ABSTRACT
From the linearized theory of Chapter VI, we see that the nature of the differential equation for steady compressible flow is entirely different for subsonic and supersonic flows. For subsonic flow, the equation is of the elliptic type, i.e., the Laplace equation in linearized theory; whereas for supersonic flow, the equation is of the hyperbolic type, i.e., the simple wave equation in linearized theory. The exact differential equation for the steady flow of a compressible fluid has the same nature as that of the linearized theory. For steady subsonic flow, the differential equation is of the elliptic type and for steady supersonic flow, the differential equation is of the hyperbolic type.
