Application of an inverse mass transfer method to the measurement of turbulent fluctuations in the velocity gradient at the wall

Mao, Zugang; Hanratty, Thomas J.

doi:10.1007/bf00198433

Cited by 17 publications

(6 citation statements)

References 6 publications

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“…Measured values of (? )I" of 0.34, 0.39 and 0.39 are quite close to the value of 0.37 determined by Mao and Hanratty (1991b) in the absence of imposed oscillations.…”

Section: No Flow Reversalsupporting

confidence: 79%

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Influence of large‐amplitude oscillations on turbulent drag

Mao

Hanratty

1994

AIChE Journal

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The effect of imposed large-amplitude oscillations on turbulent drag is studied. The system consists of water flow through a straight 5.08-em pipe. The velocity gradient at the wall is measured with flush-mounted electrochemical mass-transfer probes. Newly developed numerical algorithms are used to analyze the probe performance in the presence of unsteady flows. Sinusoidal oscillations are at large enough frequencies, uf = 0.0138-0.0306, that a pseudo-steady-state approximation cannot be made. The ratio of the time-averaged velocity gradient at the wall, with and without oscillations, 3, varies between 1.00 and 1.03, provided flow reversal does not occur. However, two experiments in which reversed flows existed at the wall for an appreciable period of time show drag reductions of 7 and 13%. Imposed nonsinusoidal oscillations are also studied for a period of favorable pressure gradient, about twice longer than that of unfavorable, and two sudden changes in the pressure gradient. Experiments at Re=9,700 with To of 2.00, 2.45, and 3.46 s, and at Re=19,200 with T0=3.46 give values of s=1.04-1.08. A t Re= 19,200 and To =2.00, 1.50, 1.00s, drag reductions are I0-15%. Thisphenomenon could be associated with the speed with which a fro w adjusts to sudden changes in the pressure gradient. introductionThe imposition of periodic oscillations on a turbulent fluid flowing through a duct causes periodic changes in the shear rate (or shear stress) at the wall, S . As shown by Hussain and Reynolds (1970), these changes can by characterized by defining S ( r ) as the sum of a phase-averaged and a fluctuating quantity,

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“…Measured values of (? )I" of 0.34, 0.39 and 0.39 are quite close to the value of 0.37 determined by Mao and Hanratty (1991b) in the absence of imposed oscillations.…”

Section: No Flow Reversalsupporting

confidence: 79%

“…15 for all of the curves shown. The sequential estimation method outlined above was used by Mao and Hanratty (1991b) to analyze measurements made in a turbulent flow. The electrode was a circular wire with a diameter of 0.0127 cm.…”

Section: S=s+smentioning

confidence: 99%

Influence of large‐amplitude oscillations on turbulent drag

Mao

Hanratty

1994

AIChE Journal

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“…Note that the vertical scaling used in this figure is based on the result of the pseudo-steady-state approximation expressed by Eq. (8).…”

Section: Resultsmentioning

confidence: 99%

“…The expressions of the transfer function were obtained considering that the fluctuating velocity gradient is given as a harmonic function and by solving a linearized version of the unsteady part of the mass transfer balance. Mao and Hanratty [8][9][10] used an inverse method to take into account the non-linearity. These authors measured the time evolution of the mass transfer rates generated on small probes in turbulent pipe flows.…”

Section: Introductionmentioning

confidence: 99%

Frequency response of an electrochemical probe to the wall shear stress fluctuations of a turbulent channel flow

Pallarès

Grau

2008

International Journal of Heat and Mass Transfer

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“…The transfer functions can provide information on the frequency-domain from a signal analysis procedure at the cost of the loss of the time-domain information. Therefore, some authors, similarly to the small Péclet number cases, have considered using other methods as, for example, the inverse mass transfer method explored firstly by Mao and Hanratty [20], to deal with the probe inertia while preserving the time-resolved ED measurements. This approach has improved the measurements of the amplitude probability distribution and the frequency spectrum of the streamwise component of the fluctuating velocity gradient.…”

Section: Introductionmentioning

confidence: 99%

A revisit of the electro-diffusional theory for the wall shear stress measurement

Havlica

Kramolis

Huchet

2021

International Journal of Heat and Mass Transfer

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This article intends to revisit the electro-diffusional theory for the wall shear stress measurement from mass transfer probes of rectangular shape by considering the existence of two components of the wall shear rate (i.e., axial and transversal). General analytical formulas for the effective transfer length and the dimensionless mass transport coefficient were derived as a function of only two parameters: a dimensionless angle of the flow direction, relative to the leading edge of the probe, and the aspect ratio between the width and the length

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Application of an inverse mass transfer method to the measurement of turbulent fluctuations in the velocity gradient at the wall

Cited by 17 publications

References 6 publications

Influence of large‐amplitude oscillations on turbulent drag

Influence of large‐amplitude oscillations on turbulent drag

Frequency response of an electrochemical probe to the wall shear stress fluctuations of a turbulent channel flow

A revisit of the electro-diffusional theory for the wall shear stress measurement

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