Drag reduction in high Weissemberg number turbulent wall-bounded flows of realistic polymer solutions*

Tom’s effect, namely the drag-reducing capability of polymers in turbulence, has been debated since its discovery in the 40s. Viscoelastic models achieve drag reduction in numerical simulations of prototypal flows. These models require unrealistically large concentrations to obtain drag reduction, well beyond the model limit of validity. Furthermore, many laboratory-scale experiments are performed at Weissenberg numbers unreachable by the viscoelastic models. In this context, Direct Numerical Simulations of DNA macromolecules, modeled as FENE dumbbells, fully coupled to the Newtonian fluid are discussed for a turbulent flow in a circular pipe using realistic parameters for the solution. A hybrid Eulerian-Lagrangian approach is used to evolve every dumbbell and the Exact Regularized Point Particle method (Gualtieri et al. 2015) is used to precisely account for the momentum coupling between the two phases. The oral presentation will provide methodological details and physical insight into the drag reduction mechanism of these high Weissemberg number flows. 

References

F. Serafini, F. Battista, P. Gualtieri, and C.M. Casciola. Drag reduction in turbulent wall-bounded flows of realistic polymer solutions. Submitted 2022.

P.S. Virk. Drag reduction fundamentals. AIChE Journal, 1975.