Abstract
The cavity buffeting noise is related to the free shear layer oscillation and the periodic vortex shedding, where weak vortices coexist with strong vortices and the strong shear phenomenon also exists at the opening of the cavity. Therefore, it is of great significance to accurately capture vortices at the opening for the control of the cavity buffeting noise. This paper first compares the Omega vortex identification method with the Q and λ2 criteria based on the large eddy simulation (LES) of the backward-facing step flow, and it is found that the Omega method enjoys the following advantages: it is not sensitive to a moderate threshold change and Ω = 0.52 can be used as a fixed threshold, it can capture both the strong and weak vortices at the same time; and it will not be contaminated by the shear. Then the Omega (Ω) method is applied to the LES of the cavity buffeting noise: the mechanism of the cavity buffeting noise is studied based on a simple cavity model firstly, and then the effects of the incoming boundary layer thicknesses and the incoming boundary layer shapes on the cavity buffeting noise are analyzed. The results show that: the Ω method clearly captures the processes of the vortex generation, development, collision and fragmentation, verifying that the generation of the cavity buffeting noise is related to the free shear layer oscillation and the periodic vortex shedding; as the thickness of the incoming boundary layer increases, the free shear layer becomes more stable and the Helmholtz resonance is avoided effectively, thereby the cavity buffeting noise is reduced effectively, adding a convexity upstream of the cavity opening to interfere the shape of the incoming boundary layer to reduce the acoustic feedback effect can reduce the cavity buffeting noise effectively.
Similar content being viewed by others
References
An C., Singh K. Sunroof buffeting suppression using a dividing bar [J]. Tohoku Journal of Experimental Medicine, 2007, 206(3): 187–194.
Guo H., Wang Y., Wang X. et al. Study on hybrid LES-LAA method for wind buffeting noise control of vehicle rear windows [J]. Noise Control Engineering Journal, 2017, 65(6): 577–589.
Kook H., Shin S., Cho J. et al. Development of an active deflector system for sunroof buffeting noise control [J]. Journal of Vibration and Control, 2014, 20(16): 2521–2529.
Wang Y. Comprehensive study of generation mechanism and reduction methods of vehicle wind rush noise and buffeting noise [D]. Doctoral Thesis, Changsha, China: Hunan University, 2011(in Chinese).
Yin S., Gu Z., Zong Y. et al. Sound quality evaluation of automobile side-window buffeting noise based on largeeddy simulation [J]. Journal of Low Frequency Noise, Vibration and Active Control, 2019, 38(2): 207–223.
Nelson P., Halliwell N., Doak P. Fluid dynamics of a flow excited resonance Part II: flow acoustic interaction [J]. Journal of Sound and Vibration, 1983, 91(3): 375–402.
Ota D., Chakravarthy S., Becher T. et al. Computational study of resonance suppression of open sunroofs [J]. Journal of Experimental Psychology, 1994, 116(4): 401–404.
Mendonca F. CFD/CAE combinations in open cavity noise predictions for real vehicle sunroof buffeting [J]. SAE International Journal of Passenger Cars-Mechanical Systems, 2013, 6(1): 360–368.
Dunai L., Lengua I., Iglesias M. et al. Buffeting-noise evaluation in passenger vehicle BMV 530d [J]. Acoustical Physics, 2019, 65(5): 578–582.
Gu Z., Xiao Z., Mo Z. Review of CFD simulation on vehicle wind buffeting [J]. Noise and Vibration Control, 2007, 27(4): 65–68.
Wang Y. P., Gu Z. Q., Yang X. et al. Numerical simulation and control of automobile sunroof buffeting noise [J]. China Journal of Highway and Transport, 2010, 23(6): 108–114.
Wang Y. P., Gu Z. Q., Yang X. Research and control of wind vibration characteristics of automobile side window [J]. Acta Aerodynamica Sinica, 2012, 30(3): 277–283.
Liu J., Yang D., Wang X. et al. Effect of turbulent boundary layer thickness on a three-dimensional cavity flow [J]. Acta Aerodynamica et Astronautica Sinica, 2016, 37(2): 475–483.
