Publication Date:
1986-09-01
Description:
Measurements are presented of the time variation of the wall shear stress caused by the imposition of a sinusoidal oscillation on a turbulent pipe flow. The amplitude of the oscillation is small enough that a linear response is obtained and the dimensionless frequency, ω+= ωv/u2is large compared with that studied by most previous investigators. The most striking feature of the results is a relaxation effect, similar to that observed for flow over a wavy surface, whereby the phase angle characterizing the temporal variation of the wall shear stress undergoes a sharp change over a rather narrow range of ω +. At ω+larger than the median frequency of the turbulence there appears to be an interaction between the imposed flow oscillation and the turbulence fluctuations in the viscous sublayer, which is not described by present theories of turbulence. © 1986, Cambridge University Press. All rights reserved.
Print ISSN:
0022-1120
Electronic ISSN:
1469-7645
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
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