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標題: 孤立波通過不同長高比之潛沒構造物時周邊渦流流場特性探討
Characteristics of vortical flow fields induced by solitary waves propagating over submerged structures with different aspect ratios
作者: 何宗浚
Ho, Tsung-Chun
關鍵字: solitary;孤立波;PIV;vortex;submerged structure;shear layer;質點影像測速儀;渦流;潛沒構造物;剪力層
出版社: 土木工程學系所
引用: Boussinesq, J. (1872). “Théorie des ondes et des ramous qui se propagent le long d''un canal rectangulaire horizontal, en commu-niquant au liquide contenu dans ce canal de vitesses sensiblement parreilles de la surface au fond.” Journal de Mathematiques Pures et Appliquées 2nd series, 17, 55-108. Bradshaw P. and Koh Y. M. (1981). “A note on Poisson''s equation for pressure in a turbulent flow.” Physics of Fluids, 24, 777. Chyan, J. M. and Hwung, H. H. (1993). “On the interaction of a turbulent jet with waves.” Journal of Hydraulic Research, 31(6), 791-810. Chu, C. C., Wang, C. T., and Hsieh, C. S. (1993). “An experimental investigation of vortex motions near surfaces.” Physics of Fluids A, 5(3), 662-676. Chu , C. C., Wang, C. T., and Chang, C. C. (1995). “A vortex ring impinging on a solid plane surface-vortex structure and surface force.” Physics of Fluids, 7(6), 1391-1401. Chang, K. A. (1999). Experimental study of wave breaking and wave-structure interaction, Ph. D. dissertation, Graduate school of Cornel University, U.S.A. Chang, K. A., Hsu, T. J., and Liu, P. L. F. (2001). “Vortex generation and evolution in water waves propagating over a submerged rectangular obstacle. Part I: Solitary waves.“ Coastal Engineering, 44, 13-36. Chang, K. A., Hsu, T. J., and Liu, P. L. F. (2005). “Vortex generation and evolution in water waves propagating over a submerged rectangular obstacle. Part II: Cnoidal waves.” Coastal Engineering, 52, 257-283. Daily, J. W., and Stephan, S. C. (1953). “Characteristics of the solitary wave.” Transactions of ASCE, 118, 575-587. Dean, R. G. and Dalrymple, R. A. (1984). Water Wave Mechanics for Engineers and Scientists, Prentice Hall, Englewood Cliffs, N. J. Frank M. W. (1991). Viscous Fluid Flow. McGraw-Hill, New York, 2nd edition, 256-259. Goring, D. G. (1990). “Propagation of long waves onto shelf.” Journal of Waterway, Port, Coastal, and Ocean Engineering, 118(1), 43-61. Grue, J. (1992). “Nonlinear water waves at a submerged obstacle or bottom topography.” Journal of Fluid Mechanics, 244, 455-476. Grilli, S. T., Subramanya, R., Svendsen, I. A. and Veeramony, J. (1993). “Shoaling of solitary waves on plane beaches.” Journal of Waterway, Port, Coastal and Ocean Engineering, 120, 609-628. Gupta, V. P., and Ranga-Raju, K. G. (1987). “Separated flow in lee of solid and porous fences.” Journal of Hydraulic Engineering, 113, 1266-1276. Hoffmann, E. R. and Joubert, P. N. (1963) “Turbulent line vortex.” Journal of Fluid Mechanics, 16, 395-411. Hwung, H. H. and Lin, C. (1989). “The characteristics of internal flow field and bottom boundary layer of waves propagating on sloping bottoms.” Bulletin of Tainan Hydraulic Laboratory, National Cheng Kung University, Taiwan. Huang, C. J. and Dong, C. M. (1999). “Wave deformation and vortex generation in water waves propagating over a submerged dike.” Coastal Engineering, 37, 123-148. Huang, C. J. and Dong, C. M. (2001). “On the interaction of a solitary wave and a submerged dike.” Coastal Engineering, 43, 265-286. Ippen, T. (1977). Estuary and coastline hydrodynamics, McGraw Hill, U.S.A., 125. Kuo, C. H., and Chang, C. W. (1998). “Shear-layer characteristics across a cavity with a horizontal top plate.” Fluid Dynamics Research, 22, 89-104. Losada, I. J., Patterson, M. D. and Losada, M. A. (1997). “Harmonic generation past a submerged porous step.” Coastal Engineering, 31, 281-304. Luton, J. A. and Ragab, S. A. (1997). “The three-dimensional interaction of a vortex pair with a wall.” Physics of Fluids, 9(10), 2967-2980. Lin, C. and Hwung, H. H. (2002). “Observation and measurement of the bottom boundary layer flow in the prebreaking zone of shoaling waves.” Ocean Engineering, 29(12), 