Transverse Dispersion in Rectangular Channels

by Y. Lam Lau, Head; Hydr. Sect., Hydr. Research Div., Canada Centre for Inland Waters, Burlington, Ontario, Canada,
Bommanna G. Krishnappan, Research Scientist; Hydr. Sect., Hydr. Research Div., Canada Centre for Inland Waters, Burlington, Ontario, Canada,


Serial Information: Journal of the Hydraulics Division, 1977, Vol. 103, Issue 10, Pg. 1173-1189


Document Type: Journal Paper

Discussion: Kouwen Nicholas (See full record)
Closure: (See full record)

Abstract: Dimensional analysis shows that the commonly used dimensionless transverse dispersion coefficient, ez/uda*h, should depend on both the friction factor and the width-to-depth ratio of the flow. Results for ez lead to the conclusion that secondary circulation, and not turbulent diffusion, is the dominant transport mechanism. These results help to explain the failure to find consistent trends in the variation of ez/u*h and suggest that u*h is not a good representation for ez. Two alternative dimensionless dispersion coefficients, ezuW and ez/uda*W, are introduced. Both appear to account for secondary circulation effects more properly. The dimensionless parameter ez/uda*W is a function of the width-to-depth ratio and appears to be affected only slightly by variations in the friction factor. The parameter ez/uW shows distinct dependence on both friction factor and width-to-depth ratio. Both of these are better dimensionless transverse dispersion coefficients to use than ez/uda*h.

Subject Headings: Friction | Parameters (statistics) | Turbulent diffusion

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