Abstract

 In this talk I will review the concept of edge state and of edge trajectory, both inspired by dynamical system theories, when applied to incompressible transitional shear flows. Edge states refer to specific, yet unstable flow regimes intermediate between laminar and turbulent regimes, they are found numerically in cases where transition occurs subcritically, i.e. the turbulent state coexists with the laminar one. The nowadays classical bisection method will be recalled together with recent computational alternatives. Although the edge concept is well developed for parallel shear flows, this talk will feature the latest developments in the context of spatially developing boundary layer flows, in terms of computations,  modelling and relevance to engineering configurations. This is joint work with Miguel Beneitez, Philipp Schlatter and Dan S. Henningson.