Accession Number : AD0620143

Title :   A MOLECULAR VISCOELASTICITY INTERPRETATION OF THE WALL SHEAR STRESS THRESHOLD IN THE TOMS EFFECT,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF AERONAUTICAL ENGINEERING

Personal Author(s) : Fabula,A. G. ; Lumley,J. L. ; Taylor,W. D.

Report Date : 1965

Pagination or Media Count : 20

Abstract : The turbulent-flow friction reduction produced by very low concentrations of linear macromolecules in good solvents was shown by Virk and by Elata and Tirosh to occur only when the pipe wall shear stress exceeds a particular threshold value for each polymer. A viscoelastic hypothesis is suggested in which the threshold corresponds to a viscoelastic dispersion like that which is theoretically and experimentally found for dilute solutions subjected to oscillatory shear about zero mean shear rate. A preliminary comparison with experiment for unfractionated polyethylene oxide show that the order of magnitude of the shear stress threshold value is predicted correctly.

Descriptors :   (*TURBULENCE, THEORY), (*VISCOELASTICITY, MOLECULES), (*SHEAR STRESSES, TURBULENCE), FRICTION, REYNOLDS NUMBER, POLYMERS, FLUID FLOW

Distribution Statement : APPROVED FOR PUBLIC RELEASE