A pressure wave , compression wave , density wave or compression wave is a longitudinal wave in a fluid or solid . Short-term fluctuations in the pressure in a medium propagate as a wave front . A fluctuation in pressure is accompanied by a fluctuation in density . Hence the waves are called both pressure and density waves.
Depending on the type of pressure change, a distinction is made between
- acoustic waves ( sound waves ) with low to moderate amplitude (compared to the ambient pressure) and constant pressure curve over time as well
- Shock waves in which the pressure changes abruptly and the amplitude is usually comparatively large (e.g. a multiple of the ambient pressure). Examples of this are detonation waves and the Mach cone .
In astrophysics , we know the density wave theory , according to which density waves cause the formation of bar, spiral and bar-spiral shapes in a galaxy . A density wave is generated due to a velocity dispersion of a wave in the thermal gas and a potential wave in that the gas falls into the potential minima and compresses there.
Explosion waves ( detonation waves ) are particularly popularly referred to as pressure waves. Colloquially, the term is also used for any short-term gusts of wind, such as the blast of air from an avalanche or a large vehicle driving by; physically, however, these are not waves, but short-term currents .
- Marcelo Alonso, Edward J. Finn: Physics. 3. Edition. Oldenbourg Wissenschaftsverlag, Munich 2000, ISBN 3-486-25327-1 .
- Heinz Herwig, Bastian Schmandt: Fluid Mechanics. Physics - mathematical models - thermodynamic aspects. 3. Edition. Springer, Berlin / Heidelberg / New York 2015, ISBN 978-3-662-45068-0 .
- Blast wave. In: Spectrum of Science. (accessed on November 23, 2015)