Tollmien-Schlichting route to elastoinertial turbulence in channel flow

Direct simulations of two-dimensional channel flow a viscoelastic fluid have revealed the existence family Tollmien-Schlichting (TS) attractors that is nonlinearly self-sustained by viscoelasticity [Shekar et al., J.Fluid Mech. 893, A3 (2020)]. Here, we describe evolution this branch in parameter space and its connections to Newtonian TS attractor elastoinertial turbulence (EIT). At Reynolds number $Re=3000$, there solution with TS-wave structure but which not connected branch. fixed Weissenberg number, $Wi$ increasing from 3000-10000, goes displaying striation weak polymer stretch localized at critical layer an extended sheet very large stretch. We show transition directly tied strength fluctuations can be attributed coil-stretch when local hyperbolic stagnation point Kelvin cat's eye wave exceeds $\frac{1}{2}$. $Re=10000$, unlike $3000$, evolves continuously into EIT state as increased zero about $13$. how stress fields changes, highlighting particular "sheet-shedding" process individual sheets associated break up form layered multisheet characteristic EIT.