UNSTEADY, LAMINAR FLOWS OF NON-NEWTONIAN FLUIDS IN PIPES

An explicit finite difference technique was developed which gives instantaneous velocities with an accuracy better than 1% for unsteady, laminar flows of power law fluids, e.g., in long, large diameter pipelines and hydraulic systems, and the resulting, typical velocity profiles are presented for start-up and oscillatory flows at power law index (n) values of 0.4-1.4. In order to get significant flow reversal in pulsating flows, low frequency and high amplitude are required. Pulsating flow can be obtained exactly by adding the start-up and oscillating flow velocities for Newtonian, but not for power law fluids (where n is not equal to one). For n equals 0.4, a frequency-dependent parameter of 10, and a 1:1 ratio of oscillatory to steady pressure gradient, however, pulsating velocities with less than 10% error can be obtained by summing start-up and oscillatory values. The test results can be extended to predict the effects of pulsations upon the flow rate of a non-Newtonian liquid.

  • Corporate Authors:

    Pergamon Press, Incorporated

    Maxwell House, Fairview Park
    Elmsford, NY  USA  10523
  • Authors:
    • Edwards, M F
    • Nellist, D A
    • Wilkinson, W L
  • Publication Date: 1972-2

Media Info

  • Features: References;
  • Pagination: p. 295-306
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00056199
  • Record Type: Publication
  • Source Agency: American Petroleum Institute
  • Files: TRIS
  • Created Date: Jul 15 1974 12:00AM