Boundary Shear Stress in Spatially Varied Flow with Increasing Discharge
Publication: Journal of Hydraulic Engineering
Volume 131, Issue 8
Abstract
The distribution of the wall shear stress on the bed and sidewalls of an open channel receiving lateral inflow was obtained from experimental measurements of the distribution of the velocity in the viscous sublayer using a laser doppler velocimeter. The experiments were conducted in a 0.4 m wide by 7.5 m long flume. Lateral inflow was provided into the channel from above via sets of nozzles positioned toward the downstream end of the flume. Lateral inflow was provided over a length of 1.9 m. The results indicate that the local boundary shear stresses are significantly influenced by lateral inflow. The significant variation occurs near and around the region where the lateral inflow enters the channel. At various measurement positions along the lateral inflow zone, mean boundary, mean wall, and mean bed shear stresses were obtained and compared. The results indicate that the mean boundary shear stresses increase from the upstream to the downstream ends of the lateral inflow zone. The results also indicate that the mean bed shear stress is always greater than the mean wall shear stress, which are approximately 30–60% of the mean bed shear stress. The friction factor in the Darcy–Weisbach equation was obtained from both the mean boundary shear stress and from the equation describing the water surface elevation in an open channel receiving lateral inflow (equation for spatially varied flow with increasing discharge). The results indicate that the estimated friction factors from the latter approach are significantly larger. Also, the estimated friction factors from both approaches are higher than the values predicted from the Blasius equation which describes the friction factor for wide uniform open channel flows. They were also higher than values predicted from the Keulegan equation, which is an empirically derived equation for flow in roof drainage gutters. The study highlights the deficiencies in the existing equations used to predict friction factors for spatially varied flow and that further research is required to explore the distribution of boundary shear stress in an open channel receiving lateral inflow.
Get full access to this article
View all available purchase options and get full access to this article.
References
Ackerman, J. D., and Hoover, T. (2001). “Measurement of local bed stress in streams using a Preston-static tube.” Limnol. Oceanogr., 46(8), 2080–2087.
Beij, K. H. (1934). “Flow in roof gutters.” J. Res. Natl. Bur. Stand., 12, 193–213.
Brown, G. L., and Joubert, P. N. (1967). “Measurement of skin friction in turbulent boundary layer with adverse pressure gradients.” J. Fluid Mech., 35(4), 737–757.
Camp, T. F. (1940). “Lateral spillway channels.” Trans. Am. Soc. Civ. Eng., 105, 606–617.
Ching, C. Y., Djenidi, L., and Antonia, R. A. (1995). “Low-Reynolds-number effect in a turbulent boundary layer.” Exp. Fluids, 19(1), 61–68.
Durst, F., Kikura, H., Lekakis, I., Jovanovk, J., and Ye, Q. (1996). “Wall shear stress determination from near-wall mean velocity data in turbulent pipe and channel flows.” Exp. Fluids, 20(6), 417–428.
Fernhoiz, H. H., Janke, G., Schober, M., Wagner, P. M., and Warnack, D. (1996). “New developments and applications of skin-friction measuring techniques.” Meas. Sci. Technol., 7(10), 1396–1409.
Faver, H. (1933). Contribution a l’etude des courants liquides, Rascher & Cie, Zurich, Switzerland (in French).
Hager, W. H., (1983). “Open channel hydraulics of flows with increasing discharge.” J. Hydraul. Res., 21(3), 177–193.
Hager, W. H. (1985). “Trapezoidal side-channel spillways.” Can. J. Civ. Eng., 12, 774–781.
Hanratty, T. J., and Campbell, J. A. (1983). “Measurements of wall shear stress.” Fluid mechanics measurements, R. J. Goldstein, ed., Hemisphere, Washington, D.C., 559–615.
Haritonidis, J. H. (1989). “The measurement of wall shear stress.” Advances in fluid mechanics measurements, M Gad-el-Hak, ed., Springer, Berlin, 229–261.
Hinds, J. (1926). “Side channel spillways.” Trans. Am. Soc. Civ. Eng., 89, 881–939.
Keulegan, G. H. (1952). “Determination of critical depth in spatially variable flow.” Proc., 2nd Midwestern Conf. on Fluid Mechanics, Bulletin 149, Ohio State Univ., Engineering Experiment Station, Columbus, Ohio, 67–80.
Khiadani, M. H. (2000). “Hydraulics of spatially varied flow with increasing discharge.” PhD Thesis, Univ. of Technology, Sydney, Australia.
Kirgoz, M. S. (1989). “Turbulent velocity profiles for smooth and rough open channel flow.” J. Hydraul. Eng., 115(11), 1543–1561.
Knight, D. W., and Patel, H. S. (1985). “Boundary shear in smooth rectangular ducts.” J. Hydraul. Div., Am. Soc. Civ. Eng., ASCE, 111(1), 29–47.
Li, W. H. (1955). “Open channels with nonuniform discharge.” Trans. Am. Soc. Civ. Eng., 120, 255–274.
Mazumder, M. K., Wanchoo, P. C., McLeod, P. C., Ballard, G. S., Mozumdar, S., and Caraballo, N. (1981). “Skin friction drag measurements by LDV.” J. Appl. Opt., 20(16), 2832–2837.
Nezu, I. and Rodi, W. (1986). “Open-channel flow measurements with a laser doppler anemometer.” J. Hydraul. Eng., 112(5), 335–355.
Winter, K. G. (1977). “An outline of the techniques available for the measurement of skin friction in turbulent boundary layers.” Prog. Aerosp. Sci., 18(1), 1–57.
Yen, B. C., and Wenzel, H. G. (1970). “Dynamic equations for steady spatially varied flow.” J. Hydraul. Div., Am. Soc. Civ. Eng., 96(3), 801–814.
Yen, B. C., Wenzel, H. G., and Yoon, N. Y. (1972). “Resistance coefficients for steady spatially varied flow.” J. Hydraul. Div., Am. Soc. Civ. Eng., 98(8), 1395–1410.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 131 • Issue 8 • August 2005
Pages: 705 - 714
Copyright
© 2005 ASCE.
History
Received: Apr 18, 2003
Accepted: Aug 18, 2004
Published online: Aug 1, 2005
Published in print: Aug 2005
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.