Prediction of Transverse Dispersion Coefficient Using Vertical Profile of Secondary Flow in Meandering Channels

다국어 초록 (Multilingual Abstract)

When the concentration data are not available, the transverse dispersion coefficient should be predicted using the basic hydraulic parameters to analyze mixing characteristics. In meandering channels, where the secondary flow plays an important role in the increase of transverse mixing, the transverse dispersion coefficient must be predicted accounting for the vertical variation of the transverse velocity. In this study, based on the vertical distribution equation for the transverse velocity, the theoretical formula for the transverse dispersion coefficient is newly developed. The merits of the theoretical formula on the transverse dispersion coefficient derived in this study are that it has the finite combination of elementary functions so that the transverse dispersion coefficient can be easily obtained compared with other theoretical methods, and that it can take into consideration the proper shear effect of the secondary flow. To verify the theoretical prediction of the transverse dispersion coefficient, both flow and tracer experiments are conducted in the meandering laboratory channel. The predicted transverse dispersion coefficient from the newly proposed equation shows better agreement with the observed transverse dispersion coefficient than those from other exiting equations.

참고문헌 (Reference)

1 Yotsukura, N., "Transverse mixing in natural channels" 12 (12): 695-704, 1976

2 Almquist, C.W., "Transverse mixing in meandering laboratory channels with rectangular and naturally varying cross sections" Univ. of Texas, Austin, Texas 1985

3 Krishnappan, B.G., "Transverse mixing in meandering channels with varying bottom topography" IAHR 15 (15): 351-371, 1977

4 Baek, K.O., "Transverse mixing in meandering channels with unsteady pollutant source" Seoul National Univ., Seoul, Korea 2004

5 Fischer, H.B., "The effect of bends on dispersion in streams" 5 (5): 496-506, 1969

6 Elder, J.W., "The dispersion of marked fluid in turbulent shear flow" 5 : 544-560, 1959

7 Gharbi, S., "Relation between longitudinal and transversal mixing coefficients in natural streams" IAHR 36 (36): 43-53, 1998

8 Seo, I.W., "Predicting longitudinal dispersion coefficient in natural stream" ASCE 124 (124): 25-32, 1998

9 Jobson, H.E., "Predicting concentration profiles in open channels" ASCE 96 (96): 1983-1996, 1970

10 Thomson, J., "On the origin and winding of rivers in alluvial plains, with remarks on the flow around bends in pipes" 25 : 5-8, 1876

11 Fischer, H.B., "Mixing in inland and coastal waters" Academic Press, New York 1979

12 Rozovskii, I.L., "Flow of water in bends of open channels" Academy of Science of Ukrainian SSR, Russia 1957

13 Kikkawa, H., "Flow and bend topography in curved open channels" ASCE 102 (102): 1327-1342, 1976

14 Baek, K.O., "Evaluation of dispersion coefficients in meandering channels from transient tracer tests" ASCE 132 (132): 1021-1032, 2006

15 Shiono, K., "Complex flow mechanisms in compound meandering channels with overbank flow" 376 : 221-261, 1998

16 Chikwendu, S.C., "Calculation of longitudinal shear dispersivity using an N-zone models as N→∞" 167 : 19-30, 1986

17 Boxall, J.B., "Analysis and prediction of transverse mixing coefficients in natural channels" ASCE 129 (129): 129-139, 2003

18 Blanckaert, J.C., "A model for flow in strongly curved channel bends" 2001

19 Seo, I.W., "2D modeling of heterogeneous dispersion in meandering channels" ASCE 134 (134): 196-204, 2008