Abstract
This paper proposes a method to identify low-pressure vortices with swirling motions around a vehicle by considering the two-dimensional pressure minimum. The existing sectional-pressure-minimum-and-swirl method combined with the finite difference method can be used to identify low-pressure vortices with swirling motions in homogeneous isotropic turbulence. To apply this method to the flow field around a vehicle, a method that extends the existing method to the finite volume method on unstructured grids and prevents the fragmentation of the vortex core lines was developed. To verify the proposed method, it was applied to the von Kármán vortices of the square cylinder on the unstructured grids. The results indicate that the von Kármán vortices, which involve low-pressure vortices with swirling motions, could be effectively captured using the proposed method. Finally, the proposed method was applied to the flow field around a vehicle. Compared with the existing method, the proposed method could better prevent the fragmentation of the vortex core lines. In addition, four known vortex structures around the vehicle could be identified by using the proposed method in combination with the isosurface method. Compared to other generally used methods in the field of vehicle aerodynamics, the proposed method could better identify the vortex core lines within a few minutes. These results demonstrate that the proposed method is effective for identifying the vortices around a vehicle.
Graphic abstract
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Banks DC, Singer BA (1995) A predictor-corrector technique for visualizing unsteady flow. IEEE Trans Vis Comput Graph 1(2):151–163
Berdahl C, Thompson D (1993) Education of swirling structure using the velocity gradient tensor. AIAA J 31(1):97–103
Günther T, Theisel H (2018) The state of the art in vortex extraction. Comput Graph Forum 37(6):149–173
Hucho WH, Sovran G (1993) Aerodynamics of road vehicles. Annu Rev Fluid Mech 25(1):485–537
Hunt JCR (1987) Vorticity and vortex dynamics in complex turbulent flows. Trans Can Soc Mech Eng 11(1):21–35
Jankun-Kelly M, Jiang M, Thompson D, Machiraju R (2006) Vortex visualization for practical engineering applications. IEEE Trans Vis Comput Graph 12(5):957–964
Jeong J, Hussain F (1995) On the identification of a vortex. J Fluid Mech 285:69–94
Kida S, Miura H (1998) Swirl condition in low-pressure vortices. J Phys Soc Jpn 67(7):2166–2169
Miura H, Kida S (1997) Identification of tubular vortices in turbulence. J Phys Soc Jpn 66(5):1331–1334
Nagashima S (1986) A spatial inclusion test for polyhedra using a spherical projection. Trans Inf Process Soc Jpn 27(7):744–746 in Japanese
Nakashima T, Morikawa Y, Tsubokura M, Okada Y, Nouzawa T (2015) Unsteady aerodynamics simulations of a sedan-type road vehicle during sinusoidal steering input. In: 33rd AIAA Applied Aerodynamics Conference, p 3307
Nouzawa T, Okada Y, Ohira Y, Okamoto S, Nakamura K (2009) Flow structure around vehicle increasing aerodynamic drag: 2nd report, characteristic flow structure of sedan vehicle. Trans Jpn Soc Mech Eng Ser B 75(757):1807–1813 (in Japanese)
Oster T, Rössl C, Theisel H (2018) Core lines in 3D second-order tensor fields. Comput Graph Forum 37(3):327–337
Saha AK, Biswas G, Muralidhar K (2003) Three-dimensional study of flow past a square cylinder at low Reynolds numbers. Int J Heat Fluid Flow 24(1):54–66
Sahner J, Weinkauf T, Hege H-C (2005) Galilean invariant extraction and iconic representation of vortex core lines. In: EuroVis05: joint eurographics—IEEE VGTC symposium on visualization, Leeds, UK, 1–3 June 2005
Shimizu K, Mita S, Nakashima T, Nouzawa T, Hiraoka T, Nakamura Y (2017) Visualization of flow structures around a front wheel of a sedan-type automobile. In: 11th Pacific symposium on flow visualization and image processing PSFVIP11-066
Sujudi D, Haimes R (1995) Identification of swirling flow in 3-D vector fields. In: 12th Computational fluid dynamics conference, p 1715
Tsubokura M, Kobayashi T, Nakashima T, Nouzawa T, Nakamura T (2009) Computational visualization of unsteady flow around vehicles using high performance computing. Comput Fluids 38(5):99–164
Wang S, Goldfeather J, Longmire EK, Interrante V (2013) Methods to identify individual eddy structures in turbulent flow. Tsinghua Sci Technol 18(2):125–136
Zhang Y, Liu K, Xian H, Du X (2018) A review of methods for vortex identification in hydroturbines. Renew Sustain Energy Rev 81:1269–1285
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Nakamura, Y., Nakashima, T., Hiraoka, T. et al. Identification of the vortex around a vehicle by considering the pressure minimum. J Vis 23, 793–804 (2020). https://doi.org/10.1007/s12650-020-00665-8
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12650-020-00665-8