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Saddle point of separation/attachment and topology transition in laminar juncture flows

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Abstract

Laminar juncture flow is numerically studied to investigate the outermost saddle point of separation/attachment (SS/SA) and the topological transition. The topological transition trends obtained through computational results are in close agreement with the experiments. The outermost topology in the symmetry plane tends to transform from attachment to separation as the obstacle shape bluntness increases or as the ratio of the boundary layer thickness to the maximum width of the obstacle δ/W decreases. A coefficient CS/A based on Lighthill’s volume flow theory is devised to estimate the separation or attachment of the fluid. The newly proposed criterion is applied to the limiting streamlines, very close to the flat surface, in the vicinity of saddle point to decide its topological nature. A single quadrant around the saddle point is considered for detailed theoretical analysis, and its further division into four subzones facilitates the application of the proposed criterion (CS/A) to assess the flow attachment and separation characteristics. The decisive coefficient is successfully applied at various locations with separation/attachment flow configurations and found consistent with the qualitative results.

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References

  • Chapman GT (1986) Topological classification of flow separation on three-dimensional bodies. AIAA Paper 86-0485

  • Chen C, Hung C (1992) Numerical study of juncture flows. AIAA J 30(7):1800–1807

    Article  MATH  Google Scholar 

  • Coon MD, Tobak M (1995) Experimental study of saddle point of attachment in laminar juncture flow. AIAA J 33(12):2288–2292

    Article  Google Scholar 

  • Foss JF (2004) Surface selections and topological constraint evaluations for flow field analyses. Exp Fluids 37:883–898

    Article  Google Scholar 

  • Hu B, Zhang H, Younis MY, Li Y, Raza MS (2015) Experimental investigation on the transition of separation/attachment in steady laminar juncture flows. Exp Fluids 56(4):74

    Article  Google Scholar 

  • Hung C, Sung C, Chen C (1992) Computation of saddle point of attachment. AIAA J 30(6):1561–1569

    Article  MATH  Google Scholar 

  • Hunt JCR, Abell CJ, Peterka JA, Woo H (1978) Kinematical studies of the flows around free or surface-mounted obstacles: applying topology to flow visualization. J Fluid Mech 86:179–200

    Article  Google Scholar 

  • Jeong J, Hussain F (1995) On the identification of a vortex. J Fluid Mech 285:69–94

    Article  MathSciNet  MATH  Google Scholar 

  • Le Clainche S, Li JI, Theofilis V, Soria J (2015) Flow around a hemisphere-cylinder at high angle of attack and low Reynolds number. Part I: experimental and numerical investigation. Aero Sci Technol 44:77–87

    Article  Google Scholar 

  • Le Clainche S, Rodriguez D, Theofilis V, Soria J (2016) Formation of three-dimensional structures in the hemisphere-cylinder. AIAA J 54(12):1–11

    Article  Google Scholar 

  • Lighthill MJ (1963) Boundary layer theory. In: Rosenhead L (ed) Laminar boundary layers. Clarendon, Oxford, pp 45–88

    Google Scholar 

  • Liu T, Woodiga S, Ma T (2011) Skin friction topology in a region enclosed by penetrable boundary. Exp Fluids 51:1549–1562

    Article  Google Scholar 

  • Perry AE, Fairlie BD (1974) Critical points in flow patterns. Adv Geophys 18(1):299–315

    Google Scholar 

  • Rizzetta DP (1994) Numerical simulation of turbulent cylinder juncture flow fields. AIAA J 32(6):1113–1119

    Article  MathSciNet  MATH  Google Scholar 

  • Rodriguez D, Theofilis V (2010) Structural changes of laminar separation bubbles induced by global linear instability. J Fluid Mech 655:280–305

    Article  MathSciNet  MATH  Google Scholar 

  • Simpson RL (2001) Junction flows. Annu Rev Fluid Mech 33:415–443

    Article  MATH  Google Scholar 

  • Surana A, Grunberg O, Haller G (2006) Exact theory of three-dimensional flow separation. Part 1. Steady separation. J Fluid Mech 564:57–103

