Longitudinal turbulence intensifies measured by split-film anemometry in degraded polymer solutions in pipe flow peaked much farther from the wall than longitudinal turbulence intensities in a Newtonian oil at the same Reynolds numbers. The peak values were at about the same level for the degraded solutions as for the oil but were higher and nearer the wall for fresh polymer solutions. Radial turbulence intensities were lower for the polymer solutions at all locations under all conditions. Drag reduction for the polymer solutions ranged from 1 to 21% based on Newtonian fluid of equal viscosity. For the fresh solutions the Reynolds stresses dropped to zero or low values much farther from the wall than normal, indicating a region of almost complete turbulence shear strain recovery near the wall (positive uv excursions balanced negative uv excursions). Numerical computations with a turbulence model involving balance equations for turbulence energy and turbulence energy dissipation rate (the k-ε model) show that the location of the peak turbulence intensity (energy) is sensitive to the model for Reynolds stress production. It was possible to model the velocity and turbulence intensity profiles and predict the correct level of drag reduction using the k-ε model with an eddy viscosity as a function of shear relaxation time. Copyright © 1977 American Institute of Physics.
G. K. Patterson et al., "Turbulence Structure In Drag Reducing Polymer Solutions," Physics of Fluids, vol. 20, no. 10, American Institute of Physics, Jan 1977.
The definitive version is available at https://doi.org/10.1063/1.861764
Chemical and Biochemical Engineering
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01 Jan 1977