Turbulent entrainment into a cylinder wake from a turbulent background

Kankanwadi, Krishna S.; Buxton, O. R. H.

doi:10.1017/jfm.2020.755

Cited by 36 publications

(63 citation statements)

References 28 publications

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“…However, as shown by Mistry et al. (2016) and Kankanwadi & Buxton (2020), acquired from the – plane is able to reflect the dominant entrainment events. Moreover, the p.d.f.s of (figure 11 c ) are qualitatively in good agreement with the results in Wolf et al.…”

Section: Entrainment Over Spanwise Heterogeneitymentioning

confidence: 90%

“…The tortuosity is defined as the area of TNTI per projected area on the wall (in 3-D) or the length of TNTI per streamwise distance (in 2-D) (Breda & Buxton 2019; Kankanwadi & Buxton 2020). From (3.1), it can be seen that larger tortuosity could result in larger nibbling: if we assume that is constant, then (3.1) writes as .…”

Section: Entrainment Over Spanwise Heterogeneitymentioning

confidence: 99%

“…2016); the total viscosity-independent entrainment flux is then achieved by the violent distorted TNTI surface (de Silva et al. 2013; Mistry, Philip & Dawson 2019; Kankanwadi & Buxton 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Globally, the integral entrainment velocity is proportional to the typical velocity scale in the turbulent region, and is not related to viscosity (Turner 1986;van Reeuwijk & Holzner 2014;Cafiero & Vassilicos 2020). Locally, the instantaneous entrainment velocity is of Kolmogorov velocity scale v η , and is determined by the local vorticity production, diffusion and dissipation (Holzner & Lüthi 2011;Jahanbakhshi & Madnia 2016;Mistry et al 2016); the total viscosity-independent entrainment flux is then achieved by the violent distorted TNTI surface (de Silva et al 2013;Mistry, Philip & Dawson 2019;Kankanwadi & Buxton 2020).…”

Section: Introductionmentioning

confidence: 99%

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Universal modulations of large-scale motions on entrainment of turbulent boundary layers

2022

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The modulations of high/low-speed large-scale motions (H/L-SMs) on the turbulent/non-turbulent interface (TNTI) and turbulent entrainment are investigated in turbulent boundary layers via both experimental and numerical studies. The spanwise locations of large-scale motions can be locked by the spanwise heterogeneity, so the boundary layers over such a configuration are investigated first as an instructive case. In the engulfment process, it is found that irrotational ‘bubbles’ near the TNTI are more likely to originate from engulfment, while bubbles far from the TNTI could be produced by the local turbulence itself. Additionally, H-SMs are found to enhance the engulfment by the sweep flow. In the nibbling process, a competition relationship is observed: L-SMs induce stronger instantaneous ‘nibbling’ events by transporting more fluids towards the TNTI, while the H-SMs induced a more distorted TNTI. Consequently, the integral nibbling flux is greater above H-SMs. Furthermore, the explored mechanisms are verified to be insensitive to the wall shapes such as smooth and homogeneous roughness walls, which demonstrates that these modulations are universal for turbulent boundary layers. Finally, a conceptual modulation model is proposed to illustrate the entrainment process above the large-scale motions.

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Section: Entrainment Over Spanwise Heterogeneitymentioning

confidence: 90%

Section: Entrainment Over Spanwise Heterogeneitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Universal modulations of large-scale motions on entrainment of turbulent boundary layers

2022

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“…For example, in (3.8), the term contains two contributions, one associated with the mean flow and one with turbulent exchanges across the interface. These can be expected to be important in environments in which there are substantial fluctuations in the ambient, such as jets in a turbulent environment (Ching, Fernando & Robles 1995; Gaskin, McKernan & Xue 2004; Kankanwadi & Buxton 2020), turbulent fountains (Hunt & Burridge 2015) or clouds (de Rooy 2013). Importantly, the turbulent transport may require different parameterisation than the mean transport .…”

Section: Discussionmentioning

confidence: 99%