    Article  MathSciNet  MATH  Google Scholar 

  • Surana A, Jacobs GB, Haller G (2007) Extraction of separation and attachment surfaces from three-dimensional steady shear flows. AIAA J 45(6):1290–1302

    Article  Google Scholar 

  • Surana A, Jacobs GB, Grunberg O, Haller G (2008) An exact theory of three-dimensional fixed separation in unsteady flows. Phys Fluids 20:107101–107122

    Article  MATH  Google Scholar 

  • Tai T, Walker M (1991) On three-dimensional flow separation criteria. AIAA Paper 91-1740

  • Tobak M, Peake DJ (1979) Topology of two-dimensional and three-dimensional separated flows. AIAA Paper 79-1480

  • Visbal MR (1991) Structure of laminar juncture flows. AIAA J 29(8):1273–1282

    Article  Google Scholar 

  • Wong JH, Png EK (2009) Numerical investigation of the wing-body junction vortex using various large Eddy simulation models. AIAA Paper 2009-4159

  • Wu J, Ma H, Zhou M (2005) Vorticity and vortex dynamics. Springer, New York

    Google Scholar 

  • Younis MY, Zhang H, Hu B, Muhammad Z, Mehmood S (2014a) Investigation of different aspects of laminar horseshoe vortex system using PIV. J Mech Sci Technol 28(2):527–537

    Article  Google Scholar 

  • Younis MY, Zhang H, Hu B, Mehmood S (2014b) Topological evolution of laminar juncture flows under different critical parameters. Sci China Technol Sci 57:1342–1351

    Article  Google Scholar 

  • Younis MY, Zhang H, Mehmood M, Aslam J (2014c) Topological investigation of unsteady laminar juncture vortex system. In: Proceedings of 2014 11th international Bhurban conference on applied sciences and technology (IBCAST); 2014 Jan 14–18; Islamabad, Pakistan. IEEE, pp 257–262

  • Zhang H (2005) Structural analysis of separated flows and vortex motion. National Defense Industry Press, Beijing

    Google Scholar 

  • Zhang H, Hu B, Younis MY, Wang H, Liu Y (2012a) Investigation on existence and evolution of attachment saddle point structure of 3-D separation in juncture flow. In: Proceedings of 2012 9th international Bhurban conference on applied sciences and technology (IBCAST); 2012 Jan 9–12; Islamabad, Pakistan. IEEE, pp 247–253

  • Zhang H, Younis MY, Hu B, Wang H, Wang X (2012b) Investigation of attachment saddle point structure of 3-D steady separation in laminar juncture flow using PIV. J Vis 15:241–252

    Article  Google Scholar 

  • Zhong H, Woodiga S, Wang P, Shang J, Cui X, Wang J, Liu T (2015) Skin-friction topology of wing-body juncture flows. Eur J Mech B Fluid 53:55–67

    Article  Google Scholar 

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Acknowledgements

The project is supported by the Natural Science Foundation of China (Grant Nos. 11372027 and 10872022).

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Authors and Affiliations

  1. Department of Engineering Mechanics, Shijiazhuang Tiedao University (STDU), Shijiazhuang, 050043, Hebei, People’s Republic of China

    Bo Hu

  2. Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province, Shijiazhuang, 050043, Hebei, People’s Republic of China

    Bo Hu

  3. Ministry-of-Education Key Laboratory of Fluid Mechanics, School of Aeronautical Science and Engineering, Beihang University (BUAA), Beijing, 100191, People’s Republic of China

    Hua Zhang

  4. Department of Mechanical Engineering, Mirpur University of Science and Technology (MUST), Mirpur, 10250, AJK, Pakistan

    Muhammad Yamin Younis

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  1. Bo Hu
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  2. Hua Zhang
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  3. Muhammad Yamin Younis
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Correspondence to Bo Hu.

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Hu, B., Zhang, H. & Younis, M.Y. Saddle point of separation/attachment and topology transition in laminar juncture flows. J Vis 22, 713–727 (2019). https://doi.org/10.1007/s12650-019-00564-7

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  • DOI: https://doi.org/10.1007/s12650-019-00564-7

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