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Examination of v-velocity fluctuations in a turbulent channel flow in the context of sediment transport

Published online by Cambridge University Press:  26 April 2006

T. Wei  and
W. W. Willmarth
T. Wei
Affiliation:
Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, NJ 08855, USA
W. W. Willmarth
Affiliation:
Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI 48109-2140, USA
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Abstract

This paper is a report on the mechanism of turbulent momentum transport normal to the wall in a turbulent wall-bounded flow. The objective of this study is to examine the ‘background’ turbulent flow field as a first step toward understanding suspended sediment transport. Specifically, the hypothesis that fine grain particles can be kept in suspension through a net upward momentum flux in a turbulent boundary layer is examined. The net momentum flux can arise if the probability density distribution of the fluctuating v–signal is positively skewed; i.e. the positive v–fluctuations are predominantly of large amplitude and short duration while the negative v-fluctuations are of small amplitude and long duration. High-resolution, two-component laser-doppler anemometer measurements of the v-velocity component in a fully developed turbulent water channel flow were examined spanning a Reynolds number range of 3000 to 23000. Averages of these signals demonstrate that, for very small particles, there is net upward momentum flux in the range y+ > 30, while there is a net downward momentum flux in the range 10 [les ] y+ [les ] 30. Preliminary results which categorize the normal velocity according to quadrants of motion are also included.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 223 , February 1991 , pp. 241 - 252
Copyright
© 1991 Cambridge University Press

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References

Bagnold, R. A.: 1966 An approach to the sediment transport problem from general physics. US Geological Survey Paper 422-I.Google Scholar
Brodkey, R. S., Wallace, J. M. & Eckelmann, H., 1974 Some properties of truncated turbulence signals in bounded shear flows. J. Fluid Mech. 63, 209.Google Scholar
Grass, A. J.: 1971 Structural features of turbulent flow over smooth and rough boundaries. J. Fluid Mech. 50, 233.Google Scholar
Grass, A. J.: 1983 The influence of boundary layer turbulence on the mechanics of sediment transport, Euromech 156: Mechanics of Sediment Transport 1982. Rotterdam: A. A. Balkema.
Jackson, R. G.: 1976 Sedimentological and fluid-dynamic implications of the turbulent bursting phenomenon in geophysical flows. J. Fluid Mech. 77, 531.Google Scholar
Klewicki, J. C. & Falco, R. E., 1988 On accurately measuring statistics associated with small scale structure in turbulent boundary layers. Mich. State Univ., Dept. of Mech. Engng Rep. TSL– 88–4.Google Scholar
Kline, S. J., Reynolds, W. C., Schraub, F. A. & Runstadler, P. W., 1967 The structure of turbulent boundary layers. J. Fluid Mech. 30, 741.Google Scholar
Leeder, M. R.: 1983 On the dynamics of sediment suspension by residual Reynolds stresses –confirmation of Bagnold's theory. Sedimentology 30, 485.Google Scholar
Sumer, B. M. & Deigaard, R., 1981 Particle motions near the bottom in turbulent flow in an open channel. J. Fluid Mech. 109, 311.Google Scholar
Sumer, B. M. & Oguz, B., 1978 Particle motions near the bottom in turbulent flow in an open channel. J. Fluid Mech. 86, 109.Google Scholar
Wei, T.: 1987 Reynolds number effects on the small scale structure of a turbulent channel flow, Ph.D. thesis, The University of Michigan.
Wei, T. & Willmarth, W. W., 1989 Reynolds number effects on the structure of a turbulent channel flow. J. Fluid Mech. 204, 57.Google Scholar