The generation of the flow discontinuity called a shock wave has been discussed in Section 6.4 in the case of one-dimensional flow. Here the treatment is extended to plane oblique and curved shocks in two-dimensional flows. Once again, the thickness of the shock wave is ignored, the fluid is assumed to be inviscid and non-heat-conducting. In practice the (thickness) distance in which the gas stabilizes its properties of state from the initial to the final conditions is small but finite. Treating a curved shock as consisting of small elements of plane oblique shock
wave is reasonable only as long as its radius of curvature is large compared to the thickness.
With these provisos, the following exact, but relatively simple, extension to the one-dimensional shock theory will provide a deeper insight into those problems of shock waves associated with aerodynamics.