In this paper, we consider the small viscosity limit problem for the isentropic compressible Navier-Stokes equations in a 2D exterior domain with impermeable boundary conditions , and the corresponding Euler equations have vortex sheet solutions.We obtain that away from the boundary and the contact discontinuous the isentropic compressible viscous flow can be approximated by the corresponding inviscid flow, near the boundary (the contact discontinuous) there is a boundary layer (vortex layer)for the angular velocity in the leading order expansion of solution, while the radial velocity and the pressure do not have boundary layers (vortex layers) in the leading order. We rigorously justify the asymptotic behavior of solutions in the $L^{\infty}$ space for the small viscosities limit in the Lagrangian coordinates.

The isentropic compressible circularly symmetric 2D flow can be approximated by inviscid flow away from the boundary, with a boundary layer for angular velocity near the contact discontinuous.

Vanishing viscosity limit to vortex sheet for the isentropic compressible circularly symmetric 2D flow

Key Takeaway: The isentropic compressible circularly symmetric 2D flow can be approximated by inviscid flow away from the boundary, with a boundary layer for angular velocity near the contact discontinuous.