Unsteady turbulent flow in a pipe

Vasil'ev, O. F.; Kvon, V. I.

doi:10.1007/bf00850464

Cited by 5 publications

(5 citation statements)

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“…Higher-order closure models have been applied to oscillatory flow through ducts, especially models which are based on the transport equation for the turbulent kinetic energy. Vasiliev & Kvon (1971), for example, calculate the oscillatory flow in a pipe. However, they evaluate their model at large amplitudes of the mean-flow velocity oscillation, obtaining wall shear stresses which are far from the experimental values obtained here (figure 12).…”

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confidence: 99%

Wall shear stress caused by small amplitude perturbations of turbulent boundary-layer flow: an experimental investigation

Ronneberger

Ahrens

1977

J. Fluid Mech.

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The oscillation of the wall shear stress caused by imposing sound on a turbulent boundary-layer flow constitutes a boundary condition for the solution of the acoustic wave equation. The no-slip condition at the wall requires the excitation of a shear wave which is superimposed on the sound wave. The shear wave propagates into the turbulent medium. The wall impedance (shear stress/velocity) of streamwise polarized shear waves has been measured in two different ways, namely (a) by evaluating the phase velocity and the attenuation of a plane sound, wave which propagates in turbulent pipe flow, and (b) by evaluating the resonance frequency and the quality factor of a longitudinally vibrating glass pipe which carries turbulent flow. The results, which were obtained over a wide range of Strouhal numbers, exhibit very good agreement between the two measuring methods. The wall shear stress impedance is strongly affected by the turbulence. This indicates that the turbulent shear stress is modulated by the shear wave. At all measuring conditions, the propagation of the shear wave was confined essentially to the inner portion of the turbulent boundary layer. In principle, two different Strouhal numbers, based on inner and outer variables respectively, describe the dynamics of the Reynolds stress, even in the inner layer (Laufer & Badri Narayanan 1971). However, it turns out that the outer Strouhal number (based on the diameter and the centre-line velocity) has no noticeable effect on the wall shear stress impedance. The dependence of the impedance on the inner Strouhal number (based on the friction velocity and the viscosity) reveals that the shear wave is strongly reflected at the edge of the viscous sublayer. It is concluded that the stress-to-strain ratio at the edge of the viscous sublayer corresponds either to a viscoelastic medium or even to a medium with negative viscosity.

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Section: ----mentioning

confidence: 99%

Wall shear stress caused by small amplitude perturbations of turbulent boundary-layer flow: an experimental investigation

Ronneberger

Ahrens

1977

J. Fluid Mech.

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“…(10) It will be assumed [2,3] that Ke=aeK, K T =C~TK, where c~ e and a T are constants. The coefficient of exchange K will be determined by using the expression [2] …”

Section: = --~L(o~lox) ~ = Vt/lmentioning

confidence: 99%

Thermally stratified flow in a basin of elongated shape

Vasil'ev¹,

Kvon²,

Chernysheva³

1974

Hydrotechnical Construction

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“…A number of experimental investigations [1][2][3][4] explaining the change in the friction coefficient in accelerated flows were performed in the past decade, However, attempts to close the equations describing unsteady flow in pipes in accordance with the semiempirical theory off.transport equations [5] run into difficulties related to the absence of experimental da6a of the temporal change of the unsteady process of Reynolds stresses-0u'v'. We conducted investigations for an experimental evaluation of the effect of unsteadiness on Reynolds stresses during acceleration of a fluid from a state of rest in pressure pipelines, Experimental Device.…”

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confidence: 99%

“…In both equations of system (i), (2) a substantial role is played by the correlations of -<u'v'>, which in numerical calculations are approximated either according to the Boussinesqor Prandtlsemiempirical theory or according to thek--Emodel, whicharedescribed in [3,7].…”

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confidence: 99%