Scaling of wall shear stress fluctuations in a turbulent duct flow

AIAA Journal ◽  
1987 ◽  
Vol 25 (1) ◽  
pp. 22-29 ◽  
Author(s):  
D.A. Shah ◽  
R.A. Antonia
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Duct Flow ◽  
Wall Shear ◽  
Turbulent Duct Flow

Wall-shear stress patterns of coherent structures in turbulent duct flow

2009 ◽  
Vol 633 ◽  
pp. 147-158 ◽  
Author(s):  
SEBASTIAN GROSSE ◽  
WOLFGANG SCHRÖDER
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Wall Shear Stress ◽  
Coherent Structures ◽  
Shear Stress Distribution ◽  
Duct Flow ◽  
Wall Shear Stress Distribution ◽  
Wall Shear ◽  
Turbulent Duct Flow ◽  
Low Shear

The wall-shear stress distribution in turbulent duct flow has been assessed using the micro-pillar shear-stress sensor MPS3. The spatial resolution of the sensor line is 10.8l+(viscous units) and the total field of view of 120l+along the spanwise direction allows to capture characteristic dimensions of the wall-shear stress distribution at sufficiently high resolution. The results show the coexistence of low-shear and high-shear regions representing ‘footprints’ of near-wall coherent structures. The regions of low shear resemble long meandering bands locally interrupted by areas of higher shear stress. Conditional averages of the flow field indicate the existence of nearly streamwise counter-rotating vortices aligned in the streamwise direction. The results further show periods of very strong spanwise wall-shear stress to be related to the occurrence of high streamwise shear regions and momentum transfer towards the wall. These events go along with a spanwise oscillation and a meandering of the low-shear regions.

Properties of Wall Shear Stress Fluctuations in a Turbulent Duct Flow

1977 ◽  
Vol 44 (3) ◽  
pp. 389-395 ◽  
Author(s):  
K. R. Sreenivasan ◽  
R. A. Antonia
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Probability Density ◽  
Duct Flow ◽  
Zero Crossing ◽  
Number Range ◽  
Stress Fluctuation ◽  
Moderate Reynolds Number ◽  
Wall Shear ◽  
Turbulent Duct Flow

Measurements of wall shear stress fluctuations have been made in a fully developed turbulent duct flow, using a surface heat transfer gauge. Measurements, made over a moderate Reynolds number range, include RMS values, probability density functions, spectra, and zero-crossing frequencies of the wall shear stress fluctuation. The ratio of RMS of the fluctuation to the mean value of the wall shear stress is found to be about 0.25. The zero-crossing frequency computed from the measured spectra using the relation derived by Rice for a Gaussian process is found to be a good approximation to the measured value, although the measured probability density function is not Gaussian. The zero crossing frequency and spectra of wall shear stress fluctuations appear to scale with outer variables for asymptotically large Reynolds numbers.

scholarly journals On the role of secondary motions in turbulent square duct flow

2018 ◽  
Vol 847 ◽  
Author(s):  
Davide Modesti ◽  
Sergio Pirozzoli ◽  
Paolo Orlandi ◽  
Francesco Grasso
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Streamwise Velocity ◽  
Normal Velocity ◽  
Duct Flow ◽  
Mean Flow ◽  
Square Duct ◽  
The Mean ◽  
Wall Shear

We use a direct numerical simulations (DNS) database for turbulent flow in a square duct up to bulk Reynolds number $Re_{b}=40\,000$ to quantitatively analyse the role of secondary motions on the mean flow structure. For that purpose we derive a generalized form of the identity of Fukagata, Iwamoto and Kasagi (FIK), which allows one to quantify the effect of cross-stream convection on the mean streamwise velocity, wall shear stress and bulk friction coefficient. Secondary motions are found to contribute approximately 6 % of the total friction, and to act as a self-regulating mechanism of turbulence whereby wall shear stress non-uniformities induced by corners are equalized, and universality of the wall-normal velocity profiles is established. We also carry out numerical experiments whereby the secondary motions are artificially suppressed, in which case their equalizing role is partially taken by the turbulent stresses.

Correction: Development of a Two-Dimensional Wall Shear Stress Sensor for Wind Tunnel Applications

2019 ◽  
Author(s):  
Brett Freidkes ◽  
David A. Mills ◽  
Casey Keane ◽  
Lawrence S. Ukeiley ◽  
Mark Sheplak
Keyword(s):  
Shear Stress ◽  
Wind Tunnel ◽  
Wall Shear Stress ◽  
Two Dimensional ◽  
Stress Sensor ◽  
Shear Stress Sensor ◽  
Wall Shear
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