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Modifying turbulent structure with drag-reducing polymer additives in turbulent channel flows

  • T. Wei (a1) and W. W. Willmarth (a2)

Abstract

New power spectra computed from LDA measurements of the fluctuating u- and v-velocity signals in a turbulent channel flow with and without drag-reducing polymer (polyethylene oxide) injection are presented. LDA data rates were sufficiently high to reconstruct the simultaneous time-dependent u- and v-velocity signals along with the time-dependent Reynolds stress signal. Time-averaged statistics of the turbulent flow are presented in conjunction with the power spectral measurements which show a dramatic reduction in both the v-velocity fluctuations and Reynolds stress fluctuations throughout the channel over all frequencies. There is also a redistribution of energy in the u-velocity fluctuations from high frequencies to low frequencies throughout the channel. Different injection conditions were examined: different polymer concentrations were injected at different flow rates such that the total amount of polymer in the channel remained constant. For certain polymer concentrations, ‘large’ negative Reynolds stress, -〈uv〉/uτ2 ≈ − 0.2, was measured in the near-wall region. In addition, there is a marked difference in the u-velocity spectra and the Reynolds stress spectra close to the wall for the different injection conditions.

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Achia, B. U. & Thompson D. W. 1977 Structure of the turbulent boundary in drag-reducing pipe flow. J. Fluid Mech. 81, 439.
Berman N. S. 1977 Flow time scales and drag reduction. Phys. Fluids 20, S168.
Berman N. S. 1986 Velocity fluctuations in non-homogeneous drag reduction. Chem. Engng Commun. 42, 37.
Berman N. S. 1990 Large eddies and polymer strings. In Structure of Turbulence and Drag Reduction (ed. A. Gyr), p. 275. Springer.
Berner, C. & Scrivener, O. 1979 Drag reduction and structure of turbulence in dilute polymer solutions. In Viscous Flow Drag Reduction (ed. G. R. Hough). Progress in Astronautics and Aeronautics, vol. 72, p. 290. AIAA.
Bewersdorff H. W. 1984 Heterogene Widerstandsverminderung bei turbulenten Rohrströ-mungen. Rheol. Acta 23, 522.
Bradshaw P. 1965 The effect of wind tunnel screens on nominally two-dimensional boundary layers. J. Fluid Mech. 22, 679.
Coles D. 1953 Measurements in the boundary layer of a smooth flat plate in supersonic flow; Part 1. The problem of the turbulent boundary layer. JPL/Cal Tech Rep. 2069.
Donohue G. L., Tiederman, W. G. & Reischman M. M. 1972 Flow visualization of the near-wall region in a drag-reducing channel flow. J. Fluid Mech. 56, 559.
Durst F., Keck, T. & Kleine. R. 1985 Turbulence quantities and Reynolds stress in pipe flow of polymer solutions. Proc. 1st Intl Conf. on Laser Anemometry - Advances and Applications, p. 31. BHRA.
Gordon R. J. 1970 Mechanism for turbulent drag reduction in dilute polymer solutions. Nature 227, 599.
Hinch E. J. 1977 Mechanical models of dilute polymer solutions in strong flows. Phys. Fluids 20, S22.
Kline S. J., Reynolds, W. C., Schraub, F. A. & Runstadtler, P. W. 1967 The structure of turbulent boundary layers. J. Fluid Mech. 30, 741.
Luchik, T. S. & Tiederman. W. G. 1988 Turbulent structure in low-concentration drag-reducing channel flows. J. Fluid Mech. 190, 241.
Lumley J. L. 1969 Drag reduction by additives. Ann. Rev. Fluid Mech. 1, 367.
McComb, W. D. & Rabie L. H. 1982 Local drag reduction due to injection of polymer solutions into turbulent flow in a pipe. AICHE J. 28, 547.
McCormick C. L., Hester, R. D., Morgan, S. E. & Safieddine, A. M. 1990a Water-soluble copolymers. 30. Effects of molecular structure on drag reduction efficiency. Macromol. 23, 2124.
McCormick C. L., Hester R. D., Morgan, S. E. & Safieddine A. M. 1990b Water-soluble copolymers. 31. Effects of molecular parameters, solvation, and polymer associations on drag reduction performance, Macromol. 23, 2132.
Perry, A. E. & Abell C. J. 1975 Scaling laws for pipe flow turbulence. J. Fluid Mech. 67, 257.
Rabin, Y. & Zielinska B. J. A. 1989 Scale-dependent enhancement and damping of vorticity disturbances by polymers in elongational flow. Phys. Rev. Lett. 63, 512.
Reischman, M. M. & Tiederman W. G. 1975 Laser-Doppler anemometer measurements in drag-reducing channel flows. J. Fluid Mech. 70, 369.
Rudd M. J. 1972 Velocity measurements made with a laser dopplermeter on the turbulent pipe flow of a dilute polymer solution. J. Fluid Mech. 51, 673.
Stenberg L. G., Lagerstedt T., Sehlén, O. & Lindgren E. R. 1977 Mechanical mixing of polymer additive in turbulent drag reduction. Phys. Fluids 20, 858.
Tiederman W. G., Luchik, T. S. & Bogard D. G. 1985 Wall-layer structure and drag reduction. J. Fluid Mech. 156, 419.
Usui H. 1990 Drag reduction caused by the injection of a polymer solution into a pipe flow. In Structure of Turbulence and Drag Reduction (ed. A. Gyr). Springer.
Virk P. S., Merrill E. W., Mickley H. S., Smith, K. A. & Mollo-Christensen E. L. 1967 The Toms phenomenon: turbulent pipe flow of dilute polymer solutions. J. Fluid Mech. 30, 305.
Wei T. 1987 Reynolds number effects on the small scale structure of a turbulent channel flow, Ph.D. thesis, The University of Michigan.
Wei, T. & Willmarth W. W. 1989 Reynolds number effects on the structure of a turbulent channel flow. J. Fluid Mech. 204, 57.
Willmarth W. W., Wei, T. & Lee C. O. 1987 Laser anemometer measurements of Reynolds stress in a turbulent channel flow with drag reducing polymer additives. Phys. Fluids 30, 933.
Zakin, J. L. & Hunston D. L. 1980 Effect of polymer molecular variables on drag reduction J. Macromol. Sci. Phys. B 18, 795.
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Modifying turbulent structure with drag-reducing polymer additives in turbulent channel flows

  • T. Wei (a1) and W. W. Willmarth (a2)

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