Theory, development and application of a perfect curvilinear flow net for transitioning open channels

This paper covers the practical application of flow nets to open channel flows. It describes graphical development of a perfect curvilinear flow net, and sets out the mathematical analysis of the families of curves involved. The curvilinear flow net is composed of three sets of curves, viz, streamlines, equipotential lines, and equivelocity lines or contours. These are shown to be three families of circles, the first two being orthogonal series centred on two axes at right angles, with all circumferences passing through the intersection of the axes, and the third family being a concentric series centred on the same origin. The usual assumption that bed contours, isoenergy lines, and equivelocity lines all coincide with the orthogonals to the streamlines is shown to be incompatible with energy requirements. The flow net is independent of the scale of the plan to which it may be applied and any suitable portion of the flow net may be used in transitioning flows. Small secondary transitions are finally needed to link the circular streamlines to the tangents of both the approach and the throat flows. These involve secondary transposition of the two axes, and comprise a secondary set of short circular arcs. The flow net has universal use in converging or diverging, or changing the direction of all subcritical open channel flows in connection with structures such as culverts, bridges, canals, weirs, flumes, chutes, spillways and outfalls.

• Record URL:
  http://arrbknowledge.com
• Authors:
  • Cottman, N H
  • Treloar, D J
• Conference:
  • Australian Road Research Board (ARRB) Conference, 10th, 1980, Sydney
• Publication Date: 1980-8

Language

• English

Media Info

• Pagination: 163-74
• Monograph Title: A grouping technique to assist pavement management
• Serial:
  • Volume: 10
  • Issue Number: 2

Subject/Index Terms

• TRT Terms: Bridges; Culverts; Hydraulics; Mathematical models; Methodology; Rivers
• ATRI Terms: Bridge; Culvert; Hydraulics; Method; Modelling; River
• Subject Areas: Bridges and other structures;

Filing Info

• Accession Number: 01439151
• Record Type: Publication
• Source Agency: ARRB
• Files: ATRI
• Created Date: Aug 24 2012 10:03PM