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A comparison of drag reduction for flows in circular tubes with flow between parallel planes
Author(s) -
Clark D. B.,
Rodriguez F.
Publication year - 1976
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1976.070200203
Subject(s) - reynolds number , drag , pressure drop , mechanics , materials science , polymer , flow (mathematics) , turbulence , composite material , physics
Drag reduction in the turbulent flow of aqueous solutions of polyacrylamide and poly(ethylene oxide) was studied in tubes and parallel plates. Friction factors were determined at Reynolds numbers up to 20,000 for polymer concentrations of 0.10 to 400g/m 3 in glass tubes run in a constant‐head, gravity flow system in which the velocity was determined from the horizontal distance traveled by the effluent stream while falling a set vertical distance; and in Plexiglas parallel plates run in a constant‐velocity, machine‐driven system in which the pressure drop between two points on the plates was measured with a differential pressure transducer. A general method of correlating fraction laminarization or drag reduction effectiveness with polymer concentration for Reynolds numbers above 6000 was developed in which two master curves, one for very low concentrations which was the same for both tubes and parallel plates, and one for higher concentrations which differed for tubes and parallel plates, were found to represent the data very well for both polymers and all conduit sizes and Reynolds numbers. Additionally, relationships were found between conduit size and maximum fraction laminarization and optimum polymer concentration.