Seems to indicate that you are thinking of a shock wave as a regular wave, hence the blunt object should catch up with it. It does not assume that if the object travels faster than the speed of sound wave front should be just touching the object that causes it ? fluid goes continuously from the front to the back of the shock wave (discontinuous are the thermodynamic properties of the gas, and the component of the perpendicular speed across the shock wave, but otherwise gas move continuously from one side to the other).Īre there surfaces where matter does not cross a surface of discontinuity? Yes, there are, and they are called contact discontinuities, which, being absolutely unstable (the term absolutely has a very special meaning in fluidodynamics), quickly disappear.
Hence, it cannot touch the object, because there must be another layer of gas between the object and the shock wave.īut now your question can become: why must there be gas on both sides of the shock wave? The reason is that fluid must cross the shock wave, i.e. Thus a shock wave has gas on both sides of it, by definition. A shock wave is a surface, an ensemble of points, where the properties of the gas change discontinuously (it is not the only surface with this characteristic, but the other class, that of contact discontinuities is absolutely unstable, and quickly disappears). Perhaps, at the root of your question, there is a misunderstanding of the nature of a shock wave.