Erratum for “Wall Shear Stress in the Early Stage of Unsteady Turbulent Pipe Flow” by S. He and C. Ariyaratne

2011 ◽  
Vol 137 (10) ◽  
pp. 1309-1309
Author(s):  
S. He ◽  
C. Ariyaratne
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pipe Flow ◽  
Early Stage ◽  
Turbulent Pipe Flow ◽  
Wall Shear

Calculations of Wall Shear Stress in Harmonically Oscillated Turbulent Pipe Flow Using a Low-Reynolds-Number k-ε Model

1996 ◽  
Vol 118 (1) ◽  
pp. 189-194 ◽  
Author(s):  
J. O. Ismael ◽  
M. A. Cotton
Keyword(s):  
Reynolds Number ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Pipe Flow ◽  
Low Reynolds Number ◽  
Turbulent Pipe Flow ◽  
Frequency Model ◽  
Wide Range ◽  
Wall Shear ◽  
Low Reynolds

The low-Reynolds-number k-ε turbulence model of Launder and Sharma is applied to the calculation of wall shear stress in spatially fully-developed turbulent pipe flow oscillated at small amplitudes. It is believed that the present study represents the first systematic evaluation of the turbulence closure under consideration over a wide range of frequency. Model results are well correlated in terms of the parameter ω+ = ωv/Uτ2 at high frequencies, whereas at low frequencies there is an additional Reynolds number dependence. Comparison is made with the experimental data of Finnicum and Hanratty.

Studies of the wall shear stress in a turbulent pulsating pipe flow

1986 ◽  
Vol 170 ◽  
pp. 545-564 ◽  
Author(s):  
Zhuo-Xiong Mao ◽  
Thomas J. Hanratty
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pipe Flow ◽  
Relaxation Effect ◽  
Viscous Sublayer ◽  
Turbulent Pipe Flow ◽  
Sharp Change ◽  
Dimensionless Frequency ◽  
Median Frequency ◽  
Wall Shear

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+ = ων/u*2, is 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.

scholarly journals Experimental techniques against RANS method in a fully-developed turbulent pipe flow

2021 ◽  
Author(s):  
Gabriela Belen Lopez-Santana ◽  
Andrew Kennaugh ◽  
Amir Keshmiri
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pipe Flow ◽  
Turbulence Models ◽  
Turbulent Pipe Flow ◽  
Experimental Techniques ◽  
Mean Velocity ◽  
Experimental Apparatus ◽  
Wall Shear ◽  
The University

Turbulence has been studied by scientists and engineers for decades as it appears in the majority of the fluids existent in nature and in engineering applications and because turbulent flow and its underlying behaviour are tremendously complex. The University of Manchester is widely viewed as the birthplace of turbulence due to the pioneering work of one of its prominent academics, Professor Osborne Reynolds (1842-1912). Building on this legacy, a classical experimental apparatus has been used in this paper to study a turbulent pipe flow with the aim of measuring the mean velocity field and wall shear stress using four experimental techniques, all developed in the 20th century, namely static pressure drop; mean square signals measured from a hot-wire; Preston tube; and the ‘Clauser Plot’. The experimental results have then been compared against those obtained using Computational Fluid Dynamics (CFD), utilising different two-equation turbulence models. The present work highlights the discrepancies evident in obtaining the value of the wall shear stress in each method. In addition, the scopes and limitations of each technique are discussed in detail, highlighting the clear evolution of turbulence study tools over the last 100 years.

Exploring wall shear stress spatiotemporal heterogeneity in coronary arteries combining correlation-based analysis and complex networks with computational hemodynamics

2020 ◽  
Vol 234 (11) ◽  
pp. 1209-1222 ◽  
Author(s):  
Karol Calò ◽  
Giuseppe De Nisco ◽  
Diego Gallo ◽  
Claudio Chiastra ◽  
Ayla Hoogendoorn ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Complex Networks ◽  
Coronary Arteries ◽  
Early Stage ◽  
Flow Direction ◽  
Computational Hemodynamics ◽  
Time Histories ◽  
Wall Shear

Atherosclerosis at the early stage in coronary arteries has been associated with low cycle-average wall shear stress magnitude. However, parallel to the identification of an established active role for low wall shear stress in the onset/progression of the atherosclerotic disease, a weak association between lesions localization and low/oscillatory wall shear stress has been observed. In the attempt to fully identify the wall shear stress phenotype triggering early atherosclerosis in coronary arteries, this exploratory study aims at enriching the characterization of wall shear stress emerging features combining correlation-based analysis and complex networks theory with computational hemodynamics. The final goal is the characterization of the spatiotemporal and topological heterogeneity of wall shear stress waveforms along the cardiac cycle. In detail, here time-histories of wall shear stress magnitude and wall shear stress projection along the main flow direction and orthogonal to it (a measure of wall shear stress multidirectionality) are analyzed in a representative dataset of 10 left anterior descending pig coronary artery computational hemodynamics models. Among the main findings, we report that the proposed analysis quantitatively demonstrates that the model-specific inlet flow-rate shapes wall shear stress time-histories. Moreover, it emerges that a combined effect of low wall shear stress magnitude and of the shape of the wall shear stress–based descriptors time-histories could trigger atherosclerosis at its earliest stage. The findings of this work suggest for new experiments to provide a clearer determination of the wall shear stress phenotype which is at the basis of the so-called arterial hemodynamic risk hypothesis in coronary arteries.

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