scholarly journals Relation between shear parameter and Reynolds number in statistically stationary turbulent shear flows

2004 ◽  
Vol 16 (8) ◽  
pp. 3094-3102 ◽  
Author(s):  
Jörg Schumacher
Keyword(s):  
Reynolds Number ◽  
Shear Flows ◽  
Turbulent Shear ◽  
Shear Parameter ◽  
Turbulent Shear Flows

scholarly journals Frequency–wavenumber mapping in turbulent shear flows

2015 ◽  
Vol 783 ◽  
pp. 166-190 ◽  
Author(s):  
Roeland de Kat ◽  
Bharathram Ganapathisubramani
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Shear Flows ◽  
Spatial Scales ◽  
Turbulent Shear ◽  
Data Set ◽  
Frequency Spectra ◽  
Taylor’S Hypothesis ◽  
Turbulent Shear Flows ◽  
High Reynolds

Spatial turbulence spectra for high-Reynolds-number shear flows are usually obtained by mapping experimental frequency spectra into wavenumber space using Taylor’s hypothesis, but this is known to be less than ideal. In this paper, we propose a cross-spectral approach that allows us to determine the entire wavenumber–frequency spectrum using two-point measurements. The method uses cross-spectral phase differences between two points – equivalent to wave velocities – to reconstruct the wavenumber–frequency plane, which can then be integrated to obtain the spatial spectrum. We verify the technique on a particle image velocimetry (PIV) data set of a turbulent boundary layer. To show the potential influence of the different mappings, the transfer functions that we obtained from our PIV data are applied to hot-wire data at approximately the same Reynolds number. Comparison of the newly proposed technique with the classic approach based on Taylor’s hypothesis shows that – as expected – Taylor’s hypothesis holds for larger wavenumbers (small spatial scales), but there are significant differences for smaller wavenumbers (large spatial scales). In the range of Reynolds number examined in this study, double-peaked spectra in the outer region of a turbulent wall flow are thought to be the result of using Taylor’s hypothesis. This is consistent with previous studies that focused on examining the limitations of Taylor’s hypothesis (del Álamo & Jiménez, J. Fluid Mech., vol. 640, 2009, pp. 5–26). The newly proposed mapping method provides a data-driven approach to map frequency spectra into wavenumber spectra from two-point measurements and will allow the experimental exploration of spatial spectra in high-Reynolds-number turbulent shear flows.

Unsteady Behavior of Turbulent Shear Flows

1990 ◽  
Author(s):  
Chih-Ming Ho ◽  
P. Huerre ◽  
L. G. Redekopp
Keyword(s):  
Shear Flows ◽  
Turbulent Shear ◽  
Turbulent Shear Flows ◽  
Unsteady Behavior
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