Drag Reduction in Turbulent Wall-Bounded Flows of Realistic Polymer Solutions

Suspensions of DNA macromolecules (0.8 wppm, 60 kbp), modeled as finitely extensible nonlinear elastic dumbbells coupled to the Newtonian fluid, show drag reduction up to 27% at friction Reynolds number 180, saturating at the previously unachieved Weissenberg number similar or equal to 10(4). At a large Weissenberg number, the drag reduction is entirely induced by the fully stretched polymers, as confirmed by the extensional viscosity field. The polymer extension is strongly non-Gaussian, in contrast to the assumptions of classical viscoelastic models.

Automated summary

In DNA suspensions, the maximal drag reduction is achieved when the macromolecules are fully stretched, contrary to the assumptions of classical viscoelastic models.