An experimental study, based on streak photograph determination of instantaneous velocities, was directed at determining the structure of turbulence within the boundary layer and core regions of circular pipes. The measurements lend support to the ejection phenomenon as the mechanism controlling drag reduction.
A correlation factor, defined as the ratio of the observed number of positive instantaneous radial velocities, to the observed number of negative instantaneous radial velocities, suggests acceleration in the radial direction as the elements of fluid move through the sublayer. The correlation factor also provides information about the thickening of the boundary layer for drag reducers relative to the Newtonian case.
Radial turbulent intensity data for 0.01% aqueous solutions of Separan AP-30 were found to be markedly lower, at all radial positions, than the intensities for Newtonian fluids. The lowering of the radial intensities being ordered according to the amount of drag reduction.
Rollin, A. L. and Seyer, F. A., "Statistical Analysis of Instantaneous Velocities in Turbulent Flow of Dilute Viscoelastic Solutions" (1973). Symposia on Turbulence in Liquids. 102.
3rd Biennial Symposium on Turbulence in Liquids (1973: Sep., Rolla, MO)
Chemical and Biochemical Engineering
Article - Conference proceedings
Turbulence in Viscoelastic Fluids
© 1973 University of Missouri--Rolla, All rights reserved.