초록

Vanoni가 1946년에 유사를 포함한 흐름에서는 Karman상수가 감소한다고 제안한 이후로 개수로 흐름에서 유사 입자가 평균 유속 분포를 변화시킨다는 것은 매우 잘 알려진 사실이다. 그러나 유사 입자가 어떤 역할을 하는지, 어떤 매개 변수가 변화할 것인지에 대해서는 현재까지도 논쟁이 계속되고 있다. 한편, 어떤 연구자들은 난류중에 유사입자가 투입되더라도 Karman 수는 변하지 않는다고 주장하였다. 본 연구에서는 Karman 수의 변화에 대한 기존의 연구들을 재평가하였다. 이를 통하여 기존 연구들의 방법에서 몇 가지 오류들을 밝혀 내었으며, 왜 이 사항이 오랜 동안 논쟁이 되어왔는가 하는 이유를 찾아내었다. 또한 분석 결과 유사 입자의 투입에 의해 Karman 수는 감소되지만 그 감소량은 기존의 연구들에서 제시된 것보다 훨씬 작음을 밝혔다. 또한 본 연구는 유사의 투입에 의해 Karman 수가 감소되는 기구를 제시하였다.

Abstract

It is well known that sediment particles introduced in open-channel turbulent flows change mean velocity profile, since Vanoni suggested the reduction of the Karman constant in 1946. However, how the sediment particles take such a role and what parameters would be changed have been debated up to now. Some researchers, on the other hand, have insisted that the constant would not be changed regardless of introducing sediment particles. The present study is a careful re-evaluation of the previous studies on this issue. The study revealed some questionable approaches or methods in the decision of the previous researches and found the reason why this issue has been debated for a long time. The result indicated that the Karman number is reduced by adding sediment particles, but the amount of reduction is much smaller than the previous researches insisted. Finally, the present study proposes a mechanism of the Karman number reduction due to sediment particles.

주제어

#난류   #유속 분포   #유사 입자   #Karman 수  

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참고문헌 (33)

