  We study supersonic flow past a convex corner which is surrounded by
quiescent gas. When the pressure of the upstream supersonic flow is larger than
that of the quiescent gas, there appears a strong rarefaction wave to rarefy
the supersonic gas. Meanwhile, a transonic characteristic discontinuity appears
to separate the supersonic flow behind the rarefaction wave from the static
gas. In this paper, we employ a wave front tracking method to establish
structural stability of such a flow pattern under non-smooth perturbations of
the upcoming supersonic flow. It is an initial-value/free-boundary problem for
the two-dimensional steady non-isentropic compressible Euler system. The main
ingredients are careful analysis of wave interactions and construction of
suitable Glimm functional, to overcome the difficulty that the strong
rarefaction wave has a large total variation.
