expansion wave

expansion wave

[ik′span·shən ‚wāv]
(fluid mechanics)
A pressure wave or shock wave that decreases the density of air as the air passes through it.

expansion wave

expansion waveclick for a larger image
In supersonic flow, expansion waves occur when bodies begin to narrow, making more space available. In passing through an expansion wave, air velocity increases, while temperature and pressures are reduced. A simple wave or progressive disturbance in the isentropic flow of a compressible fluid, such that the pressure and density of a fluid particle decrease on crossing the wave in the direction of its motion. It is the opposite of a compression wave. Also called a rarefaction wave. See also compression wave.
References in periodicals archive ?
This leads to the formation of an expansion wave, causing the gas jet to expand in the radial direction and increase the potential jet core.
Figure 11 shows the predicted results for a = 7.5[degrees], where T is time period and time reference (t = 0) is the time for radiation of an expansion wave near the trailing edge.
The 14-X B model lower surface was designed based on the two-dimensional compressible flow (oblique shock wave relationships) and expansion wave (Prandtl-Meyer theory), considering the simplest case, that is, no viscous flow, calorically perfect air ([gamma] = 1.4), and scramjet engine with power off [11].
Nevertheless, analysts generally believe the beachhead of the new expansion wave will be Germany, likely in the second half of the year.
The reason why the amplitude remains a decreasing tendency in R2 area is that there is expansion wave in the junction region (in Figure 6(a), x = 1;in Figure 6(c), x = 0) between the spherical nose and the straight cone which is caused by the surface curve discontinuity [25].
The shock wave becomes a Prandtl-Meyer expansion wave (i.e., [M.sub.2] > [M.sub.1]) for very high values of [Re.sub.2]/[Re.sub.1].
In analyzing the expansion wave at the nozzle outlet, the analysis must begin in the nozzle, move to the nozzle outlet, and then after the nozzle.
In the laser spallation test, strong pulse expansion wave was produced by the pulse laser ablation of the confined silicone grease on the opposite surface of the diamond film and was utilized to cause Mode-I delamination of diamond film.
-- During the 1990s the Wal-Mart expansion wave finally brought its brand of discounting to all 50 states, and to a few other countries as well.
Cyprus, a frontrunner for European Union membership in its next expansion wave, is an uncharted market for independent telecoms providers.
Looking ahead, Cuti says Duane Reade will continue to ride an aggressive expansion wave. "In 1999 we plan to capitalize on the significant foundation for growth that we built last year," he notes.
Still, it's notable that, per business historians, such departments have seen big jumps in their authority and prestige during three distinct periods in this century, and that each expansion wave has coincided with a period of increased pressure on companies by government, unions, or both.