paper

Stability of viscous shocks in isentropic gas dynamics

arXiv:0705.4237 · doi:10.1007/s00220-008-0487-4

Abstract

In this paper, we examine the stability problem for viscous shock solutions of the isentropic compressible Navier--Stokes equations, or -system with real viscosity. We first revisit the work of Matsumura and Nishihara, extending the known parameter regime for which small-amplitude viscous shocks are provably spectrally stable by an optimized version of their original argument. Next, using a novel spectral energy estimate, we show that there are no purely real unstable eigenvalues for any shock strength. By related estimates, we show that unstable eigenvalues are confined to a bounded region independent of shock strength. Then through an extensive numerical Evans function study, we show that there is no unstable spectrum in the entire right-half plane, thus demonstrating numerically that large-amplitude shocks are spectrally stable up to Mach number for . This strongly suggests that shocks are stable independent of amplitude and the adiabatic constant . We complete our study by showing that finite-difference simulations of perturbed large-amplitude shocks converge to a translate of the original shock wave, as expected.

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