Exceeding the asymptotic limit of polymer drag reduction Journal Article

Author(s): Choueiri, George H; Lopez, Jose M; Hof, Björn
Article Title: Exceeding the asymptotic limit of polymer drag reduction
Affiliation IST Austria
Abstract: The drag of turbulent flows can be drastically decreased by adding small amounts of high molecular weight polymers. While drag reduction initially increases with polymer concentration, it eventually saturates to what is known as the maximum drag reduction (MDR) asymptote; this asymptote is generally attributed to the dynamics being reduced to a marginal yet persistent state of subdued turbulent motion. Contrary to this accepted view, we show that, for an appropriate choice of parameters, polymers can reduce the drag beyond the suggested asymptotic limit, eliminating turbulence and giving way to laminar flow. At higher polymer concentrations, however, the laminar state becomes unstable, resulting in a fluctuating flow with the characteristic drag of the MDR asymptote. Our findings indicate that the asymptotic state is hence dynamically disconnected from ordinary turbulence. © 2018 American Physical Society.
Journal Title: APS Physics, Physical Review Letters
Volume: 120
Issue 12
ISSN: 00319007
Publisher: American Physiological Society  
Date Published: 2018-03-19
Start Page: Article number: 124501
DOI: 10.1103/PhysRevLett.120.124501
Open access: yes (repository)