On behavior of the small perturbations of one-dimensional steady transonic flows

Behavior of unsteady perturbations of steady solutions of quasilinear hyperbolic or parabolic degenerate systems of differential equations in partial derivatives is considered in the critical point neighborhood. The sought functions of analyzed equations are assumed dependent on two arguments, viz. coordinate x and time t., with an arbitrary number of sought functions. The point at which one of the system characteristic velocities vanishes, is called critical.