Axial Dispersion Coefficients in Laminar Flows of Water-Distribution Systems

Because longitudinal dispersion is becoming increasingly germane to the problem of accurately determining water quality, water-resource managers and engineers seeking to represent solute transport in drinking-water systems must be able to compute relevant dispersion coefficients. Accordingly, the present study was undertaken to develop and experimentally verify a modified advection-dispersion-reaction transport equation as well as the formulas used to calculate the axial dispersion coefficient. The analysis assumes laminar flows, constant mean velocities, and short travel times (dimensionless time, T<0.01). With regard to the modified transport equation, the dispersion term was assumed to be direction-dependent. Thus, two distinct dispersion rates (forward and backward) were recognized and quantified as opposed to the single value used in conventional dispersion models. With the dimensionless travel time taken to be the independent variable, the developed dispersion coefficients increased at about one-fourth of the growth rate exhibited by the conventional dispersion formula. The proposed scheme demonstrated a large improvement over the conventional formula when its performance was judged against experimental runs using various combinations of pipe lengths, tracer injections, mean flow velocities, and solute properties. This study’s findings should lead to accurate water-quality predictions and corresponding quantitative risk assessments, especially in pressure zones where low-speed flows prevail.

• Record URL:
  • https://doi.org/10.1061/(ASCE)HY.1943-7900.0000432
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/8672558
• Supplemental Notes:
  • Copyright © 2011 American Society of Civil Engineers
• Authors:
  • Romero-Gomez, Pedro
  • Choi, Christopher Y
• Publication Date: 2011-11-1

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 1500-1508
• Serial:
  • Journal of Hydraulic Engineering
  • Volume: 137
  • Issue Number: 11
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9429
  • Serial URL: https://ascelibrary.org/journal/jhend8

Subject/Index Terms

• TRT Terms: Dispersions (Chemistry); Fluid dynamics; Laminar flow; Optimization; Simulation; Water distribution structures; Water pipelines; Water quality
• Subject Areas: Hydraulics and Hydrology; Pipelines; I20: Design and Planning of Transport Infrastructure;

Filing Info

• Accession Number: 01361342
• Record Type: Publication
• Files: TRIS, ASCE
• Created Date: Jan 25 2012 2:23PM