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Shell model for drag reduction with polymer additives in homogeneous turbulence.
Roberto Benzi1, Elisabetta De Angelis, Rama Govindarajan
1Dipartimento di Fisica and INFM, Università Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma, Italy.
Summary
Drag reduction by polymer additives occurs in homogeneous turbulence, explained by a simple shell model. This phenomenon is not universal, peaking within specific Reynolds number and polymer relaxation rate ranges.
Area of Science:
- Fluid dynamics
- Rheology
- Polymer physics
Background:
- Polymer additives can reduce drag in turbulent flows.
- The mechanism in homogeneous turbulence was previously unclear.
Purpose of the Study:
- To explain the drag reduction mechanism in homogeneous viscoelastic flows.
- To investigate the dependence of drag reduction on model parameters.
Main Methods:
- Utilized a simplified shell model for viscoelastic flows.
- Recaptured key observations from complex direct numerical simulations.
Main Results:
- Identified drag reduction operating primarily on large scales.
- Demonstrated drag reduction is parameter-dependent.
Conclusions:
- Drag reduction is not universal; it is optimized within a specific parameter window.
- Reynolds number and polymer relaxation rate are critical for peak drag reduction.