Asymptotics toward the rarefaction waves of the solutions of a one-dimensional model system for compressible viscous gas

This paper is concerned with the asymptotic behavior toward the rarefaction waves of the solution of a one-dimensional model system associated with compressible viscous gas. If the initial data are suitably close to a constant state and their asymptotic values at x=±∞ are chosen so that the Riemann problem for the corresponding hyperbolic system admits the weak rarefaction waves, then the solution is proved to tend toward the rarefaction waves as t→+∞. The proof is given by an elementary L² energy method.