Importance of bed roughness in transversal variability of the flow patterns and bed shear stress due to secondary currents

Document Type : Article

Authors

1 Department of Civil Engineering, Faculty of Engineering, Science and Research Branch Islamic Azad University, Tehran, Iran

2 Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran

3 Department of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran

Abstract

Laboratory experiments were carried out in order to study the influence of the bed roughness on secondary circulations and lateral flow variability in a straight open channel. Flow field and bed shear stress were measured using an acoustic doppler velocimeter and a particular type of the Preston tube, respectively. All experiments attest presence of noticeable lateral variations of the flow characteristics due to the secondary currents. The observations also reveal that the lateral variations in the experiments with larger bed roughness are more intense. This implies the formation of a more stable mechanism for the maintenance of the cellular pattern in the experiments with larger bed roughness elements. Regarding formation of the secondary currents, application of double averaging method (averaging of the time averaged turbulence parameters within a thin spatial slab parallel to the bed) is also discussed. It was found that, to properly consider the lateral variations of the flow characteristics, spatial averaging should be implemented among the measured data at different spanwise locations. As such secondary current enhancements can also affect more complex and natural flow like river flows, it can also be recommended to examine the importance of such phenomenon in those areas respecting double averaging method.  

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References

References

1. Bagnold, R.A. An approach to the sediment transport
problem from general physics", Geological Survey
Professional Paper, 442-I, p. 37 (1966).
2. Bennett, S.J., Bridge, J.S., and Best, J.L. Fluid and
sediment dynamics of upper stage plane beds", Journal
of Geophysical Research: Oceans, 103(C1), pp. 1239-
1274 (1998).
3. Dancey, C.L., Balakrishnan, M., Diplas, P., and
Papanicolaou, A.N. The spatial inhomogeneity of
turbulence above a fully rough, packed bed in open
channel
ow", Experiments in Fluids, 29(4), pp. 402-
410 (2000).
4. Mehraein, M., Ghodsian, M., and Schleiss, A.J. Scour
formation due to simultaneous circular impinging jet
and wall jet", Journal of Hydraulic Research, 50(4),
pp. 395-399 (2012).
5. Mignot, E., Hurther, D., and Barthelemy, E. On the
structure of shear stress and turbulent kinetic energy

ux across the roughness layer of a gravel-bed channel

ow", Journal of Fluid Mechanics, 638, pp. 423-452
(2009).
6. Grant, S.B., Stewardson, M.J., and Marusic, I. Effective
di usivity and mass
ux across the sedimentwater
interface in streams", Water Resources Research,
48(5), p. W05548 (2012).
7. Dey, S. and Das, R. Gravel-bed hydrodynamics:
double-averaging approach", Journal of Hydraulic Engineering,
138(8), pp. 707-725 (2012).
8. Hassanzadeh, Y. and Ranjineh-Khojasteh, A. A
study of the bed roughness e ects on the dam break

ood waves propagation", in 6th International Rivers
Engineering Conference, Shahid Chamran University,
Ahvaz, Iran (2004).
9. Wang, W.C. and Dawdy, D.R. Flow resistance of
gravel bed channels", International Journal of Sediment
Research, 29(1), pp. 126-132 (2014).
10. Powell, D.M. Flow resistance in gravel-bed rivers:
Progress in research", Earth-Science Reviews, 136(0),
pp. 301-338 (2014).
11. Adrian, R.J. Hairpin vortex organization in wall
turbulence)", Physics of Fluids (1994-present), 19(4),
p. 041301 (2007).
12. Albayrak, I. and Lemmin, U. Secondary currents and
corresponding surface velocity patterns in a turbulent
open-channel
ow over a rough bed", Journal of
Hydraulic Engineering, 137(11), pp. 1318-1334 (2011).
13. Einstein, H. and Li, H. Secondary currents in
straight channels", Transaction of American Geophysical
Union, 39 pp. 1085-1088 (1958).
14. Nezu, I. and Nakagawa, H., Turbulence in Open-
Channel Flows, Balkema, Rotterdam, Brook eld, The
Netherlands (1993).
1966 S.H. Mohajeri et al./Scientia Iranica, Transactions A: Civil Engineering 25 (2018) 1956{1967
15. Nezu, I. Open-channel
ow turbulence and Its research
prospect in the 21st century", Journal of Hydraulic
Engineering, 131(4), pp. 229-246 (2005).
16. Karcz, I. Secondary currents and the con guration
of a natural stream bed", Journal of Geophysical
Research, 71(12), pp. 3109-3112 (1966).
17. Nezu, I. and Rodi, W. Experimental study on secondary
currents in open channel
ow", in the 21st
IAHR Congress., Melbourne, Australia (1985).
18. Marion, A. and Zaramella, M. E ects of velocity
gradients and secondary
ow on the dispersion of
solutes in a meandering channel", Journal of Hydraulic
Engineering, 132(12), pp. 1295-1302 (2006).
19. Nezu, I. and Nakagawa, H. Cellular secondary currents
in straight conduit", Journal of Hydraulic Engineering,
110(2), pp. 173-193 (1984).
20. Nikora, V., Goring, D., McEwan, I., and Griths,
G. Spatially averaged open-channel
ow over rough
bed", Journal of Hydraulic Engineering, 127(2), pp.
123-133 (2001).
21. Bun-Belanger, T., Rice, S., Reid, I., and Lancaster,
J. Spatial heterogeneity of near-bed hydraulics above
a patch of river gravel", Water Resources Research,
42(4), p. W04413 (2006).
22. Nikora, V., Goring, D., and Biggs, B. Silverstream
eco-hydraulics
ume: hydraulic design and tests", New
Zealand Journal of Marine and Freshwater Research,
32, pp. 607-620 (1998).
23. Rodrguez, J.F. and Garca, M.H. Laboratory measurements
of 3-D
ow patterns and turbulence in
straight open channel with rough bed", Journal of
Hydraulic Research, 46(4), pp. 454-465 (2008).
24. Cooper, J. and Tait, S. The spatial organisation of
time-averaged streamwise velocity and its correlation
with the surface topography of water-worked gravel
beds", Acta Geophysica, 56(3), pp. 614-641 (2008).
25. Blanckaert, K., Duarte, A., and Schleiss, A.J. In
uence
of shallowness, bank inclination and bank roughness
on the variability of
ow patterns and boundary
shear stress due to secondary currents in straight openchannels",
Advances in Water Resources, 33(9), pp.
1062-1074 (2010).
26. Mohajeri, S.H., Grizzi, S, Righetti, M., Romano,
G.P., and Nikora, V. The structure of gravel-bed

