LONGITUDINAL DISPERSION FOR FLOW OVER ROUGH BEDS

The longitudinal dispersion coefficient, D sub L, is evaluated on the basis of a one-dimensional analysis as affected by large bed roughness in a laboratory flume. The experimental results have shown that the dimensionless dispersion coefficient, D sub L/Yu*, in which Y is the water depth and u* is the bed shear velocity, is a function of the relative roughness height, Y/h, and the relative roughness spacing, X/Y. It is also found that D sub L/Yu* reaches a maximum value at a roughness density h/X = 0.111. The commonly used equation for estimating the longitudinal dispersion coefficient (D sub L = C Yu*) is also examined. It is found that this straight line relation between D sub L and Yu* is no longer valid of Yu* greater than 0.1 sq ft per sec (0.009 m sq/s).

• Corporate Authors:

  American Society of Civil Engineers

  345 East 47th Street
  New York, NY  United States  10017-2398
• Authors:
  • Abd El-Hadi, N D
  • Davar, K S
• Publication Date: 1976-4

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 483-498
• Serial:
  • Journal of the Hydraulics Division
  • Volume: 102
  • Issue Number: HY4
  • Publisher: American Society of Civil Engineers

Subject/Index Terms

• TRT Terms: Flow; Flumes; Hydraulics; Loads; Roughness
• Old TRIS Terms: Bed load; Dispersion
• Subject Areas: Highways; Hydraulics and Hydrology;

Filing Info

• Accession Number: 00139191
• Record Type: Publication
• Report/Paper Numbers: ASCE #12049
• Files: TRIS
• Created Date: Sep 16 1976 12:00AM