1. Best, J., Bennett, S., Bridge, J. S., and Leeder, M. (1997). 'Turbulence modulation and particle velocities over flat sand beds at low transport rates.' J. of Hydraulic Engineering, ASCE, 123(12), pp. 1118-1129 
2. Ceilino, M. (1998). Experimental study of suspension flow in open channels, Ph. D. dissertation, Ecole Polytechnique Federale de Lausanne 
3. Coles, D. (1956). 'The law of the wake in the turbulent boundary layer.' J. of Fluid Mechanics, 1, pp. 191-226 
4. Guo, J., and Julien, P. Y. (2001). 'Turbulence velocity profiles in sediment-laden flows.' J. of Hydraulic Research, 39(1), pp. 11-23 
5. Gust, G, and Southard, J. B. (1983). 'Effects of weak bed load on the universal law of the wall.' J. of Geophysical Research, 88(C10), pp. 5939-5952 
6. Guy, H. P., Simons, D. B., and Richardson, E. V. (1966). Summary of alluvial channel data from flume experiments, 1956-1961. Professional Paper 462-I, U.S. Geological Survey 
7. Itakura, T., and Kishi, T. (1980). 'Open channel flow with suspended sediments.' J. of Hydraulic Engineering, ASCE, 100(8), pp. 1325-1343 
8. Kaftari, D., Hetsroni, G, and Banerjee, S. (1998). 'The effect of particles on wall turbulence.' Int. J of Multiphise Flow, 24(3), pp. 359-386 
9. Kiger, K. T., and Pan, C. (2002). 'Suspension and turbulence modification effects of solid particles on a horizontal turbulent channel flow', J. of Turbulence, 3(1), pp. 1-17 
10. Kironoto, B. A. (1993). Turbulence characteristics of uniform and non-uniform, rough open-channel flow, Ph. D. dissertation, Swiss Federal Institute of Technology, Lausanne, Switzerland 
11. Kundu, P. K. (1990). Fluid mechanics, Academic Press 
12. Lyn, D. A. (1986). Turbulence and turbulent transport in sediment-laden open-channel flows. Report No. KH-R-49, W. M Keck Laboratory of Hydraulics and Water Resources, California Institute of Technology, Pasadena, CA 
13. McQuivey, R. S. (1973). Summary cj turbulence data from rivers, conveyance dannels, and laboratory flumes. Geological Survey Professional Paper 802-B, U.S. Geological Survey 
14. Muste, M. (2001). 'Source of bias errors in flume experiments on suspended-sediment transport.' J. of Hydraulic Research, 40(6), pp. 695-708 
15. Muste, M., and Partel, V. C. (1997). 'Velocity profiles for particles and liquid in open-channel flow with suspended sediment.' J. of Hydraulic Engineering, ASCE, 123(9), pp. 742-751 
16. Nezu, I., and Nakagawa, H. (1993). Turbulence in open-channel flows, A.A. Balkema 
17. Nouh, M (1989). 'The von Karman coefficient in sediment-laden flow.' J. of Hydraulic Research. 27(4), pp. 477-499 
18. Righetti, M., and Romano, G. P. (2004). 'Particle-fluid interactions in a plane near-wall turbulent flow', J. of Fluid Mechanics, vol. 505, pp. 93-121 
19. Umeyama, M., and Gerritsen, F. (1992). 'Velocity distribution in uniform sediment-laden flow.' J. of Hydraulic Engineering, ASCE, 118(2), pp. 229-245 
20. Vanoni, V. A. (1975). Sedimentation engineering, ASCE 
21. Vanoni, V. A., and Nomicos, G. N. (1960). 'Resistance properties of sediment-laden streams.' Trans. of ASCE, 125, pp. 1140-1164 
22. Wang, X., and Qian, N. (1989). 'Turbulence characteristics of sediment-laden flows.' J. of Hydraulic Engineering, ASCE, 115(6), pp. 781-799 
23. Wang, X., Wang, Z.-Y., Yu, M, and Li, D. (2001). 'Velocity profile of sediment suspensions and comparison of log-law and wake-law.' Journal of Hydraulic Research, 39(2), pp. 211-217 
24. Yu, K. (2004). Particle tracking of suspended-sediment velocity in open-channel flow, Ph.D. thesis, Dept. of Civil and Environmental Engineering, Univ. of Iowa, Iowa City 
25. Zagarola, M. V. (1996). Mean-flow scaling of turbulent pipe flow, Ph.D. dissertation, Princeton Univ., Princeton, NJ 
26. Einstein, H. A, and Chien, N. (1955). Effect of heavy sediment concentration near the bed on the velocity and sediment distribution. Institute of Engineering Research, University of California, Berkeley, CA 
27. Coleman, N. L. (1981). 'Velocity profiles with suspended sediment.' J. of Hydraulic Research, 19(3), pp, 211-229 
28. Keulegan, G. H. (1938). 'Laws of turbulent flow in open channels', J. Research, National Bureau of Standards, 121 
29. Guo, J. (1998). Turbulent velocity profiles in clear water and sediment-laden flows, Ph.D. dissertation, Colorado State University, Fort Collins, CO 
30. Kaftori, D., Hetsroni, G., and Banerjee, S. (1995). 'Particle behavior in the turbulent boundary layer. II. Velocity and distribution profiles.' Physics of Fluids, 7(5), pp. 1107-1121 
31. Muste, M. (1995). Particle and liquid velocity measurements in sediment-laden flows with a discriminator laser-doppler velocimeter, Ph.D. thesis, Dept. of Civil and Environmental Engineering, University of Iowa, Iowa City, IA 
32. Elata, C., and Ippen, A. T. (1961). The dynamics of open channel flow with suspensions of neutrally buoyant particles. Techinical Report No. 45, Hydrodynamics Laboratory, Massachusetts Institute of Technology 
33. Vanoni, V. A. (1946). 'Transportation of suspended sediment by running water.' Trans. of ASCE, 111, pp. 67-133 

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