Liu C., Gao Y. S., Dong X. R. et al. Third generation of vortex identification methods: Omega and Liutex/Rortex based systems [J]. Journal of Hydrodynamics, 2019, 31(2): 205–223.
Hunt J. C. R., Wray A. A., Moin P. Eddies, stream, and convergence zones in turbulent flows [R]. Proceedings of the Summer Program. Center for Turbulence Research Report CTR-S88, 1988, 193–208.
Jeong J., Hussain F. On the identification of a vortex [J]. Journal of Fluid Mechanics, 1995, 285: 69–94.
Liu C., Wang Y. Q., Yang Y. et al. New omega vortex identification method [J]. Science China Physics, Mechanics and Astronomy, 2016, 59(8): 684711.
Dong X. R., Wang Y. Q., Chen X. P. et al. Determination of epsilon for omega vortex identification method [J]. Journal of Hydrodynamics, 2018, 30(4): 541–548.
Liu J. M., Wang Y. Q., Gao Y. S. et al. Galilean invariance of omega vortex identification method [J]. Journal of Hydrodynamics, 2019, 31(2): 249–255.
Liu C., Gao Y., Tian S. et al. Rortex? A new vortex vector definition and vorticity tensor and vector decompositions [J]. Physics of Fluids, 2018, 30(3): 035103.
Gao Y., Liu C. Rortex and comparison with eigenvaluebased vortex identification criteria [J]. Physics of Fluids, 2018, 30(8): 085107.
Wang Y. Q., Gao Y. S., Liu J. M. et al. Explicit formula for the Liutex vector and physical meaning of vorticity based on the Liutex-Shear decomposition [J]. Journal of Hydrodynamics, 2019, 31(3): 464–474.
Wang Y., Gao Y., Liu C. Letter: Galilean invariance of Rortex [J]. Physics of Fluids, 2018, 30(11): 111701.
Gao Y. S., Liu J. M., Yu Y. et al. A Liutex based definition and identification of vortex core center lines [J]. Journal of Hydrodynamics, 2019, 31(3): 445–454.
Dong X. R., Cai X. S., Dong Y. et al. POD analysis on vortical structures in MVG wake by Liutex core line identification [J]. Journal of Hydrodynamics, 2020, 32(3): 497–509.
Charkrit S., Shrestha P., Liu C. Liutex core line and POD analysis on hairpin vortex formation in natural flow transition [J]. Journal of Hydrodynamics, 2020, 32(6): 1109–1121.
Dong X., Gao Y., Liu C. New normalized Rortex/Vortex identification method [J]. Physics of Fluids, 2019, 31(1): 011701.
Hao L. Numerical simulation and PIV experimental research over a backward-facing step and a square cylinder [D]. Master Thesis, Harbin, China: Harbin Institute of Technology, 2012(in Chinese).
Vogel J. C., Eaton J. K. Combined heat transfer and fluid dynamic measurements downstream of a backward-facing step [J]. Journal of Heat Transfer, 1985, 107(4): 922–929.
Wu J., Ning F. Hybrid RANS-LES method applied to backward-facing step flow [J]. Journal of Beijing University of Aeronautics and Astronautics, 2011, 37(6): 701–704(in Chinese).
Zang Y. Numerical simulation of vehicle aerodynamics [M]. Beijing, China: Peking University Press, 2011(in Chinese).
Author information
Authors and Affiliations
Corresponding author
Additional information
Projects supported by the Natural Nature Science Foundation of China (Grant No. 51875238).
Biography: Feng Pan (1991-), Yang-hui Zhang (1994-), Male, Ph. D. Candidate
Rights and permissions
About this article
Cite this article
Zhang, Yh., Hu, Xj., Lan, W. et al. Application of Omega vortex identification method in cavity buffeting noise. J Hydrodyn 33, 259–270 (2021). https://doi.org/10.1007/s42241-021-0034-8
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s42241-021-0034-8