ow with intermediate submergence: A laboratory
study", Water Resources Research, 51(11), pp. 9232-
9255 (2015).
27. Nikora, V. and Roy, A. Secondary
ows in rivers:
Theoretical framework, recent advances, and current
challenges", in Gravel-bed Rivers: Processes, Tools,
Environments, Tadoussac, Quebec, Canada: John
Wiley & Sons (2012).
28. Nikuradse, J., Stromungsgesetze in Rauhen Rohren,
VDI-Verlag (1933).
29. Mohajeri, H., Salehi Neyshbouri, A.A., and Safarzade,
A. A three tube pressure instrument for measuring
the local bed shear stress in smooth and rough beds",
in 2nd IAHR Europe Congress, Munich, Germany
(2012).
30. Storm, P.V., Newman, B.G., Storm P.V., and Newman,
B.G. A pressure instrument to measure skin
friction in turbulent boundary layers on smooth and
non-smooth walls", Journal of Aeronautical, pp. 25-32
(1993).
31. Bonakdari, H., Larrarte, F., Lassabatere, L., and Joannis,
C. Turbulent velocity pro le in fully-developed
open channel
ows", Environmental Fluid Mechanics,
8(1), pp. 1-17 (2008).
32. Ikeda, S. Self-forced straight channels in sandy beds",
Journal of Hydraulic Division (ASCE), 107, pp. 389-
406 (1981).
33. Ardiclioglu, M., Seckin, G., and Yurtal, R. Shear
stress distributions along the cross section in smooth
and rough open channel
ows", Kuwait Journal of
Science and Engineering, 33(1), pp. 155-168 (2006).
34. Bomminayuni, S. and Stoesser, T. Turbulence statistics
in an open-channel
ow over a rough bed", Journal
of Hydraulic Engineering, 137(11), pp. 1347-1358
(2011).
35. Belcher, B.J. and Fox, J.F. Laboratory measurements
of 3-D
ow patterns and turbulence in straight open
channel with rough bed", Journal of Hydraulic Research,
47(5), pp. 685-688 (2009).
36. Barros, J.M. and Christensen, K.T. Observations of
turbulent secondary
ows in a rough-wall boundary
layer", Journal of Fluid Mechanics, 748 (2014).
37. Nikora, V., McEwan, I., McLean, S., Coleman, S.,
Pokrajac, D., and Walters, R. Double-averaging concept
for rough-bed open-channel and overland
ows:
Theoretical background", Journal of Hydraulic Engineering,
133(8), pp. 873-883 (2007).
38. Nikora, V., McLean, S., Coleman, S., Pokrajac, D.,
McEwan, I., et al. Double-averaging concept for
rough-bed open-channel and overland
ows: Applications",
Journal of Hydraulic Engineering, 133(8), pp.
884-895 (2007).
39. Nikora, V. and Rowinski, P. Rough-bed
ows in
geophysical, environmental, and engineering systems:
Double-averaging approach and its applications", Acta
Geophysica, 56(3), pp. 529-533 (2008).
40. Cooper, J. and Tait, S. Spatially representative velocity
measurement over water-worked gravel beds",
Water Resources Research, 46(11), p. W11559 (2010).

Scientia Iranica
Volume 25, Issue 4 - Serial Number 4
Transactions on Civil Engineering (A)
July and August 2018
Pages 1956-1967

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History

  • Receive Date: 05 June 2016
  • Revise Date: 07 January 2017
  • Accept Date: 04 February 2017

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