Saturation of Turbulent Drag Reduction in Dilute Polymer Solutions

Abstract

Drag reduction by polymers in turbulent wall-bounded flows exhibits universal and non-universal aspects. The universal maximal mean velocity profile was explained in a recent theory. The saturation of this profile and the crossover back to the Newtonian plug are non-universal, depending on Reynolds number Re, concentration of polymer $c_p$ and the degree of polymerization $N_p$. We explain the mechanism of saturation stemming from the finiteness of extensibility of the polymers, predict its dependence on $c_p$ and $N$ in the limit of small $c_p$ and large Re, and present the excellent comparison of our predictions to experiments on drag reduction by DNA.

4 pages, 4 figs., included, PRL, submitted

References in corpus (4)

• Drag Reduction by Polymers in Wall Bounded Turbulence
• Drag Reduction by Polymers in Turbulent Channel Flows: Energy Redistribution Between Invariant Empirical Modes
• Drag Reduction by a Linear Viscosity Profile
• The Polymer Stress Tensor in Turbulent Shear Flows

Cited by in corpus (8)

• Colloquium: Theory of Drag Reduction by Polymers in Wall Bounded Turbulence
• Identification and Calculation of the Universal Maximum Drag Reduction Asymptote by Polymers in Wall Bounded Turbulence
• Drag Reduction by Microbubbles in Turbulent Flows: the Limit of Minute Bubbles
• The State of the Art in Hydrodynamic Turbulence: Past Successes and Future Challenges
• Additive Equivalence in Turbulent Drag Reduction by Flexible and Rodlike Polymers
• Drag Reduction by Bubble Oscillations
• Phenomenology of Wall Bounded Newtonian Turbulence
• Maximum Drag Reduction Asymptotes and the Cross-Over to the Newtonian Plug