Advertisement

Effects of Shear-Layer Roll-Up on Axisymmetric DNS Velocity Signals in a Coaxial Jet Configuration

  • M. OnoratoJr.
  • P. Petagna
  • M. V. Salvetti
  • G. Buresti
Conference paper
Part of the Fluid Mechanics and its Applications book series (FMIA, volume 36)

Abstract

For the characterization of developing turbulent flows, which are dominated by the dynamics of vorticity structures of different scale, it would be very useful to connect the features of the velocity fluctuations detected at a certain point with the evolution of the structures that are present in the nearby regions. To this end, outputs of DNS calculations, which can provide simultaneously both the evolution of the vorticity and the “velocity signals” corresponding to the different regions of the flow field, may be used. Obviously, only low Reynolds number conditions can be analysed, but the influence of basic mechanisms, as roll-up, passage and pairing of vortical structures, can be singled out, both as regards their “signatures” on the velocity time histories, and their effect on different statistical quantities. In particular, indications may be obtained on the processes that contribute to the production of Reynolds stresses, and thus to the average mass transport between two streams at different velocities. This type of analysis might then be considered as a very first step towards the identification of possible procedures for the recognition of the presence and evolution of the dominating vortical structures from velocity signals obtained experimentally at higher Reynolds number.

Keywords

Shear Layer Reynolds Stress Vortical Structure Velocity Signal Velocity Time History 
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.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Dahm, W.J.A., Frieler, C.E., Tryggvason G.: Vortex structure and dynamics in the near field of a coaxial jet, J. of Fluid Mech. 241 (1992), 371–402.ADSCrossRefGoogle Scholar
  2. 2.
    Salvetti, M.V., Orlandi, P., Verzicco, R.: Direct simulations of transitional axisymmetric coaxial jets, to be published in AIAA J., 34, n.12 (1996).Google Scholar
  3. 3.
    Grinstein, F.F., Hussain, F., Oran, E.S.: Vortex-ring dynamics in a transitional subsonic free jet. A numerical study, Eur. J. Mech., B/Fluids 9, n. 6 (1990), 499–525.Google Scholar
  4. 4.
    Daubechies, I.: Ten Lectures on Wavelets, SIAM, 1992.Google Scholar
  5. 5.
    Katul, G.K., Parlange, M.B., Chu, C.R.: Intermittency, local isotropy, and non Gaussian statistics in atmospheric surface layer turbulence, Phys. Fluids 6 n. 7 (1994), 2480–2492ADSCrossRefGoogle Scholar
  6. 6.
    Ho, C.M., Huerre, P.: Perturbed free shear layers, Ann. Rev. Fluid Mech. 16 (1984), 365–424ADSCrossRefGoogle Scholar
  7. 7.
    Farge, M.: Wavelet transforms and their applications to turbulence, Ann. Rev. Fluid. Mech. 24 (1992), 395–457MathSciNetADSCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • M. OnoratoJr.
    • 1
  • P. Petagna
    • 1
  • M. V. Salvetti
    • 1
  • G. Buresti
    • 1
  1. 1.Dipartimento di Ingegneria AerospazialeUniversità di PisaPisaItaly

Personalised recommendations