1479-1502. Lin, C. and Hsieh, S. C. (2003). “Convection velocity of vortex structures in the near wake of a circular cylinder.” Journal of Engineering Mechanics, ASCE, 129(10), 1108-1118. Lin, C., Lai, W. J., and Chang, K. A. (2003). “Simultaneous PIV and LDV measurements of periodical oscillatory horseshoe vortex system near square cylinder-base plate juncture.” Journal of Engineering Mechanics, ASCE, 129(10), 1173-1188. Lin, P. (2004). “A numerical study of solitary wave interaction with rectangular obstacles.” Coastal Engineering, 51, 35-51. Lin, C., Ho, T. C., Chang, S. C., Hsieh, S. C., and Chang, K. A. (2005). “Vortex shedding induced by a solitary wave propagating over a submerged vertical plate.” International Journal of Heat and Fluid Flow, 26, 894-904. Lin, C., Chang, S. C., Ho, T. C., and Chang, K. A. (2006) “Laboratory observation of a solitary wave propagating over a submerged rectangular dike.” Journal of Engineering Mechanics, ASCE, 132(5), 545-554. Lin, C., Huang, W. Y., Hsieh, S. C., and Chang, K. A. (2007) “Experimental study on mean velocity characteristics of flow over vertical drop.” Journal of Hydraulic Research, IAHR, 45(1), 33-42. Mei, C. C. and Black, J. L. (1969). “Scattering of surface waves by rectangular obstacles in waters of finite depth.” Journal of Fluid Mechanics, 38, 499-511. Madsen, O. S., and Mei, C. C. (1969). “The transformation of a solitary wave over an uneven bottom.” Journal of Fluid Mechanics, 39, 781-791. Michalke, A. (1972). “The instability of free shear layers.” Progress in Aeroscience, 12, 213–239. Naguib, A. M. and Koochesfahani, M. M. (2004). “On wall-pressure sources associated with the unsteady separation in a vortex-ring wall interaction.” Physics of Fluids, 16(7), 2613-2622. Rajaratnam, N. (1976). Turbulent Jets, Elsevier Scientific Publishing Company, Amsterdam. Rey, V., Belzons, M. and Guazzelli, E. (1992). “Propagation of surface gravity waves over a rectangular submerged bar.” Journal of Fluid Mechanics, 235, 53-479. Schlichting, H. (1933). Laminare Strahlenausbreitung, Applied Mathematics and Mechanics, 13, 260-263. Seabra-Santos, F. J., Renouard, D. P. and Temperville, A. M. (1987). “Numerical and experimental study of the transformation of a solitary wave over a shelf or isolated obstacle.” Journal of Fluid Mechanics, 176, 117-134. Saffman P. G. (1992). Vortex Dynamics, Cambridge University Press, United Kingdom. Seal, C. V., Smith, C. R., Akin, O., and Rockwell, D. (1995). “Quantitative characteristics of a laminar unsteady necklace vortex system at a rectangular block-flat plate juncture.” Journal of Fluid Mechanics, 286, 117-135. Sue, Y. C., Chern, M. J., and Hwang, R. R. (2005). “Interaction of nonlinear progressive viscous waves with a submerged obstacle.” Ocean Engineering, 32, 893-923. Tang, C. J. and Chang, J. H. (1998). “Flow separation during solitary wave passing over submerged obstacle.” Journal of Hydraulic Engineering, 124, 742-749. Ting, F. C. K., and Kim, Y. K. (1994). “Vortex generation in water waves propagation over a submerged obstacle.” Coastal Engineering, 24, 23-49. Zhuang, F., and Lee, J. J. (1996). “A viscous rotational model for wave overtopping over marine structure.” Proceedings of the 25th International Conference on Coastal Engineering, Orlando, Florida, 2178-2191. Zijnen, B. G. van der Hegge (1958). “Measurements of the velocity distribution in a plane turbulent jet of air.” Applied Scientific Research, Section A, 7, 256-276. 張興漢,黃清哲,張舜鈞,丁舜臣,黃煌煇(2002):孤立波與透水潛堤之互制作用分析,中國土木水利工程學刊,14(3),第503-514頁。 許泰文(2003):近岸水動力學,科技圖書,台北,第41頁。 張淞傑(2004):應用流場可視化與PIV技術於孤立波通過潛堤周邊渦流流場之研究,國立中興大學土木工程學系碩士論文,台中。 謝世圳(2008):建置具高時間解析度之PIV系統並應用於圓柱近域尾流特性之探討,國立中興大學土木工程學系博士論文,台中。 池田駿介、淺枝隆、野本建司、木村惠利子(1985):波動場に置かた垂直板付近の發生渦の特性とエネルギー逸散,日本土木學會論文集,第363號,第II-4頁。
本文中所設定之波高水深比(H/h)介於 0.16 ~ 0.38、潛沒構造物之長高比(L/D)介於 0.14 ~ 11.1。於流場可視化觀察中發現,在潛沒構造物前、後端皆產生渦流脫離的現象。以時間為軸,潛沒構造物後端之渦流脫離程序可區分為:剪力層產生時期、渦流產生時期、渦流運動時期和渦流潰散時期。再者,潛沒構造物後端主渦的運動型態則因實驗參數的變化而有所不同,經歸納後可將流場分類為Type A (渦心位置高於潛沒構造物頂部且渦VA與V1未合併)、Type B (主渦渦心位置未高於潛沒構造物頂部且渦VA與V1在部分實驗條件下產生合併)與Type C (渦心位置高於潛沒構造物頂部且渦VA與V1產生合併)三種流場型態。在部分實驗條件下,主渦與潛沒構造物垂直壁接觸而產生射流的現象。本文則依序針對上述各時期與型態中所存在之相似特性進行分析與探討。
