FLOW RESISTANCE FROM CYLINDRICAL ROUGHNESS

THE ROOT MEAN SQUARE OF THE HEIGHTS OF WIRES SIMULATING CROP STEMS IS FOUND TO BE A GOOD MEASURE FOR QUANTIFYING ROUGHNESS OF A CYLINDRICAL TYPE. AN EXPRESSION IS DERIVED FOR THE ROOT MEAN SQUARE IN TERMS OF THE GEOMETRIC CHARACTERISTICS OF THE ELEMENTS. THE PRANDTL-VON KARMAN UNIVERSAL VELOCITY DISTRIBUTION EQUATION FOR TURBULENT FLOW OVER A ROUGH SURFACE WAS ADOPTED IN THE FORM PRESENTED BY SAYRE AND ALBERTSON. A RELATIONSHIP BETWEEN THE RESISTANCE PARAMETER, IN THIS LATTER EQUATION, AND THE DERIVED ROOT MEAN SQUARE WAS OBTAINED AND SUBSTANTIATED WITH DATA OBTAINED FROM EXPERIMENTS PERFORMED BY WESSELS, STRELKOFF AND FENZL. THE RELATIONSHIP IS OF A POWER-TYPE FUNCTION AND HOLDS GOOD FOR VALUES OF THE RESISTANCE PARAMETER GREATER THAN 0.0015 FT (0.0005M). THE COMPOSITE RESISTANCE OF THE SOIL AND VEGETATIVE ROUGHNESS IN THE FIELD WAS INVESTIGATED. THE PERCENTAGE RELATIVE CONTRIBUTION OF THE SOIL TO THE TOTAL RESISTANCE FOLLOWS AN ASYMPTOTIC DECAY CURVE WITH INCREASING FLOW DEPTH. /ASCE/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/07339437
• Supplemental Notes:
  • APP
• Authors:
  • Nnaji, S
  • Wu, I P
• Publication Date: 1973-3

Media Info

• Features: Figures;
• Pagination: p. 15-26
• Serial:
  • Journal of Irrigation and Drainage Engineering
  • Volume: 99
  • Issue Number: 1r1
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9437
  • Serial URL: https://ascelibrary.org/journal/jidedh

Subject/Index Terms

• TRT Terms: Ditches; Erosion; Flow resistance; Irrigation; Roughness; Soils; Vegetation
• Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology;

Filing Info

• Accession Number: 00204502
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 12 1973 12:00AM