Identification of vortex structures in a coaxial jet
List of Authors
  • Safer Nabil Belkacem

Keyword
  • Large Eddy Simulation, coaxial, jet, Delta criterion, Q criterion, lamda2, omega

Abstract
  • This work examines some methods used to identify vortex structures in a coaxial compressible jet flow simulated by the 3D model (LES). The majority of these methods focus on the definition of vortices. The delta-criterion, lambda2-criterion, Q-criterion, and omega-criterion methods are considered among the most common local Eulerian vortex identification methods, based on local point analysis velocity gradient. Moreover, the delta-criterion, lambda2-criterion, and Q-criterion, vortex identification methods require selecting an appropriate criterion threshold. In contrast, the new Omega method can capture both strong and weak vortices without adjustment. Acomparative study of the different vortex identification methods was carried out to use the criterion that seems to be the most appropriate for the case study. The results show that the omega criterion identifies vortex structures more accurately than the other criteria.

Reference
  • 1. Lugt H.J. (1983). Vortex flow in nature and technology. Wiley

    2. Jeong J., Hussain F. (1995). On the Identification of a vortex”. Journal of fluid Mechanics. Vol. 285, 69-94.DOI: https://doi.org/10.1017/S0022112095000462

    3. Hussain F. (1986). Coherent Structures and Turbulence. Journal of Fluid Mechanics, JFM. Vol. 173, 303-356.https://doi.org/10.1017/s0022112086001192

    4. Kida S., Miura H. (1998). Identification and analysis of vortical structures. Eur. J. Mech. B/F 17, 471-488. https://doi.org/10.1016/S0997-7546(98)80005-8

    5. J.C.R. Hunt, A.A. Wray, and P. Moin (1988). Eddies, stream, and convergence zones in turbulent flows. Center for Turbulence Research Report, CTR-S88 :193–208.

    6. M.S. Chong, A.E. Perry, and B.J. Cantwell (1990). A general classification of three-dimensional flowfields. Physics of Fluids A, 2 :765–777.

    a. https://doi.org/10.1063/1.857730

    7. Taraneh Sayadi,Curtis W. Hamman andParviz Moin. Direct numerical simulation of complete H-type and K-type transitions with implications for the dynamics of turbulent boundary layers. Journal of Fluid Mechanics , Volume 724 , 10 June 2013 , pp. 480 – 509.https://doi.org/10.1017/jfm.2013.142.

    8. C. Liu, Y. Wang, Y. Yang, and Z. Duan (2016). New Omega Vortex Identification Method. Sci. CHINA Physics, Mech. Astron., Vol. 59, No. 8, pp. 684-711.DOI: 10.1007/s11433-016-0022-6.

    9. V. Koláˇr (2007). Vortex identification: New requirements and limitations. International Journal ofHeat and Fluid Flow, 28 :638–652,DOI10.1016/j.ijheatfluidflow.2007.03.004

    10. J. Jeong, F. Hussain, W. Schoppa, and J. Kim (1997). Coherent structures near the wall in a turbulentchannel flow. Journal of Fluid Mechanics, 332 :185–214,DOI: https://doi.org/10.1017/S0022112096003965

    11. N. B. Safer and A. Beghidja. Mixing In Turbulent Coaxial Jet.Journal of Mechanical Engineering Research & Developments (JMERD), 2019, vol. 42, issue 3, 110-119,DOI: 10.26480/jmerd.03.2019.110.119

    12. E. Gutmark andI. Wygnanski. The planar turbulent jetJournal of Fluid Mechanics , Volume 73 , Issue 3 , 10 February 1976 , pp. 465 – 495. DOI: https://doi.org/10.1017/S0022112076001468