Flow Field Topology of Impinging Jets with Fractal Inserts

  • Gioacchino CafieroEmail author
  • Stefano Discetti
  • Tommaso Astarita
Conference paper
Part of the Springer Proceedings in Physics book series (SPPHY, volume 165)


An experimental investigation of the flow field features of a round air jet equipped with a fractal (FG) and a regular (RG) grid insert impinging on a flat surface is carried out by means of 2D-2C Particle Image Velocimetry (PIV). The results are compared to those for a round jet without any grid (JWT). The test Reynolds number is set to 10,000. The average flow fields and the turbulent kinetic energy distributions are presented. In particular, the effect of the presence of the fractal grid on the turbulence intensity distribution and on the planar component of the Reynolds stress is analyzed. Some differences between the location of the maximum of the turbulence intensity profile and the data reported in the literature are found. A possible interaction process between the wakes of the grids and the growing shear layer of the jet might be responsible of this discrepancy. A comparison between the flow field and the heat transfer results obtained by the authors in a previous work is also carried out. What is underlined is that both an higher turbulence level and a much stronger axial velocity cause an increment in the heat transfer rate.


Particle Image Velocimetry Turbulent Kinetic Energy Turbulence Intensity Plenum Chamber Nozzle Exit Section 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    Mandelbrot, B.B.: Intermittent turbulence in self-similar cascades: divergence of high moments and dimension of the carrier. J. Fluid Mech. 62, 331–358 (1974)CrossRefzbMATHGoogle Scholar
  2. 2.
    Mandelbrot, B.B.: The Fractal Geometry of Nature. Freeman, San Francisco (1982)zbMATHGoogle Scholar
  3. 3.
    Sreenivasan, K.R., Maneveau, C.: The fractal facets of turbulence. J. Fluid Mech. 173, 357–386 (1986)MathSciNetCrossRefGoogle Scholar
  4. 4.
    Queiros-Conde, D., Vassilicos, J.C.: Turbulent wakes of 3-D fractal grids in Turbulent Flows and Other Dynamical Systems. Cambridge University Press, Cambridge, UK (2001)zbMATHGoogle Scholar
  5. 5.
    Staicu, A., Mazzi, B., Vassilicos, J.C., van de Water, W.: Turbulent wakes of fractal objects. Phys. Rev. Lett. E 66, 066306 (2003)CrossRefGoogle Scholar
  6. 6.
    Mazzi, B., Okkels, F., Vassilicos, J.C.: A shell-model approach to fractal-induced turbulence. Eur. Phys. J. B/Fluids 28, 243–251 (2002)Google Scholar
  7. 7.
    Mazzi, B., Vassilicos, J.C.: Fractal-generated turbulence. J. Fluid Mech. 502, 65–87 (2004)Google Scholar
  8. 8.
    Hurst, D., Vassilicos, J.C.: Scaling and decay of fractal-generated turbulence. Phys. Fluids 19 035103 (2007). doi: 10.1063/1.2676448
  9. 9.
    Geipel, P., Goh, H.K.H., Lindstedt, P.R.: Fractal generated turbulence in opposed jet flows. Flow Turbul. Comb. 85, 397–419 (2010)CrossRefzbMATHGoogle Scholar
  10. 10.
    Kinzel, M., Wolf, M., Holzner, M., Lthi, B., Tropea, C., Kinzelbach, W.: Simultaneous two-scale 3D-PTV measurements in turbulence under the influence of system rotation. Exper. Fluids 51, 75–82 (2011)CrossRefGoogle Scholar
  11. 11.
    Mazellier, N., Vassilicos, J.C.: Turbulence without Richardson-Kolmogorov cascade Physics of Fluids 22 075101 (2010). doi: 10.1063/1.3453708
  12. 12.
    Jayesh, Warhaft Z.: Probability distribution, conditional dissipation, and transport of passive temperature fluctuations in grid? generated turbulence. Phys. Fluids 4, 2292–2307 (1992)Google Scholar
  13. 13.
    Cafiero, G., Discetti, S., Astarita, T.: Heat transfer enhancement of impinging jets with fractal-generated turbulence. Int. J. Heat. Mass Trans. 75, 173–183 (2014)Google Scholar
  14. 14.
    Astarita, T.: Analysis of interpolation schemes for image deformation methods in PIV: effect of noise on the accuracy and spatial resolution. Exper. Fluids 40, 977–987 (2006)CrossRefGoogle Scholar
  15. 15.
    Astarita, T.: Analysis of velocity interpolation schemes for image deformation methods in PIV. Exper. Fluids 45, 257–266 (2008)CrossRefGoogle Scholar
  16. 16.
    Astarita, T.: Analysis of weighting windows for image deformation methods in PIV. Exper. Fluids 43, 859–872 (2007)CrossRefGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Gioacchino Cafiero
    • 1
  • Stefano Discetti
    • 2
  • Tommaso Astarita
    • 1
  1. 1.Dipartimento di Ingegneria IndustrialeUniversità Degli Studi di Napoli Federico IINapoliItaly
  2. 2.Aerospace Engineering GroupUniversidad Carlos III de MadridLeganesSpain

Personalised recommendations