Convergence to superposition of boundary layer, rarefaction and shock for the 1D Navier-Stokes equations
Sungho Han, Moon-Jin Kang, Jeongho Kim, Nayeon Kim, HyeonSeop Oh
TL;DR
This work resolves the long-standing stability problem for the subsonic inflow of the 1D barotropic Navier–Stokes equations by proving the asymptotic stability of the complex boundary-layer–rarefaction–shock superposition. The authors adapt the a-contraction with shifts framework to a weighted relative-entropy setting, introduce a dynamical shift X(t) for the viscous shock, and construct a smooth approximate rarefaction to localize the leading-order dynamics near the shock. They derive comprehensive L^2 and H^1 a priori estimates, control wave interactions, and show global existence plus convergence of the solution to the BL+1-rarefaction+2-shock profile up to a vanishing shift rate. This completes the stability classification for subsonic inflow boundary values and provides a rigorous mechanism for the time-asymptotic stabilization of complex wave interactions in 1D NS flows.
Abstract
We establish the asymptotic stability of solutions to the inflow problem for the one-dimensional barotropic Navier-Stokes equations in half space. When the boundary value is located at the subsonic regime, all the possible thirteen asymptotic patterns are classified in \cite{M01}. We consider the most complicated pattern, the superposition of the boundary layer solution, the 1-rarefaction wave, and the viscous 2-shock waves. In this superposition, the boundary layer is degenerate and large. We prove that, if the strengths of the rarefaction wave and shock wave are small, and if the initial data is a small perturbation of the superposition, then the solution asymptotically converges to the superposition up to a dynamical shift for the shock. As a corollary, our result implies the asymptotic stability for the simpler case where the superposition consists of the degenerate boundary layer solution and the viscous 2-shock. Therefore, we complete the study of the asymptotic stability of the inflow problem for the 1D barotropic Navier-Stokes equations for subsonic boundary values.
