Three Dimensional Bursting Phenomena in Open Channel Bends

Abstract:

The turbulent coherent structure of flow in open channel bends is a stochastic process in nature. The coherence structure of the flow or bursting process is very important for the entrainment of sediment particles from the bed. In this study, first-order Markov process combined with three-dimensional quadrant analysis is applied to the measured turbulent data in open channel bends. The turbulent data was measured in an experimental flume using three-dimensional acoustic Doppler velocity meter (ADV). It was found that the stable movements of velocity fluctuations have higher transition probabilities than other movements, and the cross movements have the least transition probability. In addition, the internal group of events occurs more frequently than external group, particularly the internal ejection and internal sweep events and the probabilities decrease from the concave bank to the convex bank periodically, and reach the maximum at the top of the curved concave bank.

• Periodical: Applied Mechanics and Materials (Volumes 405-408)
• Pages: 2277-2282
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.405-408.2277
• Online since: September 2013
• Authors: Yan Wu, Yu Chuan Bai
• Keywords: Open Channel Bends, Three-Dimensional Bursting Events, Transition Probability

References

[1] Kline SJ, Reynolds WC, Schraub FA, Runstadler PW. The structure of turbulent boundary layers. J Fluid Mech1967, 30(4): 741-73.

DOI: 10.1017/s0022112067001740

[2] Lu S S, Willmarth W W. Measurements of the structure of the Reynolds stress in a turbulent boundary layer [J]. Journal of Fluid Mechanics, 1973(60), 481-511.

DOI: 10.1017/s0022112073000315

[3] Bridge JS, Bennett SJ. A model for the entrainment and transport of sediment grains of mixed sizes, shapes and dencities. Water Resourse Res 28(2): 337-363.

DOI: 10.1029/91wr02570

[4] Nezu I, Nakagawa H. Turbulence in open channel flows. IAHR Monograph, Balkema, Rotterdam, (1993).

[5] Grass A J. Structure features of turbulent flow over smooth and rough boundaries[J]. Journal of Fluid Mechanics, 1971, 50(2): 233-255.

DOI: 10.1017/s0022112071002556

[6] Keshavarzi AR, Ball JE (1999) An application of image processing in the study of sediment motion. J Hydra Res 37(4): 559–576.

[7] Bai Yuchuan, Yang Yanhua. The dynamic stability of the flow in meander channel[J]. Science China-Technological Science, 2011, 54(4): 931-940.

DOI: 10.1007/s11431-011-4316-1

[8] Keshavarzi AR, Gheisi AR. Stochastic nature of three dimensional bursting events and sediment entrainment in vortex chamber[J]. Stochastic Environmental Research and Risk Assessment, 2006, 21(1): 75–87.

DOI: 10.1007/s00477-006-0045-6