Laminar-turbulent boundary and its implication for friction drag reduction in Newtonian and viscoelastic turbulent flows

A dynamic perspective of MDR: MDR is a statistical consequence of the increased intermittent occurrence of weak/hibernating turbulence. • Edge state flow statistics not affected by polymers: an upper bound must exist for polymer DR. • Edge state dominated by localized turbulent spots with quasiperiodic dynamics. • Further understanding of the polymer effects on the edge state could lead to new insights into DR mechanism and new strategies for flow control.