本篇論文旨在探討完全發展紊流於透水底床上流速變化情形。水流在透水底床上及內部之流速分佈剖面，以往使用對數律流速剖面公式及達西定律來描述其現象，但是由於透水底床上方之水流與孔隙介質交界面存在有動量交換，限制傳統對數律流速剖面公式與達西定律之使用範圍。為了了解水流於透水底床之流速特性，在本篇論文中，藉由兩種不同粒徑玻璃彈珠組合而成之透水底床，其孔隙率分別為34.9%及43.3%，以實驗的方式利用聲波都譜勒流速儀與電磁式流速儀來量測透水底床之垂向流速分佈，並藉由改變相對水深、雷諾數、坡度及透水底床內組成顆粒粒徑之孔隙率及滲透係數等參數，檢視分析各參數變化對於紊流通過透水底床之流速特性的影響，希望對於透水底床上方及內部紊流基本特性的了解有所幫助。從實驗量測所得之垂向流速分佈顯示由於紊流的影響及交界面附近動量的交換，造成孔隙介質上方之流速分佈隨著滲透係數增加而減少，而紊流穿透進入多孔介質底床之厚度僅與滲透係數有關而與孔隙介質上方之流速分佈剖面之型態無關。

　This study experimentally investigates the velocity distribution of fully developed turbulent flow over and within a porous bed. The porous bed is simulated by two glass beads, having porosity equal to 34.9% and 43.3%. The characteristics of turbulent flow in an open channel with a porous bed are measured by an Acoustic Doppler Velocimeter(ADV) and Electromagnetic flowmeter. Effects of several parameters on the velocity distribution, such as, relative porous depth, Reynolds number, channel slope and permeability (K) are investigated and discussed. The Reynolds numbers, based on the mean velocity of clear fluid region and the clear fluid depth, vary from about 9094.31 to 43537.67. The measured velocity distributions show a significant decrease of velocity over a porous bed with increasing permeability due to the penetration of turbulence into the porous medium and momentum transfer near the interface. The thickness of turbulence penetration is only dependent on the permeability of a porous bed rather than the flow conditions over a porous bed.

參考文獻
1.Bingjun Li and Vinod K. Garga, ‘‘Theoretical Solution for Seepage Flow in Overtopped Rockfill,’’ Journal of Hydraulic Engineering, Vol.124,No.2,p213-217 February, 1998
2.Breugem W.P. and B.J. Boersma ,‘‘The turbulent flow over a permeable wall, ’’ Center for Turbulence Research Proceedings of the Summer Program,2002
3.Carollo F.G..,V Ferro and D.Termini, ‘‘Flow Velocity Measurements in Vegetated Channels, ’’ Journal of Hydraulic Engineering, Vol.128,No.7,p664-673,July,2002
4.Chen Xingwei and Yee-Meng Chiew, M., ‘‘ Response of Velocity and Turbulence to Sudden Change of Bed Roughness in Open-Channel Flow, ’’ Journal of Hydraulic Engineering, Vol. 129,No. 1, p35-43,January , 2003
5.Chen Xingwei and Yee-Meng Chiew, M.,‘‘Velocity Distribution of Turbulent Open-Channel Flow with Bed Suction, ’’ Journal of hydraulic Engineering, Vol 130, No2 ,p140-148, February,2004
6.Cheng, X. and Y. M. Chiew, ‘‘Modified Logarithmic Law for Velocity Distribution Subjected to Upward Seepage,’’ Journal of hydraulic Engineering, Vol 124 ,No12,p1234-1241,1998
7.Cheng, X. and Y. M. Chiew, ‘‘Modified Logarithmic Law for Velocity Distribution Subjected to Upward Seepage., ’’J. Env. Engrg., ’’ Vol. 124,No. 12, p1235-1241,1998
8.Hiroshi Nagaoka and Shinichiro Ohgaki, ‘‘Mass Transfer Mechanism in a Porous Riverbed, ’’Wat. Res., Vol 24,No.4,p417-425,1990
9.Marcelo J.S. de Lemos, ‘‘ Turbulent Kinetic Energy Distribution across the Interface between a Porous Medium and a Clear Region Intern, ’’ International Communications in Heat and Mass Transfer 32, p107-115,2005
10.Marco Ghisalberti and Heidi M. Nepf, ‘‘ Mixing layers and coherent structures in vegetated aquatic flows, ’’ Journal of Geophysical Research,Vol.107, No.C2, p3-1-3-10,February ,2002.
11.Prinos P., ‘‘Bed-Suction Effects on Structure of Turbulent Open-Channel Flow, ’’ Journal of Hydraulic Engineering, ’’ Vol. 121,No. 5, p404-412,May,1995
12.Prinos Panayotis and Evangelos Keramaris, ‘‘Characteristics of turbulent flow over a porous bed, ’’ ,1998
13.Prinos Panayotis, Dimitrios Sofialidis and Evangelos Keramaris, ‘‘ Turbulent flow over and within a porous bed, ’’ Journal of Hydraulic Engineering, Vol. 29,No. 9, p720-733,September , 2003
14.Sahraoui,M. and M. Kaviany, ‘‘Slip and no-slip velocity boundary condition at interface of porous,plain media Int,Journal Heat Mass Transfer,’’ Vol 35,p927-943,1992
15.Shimizu, Y., T. Tsujimoto, and H. Nakagawa, ‘‘ Experimental and Macroscopic modeling of flow in highly porous medium under free-surface flow, ’’Journal of Hydroscience and Hydraulic. Engineering, Vol. 8, No. 1, p69-78,October , 1990
16.Uhlmann M. & J. Jimenez, G..Kawahara, A. Pinelli ,‘‘Turbulence Characteristics Near A Porous Surface, ’’ February, 2000
17.Wang F.H. , G..D. Jiang , K. Lam, ‘‘ A study of velocity fields in the near wake of a wavy (varicose) cylinder by LDA, ’’ Flow Measurement and Instrumentation 15,p 105-110, 2004
18.黃偉哲，「水流通過透水式橋墩保護工之流況分析」，國立成功大學水利及海洋工程研究所碩士論文，(2002)
19.楊明聖，「明渠中方型透水結構物附近之流速量測與紊流特性分析」，國立成功大學水利及海洋工程研究所碩士論文，(2005)
20.呂易衛，「孔隙介質間水流視速度之影像分析研究」，國立成功大學水利及海洋工程研究所碩士論文，(2005)
21.郭律君，「水流流經群樁之水理特性研究」，國立成功大學水利及海洋工程研究所碩士論文，(2005)