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Reference 1: http://physics.info/shock/
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A shockwave is high pressure wave produced by an object that travels faster than the speed of sound according to the same medium characteristics, in which different changes can be measured for example; extreme pressure and rising of the temperature.
The visualisation of the shockwave can be seen in the following picture.
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History
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 Image Added
Reference 2: http://nasa/2.pdf
| Rankine, was the first relevant figure who developed the theory, he makes his main contribution in his 1870 paper on the thermodynamic theory of waves published in the Philosophical Transactions of the Royal Society of London.
- He begins with: “The object of the present investigation is to determine the relations which must exist between the laws of the elasticity of any substance, whether gaseous, liquid, or solid, and those of the wave-like propagation of a finite longitudinal disturbance in that substance.”
- Later he writes: “It is to be observed, in the first place, that no substance yet known fulfills the condition expressed by the equation  Image Added, between finite limits of disturbance, at a constant temperature, nor in a permanency of type may be possible in a wave of longitudinal disturbance there must be both change of temperature and conduction of heat during the disturbance”.
Therefore, Rankine by explaining that the shock transition is a non-adiabatic process, where the particles exchange heat with each other, but no heat is received from the outside, resolved the objections that had been raised by Rayleigh and others concerning the conservation of energy.
He goes on to find, for a perfect gas, the jump conditions for a shock wave moving with speed a into an undisturbed medium with pressure and specific volume defined respectively by P and S. |
Shockwave
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As an object moves through a gas, the gas molecules are deflected around the object. If the speed of the object is much less than the speed of sound of the gas, the density of the gas remains constant and the flow of gas can be described by conserving momentum and energy. As the speed of the object increases towards the speed of sound, we must consider compressibility effects on the gas. The density of the gas varies locally as the gas is compressed by the object
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Reference 1: http://physics.info/shock/
Reference 2: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060047586_2006228914.pdf
Reference 2: http://www.grc.nasa.gov/WWW/k-12/airplane/machang.html
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