The scaling of the turbulent/non-turbulent interface at high Reynolds numbers

• Published in: Journal of fluid mechanics Vol. 843; pp. 156 - 179
• Main Authors: Silva, Tiago S., Zecchetto, Marco, da Silva, Carlos B.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 25.05.2018
• Subjects: Computer simulation; JFM Papers; Reynolds number; Scaling; Turbulence; shear layer turbulence; turbulent flows; jets
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/jfm.2018.143

The scaling of the turbulent/non-turbulent interface (TNTI) at high Reynolds numbers is investigated by using direct numerical simulations (DNS) of temporal turbulent planar jets (PJET) and shear free turbulence (SFT), with Reynolds numbers in the range $142\leqslant Re_{\unicode[STIX]{x1D706}}\leqslant 400$ . For $Re_{\unicode[STIX]{x1D706}}\gtrsim 200$ the thickness of the TNTI ( $\unicode[STIX]{x1D6FF}_{\unicode[STIX]{x1D714}}$ ), like that of its two sublayers – the viscous superlayer (VSL, $\unicode[STIX]{x1D6FF}_{\unicode[STIX]{x1D708}}$ ) and the turbulent sublayer (TSL, $\unicode[STIX]{x1D6FF}_{\unicode[STIX]{x1D70E}}$ ) – all scale with the Kolmogorov micro-scale $\unicode[STIX]{x1D702}$ , while the particular scaling constant depends on the sublayer. Specifically, for $Re_{\unicode[STIX]{x1D706}}\gtrsim 200$ while the VSL is always of the order of $\unicode[STIX]{x1D702}$ , with $4\leqslant \langle \unicode[STIX]{x1D6FF}_{\unicode[STIX]{x1D708}}\rangle /\unicode[STIX]{x1D702}\leqslant 5$ , the TSL and the TNTI are typically equal to $10\unicode[STIX]{x1D702}$ , with $10.4\leqslant \langle \unicode[STIX]{x1D6FF}_{\unicode[STIX]{x1D70E}}\rangle /\unicode[STIX]{x1D702}\leqslant 12.5$ , and $15.4\leqslant \langle \unicode[STIX]{x1D6FF}_{\unicode[STIX]{x1D714}}\rangle /\unicode[STIX]{x1D702}\leqslant 16.8$ , respectively.