Dyamics and flow structures of the lamiar-turbulet edge state for uderstadig polymer drag reductio

Solution for the "marginal" or "weakest" form of turbulence - the edge state - is numerically obtained. • Mean flow statistics of the edge state are insensitive to polymer effects, explaining the existence of a universal upper bound for polymer DR. • Dynamics of the edge state is quasi-periodic and spatially localized. • Spatial localization of the edge state means it cannot be the only state responsible for MDR. • Flow structures of the edge …