Quasineutral limit of the Euler-Poisson system for ions in a domain with   boundaries II
  In this paper, we study the quasineutral limit of the isothermal Euler-Poisson equation for ions, in a domain with boundary. This is a follow-up to our previous work \cite{GVHKR}, devoted to no-penetration as well as subsonic outflow boundary conditions. We focus here on the case of supersonic outflow velocities. The structure of the boundary layers and the stabilization mechanism are different. 
David G\'erard-Varet, Daniel Han-Kwan, Fr\'ed\'eric Rousset
math.AP