Passing through a shock front moving with a speed , the physical variables , , and
change abruptly.
Since the basic equations of hydrodynamics is unchanged after chosing a system moving ,
the continuity equation

(A.26) |

(A.27) |

(A.28) |

where the quatities with suffix 1 are for preshock and those with suffix 2 are for postshock.

Equation of motion for steady state

(A.30) |

where we used equation(A.29).