於剪力層分析方面,在選定適當的長度尺度與速度尺度,並對於剪力層之速度分布進行無因次化後可獲得一相似性剖面。文中亦針對特徵尺度與實驗參數的相關性,以及此相似性方程式所適用之範圍進行探討。在Type A型態下,主渦之速度分布可依其出現時間主要分為stage I、stage II與stage III三個時期,各時期之速度分布可用相同之相似性方程式模擬,並將結果與Lamb-Oseen渦流進行比較。此外,在D/h 0.3的實驗條件下,主渦接觸潛沒構造物後端垂直壁後流場中出現射流的現象,而此現象之速度分布可利用二維平面射流之相似性方程式描述。文中亦針對其特徵尺度隨著時間的變化情形進行討論,並觀察實驗參數之影響。
最後,本文分析單一實驗條件下(H/h = 0.1、L/h = 1.4、D/h = 0.5、h = 10.0 cm)之反射係數、透射係數與消能係數,並與Lin (2004)中所提出之數值分析結果比較。實驗結果之反射係數為0.0139、透射係數為0.9073及消能係數為0.0788,所得係數皆與數值分析結果相近。計算所有渦流之動能後得到的渦流消能係數為0.0498,由此可知:除了波浪反射之外,渦流之運動為主要消能機制,而摩擦損失則較小。在Type A運動型態的實驗條件下,發現主渦環流量強度變化趨勢可利用一相似性方程式表示之,另主渦環流量最大值與後端渦流消能係數間亦存在一明顯相關性,可以雙曲線正切函數表示。分析各實驗參數對於主渦環流量最大值與後端渦流消能係數之影響後,發現流場型態與渦流能量變化之間有明顯的相關性。

The flow characteristics induced by a solitary wave propagating over a bottom-mounted rectangular dike were studied experimentally, using time-resolved particle image velocimetry (PIV) and particle trajectories photography for flow visualization. The time-resolved PIV consisted of a phantom camera and a high power Ar-ion laser. Image processing techniques developed by Hsieh (2008) were utilized to improve both time and space resolutions of the PIV system.
The main parameters of this study are wave steepness (H/h = 0.16 ~ 0.38) and aspect ratios of submerged dikes (L/D = 0.14 ~ 11.1). Based on the flow visualization results, vortices are generated around the leading and trailing edges of the dike. The vortex shedding process near trailing edge can be divided into the following phases: the formation of a separated shear layer, the generation and evolution of vortices, and the breakdown of the vortices. On the other hand, the motions of primary vortex are different due to the change of experimental parameters. By summarizing the motions of primary vortices, flow patterns can be categorized into three types: Type A, Type B and Type C.
In some cases, the formation of a jet flow is clearly evidenced due to the interaction between primary vortex and vertical boundary of the submerged dike. The characteristics of these formations are investigated sequentially.
In the formation of shear layer, the similarity profile is found by choosing proper length and velocity scales. The relationship between characteristic scales and non-dimensional experimental parameters are investigated. For the flow fields of Type A, the velocity distributions of primary vortex can be categorized into three stages including Stages I, II and III during the processes of vortex generation and evolution. The similarity profile is also found and used to modify velocity distributions of these stages. These profiles are compared with that of Lamb-Oseen vortex. Moreover, jet flow is found in the conditions of D/h <= 0.3. The similarity profile of the jet flow is obtained and compared with the equation of traditional plane jet. The relationships between characteristic scales and experimental parameters are analyzed and discussed.
Finally, the reflection, transmission and dissipation coefficients of one single case (H/h = 0.1, L/h = 1.4, D/h = 0.5 and h = 10.0 cm) are calculated. The corresponding result is also compared with the numerical result reported by Lin (2004). It is found that the result is reasonable, and energy loss is mainly due to the energy dissipation of vortex shedding process except wave reflection. For the cases of Type A, a similarity curve is also found and used to demonstrate the variation of circulation of primary vortex. The relationship between maximum circulation of primary vortex and kinetic energy of vortices near the trailing edge can be expressed as the function of hyperbolic tangent. The effect of experimental parameters on the maximum circulation and dissipation coefficient of vortices around the trailing edge is also investigated. The variations of circulation of primary vortex and dissipation coefficient are closely associated with the types of vortex motions.
其他識別: U0005-2604200917275400
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