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Turbulent entrainment into a cylinder wake from a turbulent background

Published online by Cambridge University Press:  04 November 2020

Krishna S. Kankanwadi Open the ORCID record for Krishna S. Kankanwadi [Opens in a new window]  and
Oliver R. H. Buxton Open the ORCID record for Oliver R. H. Buxton [Opens in a new window]
Krishna S. Kankanwadi*
Affiliation:
Department of Aeronautics, Imperial College London, South Kensington Campus, LondonSW7 2AZ, UK
Oliver R. H. Buxton
Affiliation:
Department of Aeronautics, Imperial College London, South Kensington Campus, LondonSW7 2AZ, UK
*
†Email address for correspondence: krishna.kankanwadi12@imperial.ac.uk
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Abstract

The effects of background turbulence on the entrainment process, as well as the nature of the interfacial region between two bodies of turbulent fluid, were examined through an investigation of the far wake of a circular cylinder that is subjected to free-stream turbulence. Simultaneous particle image velocimetry and planar laser induced fluorescence measurements were conducted 40 diameters downstream of the cylinder. Despite the availability of turbulent, rotational fluid in the background, the outer interface between the wake and the ambient fluid exhibits an enstrophy jump akin to the classical result of a turbulent/non-turbulent interface. This jump at the wake boundary persists even when the intensity of the background turbulence is greater than the turbulence intensity of the wake itself. Analysis on the structure of the wake boundary reveals that an increase in background turbulence intensity results in an increased interfacial surface area relative to the non-turbulent case. However, instead of the intuitive result of increased entrainment as a result of increased surface area, a reduction in mean entrainment mass flux is observed with increased background turbulence intensity. Through the analysis of the flux probability density functions, the reduction in mean entrainment can be attributed to a tip in balance of extreme entrainment and detrainment events to the detrainment side in the presence of background turbulence. Lastly, a scale by scale analysis of entrainment behaviour revealed that free-stream turbulence affects entrainment behaviour across all length scales and is not just limited to the energy containing scales.

JFM classification

Mixing: Turbulent mixing Wakes/Jets: Wakes
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 905 , 25 December 2020 , A35
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Copyright
© The Author(s), 2020. Published by Cambridge University Press

