TRANSVERSE DISPERSION IN RECTANGULAR CHANNELS

Dimensional analysis shows that the commonly used dimensionless transverse dispersion coefficient, e sub z uda h, should depend on both the friction factor and the width-to-depth ratio of the flow. Results for e sub z 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 e sub z/uh and suggest that uh is not a good representation for e sub z. Two alternative dimensionless dispersion coefficients, e sub z and e sub z/uda W, are introduced. Both appear to account for secondary circulation effects more properly. The dimensionless parameter e sub z/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 e sub z/uW shows distinct dependence on both friction factor and width-to-depth ratio. Both of these are better dimenstionless transverse dispersion coefficients to use than e sub z/udah. /ASCE/

• Corporate Authors:

  American Society of Civil Engineers

  345 East 47th Street
  New York, NY  United States  10017-2398
• Authors:
  • Lau, Y L
  • Krishnappan, B G
• Publication Date: 1977-10

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 1173-89
• Serial:
  • Journal of the Hydraulics Division
  • Volume: 103
  • Issue Number: HY10
  • Publisher: American Society of Civil Engineers

Subject/Index Terms

• TRT Terms: Coefficients; Conduits; Depth; Ditches; Friction factor; Ratios; Width
• Uncontrolled Terms: Transverse movement
• Old TRIS Terms: Dispersion; Rectangular conduits
• Subject Areas: Highways; Hydraulics and Hydrology;

Filing Info

• Accession Number: 00164906
• Record Type: Publication
• Report/Paper Numbers: ASCE 13294 Proceeding
• Files: TRIS
• Created Date: Nov 9 1977 12:00AM