The weak/strong uniqueness principle of Dafermos and Di Perna shows that Lipschitz solutions to Euler equations are stable and unique among weak entropic solutions. We provide generalizations of this principle for the stability or predictability of discontinuous patterns, such as shocks for the compressible Euler or shear flows for the incompressible Euler. For this study, we show that the notion of weak inviscid limit of Navier-Stokes solutions is better suited than the notion of weak solutions to Euler. Convex Integration shows that shear flows at the boundary for incompressible Euler are not unique among the weak solutions of Euler, a phenomenon called layer separation. In this case, we can show that the layer separation predicted by the Convex Integration is the largest separation possible.
- Séminaire Analyse non linéaire et EDP