# critical velocity

## critical velocity

[′krid·ə·kəl və′läs·əd·ē]
(aerospace engineering)
In rocketry, the speed of sound at the conditions prevailing at the nozzle throat. Also known as throat velocity.
(cryogenics)
The velocity of a superfluid in very narrow channels (on the order of 10-5 centimeter), which is nearly constant. Also known as critical speed.
(fluid mechanics)
The speed of flow equal to the local speed of sound. Also known as critical speed.
The speed of fluid flow through a given conduit above which it becomes turbulent.

## critical velocity

Of a liquid flowing in a pipe, the velocity at which the flow changes from laminar flow to turbulent flow.
References in periodicals archive ?
To succeed, a sperm must reach a critical velocity to navigate upstream and avoid being caught in one of a series of bottleneck traps.
(25) determined that at the estimated critical velocity, physical activity could not be sustained for more than 60 min.
Using (73), (77), and (78), we discuss the stationary solution, the stability conditions of straight motion, and the critical velocity of circular motion.
Finally, possible experimental runs were selected up to where the approach velocity in the laboratory model became close to the critical velocity calculated by Keulegan's equation to conduct the experiment in clear-water scour regime.
In petroleum engineering, generally there is a critical velocity associated with sand production in oil and gas reservoirs.
The critical velocity required to resist smoke backlayering increases with the increase in the HRR of the fire but levels off at about 3 m/s (9.8 ft/s) for large fires greater than 100 MW (94800 BTU/s).
Can Critical Velocity and Anaerobic Swimming Capacity be Determined from Estimated Performance Times in Collegiate Swimmers?
In Section 3, the complex and natural frequencies of the system are computed together with the relationship of the system's natural frequency with the flow critical velocity. Section 4 analyses the dynamic responses for purely elastic pipe in three cases, namely, simple supports at both ends, cantilever pipe, and a clamped-pinned ends pipe.
Numerically found threshold [M.sub.A] for initiating KH instability of the kink (m = 1) mode in moving untwisted magnetic flux tube of compressible plasma is 12.435 that yields a critical velocity of 607km [s.sup.-1].
The critical velocity "wcr" is just the sufficient velocity provided by the ventilation system, able to prevent formation of this reverse stratified layer.
In terms of R, it can be classified as small, medium, and large numbers, and the corresponding critical values are assumed to be [R.sub.cr1] = [w.sub.cr1]D/v = 0.1 and [R.sub.cr2] = [w.sub.cr2]D/v = 1000 [13, 18], where [w.sub.cr1 = 0.1v/D is defined as the first critical velocity between small and medium R zones, [w.sub.cr2 = 1000v/D is defined as the second critical value between medium and large R zones, and their corresponding times were defined as [t.sub.cr1] and [t.sub.cr2], respectively.

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