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References

REFERENCES

Arcoumanis, C., McGuirk, J. J. & Palma, J. M. L. M. 1990 On the use of fluorescent dyes for concentration measurements in water flows. Exp. Fluids 10 (2), 177–180.CrossRefGoogle Scholar
Baj, P., Bruce, P. J. K. & Buxton, O. R. H. 2016 On a PLIF quantification methodology in a nonlinear dye response regime. Exp. Fluids 57 (6), 1–19.CrossRefGoogle Scholar
Baj, P. & Buxton, O. R. H. 2019 Passive scalar dispersion in the near wake of a multi-scale array of rectangular cylinders. J. Fluid Mech. 864, 181–220.CrossRefGoogle Scholar
Betchov, R. 1956 An inequality concerning the production of vorticity in isotropic turbulence. J. Fluid Mech. 1 (5), 497–504.CrossRefGoogle Scholar
Bisset, D. K., Hunt, J. C. R. & Rogers, M. M. 2002 The turbulent/non-turbulent interface bounding a far wake. J. Fluid Mech. 451, 383–410.CrossRefGoogle Scholar
Breda, M. & Buxton, O. R. H. 2019 Behaviour of small-scale turbulence in the turbulent/non-turbulent interface region of developing turbulent jets. J. Fluid Mech. 879, 187–216.CrossRefGoogle Scholar
Buxton, O. R. H., Breda, M. & Dhall, K. 2019 Importance of small-scale anisotropy in the turbulent/nonturbulent interface region of turbulent free shear flows. Phys. Rev. Fluids 4 (3), 1–17.CrossRefGoogle Scholar
Ching, C. Y., Fernando, H. J. S. & Robles, A. 1995 Breakdown of line plumes in turbulent environments. J. Geophys. Res. 100 (C3), 4707–4713.CrossRefGoogle Scholar
Corrsin, S. & Kistler, A. L. 1955 Free-stream boundaries of turbulent flows. NACA Tech. Rep. 1244.Google Scholar
Eames, I., Jonsson, C. & Johnson, P. B. 2011 The growth of a cylinder wake in turbulent flow. J. Turbul. 12, N39.CrossRefGoogle Scholar
Elsinga, G. E. & da Silva, C. B. 2019 How the turbulent/non-turbulent interface is different from internal turbulence. J. Fluid Mech. 866, 216–238.CrossRefGoogle Scholar
Gaskin, S. J., McKernan, M. & Xue, F. 2004 The effect of background turbulence on jet entrainment: an experimental study of a plane jet in a shallow coflow. J. Hydraul. Res. 42 (5), 533–542.CrossRefGoogle Scholar
Holzner, M. & Lüthi, B. 2011 Laminar superlayer at the turbulence boundary. Phys. Rev. Lett. 106 (13), 134503.CrossRefGoogle ScholarPubMed
Kankanwadi, K. S. & Buxton, O. R. H. 2019 Turbulent entrainment from a turbulent background. In 11th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2019, pp. 1–6. TSFP.Google Scholar
Kwok, K. C. S. 1986 Turbulence effect on flow around circular-cylinder. J. Engng Mech.-ASCE 112 (11), 1181–1197.CrossRefGoogle Scholar
Laizet, S. & Vassilicos, J. C. 2012 Fractal space-scale unfolding mechanism for energy-efficient turbulent mixing. Phys. Rev. E 86 (4), 1–5.CrossRefGoogle ScholarPubMed
Mandelbrot, B. B. 1983 The Fractal Geometry of Nature, p. 173. W. H. Freeman.Google Scholar
Melina, G., Bruce, P. J. K., Hewitt, G. F. & Vassilicos, J. C. 2017 Heat transfer in production and decay regions of grid-generated turbulence. Intl J. Heat Mass Transfer 109, 537–554.CrossRefGoogle Scholar
Mistry, D., Philip, J., Dawson, J. R. & Marusic, I. 2016 Entrainment at multi-scales across the turbulent/non-turbulent interface in an axisymmetric jet. J. Fluid Mech. 802, 690–725.CrossRefGoogle Scholar
Philip, J., Meneveau, C., de Silva, C. M. & Marusic, I. 2014 Multiscale analysis of fluxes at the turbulent/non-turbulent interface in high Reynolds number boundary layers. Phys. Fluids 26, 015105.CrossRefGoogle Scholar
Sadeh, W. Z. & Brauer, H. J. 1980 A visual investigation of turbulence in stagnation flow about a circular cylinder. J. Fluid Mech. 99 (1), 53–64.CrossRefGoogle Scholar
da Silva, C. B., Hunt, J. C. R., Eames, I. & Westerweel, J. 2014 Interfacial layers between regions of different turbulence intensity. Annu. Rev. Fluid Mech. 46 (1), 567–590.CrossRefGoogle Scholar
Sreenivasan, K. R., Ramshankar, R. & Meneveau, C. 1989 Mixing, entrainment and fractal dimensions of surfaces in turbulent flows. Proc. R. Soc. Lond. A 421, 79–108.Google Scholar
Taylor, G. I. 1936 Statistical theory of turbulence V-effect of turbulence on boundary layer theoretical discussion of relationship between scale of turbulence and critical resistance of spheres. Proc. R. Soc. Lond. A 156 (888), 307–317.Google Scholar
Townsend, A. A. 1976 The Structure of Turbulent Shear Flow. Cambridge University Press.Google Scholar
Van Reeuwijk, M. & Holzner, M. 2013 The turbulence boundary of a temporal jet. J. Fluid Mech. 739, 254–275.CrossRefGoogle Scholar
Vanderwel, C. & Tavoularis, S. 2014 On the accuracy of PLIF measurements in slender plumes. Exp. Fluids 55 (8), 1801.CrossRefGoogle Scholar
Watanabe, T., Sakai, Y., Nagata, K., Ito, Y. & Hayase, T. 2014 Vortex stretching and compression near the turbulent/non-turbulent interface in a planar jet. J. Fluid Mech. 758, 754–785.CrossRefGoogle Scholar
Westerweel, J., Fukushima, C., Pedersen, J. & Hunt, J. C. R. 2005 Mechanics of the turbulent-nonturbulent interface of a jet. Phys. Rev. Lett. 95 (17), 1–4.Google ScholarPubMed
Williamson, C. H. K. 1996 Vortex dynamics in the cylinder wake. Annu. Rev. Fluid Mech. 28, 477–539.CrossRefGoogle Scholar
Zhou, Y. & Vassilicos, J. C. 2017 Related self-similar statistics of the turbulent/non-turbulent interface and the turbulence dissipation. J. Fluid Mech. 821, 440–457.CrossRefGoogle Scholar
Supplementary material: File

Kankanwadi and Buxton supplementary movie 1

Video of run 1a (no-grid case) highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 1(File)
File 9.7 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 2

Video of run 1b highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 2(File)
File 9.4 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 3

Video of run 2a highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 3(File)
File 8.5 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 4

Video of run 2b highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 4(File)
File 9.7 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 5

Video of run 2c highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 5(File)
File 9.3 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 6

Video of run 2d highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 6(File)
File 7.7 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 7

Video of run 2e highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 7(File)
File 8.2 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 8

Video of run 3a highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 8(File)
File 9 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 9

Video of run 3b highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 9(File)
File 8.3 MB
Supplementary material: File

Kankanwadi and Buxton supplementary movie 10

Video of run 3c highlighting entrainment behaviour.

Download Kankanwadi and Buxton supplementary movie 10(File)
File 8.1 MB