SHALLOW LAMINAR FLOWS OVER ROUGH GRANULAR SURFACES

Several investigations have established that at high values of relative roughness mean depths of liquid in laminar shear flow over rough surfaces are greater than the corresponding depths on a smooth surface. In this investigation the nature of the flow field in the vicinity of isolated roughness elements fixed to a smooth base is demonstrated using a flow visualization technique. Velocity profiles measured with an optical velocity meter are shown to be governed by the Nusselt equation, but surface velocity is a function of relative roughness and is less than the corresponding value for a smooth surface. An analytical model is proposed to explain an empirical relationship between friction coefficient, relative roughness, and Reynolds number. The equation developed is used to calculate the product of the coefficient of drag of a sphere resting on a plane surface and the tip Reynolds number and also to demonstrate the influence of velocity distribution on the drag coefficient.

• Corporate Authors:

  American Society of Civil Engineers

  345 East 47th Street
  New York, NY  United States  10017-2398
• Authors:
  • Phelps, H O
• Publication Date: 1975-3

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 367-384
• Serial:
  • Journal of the Hydraulics Division
  • Volume: 101
  • Issue Number: HY3
  • Publisher: American Society of Civil Engineers

Subject/Index Terms

• TRT Terms: Coefficient of friction; Drag; Flow; Flowmeters; Fluid dynamics; Laminar flow; Reynolds number; Roughness
• Uncontrolled Terms: Fluid flow
• Subject Areas: Highways; Hydraulics and Hydrology;

Filing Info

• Accession Number: 00096112
• Record Type: Publication
• Report/Paper Numbers: ASCE 11166 Proc Paper
• Files: TRIS
• Created Date: Jul 2 1975 12:00AM