Vorticity vs TNTI - Entrainment Fundamentals

A recent contribution by C. da Silva, et al. [1] presents results for the simulated flow: PJET, a temporally developing plane jet that could not be realized in a physical experiment. However, their results can be referenced to the PIV based vorticity observations of Foss, et al. [2]. Quantitatively similar results for the i) enstrophy distribution in [1] and ii) the mean square ω_z distribution in [2] are found, relative to the border (IB) between the irrotational (entraining) and the vortical (interior) fluid domains. However, the physical features of interest: i) length of the IB with respect to its linear projection, ii) the intermittency distribution and iii) acceleration of the entraining fluid in its approach to the IB, are not available for the faux flow. The relatively high Reynolds number (Re_λ) was 371 for [1], and higher: 590 for [2] using data from [3] for Re_λ.

[1] Silva, et al. “The scaling of the TNTI at high Reynolds numbers” JFM (2018) vol. 843 

[2] Foss, et al. (2017) “Single Stream Shear Layer and the Viscous Superlayer”, 10 C 4, Tenth International Symposium on Turbulence and Shear Flow Phenomena 

[3] Morris, S.C. (2002) “The velocity and vorticity fields of a single stream shear layer” PhD Dissertation, Michigan State University