Evaluation of Dispersion Coefficients in Meandering Channels from Transient Tracer Tests
Publication: Journal of Hydraulic Engineering
Volume 132, Issue 10
Abstract
Mixing characteristics of conservative pollutants were examined two-dimensionally in a laboratory meandering channel, and a method to compute the dispersion coefficients was developed based on the measured concentration data. To investigate how the hydrodynamics influences pollutant mixing in meandering channels, both flow and tracer experiments were conducted in an S-curved laboratory channel. A two-dimensional routing procedure was presented to evaluate the longitudinal dispersion coefficient as well as the transverse dispersion coefficient under the unsteady concentration condition. The results of the tracer experiments showed that the tracer cloud behaved quite differently depending on whether or not the tracer cloud was transported following the filament of maximum velocity. Also, separation and reemerging of the tracer cloud were promoted by secondary currents. The observed transverse dispersion coefficients obtained by the routing procedure were close to those obtained by existing moment methods. The transverse dispersion coefficient tended to increase with an increasing aspect ratio, whereas it is not sensitive to the injection location. However, the longitudinal dispersion coefficient was sensitive to the injection location as well as the aspect ratio.
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Acknowledgments
This research work was partly supported by the 21C Frontier project of the Ministry of Science and Technology of Korea. This research was conducted at the Research Institute of Engineering Science of Seoul National University, Seoul, Korea. The writers wish to thank Mr. K. H. Sung at the Department of Civil Engineering of Seoul National University for carrying out the laboratory experiments.
References
Almquist, C. W., and Holley, E. R. (1985). “Transverse mixing in meandering laboratory channels with rectangular and naturally varying cross sections.” Technical Rep. CRWR-205, Univ. of Texas, Austin, Tex.
Bansal, M. K. (1971). “Dispersion in natural streams.” J. Hydraul. Div., Am. Soc. Civ. Eng., 97(11), 1867–1886.
Bates, D. M., and Watts, D. G. (1988). Nonlinear regression analysis and its applications, Wiley, New York.
Beltaos, S. (1975). “Evaluation of transverse mixing coefficients from slug tests.” J. Hydraul. Res., 13(4), 351–360.
Blanckaert, K. (2001). “A model for flow in strongly curved channel bends.” Proc., 29th IAHR Congress, International Association for Hydraulic Research, Delft, The Netherlands.
Boxall, J. B., and Guymer, I. (2003). “Analysis and prediction of transverse mixing coefficients in natural channels.” J. Hydraul. Eng., 129(2), 129–139.
Boxall, J. B., Guymer, I., and Marion, A. (2003). “Transverse mixing in sinuous natural open channel flows.” J. Hydraul. Res., 41(2), 153–165.
Carslaw, H. S., and Jaeger, J. C. (1959). Conduction of heat in solids, Oxford University Press, New York.
Chang, Y. (1971). “Lateral mixing in meandering channels.” Ph.D. thesis, Univ. of Iowa, Iowa City, Iowa.
Elder, J. W. (1959). “The dispersion of marked fluid in turbulent shear flow.” J. Fluid Mech., 5, 544–560.
Fischer, H. B. (1968). “Dispersion predictions in natural streams.” J. Sanit. Eng. Div., Am. Soc. Civ. Eng., 94(A5), 927–943.
Fischer, H. B. (1969). “The effect of bends on dispersion in streams.” Water Resour. Res., 5(2), 496–506.
Fischer, H. B., List, E. J., Koh, R. C. Y., Imberger, J., and Brooks, N. H. (1979). Mixing in inland and coastal waters, Academic, New York.
Guymer, I. (1998). “Longitudinal dispersion in sinuous channel with changes in shape.” J. Hydraul. Eng., 124(1), 33–40.
Henderson, F. M. (1996). Open-channel flow, Macmillan, New York.
Holley, E. R. (1971). “Transverse mixing in rivers.” Laboratory Rep. No. S-132, Delft Hydraulics Laboratory, Delft, The Netherlands.
Holley, E. R., Siemons, J., and Abraham, G. (1972). “Some aspects of analyzing transverse diffusion in rivers.” J. Hydraul. Res., 10(1), 27–57.
Holly, F. M., Jr. (1975). “Two-dimensional mass dispersion in rivers.” Hydrology paper no. 78, Colorado State Univ., Fort Collins, Colo.
Kennedy, W. J., and Gentle, J. E. (1980). Statistical computing, Marcel Dekker, New York.
Krishnappan, B. G., and Lau, Y. L. (1977). “Transverse mixing in meandering channels with varying bottom topography.” J. Hydraul. Res., 15(4), 351–371.
Lau, Y. L., and Krishnappan, B. G. (1977). “Transverse dispersion in rectangular channels.” J. Hydraul. Div., Am. Soc. Civ. Eng., 103(10), 1173–1189.
Leopold, L. B., and Wolman, M. G. (1960). “River meanders.” Bulletin of the Geological Society of America, 71, 769–794.
Miller, A. C., and Richardson, E. V. (1974). “Diffusion and dispersion in open-channel flow.” J. Hydraul. Div., Am. Soc. Civ. Eng., 100(1), 159–171.
Nokes, R. I., and Wood, I. R. (1988). “Vertical and lateral turbulent dispersion: Some experimental results.” J. Fluid Mech., 187, 373–394.
Rutherford, J. C. (1994). River mixing, Wiley, Chichester, U.K.
Sayre, W. W., and Chang, F. M. (1968). “A laboratory investigation of open-channel dispersion processes for dissolved, suspended, and floating dispersants.” Professional paper no. 433-E, USGS, Reston, Va.
Shiono, K., and Muto, Y. (1998). “Complex flow mechanisms in compound meandering channels with overbank flow.” J. Fluid Mech., 376, 221–261.
Sung, K. H. (2004). “Flow characteristics of secondary currents in curved channels.” MS thesis, Seoul National Univ., Seoul, Korea.
Taylor, G. I. (1921). “Diffusion by continuous movements.” Proc., London Math. Soc., 2, 25, 196–212.
Webel, G., and Schatzmann, M. (1984). “Transverse mixing in open- channel flow.” J. Hydraul. Eng., 110(4), 423–435.
Yotsukura, N., and Sayre, W. W. (1976). “Transverse mixing in natural channels.” Water Resour. Res., 12(4), 695–704.
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Published In
Journal of Hydraulic Engineering
Volume 132 • Issue 10 • October 2006
Pages: 1021 - 1032
Copyright
© 2006 ASCE.
History
Received: Sep 9, 2004
Accepted: Oct 28, 2005
Published online: Oct 1, 2006
Published in print: Oct 2006
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