Abstract
Abstract
Highlights
The observed clustering of vortices is consistent with the apparent self-organization of the instantaneous flow in high-Reynolds-number boundary layers into large-scale velocity structures separated by relatively thin layers of concentrated shear and vorticity (Meinhart & Adrian 1995; Priyadarshana et al 2007; Eisma et al 2015; de Silva et al 2017)
Rather than directly detecting the internal shear layers (ISLs) using a threshold on instantaneous values of ∂u/∂z, we instead infer the properties of ISLs from detected interfaces of uniform momentum zone (UMZ)
While the UMZ and large-eddy turnover times in figure 11 are based on flow properties measured in the x–z plane, the Burgers model for spanwise vortices requires the UMZs to have a diverging spanwise velocity component to exert a tensile stress on the vortices
Summary
Similitude is one of the few properties of turbulence that makes understanding the phenomenon more tractable. The observed clustering of vortices is consistent with the apparent self-organization of the instantaneous flow in high-Reynolds-number boundary layers into large-scale velocity structures separated by relatively thin layers of concentrated shear and vorticity (Meinhart & Adrian 1995; Priyadarshana et al 2007; Eisma et al 2015; de Silva et al 2017). These thin layers are referred to here as internal shear layers (ISLs). In addition to the limited number of detailed studies on vortex cores and ISLs in high-Reynolds-number boundary layer turbulence, even fewer works have quantitatively explored possible relations between the coherent velocity structures, vortices and shear layers. Two appendices are included to examine the influence of spatial resolution on the results and to justify assumptions made in the analysis
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