamson CHK. Vortex dynamics in the cylinder wake. Annu Rev. Fluid Mech. 1996; 28: 477-539.
[23] Wu T-R, Chu C-R, Huang C-J, Wang C-Y, Chien S-Y, Chen M-Z. A two-way coupled simulation of moving solids in free-surface flows. Computers and Fluids. 2014; 100: 347-355.
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