Shocks and Rarefactions
The word “shock” is used very widely in common experience. One is shocked by an unexpected event; a wounded victim goes into shock; and one shocks a material by suddenly cooling it. A “shock wave” is a sudden transition in the properties of a fluid medium, involving a difference in flow velocity across a narrow (ideally, abrupt) transition. In high-energy-density physics, nearly any experiment involves at least one shock wave. Such shock waves may be produced by applying pressure to a surface or by creating a collision between two materials. In astrophysics, nearly every sudden event produces a shock wave. Yet in common experience one encounters very few shock waves. We hear thunder after lightning, which is a long-term consequence of the shock wave produced by the lightning channel, but as we shall see below one would hope never to directly experience this shock wave. Most of us hear sonic booms infrequently, but they are the only shock wave of human origin we typically encounter.
KeywordsShock Wave Sound Speed Density Ratio Blast Wave Rarefaction Wave
Unable to display preview. Download preview PDF.